Loading ...
Sorry, an error occurred while loading the content.

RE: [mill_drill] measuring a mill's out of "tramness"

Expand Messages
  • Rick Sparber
    Mike, If you mount your vise so it sits solidly on the table with no crown lifting up an end, you can use softjaws to get an alignment that is the best that
    Message 1 of 19 , Sep 11, 2009
    • 0 Attachment
      Mike,

      If you mount your vise so it sits solidly on the table with no crown
      lifting up an end, you can use softjaws to get an alignment that is
      the best that can be had on your machine. I can't cancel the tram
      error but will give you X and Z alignment assuming the vise is
      oriented with the crank facing forward. That accuracy will persist
      until you move the vise.

      For more on softjaws, see

      http://rick.sparber.org/Articles/sj/sj6.pdf

      You may notice that this article is on Version 6. That is because a
      large number of people in the community contributed insights and
      tricks. I have talked with many professional machinists that routinely
      use softjaws during production runs. Such a simple idea yet extremely
      useful.

      Rick


      -----Original Message-----
      From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com]
      On Behalf Of Dragonflight
      Sent: Thursday, September 10, 2009 8:18 PM
      To: mill_drill@yahoogroups.com
      Subject: RE: [mill_drill] measuring a mill's out of "tramness"

      Yes well I am not concerned about the head being out of tram, only
      that
      if I fix it at one point it is far off at another point because of a
      bent column.

      as for the table most of the error is at the front edge, between the
      tslots the crown is more like .0003". Luckily most stuff I do is in
      the
      vise so I just have to be careful how I install/shim? the vise. As
      always forewarned is forearmed. I may swap tables if the crowning is
      out
      of spec - they may say less than 1 thou is within spec

      mike

      On Thu, 2009-09-10 at 19:53 -0700, Rick Sparber wrote:
      >
      > Mike,
      >
      > If you do test the column with a straight edge, I assume you will
      run
      > the edge all the way around it since the head grips the column in at
      > least 3 places.
      >
      > My mill came is a big crate. No chance of easily seeing it until I
      got
      > it home.
      >
      > IMHO, I would be more concerned about your crowned table than the
      head
      > being out of tram.
      >
      > Rick
      >
      > -----Original Message-----
      > From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com]
      > On Behalf Of Dragonflight
      > Sent: Thursday, September 10, 2009 7:46 PM
      > To: mill_drill@yahoogroups.com
      > Subject: RE: [mill_drill] measuring a mill's out of "tramness"
      >
      > On Thu, 2009-09-10 at 18:42 -0700, Rick Sparber wrote:
      > > 09/10/09 18:34
      > > How do you plan to measure a column that has been bent a few thou?
      > My
      > > RF30 column is part of the casting and was turned on a lathe. If
      it
      > > was bent, I would expect to see a massive dent in the side. It may
      > > look like a piece of pipe fit into a base but it is one piece, at
      > > least on my mill.
      > >
      > > When I got my mill, I was faced with exactly the same problem. My
      > head
      > > was off about 0.015". Sure I could bring it back but the effort of
      > > pulling it out of the basement, onto a truck, and back to Enco was
      > > insane. After I got over the trauma of cutting through the Bondo
      > that
      > > covered the seam between base and column, the rest was easy. There
      > is
      > > certainly no guarantee that the next mill you get will be any
      > better.
      > >
      > > Rick
      >
      > was your mill Taiwanese or Chinese. If it is normal for the
      Taiwanese
      > ones to be off by .004 in 6" as mine is then I am not really worried
      > too
      > much about the column, it is just that it is my understanding that
      it
      > was supposed to leave the factory in better shape.
      >
      > As for measuring the column that is a problem. The simplest is to
      > remove
      > the head and put my straight edge up against it which is supposed to
      > be
      > within .0015 of straight and as far as I can tell from my surface
      > plate
      > is somewhat better than that.
      >
      > And as for the next one being just as bad or worse, I would test it
      at
      > their place BEFORE I took mine out of the basement!
      >
      > mike
      >
      > ------------------------------------
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
      >



      ------------------------------------

      Yahoo! Groups Links
    • cnc4cheap
      Guys, One of the main things that you have to keep in mind when picking at the precision? of these hobby machines is the quality and characteristics of the
      Message 2 of 19 , Sep 12, 2009
      • 0 Attachment
        Guys,

        One of the main things that you have to keep in mind when picking at the precision? of these hobby machines is the quality and characteristics of the iron used in the castings. The column was probably true when at the completion of the machining process there was stress relieved when the material was removed and that set in motion a squirmming & worming process that has an effect on the machines precision factor. I have forty plus years of experience working with and on precision machinery and I have alot of experience with various types of materials. I'm sure that most of you have heard about Meehanite iron and you more than likely associate it with machinery like milling machines and lathes. One of the key characteristics of Meehanite iron is it's stability and it is that characteristic that is lacking in the Chinese iron that is used in the casting for these hobby machines.

        To the man with .0003 crown in his table, it just as well could have been .003. Over my years I have built some very sophisticated projects on Bridgeport milling machines that were probably in a heck of lot worst shape. I have turned close tolerance bushings on worn out bushing head lathes where I had to average several O.D. measurements in order to hold tolerance.

        Now after stating all of that, I cannot believe that I actually purchased a Chinese hobby mill. I know that it's going to drive me nuts when I get around to Nit-Picking the precision aspects of the machine.

        C4C

        --- In mill_drill@yahoogroups.com, "Rick Sparber" <rgsparber@...> wrote:
        >
        > Mike,
        >
        > If you mount your vise so it sits solidly on the table with no crown
        > lifting up an end, you can use softjaws to get an alignment that is
        > the best that can be had on your machine. I can't cancel the tram
        > error but will give you X and Z alignment assuming the vise is
        > oriented with the crank facing forward. That accuracy will persist
        > until you move the vise.
        >
        > For more on softjaws, see
        >
        > http://rick.sparber.org/Articles/sj/sj6.pdf
        >
        > You may notice that this article is on Version 6. That is because a
        > large number of people in the community contributed insights and
        > tricks. I have talked with many professional machinists that routinely
        > use softjaws during production runs. Such a simple idea yet extremely
        > useful.
        >
        > Rick
        >
        >
        > -----Original Message-----
        > From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com]
        > On Behalf Of Dragonflight
        > Sent: Thursday, September 10, 2009 8:18 PM
        > To: mill_drill@yahoogroups.com
        > Subject: RE: [mill_drill] measuring a mill's out of "tramness"
        >
        > Yes well I am not concerned about the head being out of tram, only
        > that
        > if I fix it at one point it is far off at another point because of a
        > bent column.
        >
        > as for the table most of the error is at the front edge, between the
        > tslots the crown is more like .0003". Luckily most stuff I do is in
        > the
        > vise so I just have to be careful how I install/shim? the vise. As
        > always forewarned is forearmed. I may swap tables if the crowning is
        > out
        > of spec - they may say less than 1 thou is within spec
        >
        > mike
        >
        > On Thu, 2009-09-10 at 19:53 -0700, Rick Sparber wrote:
        > >
        > > Mike,
        > >
        > > If you do test the column with a straight edge, I assume you will
        > run
        > > the edge all the way around it since the head grips the column in at
        > > least 3 places.
        > >
        > > My mill came is a big crate. No chance of easily seeing it until I
        > got
        > > it home.
        > >
        > > IMHO, I would be more concerned about your crowned table than the
        > head
        > > being out of tram.
        > >
        > > Rick
        > >
        > > -----Original Message-----
        > > From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com]
        > > On Behalf Of Dragonflight
        > > Sent: Thursday, September 10, 2009 7:46 PM
        > > To: mill_drill@yahoogroups.com
        > > Subject: RE: [mill_drill] measuring a mill's out of "tramness"
        > >
        > > On Thu, 2009-09-10 at 18:42 -0700, Rick Sparber wrote:
        > > > 09/10/09 18:34
        > > > How do you plan to measure a column that has been bent a few thou?
        > > My
        > > > RF30 column is part of the casting and was turned on a lathe. If
        > it
        > > > was bent, I would expect to see a massive dent in the side. It may
        > > > look like a piece of pipe fit into a base but it is one piece, at
        > > > least on my mill.
        > > >
        > > > When I got my mill, I was faced with exactly the same problem. My
        > > head
        > > > was off about 0.015". Sure I could bring it back but the effort of
        > > > pulling it out of the basement, onto a truck, and back to Enco was
        > > > insane. After I got over the trauma of cutting through the Bondo
        > > that
        > > > covered the seam between base and column, the rest was easy. There
        > > is
        > > > certainly no guarantee that the next mill you get will be any
        > > better.
        > > >
        > > > Rick
        > >
        > > was your mill Taiwanese or Chinese. If it is normal for the
        > Taiwanese
        > > ones to be off by .004 in 6" as mine is then I am not really worried
        > > too
        > > much about the column, it is just that it is my understanding that
        > it
        > > was supposed to leave the factory in better shape.
        > >
        > > As for measuring the column that is a problem. The simplest is to
        > > remove
        > > the head and put my straight edge up against it which is supposed to
        > > be
        > > within .0015 of straight and as far as I can tell from my surface
        > > plate
        > > is somewhat better than that.
        > >
        > > And as for the next one being just as bad or worse, I would test it
        > at
        > > their place BEFORE I took mine out of the basement!
        > >
        > > mike
        > >
        > > ------------------------------------
        > >
        > > Yahoo! Groups Links
        > >
        > >
        > >
        > >
        > >
        >
        >
        >
        > ------------------------------------
        >
        > Yahoo! Groups Links
        >
      • Dragonflight
        I am told that the Taiwanese machines are supposed to be better - who knows. I am having fun with it, and now having a grand total of 5 months experience with
        Message 3 of 19 , Sep 13, 2009
        • 0 Attachment
          I am told that the Taiwanese machines are supposed to be better - who
          knows.
          I am having fun with it, and now having a grand total of 5 months
          experience with a mill, the small crown will not be my limiting factor
          when it comes to making things!

          mike

          PS remember precision is getting the same answer each time, accuracy is
          getting the right answer.

          and all of it is wasted if you can't measure it properly - doing my
          woodworking, despite the old adage of measure twice cut once, I always
          seemed to measure several times and still cut several times! ow well new
          machines to blame it on!

          On Sun, 2009-09-13 at 02:20 +0000, cnc4cheap wrote:
          >
          > Guys,
          >
          > One of the main things that you have to keep in mind when picking at
          > the precision? of these hobby machines is the quality and
          > characteristics of the iron used in the castings. The column was
          > probably true when at the completion of the machining process there
          > was stress relieved when the material was removed and that set in
          > motion a squirmming & worming process that has an effect on the
          > machines precision factor. I have forty plus years of experience
          > working with and on precision machinery and I have alot of experience
          > with various types of materials. I'm sure that most of you have heard
          > about Meehanite iron and you more than likely associate it with
          > machinery like milling machines and lathes. One of the key
          > characteristics of Meehanite iron is it's stability and it is that
          > characteristic that is lacking in the Chinese iron that is used in the
          > casting for these hobby machines.
          >
          > To the man with .0003 crown in his table, it just as well could have
          > been .003. Over my years I have built some very sophisticated projects
          > on Bridgeport milling machines that were probably in a heck of lot
          > worst shape. I have turned close tolerance bushings on worn out
          > bushing head lathes where I had to average several O.D. measurements
          > in order to hold tolerance.
          >
          > Now after stating all of that, I cannot believe that I actually
          > purchased a Chinese hobby mill. I know that it's going to drive me
          > nuts when I get around to Nit-Picking the precision aspects of the
          > machine.
          >
          > C4C
          >
          > --- In mill_drill@yahoogroups.com, "Rick Sparber" <rgsparber@...>
          > wrote:
          > >
          > > Mike,
          > >
          > > If you mount your vise so it sits solidly on the table with no crown
          > > lifting up an end, you can use softjaws to get an alignment that is
          > > the best that can be had on your machine. I can't cancel the tram
          > > error but will give you X and Z alignment assuming the vise is
          > > oriented with the crank facing forward. That accuracy will persist
          > > until you move the vise.
          > >
          > > For more on softjaws, see
          > >
          > > http://rick.sparber.org/Articles/sj/sj6.pdf
          > >
          > > You may notice that this article is on Version 6. That is because a
          > > large number of people in the community contributed insights and
          > > tricks. I have talked with many professional machinists that
          > routinely
          > > use softjaws during production runs. Such a simple idea yet
          > extremely
          > > useful.
          > >
          > > Rick
          > >
          > >
          > > -----Original Message-----
          > > From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com]
          > > On Behalf Of Dragonflight
          > > Sent: Thursday, September 10, 2009 8:18 PM
          > > To: mill_drill@yahoogroups.com
          > > Subject: RE: [mill_drill] measuring a mill's out of "tramness"
          > >
          > > Yes well I am not concerned about the head being out of tram, only
          > > that
          > > if I fix it at one point it is far off at another point because of a
          > > bent column.
          > >
          > > as for the table most of the error is at the front edge, between the
          > > tslots the crown is more like .0003". Luckily most stuff I do is in
          > > the
          > > vise so I just have to be careful how I install/shim? the vise. As
          > > always forewarned is forearmed. I may swap tables if the crowning is
          > > out
          > > of spec - they may say less than 1 thou is within spec
          > >
          > > mike
          > >
          > > On Thu, 2009-09-10 at 19:53 -0700, Rick Sparber wrote:
          > > >
          > > > Mike,
          > > >
          > > > If you do test the column with a straight edge, I assume you will
          > > run
          > > > the edge all the way around it since the head grips the column in
          > at
          > > > least 3 places.
          > > >
          > > > My mill came is a big crate. No chance of easily seeing it until I
          > > got
          > > > it home.
          > > >
          > > > IMHO, I would be more concerned about your crowned table than the
          > > head
          > > > being out of tram.
          > > >
          > > > Rick
          > > >
          > > > -----Original Message-----
          > > > From: mill_drill@yahoogroups.com
          > [mailto:mill_drill@yahoogroups.com]
          > > > On Behalf Of Dragonflight
          > > > Sent: Thursday, September 10, 2009 7:46 PM
          > > > To: mill_drill@yahoogroups.com
          > > > Subject: RE: [mill_drill] measuring a mill's out of "tramness"
          > > >
          > > > On Thu, 2009-09-10 at 18:42 -0700, Rick Sparber wrote:
          > > > > 09/10/09 18:34
          > > > > How do you plan to measure a column that has been bent a few
          > thou?
          > > > My
          > > > > RF30 column is part of the casting and was turned on a lathe. If
          > > it
          > > > > was bent, I would expect to see a massive dent in the side. It
          > may
          > > > > look like a piece of pipe fit into a base but it is one piece,
          > at
          > > > > least on my mill.
          > > > >
          > > > > When I got my mill, I was faced with exactly the same problem.
          > My
          > > > head
          > > > > was off about 0.015". Sure I could bring it back but the effort
          > of
          > > > > pulling it out of the basement, onto a truck, and back to Enco
          > was
          > > > > insane. After I got over the trauma of cutting through the Bondo
          > > > that
          > > > > covered the seam between base and column, the rest was easy.
          > There
          > > > is
          > > > > certainly no guarantee that the next mill you get will be any
          > > > better.
          > > > >
          > > > > Rick
          > > >
          > > > was your mill Taiwanese or Chinese. If it is normal for the
          > > Taiwanese
          > > > ones to be off by .004 in 6" as mine is then I am not really
          > worried
          > > > too
          > > > much about the column, it is just that it is my understanding that
          > > it
          > > > was supposed to leave the factory in better shape.
          > > >
          > > > As for measuring the column that is a problem. The simplest is to
          > > > remove
          > > > the head and put my straight edge up against it which is supposed
          > to
          > > > be
          > > > within .0015 of straight and as far as I can tell from my surface
          > > > plate
          > > > is somewhat better than that.
          > > >
          > > > And as for the next one being just as bad or worse, I would test
          > it
          > > at
          > > > their place BEFORE I took mine out of the basement!
          > > >
          > > > mike
          > > >
          > > > ------------------------------------
          > > >
          > > > Yahoo! Groups Links
          > > >
          > > >
          > > >
          > > >
          > > >
          > >
          > >
          > >
          > > ------------------------------------
          > >
          > > Yahoo! Groups Links
          > >
          >
          >
          >
          >
          >
        Your message has been successfully submitted and would be delivered to recipients shortly.