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Re: [multimachine] Lathe Spindle

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  • David G. LeVine
    ... It should, I would suggest that DOM tubing might be a better choice (since the through hole will already be there), as long as you can cut threads. ...
    Message 1 of 28 , Dec 29, 2012
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      On 12/29/2012 12:41 PM, drpshops@... wrote:
      Hi Group
      If I was building the spindle, would an inch& half (1.500) shaft  work?

      It should, I would suggest that DOM tubing might be a better choice (since the through hole will already be there), as long as you can cut threads.

      Would a needle bearing work as a thrust bearing on the front, the chuck end?

      Yes, but why, when tapered bearings (like many wheel bearings) work so well?  The trick is to mount them close together, then put a "loose" radial bearing at the other end of the shaft.

      The O-ring is left out so oil can get to the thrust bearing.  If it has no oil it will not have any lube, and maybe burn up.

      Using tapered roller bearings and a grease seal eliminates that issue.  Add a slinger and an oil catcher between the bearing and seal so you recover most of the lubricant.

       Now how to get a 8tpi on the shaft.
      
       Keith
      

      Why?  Which mount are you using?  A 1 1/2-8 shaft needs a bigger shoulder and register than 1.5", it is a bit tricky.  See http://www.lathe-chucks.com/SPINDLESPECS.HTM for details on the profile. 

      If you start with a bolt of the right size, you often can make the spindle from that.  You do need the shoulder and register or the chuck runout will be pretty horrible.  Figure a big bolt and a nut, cut the register and shoulder on the nut _after_ you lock it onto the bolt, cut the bolt to length, but assume a 1/8" long dog type point, it makes attaching the chucks and faceplates MUCH simpler.  Lock with Loctite RED.  A heavy hex nut should have plenty of "meat" to allow you to machine a shoulder and register.  Two nuts "back to back" will allow you to machine for a larger oil seal if needed, but 1.5" seals are available, just not as common.  Truck oil seals are available near that size (37.8-38.4 mm), so I would look there.  Using 40 mm, a nut would allow a short round section on which to seal.

      If you do use two nuts, just make them good and tight with Loctite red, then machine off the hexes.  You won't be moving them after that anyway.

      A 1"-8 shaft is for woodworking, a 1"-10 is for metal.  Woodworking chucks, etc. will fail if used on steel, since they are not rated for the load, aluminum should be okay.

      Did that help?

      Dave  8{)

      --

      "The first method for estimating the intelligence of a ruler is to look at the men he has around him."
      Niccolo Machiavelli

      NOTE TO ALL:

      When forwarding emails, please use only "Blind Carbon Copy" or "Bcc" for all recipients. Please "delete" or "highlight & cut" any forwarding history which includes my email address! It is a courtesy to me and others who may not wish to have their email addresses sent all over the world! Erasing the history helps prevent Spammers from mining addresses and viruses from being propagated.


      THANK YOU!
    • keith gutshall
      Hi David I was planing on use a piece of DOM tube,1.500 OD with a 0.750 ID for  the spindle. That will fit a #3 morse taper in the end.    I was going to
      Message 2 of 28 , Dec 29, 2012
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        Hi David
        I was planing on use a piece of DOM tube,1.500 OD with a 0.750 ID for
         the spindle. That will fit a #3 morse taper in the end.
         
         I was going to build a spindle useing the bronze bushing like the concrete
         lathe has in it. The thrust bearing ( ENCO #327-8047and #327-8050)
        to be the front of the shaft.
         
         I am close to get the machine I have to thread,I have all the parts to assemble.
         I just need a few warm day to work on it.It get cold in florida in the winter, 40*F
        was the high today.
        Right now I am recovering from Aoric Aneurysm repair surgery.
         I have to grind a tool to cut the threads, a 1/4 tool blank should work?
         
         Keith
         
        Deep Run Portage
        Back Shop
        " The Lizard Works"
        From: David G. LeVine <dlevine@...>
        To: multimachine@yahoogroups.com
        Sent: Saturday, December 29, 2012 5:39 PM
        Subject: Re: [multimachine] Lathe Spindle
         
        On 12/29/2012 12:41 PM, drpshops@... wrote:
        Hi Group
        If I was building the spindle, would an inch& half (1.500) shaft  work?
        It should, I would suggest that DOM tubing might be a better choice (since the through hole will already be there), as long as you can cut threads.
        Would a needle bearing work as a thrust bearing on the front, the chuck end?
        Yes, but why, when tapered bearings (like many wheel bearings) work so well?  The trick is to mount them close together, then put a "loose" radial bearing at the other end of the shaft.
        The O-ring is left out so oil can get to the thrust bearing.  If it has no oil it will not have any lube, and maybe burn up.
        Using tapered roller bearings and a grease seal eliminates that issue.  Add a slinger and an oil catcher between the bearing and seal so you recover most of the lubricant.
         Now how to get a 8tpi on the shaft.
        
         Keith
        
        Why?  Which mount are you using?  A 1 1/2-8 shaft needs a bigger shoulder and register than 1.5", it is a bit tricky.  See http://www.lathe-chucks.com/SPINDLESPECS.HTM for details on the profile.  If you start with a bolt of the right size, you often can make the spindle from that.  You do need the shoulder and register or the chuck runout will be pretty horrible.  Figure a big bolt and a nut, cut the register and shoulder on the nut _after_ you lock it onto the bolt, cut the bolt to length, but assume a 1/8" long dog type point, it makes attaching the chucks and faceplates MUCH simpler.  Lock with Loctite RED.  A heavy hex nut should have plenty of "meat" to allow you to machine a shoulder and register.  Two nuts "back to back" will allow you to machine for a larger oil seal if needed, but 1.5" seals are available, just not as common.  Truck oil seals are available near that size (37.8-38.4 mm), so I would look there.  Using 40 mm, a nut would allow a short round section on which to seal. If you do use two nuts, just make them good and tight with Loctite red, then machine off the hexes.  You won't be moving them after that anyway. A 1"-8 shaft is for woodworking, a 1"-10 is for metal.  Woodworking chucks, etc. will fail if used on steel, since they are not rated for the load, aluminum should be okay. Did that help? Dave  8{)
        -- "The first method for estimating the intelligence of a ruler is to look at the men he has around him." Niccolo Machiavelli
        NOTE TO ALL:

        When forwarding emails, please use only "Blind Carbon Copy" or "Bcc" for all recipients. Please "delete" or "highlight & cut" any forwarding history which includes my email address! It is a courtesy to me and others who may not wish to have their email addresses sent all over the world! Erasing the history helps prevent Spammers from mining addresses and viruses from being propagated.
        THANK YOU!
      • David G. LeVine
        ... Sounds good to me. ... Sounds like a poor choice to me. If you look at the thrust bearing, it needs two precisely machined surfaces on which to run. In
        Message 3 of 28 , Dec 29, 2012
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          On 12/29/2012 07:28 PM, keith gutshall wrote:
          Hi David
          I was planing on use a piece of DOM tube,1.500 OD with a 0.750 ID for
           the spindle. That will fit a #3 morse taper in the end.

          Sounds good to me.

          I was going to build a spindle useing the bronze bushing like the concrete lathe has in it. The thrust bearing ( ENCO #327-8047 and #327-8050) to be the front of the shaft.

          Sounds like a poor choice to me.  If you look at the thrust bearing, it needs two precisely machined surfaces on which to run.  In addition, the race is thin and will flex AND the race is NOT self centering, you would need two races and two accurately machined surfaces.  The cage unit needs to sit on the shaft between the two races, so a 327-8041 would be needed on each end of the shaft.  Two thrust bearings and four races plus machining.

          Why so many?  Cutting from right to left loads the shaft into the spindle, cutting from left to right pulls it out.  Without thrust bearings for both directions, things get pretty sloppy in a big hurry.

          But why do it that way?  Since you are looking at bushings, a 404-2691 has a flange which will be just fine as a thrust bearing in each direction.  All you need is a surface against which you wish to run them and a means of adjusting out backlash.  And, of course, one on EACH end of the shaft. 

          If you were using something like a 404-2580, there would be no flange so the 2 thrust bearings, 4 races and 4 machined surfaces would be needed.

           I am close to get the machine I have to thread, I have all the parts to assemble.   I just need a few warm day to work on it.  It get cold in florida in the winter, 40*F  was the high today.

          We have snow which is not going to melt for a while, you lucky stiff!  :^P

          Right now I am recovering from Aoric Aneurysm repair surgery. I have to grind a tool to cut the threads, a 1/4 tool blank should work?

          Since this thread is 1/8" wide, I would expect so.

          Keith

          Another thought, unless you want to build a means of keeping chips out of the thrust bearings, why not put them inside the headstock?  Lubrication is easier and the bushings are no more difficult to install.

          The "olde tyme" lathes used tapered bushings both to handle thrust and wear.  As the bore wore, the cones were pushed inward  or outward to compensate.  Actually, I have seen other shapes used also, but that would get too complex.

          Hope that helps and your surgery was flawless.

          Dave  8{)

          --

          "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."
          Mohandus Ghandi, An Autobiography, Page 446.

        • David G. LeVine
          ... The problem here is that as the bit bites , the shaft will move out and then, chatter central. Dave 8{) -- / Among the many misdeeds of British rule in
          Message 4 of 28 , Dec 29, 2012
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            On 12/29/2012 07:28 PM, keith gutshall wrote:
             I was going to build a spindle useing the bronze bushing like the concrete
             lathe has in it. The thrust bearing ( ENCO #327-8047and #327-8050)
            to be the front of the shaft.

            The problem here is that as the bit "bites", the shaft will move out and then, chatter central.

            Dave  8{)

            --

            "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."
            Mohandus Ghandi, An Autobiography, Page 446.
          • keith gutshall
            Hi David  Yea, it might be easier just to use some pillow block bearing like the rest of my stuff has. They seem to work good.    Keith Deep Run Portage
            Message 5 of 28 , Jan 1, 2013
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              Hi David
               Yea, it might be easier just to use some pillow block bearing like the rest of
              my stuff has. They seem to work good.
               
               Keith
               
              Deep Run Portage
              Back Shop
              " The Lizard Works"
              From: David G. LeVine <dlevine@...>
              To: multimachine@yahoogroups.com
              Sent: Saturday, December 29, 2012 7:36 PM
              Subject: Re: [multimachine] Lathe Spindle
               
              On 12/29/2012 07:28 PM, keith gutshall wrote:
              Hi David
              I was planing on use a piece of DOM tube,1.500 OD with a 0.750 ID for
               the spindle. That will fit a #3 morse taper in the end.
              Sounds good to me.
              I was going to build a spindle useing the bronze bushing like the concrete lathe has in it. The thrust bearing ( ENCO #327-8047 and #327-8050) to be the front of the shaft.
              Sounds like a poor choice to me.  If you look at the thrust bearing, it needs two precisely machined surfaces on which to run.  In addition, the race is thin and will flex AND the race is NOT self centering, you would need two races and two accurately machined surfaces.  The cage unit needs to sit on the shaft between the two races, so a 327-8041 would be needed on each end of the shaft.  Two thrust bearings and four races plus machining. Why so many?  Cutting from right to left loads the shaft into the spindle, cutting from left to right pulls it out.  Without thrust bearings for both directions, things get pretty sloppy in a big hurry. But why do it that way?  Since you are looking at bushings, a 404-2691 has a flange which will be just fine as a thrust bearing in each direction.  All you need is a surface against which you wish to run them and a means of adjusting out backlash.  And, of course, one on EACH end of the shaft.  If you were using something like a 404-2580, there would be no flange so the 2 thrust bearings, 4 races and 4 machined surfaces would be needed.
               I am close to get the machine I have to thread, I have all the parts to assemble.   I just need a few warm day to work on it.  It get cold in florida in the winter, 40*F  was the high today.
              We have snow which is not going to melt for a while, you lucky stiff!  :^P
              Right now I am recovering from Aoric Aneurysm repair surgery. I have to grind a tool to cut the threads, a 1/4 tool blank should work?
              Since this thread is 1/8" wide, I would expect so.
              Keith
              Another thought, unless you want to build a means of keeping chips out of the thrust bearings, why not put them inside the headstock?  Lubrication is easier and the bushings are no more difficult to install. The "olde tyme" lathes used tapered bushings both to handle thrust and wear.  As the bore wore, the cones were pushed inward  or outward to compensate.  Actually, I have seen other shapes used also, but that would get too complex. Hope that helps and your surgery was flawless. Dave  8{) --
              "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest." Mohandus Ghandi, An Autobiography, Page 446.
            • David G. LeVine
              ... Not a bad way to go, but pillow blocks are not rigid enough for heavier cutting forces. You are asking important questions which I really need to think
              Message 6 of 28 , Jan 1, 2013
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                On 01/01/2013 04:02 PM, keith gutshall wrote:

                Hi David
                 Yea, it might be easier just to use some pillow block bearing like the rest of
                my stuff has. They seem to work good.
                 
                 Keith

                Not a bad way to go, but pillow blocks are not rigid enough for heavier cutting forces.  You are asking important questions which I really need to think about. 

                Let's go back:

                <WARNING:  ASCII ART!>

                      /|          |\
                |---------------------|
                |=====================|
                |---------------------|
                      \|          |/
                Shaft Bearing 1   Bearing 2

                Assume a block of "stuff" between bearing 1 and bearing 2.  As the bearing flats hit the block, the shaft is not going to move.  Assume radial bearings with no slop, and apply a cutting load near the shaft end near bearing 2.  There are three likely components:  A tangential one caused by the tool pulling metal from the surface, an axial one from the tool forces which push it into the work, and a radial one which is partially from the tangential forces. 

                Let's start with the simplest force, axial.  As the tool is forced into the workpiece, the load will shift as the force against the surface (pushing into the headstock) to cutting pulling the tool away from the headstock.  As the spindle moves, chatter occurs.

                Now tangential, as the cutting forces change, the forces on the tool change, since everything looks like a stiff spring and weight, it starts to oscillate.  Either chatter mode can be affected by touching the tool with a non-resilient material, like lead.  So all the clearances will need to be small or chatter will appear.

                See how (and why) preload is necessary?

                Dave  8{)

                --

                "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."
                Mohandus Ghandi, An Autobiography, Page 446.
              • keith gutshall
                Hi David  I am asking the question that I have about the project. The queation seemed good for someone who is building the lathe. I not building one, but if I
                Message 7 of 28 , Jan 2, 2013
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                  Hi David
                   I am asking the question that I have about the project. The queation seemed
                  good for someone who is building the lathe.
                  I not building one, but if I was these seem like good questions.
                   
                   I am picking components that seem the right size for the machine?
                   I am picking part that fit together and are common size parts.
                   I even found a source for 1 1/2-8TPI nuts.
                   At that point ,I am figureing that the builder has very few tools to work with.
                   The main idea that Pat has seems to to be , is for somebody to build a machine in
                  their backyard.
                   If their backyard is a remote place access to a machine shop may be limited.
                   
                   Maybe the problem that I see,Is how can you build a machine with little
                  or no machineing?
                  This has seem the thing that I am seeing, am I looking at the problem wrong?
                   Does the builder need more infomation to build a machine?
                   
                   Keith
                   
                   
                   
                   
                  Deep Run Portage
                  Back Shop
                  " The Lizard Works"
                  From: David G. LeVine <dlevine@...>
                  To: multimachine@yahoogroups.com
                  Sent: Tuesday, January 1, 2013 8:09 PM
                  Subject: Re: [multimachine] Lathe Spindle
                   
                  On 01/01/2013 04:02 PM, keith gutshall wrote:

                  Hi David
                   Yea, it might be easier just to use some pillow block bearing like the rest of
                  my stuff has. They seem to work good.
                   
                   Keith
                  Not a bad way to go, but pillow blocks are not rigid enough for heavier cutting forces.  You are asking important questions which I really need to think about.  Let's go back: <WARNING:  ASCII ART!>      /|          |\
                  |---------------------|
                  |=====================|
                  |---------------------|
                        \|          |/
                  Shaft Bearing 1   Bearing 2

                  Assume a block of "stuff" between bearing 1 and bearing 2.  As the bearing flats hit the block, the shaft is not going to move.  Assume radial bearings with no slop, and apply a cutting load near the shaft end near bearing 2.  There are three likely components:  A tangential one caused by the tool pulling metal from the surface, an axial one from the tool forces which push it into the work, and a radial one which is partially from the tangential forces.  Let's start with the simplest force, axial.  As the tool is forced into the workpiece, the load will shift as the force against the surface (pushing into the headstock) to cutting pulling the tool away from the headstock.  As the spindle moves, chatter occurs. Now tangential, as the cutting forces change, the forces on the tool change, since everything looks like a stiff spring and weight, it starts to oscillate.  Either chatter mode can be affected by touching the tool with a non-resilient material, like lead.  So all the clearances will need to be small or chatter will appear. See how (and why) preload is necessary? Dave  8{)
                  -- "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest." Mohandus Ghandi, An Autobiography, Page 446.
                • David G. LeVine
                  ... No, they seem too small to me, but I am biased. ... Probably a good idea, but in MOST places, the parts should, then, be metric. ... Again, metric is
                  Message 8 of 28 , Jan 2, 2013
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                    On 01/02/2013 04:50 PM, keith gutshall wrote:
                     I am picking components that seem the right size for the machine?

                    No, they seem too small to me, but I am biased.

                     I am picking part that fit together and are common size parts.

                    Probably a good idea, but in MOST places, the parts should, then, be metric.

                     I even found a source for 1 1/2-8TPI nuts.

                    Again, metric is better in places where metric is common -- as in most of the world.

                     At that point ,I am figureing that the builder has very few tools to work with.

                    Agreed.

                     The main idea that Pat has seems to to be , is for somebody to build a machine in their backyard.

                    Again, pretty much, or in a shed or ...  The location is not that critical, the resources are.

                     If their backyard is a remote place access to a machine shop may be limited.

                    Agreed, but the shed in the jungle may be just as bad.

                      Maybe the problem that I see,Is how can you build a machine with little or no machineing?

                    Probably the way the Afghani gunsmiths do firearms, no tooling more sophisticated than a file.

                    This has seem the thing that I am seeing, am I looking at the problem wrong?

                    No, but you are looking at the engineering without understanding. 

                    Why does the spindle need TWO thrust bearings?  Why not just use pillow blocks?  Hint:  Where will you get them?

                     Does the builder need more infomation to build a machine?

                    No, he needs more resources.  The resources may be information (like "Where do I get,,,") or skills or parts.

                    For instance, setscrews are common for holding fixtures in Gingery tools, because they are simple and cheap.  Can you tell me why a half-dog setscrew is superior to a cup point setscrew for holding a faceplate?  The builder needs the WHY, and needs to know how to get around the lack of availability.  We tell builders to grind the tool bits, but not how (YOU have a bench grinder and/or a drill with a wheel, the remote builder doesn't.)

                    Now do you see the problem?

                    Dave  8{)
                    --


                    "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

                    Mohandus Ghandi, An Autobiography, Page 446.
                  • Ian Newman
                    Hi Dave, I m a little puzzled as to your use of the quote that Ghandi made regarding the recruitment of Indians in to the British Army during the First World
                    Message 9 of 28 , Jan 4, 2013
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                      Hi Dave,

                      I'm a little puzzled as to your use of the quote that Ghandi made regarding the recruitment of Indians in to the British Army during the First World War.

                      The attitude towards the concept of Colonial members of the British Army changed largely as a result of the invaluable contribution and sacrifice that the Indian Army made - over 74 thousand Indian soldiers died in the First World War.

                      What is the point that you wish to make?

                      All the best,
                      Ian

                      On 3 Jan 2013, at 06:40, "David G. LeVine" <dlevine@...> wrote:

                       



                      "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

                      Mohandus Ghandi, An Autobiography, Page 446.

                    • Bruce Bellows
                      I have a 8 tpi thread on a piece of 1 shaft. It was threaded on a lathe and then a shrink fit collar was put on to act as the shoulder at the bottom of the
                      Message 10 of 28 , Jan 4, 2013
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                        I have a 8 tpi thread on a piece of 1" shaft. It was threaded on a lathe and then a shrink fit collar was put on to act as the shoulder at the bottom of the thread. To get the collar off it would have to be cut off . For a spindle on a wood lathe an 1 1/2 would be the smallest that I would use.

                        In order to answer you question more info is needed, such as distance between the bearings , speed and how much load it will be caring.

                        Bruce

                        On 12/29/2012 12:41 PM, drpshops@... wrote:
                         

                        Hi Group
                        If I was building the spindle, would an inch& half (1.500)
                        shaft work?
                        Would a needle bearing work as a thrust bearing on the front,
                        the chuck end?
                        The O-ring is left out so oil can get to the thrust bearing.
                        If it has no oil it will not have any lube, and maybe burn up.

                        Now how to get a 8tpi on the shaft.

                        Keith

                      • keith gutshall
                        HI Bruce  I was looking in to makeing a lathe spindle with a 1 1/2 spindle.  I had planed to use oillite bronze bushing for bearing.  David and I discussed
                        Message 11 of 28 , Jan 4, 2013
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                          HI Bruce
                           I was looking in to makeing a lathe spindle with a 1 1/2 spindle.
                           I had planed to use oillite bronze bushing for bearing.
                           David and I discussed it and found two major problems
                           One, is the axial thrust/play in the spindle.
                          Two, the radial clearance in the bushing to spindle.
                           
                          How to overcome these two problem is the bottom line.
                           
                           I have built reduction shaft with the bushings for bearing..
                           That works good ,because the pulley can wobble a little
                           with no problem.
                           With a lathe spindle, if it wobble around it would effect the
                          accurrcy of the work. That is not a good thing to have.
                           
                           Keith
                           
                          Deep Run Portage
                          Back Shop
                          " The Lizard Works"
                          From: Bruce Bellows <bbellows@...>
                          To: multimachine@yahoogroups.com
                          Sent: Friday, January 4, 2013 1:13 PM
                          Subject: Re: [multimachine] Lathe Spindle
                           
                          I have a 8 tpi thread on a piece of 1" shaft. It was threaded on a lathe and then a shrink fit collar was put on to act as the shoulder at the bottom of the thread. To get the collar off it would have to be cut off . For a spindle on a wood lathe an 1 1/2 would be the smallest that I would use.

                          In order to answer you question more info is needed, such as distance between the bearings , speed and how much load it will be caring.

                          Bruce

                          On 12/29/2012 12:41 PM, drpshops@... wrote:
                           
                          Hi Group
                          If I was building the spindle, would an inch& half (1.500)
                          shaft work?
                          Would a needle bearing work as a thrust bearing on the front,
                          the chuck end?
                          The O-ring is left out so oil can get to the thrust bearing.
                          If it has no oil it will not have any lube, and maybe burn up.

                          Now how to get a 8tpi on the shaft.

                          Keith

                        • StoneTool
                          I use a lathe all the time with babbitt bearings.... There is no problem with accuracy. The headstock is split horizontally and the two haves are shimmed to
                          Message 12 of 28 , Jan 4, 2013
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                            I use a lathe all the time with babbitt bearings.... There is no problem with accuracy.  The headstock is split horizontally and the two haves are shimmed to take out any play.  I use a steady oil drip while I'm operating it.  I've used it for quite a few years and only once changed the shims.  I think you are making a bigger deal out of it than it really is.   I would recommend babbitt rather than bronze though.  You pour it with a shaft in position, then separate the two halves, shim and line bore.  It's old technology....but it works.

                                                                                                            Howard

                            On 01/04/2013 03:05 PM, keith gutshall wrote:
                            HI Bruce
                             I was looking in to makeing a lathe spindle with a 1 1/2 spindle.
                             I had planed to use oillite bronze bushing for bearing.
                             David and I discussed it and found two major problems
                             One, is the axial thrust/play in the spindle.
                            Two, the radial clearance in the bushing to spindle.
                             
                            How to overcome these two problem is the bottom line.
                             
                             I have built reduction shaft with the bushings for bearing..
                             That works good ,because the pulley can wobble a little
                             with no problem.
                             With a lathe spindle, if it wobble around it would effect the
                            accurrcy of the work. That is not a good thing to have.
                             
                             Keith
                             
                            Deep Run Portage
                            Back Shop
                            " The Lizard Works"
                            From: Bruce Bellows <bbellows@...>
                            To: multimachine@yahoogroups.com
                            Sent: Friday, January 4, 2013 1:13 PM
                            Subject: Re: [multimachine] Lathe Spindle
                             
                            I have a 8 tpi thread on a piece of 1" shaft. It was threaded on a lathe and then a shrink fit collar was put on to act as the shoulder at the bottom of the thread. To get the collar off it would have to be cut off . For a spindle on a wood lathe an 1 1/2 would be the smallest that I would use.

                            In order to answer you question more info is needed, such as distance between the bearings , speed and how much load it will be caring.

                            Bruce

                            On 12/29/2012 12:41 PM, drpshops@... wrote:
                             
                            Hi Group
                            If I was building the spindle, would an inch& half (1.500)
                            shaft work?
                            Would a needle bearing work as a thrust bearing on the front,
                            the chuck end?
                            The O-ring is left out so oil can get to the thrust bearing.
                            If it has no oil it will not have any lube, and maybe burn up.

                            Now how to get a 8tpi on the shaft.

                            Keith


                          • pokerbacken
                            Babbit bearings are GREAT if you want high precision lathe, even better are bronze percussion shaped to the spindle in question. as for precission, soft
                            Message 13 of 28 , Jan 5, 2013
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                              Babbit bearings are GREAT if you want high precision lathe, even better are bronze percussion shaped to the spindle in question.
                              as for precission, "soft" bearings (soft bronze) is still used on high precision instrument-maker lathes to give highest possible precision, the one I was trained on (late 1980's) was guaranteed to have UNDER 0.002mm tolerance on the spindle radially and axially, in inches that is under 0.0001" (or said in another way 0.1 thousandth of an inch), this using conical bronze bearings, not many can measure that fine in their home shop...

                              at school we all "had" to replace bearings on one lathe just to show we knew how to adjust things.
                              hardest part was adjusting rear bearing so chuck was parallel to bed in both horizontal and vertical axis then came the lapping and tightening the spindle aainst the cone bearings.

                              one important thing was not tightening the two nuts (nut and locknut) at back too much and thus make the thing bind.
                              we where told to use fingers to tighten then run spindle few laps (by hand as drive train was disengaged) and repeat, when we could not rotate spindle by hand it was time to back of shade under 1/10th of a turn on the nut (something like 0.2mm thread pitch), otherwise it would bind from friction heating things up later, then after a days work we where to repeat the tightening to take up "slack" form spindle and bearing "working into each other", we where supposed to keep doing this for 5 days after bearing change (after two days they mostly needed checking alone and rarely actual tightening).
                            • Pierre Coueffin
                              I used to work with a guy who owned a company that had a swiss made tool-room lathe that had air-bearings in the spindle... He showed me how they worked one
                              Message 14 of 28 , Jan 5, 2013
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                                I used to work with a guy who owned a company that had a swiss made tool-room lathe that had air-bearings in the spindle...  He showed me how they worked one time, by hooking up a line from the compressor to the headstock of the lathe, which made the spindle turn freely on a few micron cushion of air.  He spun the spindle up with his finger tip (the machine was unplugged) and we went and had our meeting.  We came out half an hour later and the spindle was still slowly turning.

                                Essentially they are a fluid bearing, like a sintered bronze bushing, but the working fluid is air, forced into the very narrow gap under high pressure.  Any force that tilts the shaft in the gap makes the gap narrower on one side than the other.  This increases the amount of air pressure on that side rapidly, which re-centers the shaft.

                                http://en.wikipedia.org/wiki/Fluid_bearing

                                Anyone who has ever played air-hockey will be familiar with the related linear version of this bearing.

                                If a person had built a multimachine capable of the required precision, and they had access to large volumes of compressed air, it would be a neat upgrade to make a cartridge spindle for their multimachine using an air-bearing setup...  It would be quite straight forward to create a thrust bearing and a radial bearing surface, and combine them into one spindle.  The precision fit required is finicky, but could probably be achievable by hand lapping or scraping if you had the ability to measure your results.
                              • StoneTool
                                Pierre: I presume the air entered the bearing clearance area from numerous small holes, and that the bearing clearance was extremely small, and furthermore
                                Message 15 of 28 , Jan 5, 2013
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                                  Pierre:
                                      I presume the air entered the bearing clearance area from numerous small holes, and that the bearing clearance was extremely small, and furthermore that the air leakage probably wasn't all that great.   I superb idea.  The surface area of the spindle and the pressure of the air would be important related to the load. It probably wasn't designed for really heavy work.

                                                                                                              Howard



                                  On 01/05/2013 09:43 AM, Pierre Coueffin wrote:
                                  I used to work with a guy who owned a company that had a swiss made tool-room lathe that had air-bearings in the spindle...  He showed me how they worked one time, by hooking up a line from the compressor to the headstock of the lathe, which made the spindle turn freely on a few micron cushion of air.  He spun the spindle up with his finger tip (the machine was unplugged) and we went and had our meeting.  We came out half an hour later and the spindle was still slowly turning.

                                  Essentially they are a fluid bearing, like a sintered bronze bushing, but the working fluid is air, forced into the very narrow gap under high pressure.  Any force that tilts the shaft in the gap makes the gap narrower on one side than the other.  This increases the amount of air pressure on that side rapidly, which re-centers the shaft.

                                  http://en.wikipedia.org/wiki/Fluid_bearing

                                  Anyone who has ever played air-hockey will be familiar with the related linear version of this bearing.

                                  If a person had built a multimachine capable of the required precision, and they had access to large volumes of compressed air, it would be a neat upgrade to make a cartridge spindle for their multimachine using an air-bearing setup...  It would be quite straight forward to create a thrust bearing and a radial bearing surface, and combine them into one spindle.  The precision fit required is finicky, but could probably be achievable by hand lapping or scraping if you had the ability to measure your results.

                                • Pierre Coueffin
                                  Exactly right about how it works. You might be surprised on how heavy loads are carried by air bearings though... His little swiss lathe was smaller than my
                                  Message 16 of 28 , Jan 5, 2013
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                                    Exactly right about how it works.  You might be surprised on how heavy loads are carried by air bearings though...  His little swiss lathe was smaller than my sherline, and probably never took heavy loads, but there are massive machines using air bearings.

                                    A little reading on the topic is very interesting.  At some point I want to put a bunch of heavy tools on bases that float off the concrete shop floor when air is applied, but sit solidly when the hose comes off.


                                    On Sat, Jan 5, 2013 at 10:37 AM, StoneTool <owly@...> wrote:
                                     

                                    Pierre:
                                        I presume the air entered the bearing clearance area from numerous small holes, and that the bearing clearance was extremely small, and furthermore that the air leakage probably wasn't all that great.   I superb idea.  The surface area of the spindle and the pressure of the air would be important related to the load. It probably wasn't designed for really heavy work.

                                                                                                                Howard





                                    On 01/05/2013 09:43 AM, Pierre Coueffin wrote:
                                    I used to work with a guy who owned a company that had a swiss made tool-room lathe that had air-bearings in the spindle...  He showed me how they worked one time, by hooking up a line from the compressor to the headstock of the lathe, which made the spindle turn freely on a few micron cushion of air.  He spun the spindle up with his finger tip (the machine was unplugged) and we went and had our meeting.  We came out half an hour later and the spindle was still slowly turning.

                                    Essentially they are a fluid bearing, like a sintered bronze bushing, but the working fluid is air, forced into the very narrow gap under high pressure.  Any force that tilts the shaft in the gap makes the gap narrower on one side than the other.  This increases the amount of air pressure on that side rapidly, which re-centers the shaft.

                                    http://en.wikipedia.org/wiki/Fluid_bearing

                                    Anyone who has ever played air-hockey will be familiar with the related linear version of this bearing.

                                    If a person had built a multimachine capable of the required precision, and they had access to large volumes of compressed air, it would be a neat upgrade to make a cartridge spindle for their multimachine using an air-bearing setup...  It would be quite straight forward to create a thrust bearing and a radial bearing surface, and combine them into one spindle.  The precision fit required is finicky, but could probably be achievable by hand lapping or scraping if you had the ability to measure your results.


                                  • Shannon DeWolfe
                                    Keep in mind that air bearings require high pressures and large volume. I have spent a lot, make that, A LOT of time researching ways to compress air. It takes
                                    Message 17 of 28 , Jan 5, 2013
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                                      Keep in mind that air bearings require high pressures and large volume.
                                      I have spent a lot, make that, A LOT of time researching ways to
                                      compress air. It takes horsepower. More than 150 lbs./in.² at industrial
                                      volume takes A LOT of horsepower. Also, air bearings do not like oil,
                                      water, nor dirt.

                                      When building the concrete lathe simplicity and low cost are the goals.

                                      My preferences for bearings:

                                      Plain bearings for all loads. White metal would be nice but hardwood and
                                      lots of oil would work. If lightly loaded, say for making toys or game
                                      pieces or whatever for sale to tourists, this lathe may be all that is
                                      ever needed. Heavier loads require heavier bearings. But, the entire
                                      western economy was built on plain bearings.

                                      Next up the food chain would be Keith Gutshall's designs using pillow
                                      blocks. He has proven that some really heavy work can be done with
                                      pillow blocks. Pillow blocks probably would not stand up to any sort of
                                      production work but they certainly can build improved machines for the
                                      owner.

                                      Salvaged front wheel drive bearings. Tolerances would not be conducive
                                      to precision work but when "close enough for government work" will do,
                                      so will salvaged bearings. As Pat has pointed out, finish work can be
                                      done with grinders and files. We assume that THE one thing the builder
                                      has is time.

                                      Pat's spindle cassette design. Pat proved on the original MultiMachine
                                      that his spindle is capable of close tolerance and heavy cuts. There is
                                      no reason this design could not work in any application from a jeweler's
                                      lathe to a lathe large enough to machine wheels for rail cars.

                                      Once the concrete lathe builder has outgrown those designs, he has
                                      outgrown the concrete lathe.

                                      Regards,

                                      Mr. Shannon DeWolfe
                                      --I've taken to using Mr. because my name misleads folks on the WWW. I am a 56 year old fat man.

                                      On 1/5/2013 12:37 PM, StoneTool wrote:
                                      >
                                      > Pierre:
                                      > I presume the air entered the bearing clearance area from numerous
                                      > small holes, and that the bearing clearance was extremely small, and
                                      > furthermore that the air leakage probably wasn't all that great. I
                                      > superb idea. The surface area of the spindle and the pressure of the
                                      > air would be important related to the load. It probably wasn't
                                      > designed for really heavy work.
                                      >
                                      > Howard
                                      >
                                    • Shannon DeWolfe
                                      Howard, If you still need to move that house, talk to the man who has this site: http://www.theforgottentechnology.com/ Be sure to see the pole barn he moved
                                      Message 18 of 28 , Jan 5, 2013
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                                        Howard,

                                        If you still need to move that house, talk to the man who has this site:

                                        http://www.theforgottentechnology.com/

                                        Be sure to see the pole barn he moved on page two.

                                        Regards,

                                        Mr. Shannon DeWolfe
                                        --I've taken to using Mr. because my name misleads folks on the WWW. I am a 56 year old fat man.

                                        On 1/5/2013 2:51 PM, StoneTool wrote:
                                        >
                                        > Pierre:
                                        > At one time I had intentions of moving a small house in this way a
                                        > short distance.
                                        >
                                      • StoneTool
                                        Pierre: At one time I had intentions of moving a small house in this way a short distance.......... The floor would be braced to sustain the pressure, and
                                        Message 19 of 28 , Jan 5, 2013
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                                          Pierre:
                                              At one time I had intentions of moving a small house in this way a short distance..........   The floor would be braced to sustain the pressure, and fans would create lift like a hovercraft.  Irrigation dam canvas would have been stapled all around the house with the pocket filled with sand for a skirt.  The idea was to at least "lighten" the house so it could be skidded.  It is an ancient log house built of small logs which are very dry so with the interior gutted, weight would have been fairly low as compared to surface area.

                                                                                                                                      Howard

                                          On 01/05/2013 12:32 PM, Pierre Coueffin wrote:
                                          Exactly right about how it works.  You might be surprised on how heavy loads are carried by air bearings though...  His little swiss lathe was smaller than my sherline, and probably never took heavy loads, but there are massive machines using air bearings.

                                          A little reading on the topic is very interesting.  At some point I want to put a bunch of heavy tools on bases that float off the concrete shop floor when air is applied, but sit solidly when the hose comes off.


                                          On Sat, Jan 5, 2013 at 10:37 AM, StoneTool <owly@...> wrote:
                                           

                                          Pierre:
                                              I presume the air entered the bearing clearance area from numerous small holes, and that the bearing clearance was extremely small, and furthermore that the air leakage probably wasn't all that great.   I superb idea.  The surface area of the spindle and the pressure of the air would be important related to the load. It probably wasn't designed for really heavy work.

                                                                                                                      Howard





                                          On 01/05/2013 09:43 AM, Pierre Coueffin wrote:
                                          I used to work with a guy who owned a company that had a swiss made tool-room lathe that had air-bearings in the spindle...  He showed me how they worked one time, by hooking up a line from the compressor to the headstock of the lathe, which made the spindle turn freely on a few micron cushion of air.  He spun the spindle up with his finger tip (the machine was unplugged) and we went and had our meeting.  We came out half an hour later and the spindle was still slowly turning.

                                          Essentially they are a fluid bearing, like a sintered bronze bushing, but the working fluid is air, forced into the very narrow gap under high pressure.  Any force that tilts the shaft in the gap makes the gap narrower on one side than the other.  This increases the amount of air pressure on that side rapidly, which re-centers the shaft.

                                          http://en.wikipedia.org/wiki/Fluid_bearing

                                          Anyone who has ever played air-hockey will be familiar with the related linear version of this bearing.

                                          If a person had built a multimachine capable of the required precision, and they had access to large volumes of compressed air, it would be a neat upgrade to make a cartridge spindle for their multimachine using an air-bearing setup...  It would be quite straight forward to create a thrust bearing and a radial bearing surface, and combine them into one spindle.  The precision fit required is finicky, but could probably be achievable by hand lapping or scraping if you had the ability to measure your results.



                                        • jacot
                                          Ì know a mercury mirror of 4 meter on air bearing here in quebec city astronomy department Jack 47’n 71’”w Exactly right about how it works. You might
                                          Message 20 of 28 , Jan 5, 2013
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                                            Ì know a mercury mirror of 4 meter on  air bearing here in quebec city astronomy department

                                             

                                            Jack 47’n 71’”w

                                             




                                            Exactly right about how it works.  You might be surprised on how heavy loads are carried by air bearings though...  His little swiss lathe was smaller than my sherline, and probably never took heavy loads, but there are massive machines using air bearings.

                                            A little reading on the topic is very interesting.  At some point I want to put a bunch of heavy tools on bases that float off the concrete shop floor when air is applied, but sit solidly when the hose comes off.

                                             

                                            On Sat, Jan 5, 2013 at 10:37 AM, StoneTool <owly@...> wrote:

                                             

                                            Pierre:
                                                I presume the air entered the bearing clearance area from numerous small holes, and that the bearing clearance was extremely small, and furthermore that the air leakage probably wasn't all that great.   I superb idea.  The surface area of the spindle and the pressure of the air would be important related to the load. It probably wasn't designed for really heavy work.

                                                                                                                        Howard





                                            On 01/05/2013 09:43 AM, Pierre Coueffin wrote:

                                            I used to work with a guy who owned a company that had a swiss made tool-room lathe that had air-bearings in the spindle...  He showed me how they worked one time, by hooking up a line from the compressor to the headstock of the lathe, which made the spindle turn freely on a few micron cushion of air.  He spun the spindle up with his finger tip (the machine was unplugged) and we went and had our meeting.  We came out half an hour later and the spindle was still slowly turning.

                                            Essentially they are a fluid bearing, like a sintered bronze bushing, but the working fluid is air, forced into the very narrow gap under high pressure.  Any force that tilts the shaft in the gap makes the gap narrower on one side than the other.  This increases the amount of air pressure on that side rapidly, which re-centers the shaft.

                                            http://en.wikipedia.org/wiki/Fluid_bearing

                                            Anyone who has ever played air-hockey will be familiar with the related linear version of this bearing.

                                             

                                            If a person had built a multimachine capable of the required precision, and they had access to large volumes of compressed air, it would be a neat upgrade to make a cartridge spindle for their multimachine using an air-bearing setup...  It would be quite straight forward to create a thrust bearing and a radial bearing surface, and combine them into one spindle.  The precision fit required is finicky, but could probably be achievable by hand lapping or scraping if you had the ability to measure your results.

                                             

                                             




                                          • David G. LeVine
                                            ... Actually, my memory is a bit different. Air bearings CAN require a lot of volume (look at one being used to move heavy equipment on a floor), but for
                                            Message 21 of 28 , Jan 5, 2013
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                                              On 01/05/2013 03:21 PM, Shannon DeWolfe wrote:
                                              Keep in mind that air bearings require high pressures and large volume. 
                                              I have spent a lot, make that, A LOT of time researching ways to 
                                              compress air. It takes horsepower. More than 150 lbs./in.² at industrial 
                                              volume takes A LOT of horsepower. Also, air bearings do not like oil, 
                                              water, nor dirt.

                                              Actually, my memory is a bit different.  Air bearings CAN require a lot of volume (look at one being used to move heavy equipment on a floor), but for tight clearance loads (like a good spindle), the airflow is related to the clearance.  A very tight system (say 0.00005" - that is 50 MILLIONTHS of an inch) will have low leakage and will probably not be able to be turned without air.  A loose system (say 0.005", 5 thousandths of an inch) will need a lot of flow to work.

                                              Skirts are often used with very loose fitting setups (like the machine on a concrete floor.) 

                                              So yes and no, air bearings CAN need a lot of flow, but they don't have to.

                                              Dave  8{)

                                              --


                                              "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

                                              Mohandus Ghandi, An Autobiography, Page 446.
                                            • StoneTool
                                              Thanks: Great site! The outrageously unconventional idea of moving it on a cushion of air was the driver behind the proposed project. At this point, I
                                              Message 22 of 28 , Jan 5, 2013
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                                                Thanks:
                                                Great site! The outrageously unconventional idea of moving it on
                                                a cushion of air was the driver behind the proposed project. At this
                                                point, I don't foresee ever moving it intact, as any location I would
                                                now move it to would be too distant. This house was built near the
                                                turn of the century out of green pine logs that were flattened on two
                                                sides using an adze and a broad axe. The flattened sides were inside
                                                and out. The outside was covered with sheet metal not long after it was
                                                built, and the interior was covered with beaver board......... something
                                                most folks have never heard of these days. A kind of pressed board like
                                                very heavy liner-board (shoe box material) about a quarter inch thick.
                                                Beneath the beaver board they insulated with newspaper. The newspaper
                                                dates from the late 1800's and is from California mostly (bay area).
                                                It's been sealed from light for many years and though crumbly is
                                                readable until it crumbles. The logs were fresh, and in many places
                                                the paper adhered to the freshly hewn surfaces, leaving readable
                                                articles on the surface of the logs. Everything from period
                                                advertizing to political commentary to stories about hangings and
                                                crimes, etc. It's a history book, but the only parts that can be saved
                                                are the parts stuck to the logs. My plan was to use epoxy clearcoat
                                                such as "Super Glaze", to seal the paper to the log where it was stuck
                                                and to provide a clear protective layer, and then expose the logs on the
                                                interior, preserving hand hewn logs with readable snippets of ancient
                                                newspaper for a truly unique effect.
                                                As it currently stands, I will never move the house..... which is
                                                an old wreck, or I will strip the interior and preserve the newspapers,
                                                and dismantle it carefully and transport it a considerable distance and
                                                reassemble it on site. The sheet metal on the exterior has left the
                                                logs in very good shape along with our extremely dry climate (Eastern
                                                Montana).


                                                Howard


                                                On 01/05/2013 01:27 PM, Shannon DeWolfe wrote:
                                                > Howard,
                                                >
                                                > If you still need to move that house, talk to the man who has this site:
                                                >
                                                > http://www.theforgottentechnology.com/
                                                >
                                                > Be sure to see the pole barn he moved on page two.
                                                >
                                                > Regards,
                                                >
                                                > Mr. Shannon DeWolfe
                                                > --I've taken to using Mr. because my name misleads folks on the WWW. I am a 56 year old fat man.
                                                >
                                                > On 1/5/2013 2:51 PM, StoneTool wrote:
                                                >> Pierre:
                                                >> At one time I had intentions of moving a small house in this way a
                                                >> short distance.
                                                >>
                                                >
                                                >
                                                > ------------------------------------
                                                >
                                                > -------------
                                                > We have a sister site for files and pictures dedicated to concrete machine framed machine tools. You will find a great deal of information about concrete based machines and the inventor of the concrete frame lathe, Lucian Ingraham Yeomans. Go to http://groups.yahoo.com/group/Multimachine-Concrete-Machine-Tools/
                                                >
                                                > Also visit the Joseph V. Romig group for even more concrete tool construction, shop notes, stories, and wisdom from the early 20th Century.
                                                > http://tech.groups.yahoo.com/group/romig_designs/
                                                > -------------Yahoo! Groups Links
                                                >
                                                >
                                                >
                                                >
                                              • StoneTool
                                                David Clearances such as you are talking about are entirely impractical. The slightest thermal changes cause interference and galling and seizure instantly.
                                                Message 23 of 28 , Jan 5, 2013
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                                                  David
                                                      Clearances such as you are talking about are entirely impractical.  The slightest thermal changes cause interference and galling and seizure instantly.  I've played with some extremely tight clearances........ down under .001 and even a light film of oil will prevent things from slipping together.   You can achieve some incredibly tight tolerances with a pin hone (wrist pin hone).  Fuel injection parts are sealed entirely by clearances that allow the part to move but the oil cannot pass through.  Hydraulic valves, likewise do NOT have seals, and depend entirely on tolerances.  They are nowhere near the numbers you are talking about.........

                                                      That said, I agree entirely that clearance is the critical factor as far as maximizing support for a given airflow.   Sealing however is counter productive.  You have to have flow to get the support.  There is an optimal clearance and an optimal airflow & pressure.  If your clearance is too close, the pressure must be significantly higher.   Pressure (in psi) * Flow (cubic feet per minute) / 12790 = Horsepower..........    Clearly increasing pressure or increasing flow has an equal effect on horsepower.   Tighten your clearances and you need more pressure.......... loosen your clearances and you need more flow (within reason), the result within a reasonable range is going to be a roughly equal horsepower requirement on your compressor.

                                                                                                                          Howard

                                                  On 01/05/2013 09:18 PM, David G. LeVine wrote:
                                                  On 01/05/2013 03:21 PM, Shannon DeWolfe wrote:
                                                  Keep in mind that air bearings require high pressures and large volume. 
                                                  I have spent a lot, make that, A LOT of time researching ways to 
                                                  compress air. It takes horsepower. More than 150 lbs./in.² at industrial 
                                                  volume takes A LOT of horsepower. Also, air bearings do not like oil, 
                                                  water, nor dirt.

                                                  Actually, my memory is a bit different.  Air bearings CAN require a lot of volume (look at one being used to move heavy equipment on a floor), but for tight clearance loads (like a good spindle), the airflow is related to the clearance.  A very tight system (say 0.00005" - that is 50 MILLIONTHS of an inch) will have low leakage and will probably not be able to be turned without air.  A loose system (say 0.005", 5 thousandths of an inch) will need a lot of flow to work.

                                                  Skirts are often used with very loose fitting setups (like the machine on a concrete floor.) 

                                                  So yes and no, air bearings CAN need a lot of flow, but they don't have to.

                                                  Dave  8{)

                                                  --


                                                  "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

                                                  Mohandus Ghandi, An Autobiography, Page 446.

                                                • jacot
                                                  A bit off topic But Any of you have made chrismes ornament un wood or brass or allu Jacxk 47’n 71’LW On 01/05/2013 03:21 PM, Shannon DeWolfe wrote: Keep
                                                  Message 24 of 28 , Jan 6, 2013
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                                                    A  bit off topic

                                                    But

                                                    Any of you have made  chrismes ornament un wood or brass or allu

                                                     

                                                    Jacxk 47’n 71’LW




                                                    On 01/05/2013 03:21 PM, Shannon DeWolfe wrote:

                                                    Keep in mind that air bearings require high pressures and large volume. 
                                                    I have spent a lot, make that, A LOT of time researching ways to 
                                                    compress air. It takes horsepower. More than 150 lbs./in.² at industrial 
                                                    volume takes A LOT of horsepower. Also, air bearings do not like oil, 
                                                    water, nor dirt.


                                                    Actually, my memory is a bit different.  Air bearings CAN require a lot of volume (look at one being used to move heavy equipment on a floor), but for tight clearance loads (like a good spindle), the airflow is related to the clearance.  A very tight system (say 0.00005" - that is 50 MILLIONTHS of an inch) will have low leakage and will probably not be able to be turned without air.  A loose system (say 0.005", 5 thousandths of an inch) will need a lot of flow to work.

                                                    Skirts are often used with very loose fitting setups (like the machine on a concrete floor.) 

                                                    So yes and no, air bearings CAN need a lot of flow, but they don't have to.

                                                    Dave  8{)

                                                    --


                                                    "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

                                                    Mohandus Ghandi, An Autobiography, Page 446.




                                                  • David G. LeVine
                                                    ... Howard, New Way in its application guide at ... Four standard cubic feet per HOUR is not a lot of air, that is about 1/60 of the output of a common 2 HP
                                                    Message 25 of 28 , Jan 6, 2013
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                                                      On 01/06/2013 12:34 AM, StoneTool wrote:

                                                      David
                                                          Clearances such as you are talking about are entirely impractical.  The slightest thermal changes cause interference and galling and seizure instantly.  I've played with some extremely tight clearances........ down under .001 and even a light film of oil will prevent things from slipping together.   You can achieve some incredibly tight tolerances with a pin hone (wrist pin hone).  Fuel injection parts are sealed entirely by clearances that allow the part to move but the oil cannot pass through.  Hydraulic valves, likewise do NOT have seals, and depend entirely on tolerances.  They are nowhere near the numbers you are talking about.........

                                                          That said, I agree entirely that clearance is the critical factor as far as maximizing support for a given airflow.   Sealing however is counter productive.  You have to have flow to get the support.  There is an optimal clearance and an optimal airflow & pressure.  If your clearance is too close, the pressure must be significantly higher.   Pressure (in psi) * Flow (cubic feet per minute) / 12790 = Horsepower..........    Clearly increasing pressure or increasing flow has an equal effect on horsepower.   Tighten your clearances and you need more pressure.......... loosen your clearances and you need more flow (within reason), the result within a reasonable range is going to be a roughly equal horsepower requirement on your compressor.

                                                                                                                              Howard

                                                      Howard,

                                                      New Way in its application guide at http://www.newwayairbearings.com/design/application-guide says:

                                                      Airflow through a bearing gap is quite sensitive to the gap; in fact it is a cube function of the gap. As
                                                      an example of two inch diameter bearing with 75 pounds of load would consume 4 standard cubic
                                                      feet per hour at 200 micro inches of lift. For this bearing to carry the same load at 400 micro inches
                                                      of lift 64 standard cubic feet per hour of air would be required. It can easily be seen that small gaps
                                                      keep restriction high and hence reduce flow and power requirements. Less airflow means less air
                                                      needs to be compressed cleaned and dried reducing cost of ownership issues.

                                                      Four standard cubic feet per HOUR is not a lot of air, that is about 1/60 of the output of a common 2 HP compressor.  In fact, a 1/8 HP Harbor Freight compressor runs 30 CFH at 20 PSI (0.5 CFM), less at higher pressure, and this is not a high end compressor.  They are talking 200 micro inches, 0.0002" in this example, depending on finish that may be way too big a gap.

                                                      Most air bearings these days will not allow one to move the supported structure without damage without air pressure.

                                                      It sounds like technology has changed quite a bit since your experiences.

                                                      Dave  8{)


                                                      --


                                                      "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

                                                      Mohandus Ghandi, An Autobiography, Page 446.
                                                    • StoneTool
                                                      David: I would suggest that you try assembling something with that sort of clearance............... Howard
                                                      Message 26 of 28 , Jan 6, 2013
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                                                        David:
                                                            I would suggest that you try assembling something with that sort of clearance...............

                                                                                                                                    Howard

                                                        On 01/06/2013 10:10 AM, David G. LeVine wrote:
                                                        On 01/06/2013 12:34 AM, StoneTool wrote:

                                                        David
                                                            Clearances such as you are talking about are entirely impractical.  The slightest thermal changes cause interference and galling and seizure instantly.  I've played with some extremely tight clearances........ down under .001 and even a light film of oil will prevent things from slipping together.   You can achieve some incredibly tight tolerances with a pin hone (wrist pin hone).  Fuel injection parts are sealed entirely by clearances that allow the part to move but the oil cannot pass through.  Hydraulic valves, likewise do NOT have seals, and depend entirely on tolerances.  They are nowhere near the numbers you are talking about.........

                                                            That said, I agree entirely that clearance is the critical factor as far as maximizing support for a given airflow.   Sealing however is counter productive.  You have to have flow to get the support.  There is an optimal clearance and an optimal airflow & pressure.  If your clearance is too close, the pressure must be significantly higher.   Pressure (in psi) * Flow (cubic feet per minute) / 12790 = Horsepower..........    Clearly increasing pressure or increasing flow has an equal effect on horsepower.   Tighten your clearances and you need more pressure.......... loosen your clearances and you need more flow (within reason), the result within a reasonable range is going to be a roughly equal horsepower requirement on your compressor.

                                                                                                                                Howard

                                                        Howard,

                                                        New Way in its application guide at http://www.newwayairbearings.com/design/application-guide says:

                                                        Airflow through a bearing gap is quite sensitive to the gap; in fact it is a cube function of the gap. As
                                                        an example of two inch diameter bearing with 75 pounds of load would consume 4 standard cubic
                                                        feet per hour at 200 micro inches of lift. For this bearing to carry the same load at 400 micro inches
                                                        of lift 64 standard cubic feet per hour of air would be required. It can easily be seen that small gaps
                                                        keep restriction high and hence reduce flow and power requirements. Less airflow means less air
                                                        needs to be compressed cleaned and dried reducing cost of ownership issues.

                                                        Four standard cubic feet per HOUR is not a lot of air, that is about 1/60 of the output of a common 2 HP compressor.  In fact, a 1/8 HP Harbor Freight compressor runs 30 CFH at 20 PSI (0.5 CFM), less at higher pressure, and this is not a high end compressor.  They are talking 200 micro inches, 0.0002" in this example, depending on finish that may be way too big a gap.

                                                        Most air bearings these days will not allow one to move the supported structure without damage without air pressure.

                                                        It sounds like technology has changed quite a bit since your experiences.

                                                        Dave  8{)


                                                        --


                                                        "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

                                                        Mohandus Ghandi, An Autobiography, Page 446.

                                                      • David G. LeVine
                                                        ... Back in the 1970s I did, it was tricky, but not impossible (and that was many moons ago!) It took a lot of jigging and pressure, but it worked. The
                                                        Message 27 of 28 , Jan 6, 2013
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                                                          On 01/06/2013 01:38 PM, StoneTool wrote:

                                                          David:
                                                              I would suggest that you try assembling something with that sort of clearance...............

                                                                                                                                      Howard

                                                          Back in the 1970s I did, it was tricky, but not impossible (and that was many moons ago!)  It took a lot of jigging and pressure, but it worked.  The surface cleanliness was simply incredible (I worked in an optical encoder and metrology company.) 

                                                          Air bearings are often sintered porous graphite these days (like a fish tank stone) and MUST be assembled with pressure on or they won't go.  Put the bearing in the housing with o-rings to support and seal it, apply 90 PSI, press the shaft into place.  The shaft is self aligning, there can be no steps as the shaft tapers to the correct diameter, but if the shaft starts at .002-.005" undersize with a conic section leading to the bearing surface, that is okay.  It CAN NOT be assembled without air pressure, it just jams and galls.  The stiffness is amazing -- 2 million pounds per inch!

                                                          The trick is the powdered graphite bearing, even with clearances of 1/4" (that is HUGE), the bearing has enough resistance to flow that the pressure can be maintained.

                                                          Read the New Way manual, the world has changed.

                                                          Dave  8{)

                                                          --


                                                          "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

                                                          Mohandus Ghandi, An Autobiography, Page 446.
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