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Re: Atlas 10F collets help

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  • Richard Marchi
    Since this is a collett thread, can I ask a slightly off-topic question? Does anyone have the length of the drawbar for # 3 MT collets on an Atlas 10
    Message 1 of 24 , Sep 10, 2013
      Since this is a collett thread, can I ask a slightly off-topic question? Does anyone have the length of the drawbar for # 3 MT collets on an Atlas 10" headstock. I have as set of collets and a handwheel and want to make a drawbar. The dimension from the shoulder on the left side of the spindle to the end of the thread would be ideal. I had this dimension, once, but seem to have misplaced it.

      Any help will be appreciated.

      Dick


      Richard Marchi
      600 Water Street, SW
      NBU 8-2
      Gangplank Marina Slip H-22
      Washington, DC 20024

    • wa5cab
      Dick, The Atlas factory 3/8-16 drawbar which fits both 10 and 12 machines has 9-1/2 to 9-9/16 of 3.8 dia. rod from the tip of the threads to the face of
      Message 2 of 24 , Sep 10, 2013
        Dick,

        The Atlas factory 3/8-16 drawbar which fits both 10" and 12" machines has 9-1/2" to 9-9/16" of 3.8" dia. rod from the tip of the threads to the face of the handwheel hub.  Then there is a thrust washer/spacer free to spin on the rod that sits against the handwheel hub and the left end of the spindle.  The factory one is actually tapered on both ends but I have found in practice that a stepped or shouldered spacer works better as the rod will stay centered when loose.  In any case, the effective length of the spacer is 1-1/4" whichever way you make it.  Leaving 8-1/4" of exposed 3/8" dia. rod.  The threads on the end are about 3/4" long. 

        This drawbar works with both 3MT cutter holders and 3MT collets (I've used it for both).

        Robert Downs - Houston
        wa5cab dot com (Web Store)
        MVPA 9480

        In a message dated 09/10/2013 17:08:57 PM Central Daylight Time, rfmarchi@... writes:
        Since this is a collett thread, can I ask a slightly off-topic question? Does anyone have the length of the drawbar for # 3 MT collets on an Atlas 10" headstock.  I have as set of collets and a handwheel and want to make a drawbar. The dimension from the shoulder on the left side of the spindle to the end of the thread would be ideal. I had this dimension, once, but seem to have misplaced it.

        Any help will be appreciated.

        Dick




        Richard Marchi
        600 Water Street, SW
        NBU 8-2
        Gangplank Marina Slip H-22
        Washington, DC 20024



      • julianworks2
        So, what you are saying is that you use 3C collets naked with a drawbar in the 3MT spindle? If so, doesn t this setup encourage runout by not aligning the back
        Message 3 of 24 , Sep 10, 2013

          So, what you are saying is that you use 3C collets naked with a drawbar in the 3MT spindle?   If so, doesn't this setup encourage runout by not aligning the back end of the collet in a proper adapter?



          --- In atlas_craftsman@yahoogroups.com, <jerdal@...> wrote:

          3C work great in a 3MT taper spindle.   all you need is the right length drawtube.
           
          The good part is because all the Atlas owners "know" that they are no good for Atlas (MUST use 3AT) they are a bunch cheaper.......
           
          I have them in a Logan..... allee same-same with 3MT spindle.
           
          JT
          ----- Original Message -----
          Sent: Monday, September 09, 2013 6:56 PM
          Subject: Re: [atlas_craftsman] Atlas 10F collets help

          I have done the reverse.

          South Bend 9 specifies 3C collets, with a 3 MT to 3C spindle nose adapter.<SNA>
          South Bend makes one SNA with a collar and Atlas makes one with no collar.

          I have used the Atlas Draw tube and SNA in the SBL 9 spindle.
          Works fine.

          So, with all the righteousness of ignorance, I suggest that a 3MT to 3C SNA could be bought, a wheel draw tube can be made and you can use your 3C collets in your 3MT spinlde nose.
          Getting the length of the draw tube and the taper on the wheel end is important, 
          but not brain surgery.

          lance
          ++++

          On Sep 9, 2013, at 7:41 PM, <julian.p.67@...> <julian.p.67@...> wrote:

          I am pretty sure that these machines require "3AT" collets.  Correct?

          If so, how dissimilar are 3C collets, and what would be involved in making/buying collet adaptor/chucks for the 3C collets to be used on the 10F?  Or would that even be necessary?  

          the only reason I am apparently fixated on 3C vs. any other collet system is that I got a set of hardinge 3C collets for free and they seem to be great candidated for my lathe with little or no adaptation involved.

          So, is it worth exploring first of all?  Secondly, has anyone had any experience with using 3C collets on these machines?  Thirdly, what was your experience with getting them to work on the 10f?


        • julianworks2
          Thank you all for the info so far. You have given me a good base to start from. What I am wondering now is: How difficult and practical would it be to machine
          Message 4 of 24 , Sep 10, 2013

            Thank you all for the info so far.  You have given me a good base to start from.  


            What I am wondering now is: How difficult and practical would it be to machine an accurate enough 3MT to 3C adapter?  I'm looking at them online and they seem ridiculously priced, given what they are, or am I missing something that I should be accounting for in the price?



            --- In atlas_craftsman@yahoogroups.com, <julian.p.67@...> wrote:

            So, what you are saying is that you use 3C collets naked with a drawbar in the 3MT spindle?   If so, doesn't this setup encourage runout by not aligning the back end of the collet in a proper adapter?



            --- In atlas_craftsman@yahoogroups.com, <jerdal@...> wrote:

            3C work great in a 3MT taper spindle.   all you need is the right length drawtube.
             
            The good part is because all the Atlas owners "know" that they are no good for Atlas (MUST use 3AT) they are a bunch cheaper.......
             
            I have them in a Logan..... allee same-same with 3MT spindle.
             
            JT
            ----- Original Message -----
            Sent: Monday, September 09, 2013 6:56 PM
            Subject: Re: [atlas_craftsman] Atlas 10F collets help

            I have done the reverse.

            South Bend 9 specifies 3C collets, with a 3 MT to 3C spindle nose adapter.<SNA>
            South Bend makes one SNA with a collar and Atlas makes one with no collar.

            I have used the Atlas Draw tube and SNA in the SBL 9 spindle.
            Works fine.

            So, with all the righteousness of ignorance, I suggest that a 3MT to 3C SNA could be bought, a wheel draw tube can be made and you can use your 3C collets in your 3MT spinlde nose.
            Getting the length of the draw tube and the taper on the wheel end is important, 
            but not brain surgery.

            lance
            ++++

            On Sep 9, 2013, at 7:41 PM, <julian.p.67@...> <julian.p.67@...> wrote:

            I am pretty sure that these machines require "3AT" collets.  Correct?

            If so, how dissimilar are 3C collets, and what would be involved in making/buying collet adaptor/chucks for the 3C collets to be used on the 10F?  Or would that even be necessary?  

            the only reason I am apparently fixated on 3C vs. any other collet system is that I got a set of hardinge 3C collets for free and they seem to be great candidated for my lathe with little or no adaptation involved.

            So, is it worth exploring first of all?  Secondly, has anyone had any experience with using 3C collets on these machines?  Thirdly, what was your experience with getting them to work on the 10f?


          • jtiers
            Very practical to do. And capable of being MORE accurate than the usual toleranced factory item. All it takes is care, and once you have done it, you will
            Message 5 of 24 , Sep 10, 2013
              
              Very practical to do.  
               
              And capable of being MORE accurate than the usual toleranced factory item.     All it takes is care, and once you have done it, you will know how to do it even better if you ever decide to make a new one.  
               
              Accuracy is very much a "nothing ventured, nothing gained" activity.  You get better by doing your best repeatedly on different projects.
               
              The pic of the set that I put up the link to, drawtube, closer, and thread protector, shows parts I made myseld.   ALL made in two evenings.  Runout is quite good, I don't recall the number any more (it's been years), but well under 0.001".  Small enough that I didn't worry about it.
               
              I machined the OUTSIDE of the closer first, then set it in the spindle, using an extra sacrificial piece at the back with a drawbar in it to hold it in.  Then the inside was machined to dimension, and tested with collets.   That ensured all irregularities were compensated as well as possible.   When finished, it was extracted and the sacrificial back part cut off to dimension so that the collet thread is exposed for the drawbar.
               
              The last trick is to mark the location it was in  when machined, and always put it back that way.  That makes it as accurate as the original machining, compensating for any oddities about your individual spindle, something a "store boughten", or abused "ebay bought" unit can never do.
               
              The closer has the MT3 OD, not hard to do using the spindle as a model, and the compound set to the angle for a "zero-zero" on the dial indicator when moving along the taper.
               
              The ID is a cylinder to fit the collet OD closely but not in any way a wringing fit.  Then the closer angle is set.  You *can* use the compound dial for that, I did it with angle blocks.  I don't know how much better that is.... the angle is approximate anyway due to the movement when the collet closes, which slightly steepens the angle.    Ideally, it would be exact when correctly closed.  I expect a little steeper is better, it avoids having the collet hit only at the back of the taper as it closes.
               
              Drawtube was a piece of water pipe, with a better quality steel nose hard-soldered into the tube for the threads.  I measured that with a collet in place, for a bearing sleeve which I added afterwards, along with the hand wheel.
               
              JT
              ----- Original Message -----
              Sent: Tuesday, September 10, 2013 7:25 PM
              Subject: [atlas_craftsman] RE: Atlas 10F collets help

              Thank you all for the info so far.  You have given me a good base to start from.  


              What I am wondering now is: How difficult and practical would it be to machine an accurate enough 3MT to 3C adapter?  I'm looking at them online and they seem ridiculously priced, given what they are, or am I missing something that I should be accounting for in the price?



              --- In atlas_craftsman@yahoogroups.com, <julian.p.67@...> wrote:

              So, what you are saying is that you use 3C collets naked with a drawbar in the 3MT spindle?   If so, doesn't this setup encourage runout by not aligning the back end of the collet in a proper adapter?



              --- In atlas_craftsman@yahoogroups.com, <jerdal@...> wrote:

              3C work great in a 3MT taper spindle.   all you need is the right length drawtube.
               
              The good part is because all the Atlas owners "know" that they are no good for Atlas (MUST use 3AT) they are a bunch cheaper.......
               
              I have them in a Logan..... allee same-same with 3MT spindle.
               
              JT
              ----- Original Message -----
              Sent: Monday, September 09, 2013 6:56 PM
              Subject: Re: [atlas_craftsman] Atlas 10F collets help

              I have done the reverse.

              South Bend 9 specifies 3C collets, with a 3 MT to 3C spindle nose adapter.<SNA>
              South Bend makes one SNA with a collar and Atlas makes one with no collar.

              I have used the Atlas Draw tube and SNA in the SBL 9 spindle.
              Works fine.

              So, with all the righteousness of ignorance, I suggest that a 3MT to 3C SNA could be bought, a wheel draw tube can be made and you can use your 3C collets in your 3MT spinlde nose.
              Getting the length of the draw tube and the taper on the wheel end is important, 
              but not brain surgery.

              lance
              ++++

              On Sep 9, 2013, at 7:41 PM, <julian.p.67@...> <julian.p.67@...> wrote:

              I am pretty sure that these machines require "3AT" collets.  Correct?

              If so, how dissimilar are 3C collets, and what would be involved in making/buying collet adaptor/chucks for the 3C collets to be used on the 10F?  Or would that even be necessary?  

              the only reason I am apparently fixated on 3C vs. any other collet system is that I got a set of hardinge 3C collets for free and they seem to be great candidated for my lathe with little or no adaptation involved.

              So, is it worth exploring first of all?  Secondly, has anyone had any experience with using 3C collets on these machines?  Thirdly, what was your experience with getting them to work on the 10f?


            • jtiers
              Gosh......................... This, when I posted the picture link for closer, drawtube, and thread protector? ;-) JT ... From: julian.p.67@gmail.com To:
              Message 6 of 24 , Sep 10, 2013
                
                Gosh......................... This, when I posted the picture link for closer, drawtube, and thread protector?    ;-)
                 
                JT
                ----- Original Message -----
                Sent: Tuesday, September 10, 2013 7:19 PM
                Subject: [atlas_craftsman] RE: Atlas 10F collets help

                So, what you are saying is that you use 3C collets naked with a drawbar in the 3MT spindle?   If so, doesn't this setup encourage runout by not aligning the back end of the collet in a proper adapter?

                 
              • jtiers
                I assumed you DID have the problem, you are not particularly given to telling tall tales, in my experience here...... ;-) But I feel pretty sure it is a defect
                Message 7 of 24 , Sep 10, 2013
                  I assumed you DID have the problem, you are not particularly given to telling tall tales, in my experience here...... ;-)
                   
                  But I feel pretty sure it is a defect in your setup.  
                   
                  The 24 degree included angle vs 30 deg included angle is hardly enough to produce a difference in "jamming" , or in fact ANY jamming at all in the first place.
                   
                  Here is a link to a comparison of the collets, along with collet closer dimensions for both 3AT and 3C.  Mr Hoffman is a pretty reliable source, careful and thorough..
                   
                   
                  You may ask yourself if there is a credible argument for a self-holding action in 3C collets (when not defective), based on a 6 degree difference in included taper angle, amounting to a 20% net change.
                   
                  I would argue there is not, and that if you have to pound tours out hard enough to hurt your hand, there is a problem.   My 2MT and 3MT collets and tapers don't need heavy pounding, let alone the 3C.
                   
                  JT
                  ----- Original Message -----
                  Sent: Tuesday, September 10, 2013 2:57 PM
                  Subject: Re: [atlas_craftsman] Atlas 10F collets help



                  Sorry, but if I hadn't experienced it, I wouldn't have written it.  And the taper angles are definitely not the same.  3AT is 15 deg.  3C is 12 deg.  According to Hardinge drawings that I have.

                   
                • wa5cab
                  I don t know why I had the problem with the 3C either. But it was consistant across a full set of collets. One wouldn t normally have occassion to use every
                  Message 8 of 24 , Sep 10, 2013
                    I don't know why I had the problem with the 3C either.  But it was consistant across a full set of collets.  One wouldn't normally have occassion to use every collet in a set in a single evening.  But I had discovered that the three smallest collets had tremendous angular runout and consequentially checked all of them at one sitting.  And all required banging on the handwheel as you would expect to have to do with 2MT or 3MT.  I couldn't see anything wrong with the finish on either the collets or the adaptor.  But I did do the whole series of tests with one adaptor.  Perhaps it is at fault.

                    Robert Downs - Houston
                    wa5cab dot com (Web Store)
                    MVPA 9480

                    In a message dated 09/10/2013 20:22:28 PM Central Daylight Time, jerdal@... writes:
                    I assumed you DID have the problem, you are not particularly given to telling tall tales, in my experience here...... ;-)

                     
                    But I feel pretty sure it is a defect in your setup.  

                    The 24 degree included angle vs 30 deg included angle is hardly enough to produce a difference in "jamming" , or in fact ANY jamming at all in the first place.
                     
                    Here is a link to a comparison of the collets, along with collet closer dimensions for both 3AT and 3C.  Mr Hoffman is a pretty reliable source, careful and thorough..
                     
                    http://www.conradhoffman.com/Collet%20Adapters.PDF
                     
                    You may ask yourself if there is a credible argument for a self-holding action in 3C collets (when not defective), based on a 6 degree difference in included taper angle, amounting to a 20% net change.
                     
                    I would argue there is not, and that if you have to pound tours out hard enough to hurt your hand, there is a problem.   My 2MT and 3MT collets and tapers don't need heavy pounding, let alone the 3C.
                     
                    JT

                    ----- Original Message -----
                    From: wa5cab@...
                    To: atlas_craftsman@yahoogroups.com
                    Sent: Tuesday, September 10, 2013 2:57 PM
                    Subject: Re: [atlas_craftsman] Atlas 10F collets help




                    Sorry, but if I hadn't experienced it, I wouldn't have written it.  And the taper angles are definitely not the same.  3AT is 15 deg.  3C is 12 deg.  According to Hardinge drawings that I have.






                  • jtiers
                    An alignment problem with the drawtube can cause that, if it cocks the collets a bit, maybe only jamming when under tension. Or the tapered closer section
                    Message 9 of 24 , Sep 10, 2013
                       
                      An alignment problem with the drawtube can cause that, if it cocks the collets a bit, maybe only jamming when under tension.   Or the tapered closer section not being accurately concentric with the body recess.
                       
                      If anything acts to cock the collet, it will cause trouble, there normally isn't much clearance in the closer over the body of the collets.  No telling from here.
                       
                      But it shouldn't be anything typical of 3C.  Either 3AT or 3C should work about the same with properly fitted closers and drawtubes..
                       
                      The taper of the very popular 5C is even less, 20 degrees included angle.  They seem to work pretty well, though!
                       
                      JT
                       
                      ----- Original Message -----
                      Sent: Tuesday, September 10, 2013 10:15 PM
                      Subject: Re: [atlas_craftsman] Atlas 10F collets help



                      I don't know why I had the problem with the 3C either.  But it was consistant across a full set of collets.  One wouldn't normally have occassion to use every collet in a set in a single evening.  But I had discovered that the three smallest collets had tremendous angular runout and consequentially checked all of them at one sitting.  And all required banging on the handwheel as you would expect to have to do with 2MT or 3MT.  I couldn't see anything wrong with the finish on either the collets or the adaptor.  But I did do the whole series of tests with one adaptor.  Perhaps it is at fault.

                      Robert Downs - Houston
                      wa5cab dot com (Web Store)
                      MVPA 9480

                    • julianworks2
                      I m sorry, I got confused, and thought someone else had posted that link. --- In atlas_craftsman@yahoogroups.com, wrote: 
                      Message 10 of 24 , Sep 11, 2013

                        I'm sorry, I got confused, and thought someone else had posted that link.   



                        --- In atlas_craftsman@yahoogroups.com, <jerdal@...> wrote:

                        
                        Gosh......................... This, when I posted the picture link for closer, drawtube, and thread protector?    ;-)
                         
                        JT
                        ----- Original Message -----
                        Sent: Tuesday, September 10, 2013 7:19 PM
                        Subject: [atlas_craftsman] RE: Atlas 10F collets help

                        So, what you are saying is that you use 3C collets naked with a drawbar in the 3MT spindle?   If so, doesn't this setup encourage runout by not aligning the back end of the collet in a proper adapter?

                         
                      • wa5cab
                        I ll try to determine the cause the next time I have time. However, it isn t the draw tube as at the time I only had one aftermarket one that is ad justable
                        Message 11 of 24 , Sep 11, 2013
                          I'll try to determine the cause the next time I have time.  However, it isn't the draw tube as at the time I only had one aftermarket one that is adjustable for length.

                          Robert Downs - Houston
                          wa5cab dot com (Web Store)
                          MVPA 9480

                          In a message dated 09/10/2013 23:01:11 PM Central Daylight Time, jerdal@... writes:
                          An alignment problem with the drawtube can cause that, if it cocks the collets a bit, maybe only jamming when under tension.   Or the tapered closer section not being accurately concentric with the body recess.


                          If anything acts to cock the collet, it will cause trouble, there normally isn't much clearance in the closer over the body of the collets.  No telling from here.
                           
                          But it shouldn't be anything typical of 3C.  Either 3AT or 3C should work about the same with properly fitted closers and drawtubes..
                           
                          The taper of the very popular 5C is even less, 20 degrees included angle.  They seem to work pretty well, though!
                           
                          JT
                           

                          ----- Original Message -----
                          From: wa5cab@...
                          To: atlas_craftsman@yahoogroups.com
                          Sent: Tuesday, September 10, 2013 10:15 PM
                          Subject: Re: [atlas_craftsman] Atlas 10F collets help




                          I don't know why I had the problem with the 3C either.  But it was consistant across a full set of collets.  One wouldn't normally have occassion to use every collet in a set in a single evening.  But I had discovered that the three smallest collets had tremendous angular runout and consequentially checked all of them at one sitting.  And all required banging on the handwheel as you would expect to have to do with 2MT or 3MT.  I couldn't see anything wrong with the finish on either the collets or the adaptor.  But I did do the whole series of tests with one adaptor.  Perhaps it is at fault.

                          Robert Downs - Houston



                        • anthrhodes
                          JT, Robert, et al, It s interesting to look at the closing taper angles of some common collets: 1C = 15 deg. 2C = 15 deg. 3C = 12 deg. 4C = 12 deg. 5C = 10
                          Message 12 of 24 , Sep 11, 2013
                            JT, Robert, et al,
                             
                            It's interesting to look at the closing taper angles of some common collets:
                            1C = 15 deg.
                            2C = 15 deg.
                            3C = 12 deg.
                            4C = 12 deg.
                            5C = 10 deg. 1 min.
                             
                            3AT = 15 deg. 1 min.
                            M6-751 = 15 deg. (Atlas 6" lathe)
                             
                            R8 = 1-1/2 deg.
                             
                            These are all 1/2 angle, taken from the center of rotation. All but the M6-751 are from Hardinge drawings, the M6-751 is from an Atlas Press drawing. Per the Hardinge drawings, the adapters for closing the collet are the same angle as the collet except for:
                            5C = 10 deg.
                            3AT = 15 deg.
                            R8 = 16 deg. 51 min. incl. (or 8.425 deg. single angle).. Yes, this what the drawing shows!
                             
                            I said common collets. 1C and 2C are not exactly common but I included them to illustrate that Hardinge used a larger angle on the smaller collets. It may be that they found small diameter collets were more prone to locking at a given angle than larger diameter ones so they increased the angle for smaller collets. Just a speculation on my part. The other interesting thing is the closing adapters for the 5C and 3AT having a minutely larger angle and the R8 closer having a slightly smaller angle. The R8 closer drawing has a note idetifying it as for Bridgeport so it may be per Bridgeport specs.
                             
                            All of the above and my speculations are purely for general interest and not intended to support or denigrate the position of any of the participants in this discussion.
                             
                            Anthony
                            Berkeley, Calif.
                            **********************************************
                            In a message dated Tue Sep 10, 2013 6:21 pm (PDT), jtiers writes:
                            I assumed you DID have the problem, you are not particularly given to telling tall tales, in my experience here...... ;-)

                            But I feel pretty sure it is a defect in your setup.

                            The 24 degree included angle vs 30 deg included angle is hardly enough to produce a difference in "jamming" , or in fact ANY jamming at all in the first place.

                            Here is a link to a comparison of the collets, along with collet closer dimensions for both 3AT and 3C. Mr Hoffman is a pretty reliable source, careful and thorough..

                            http://www.conradho ffman.com/ Collet%20Adapter s.PDF
                          • Rexarino
                            Robert, I suspect that you meant 3/8 dia. rod? 3.8 would not quite fit through the spindle... ;-) Rex Bosse Portland, Oregon
                            Message 13 of 24 , Sep 11, 2013
                              Robert, I suspect that you meant 3/8 " dia. rod?  3.8" would not quite fit through the spindle...   ;-)

                              Rex Bosse
                              Portland, Oregon


                              On Tue, Sep 10, 2013 at 5:08 PM, <wa5cab@...> wrote:


                              Dick,

                              The Atlas factory 3/8-16 drawbar which fits both 10" and 12" machines has 9-1/2" to 9-9/16" of 3.8" dia. rod 
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