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

Re: [taigtools] Lathe Cross slide backlash

Expand Messages
  • Tony Jeffree
    No problem. Regards, Tony ... [Non-text portions of this message have been removed]
    Message 1 of 30 , Apr 2, 2013
    • 0 Attachment
      No problem.

      Regards,
      Tony
      On Apr 1, 2013 10:04 PM, "chuck" <chuckels@...> wrote:

      > thanx Tony,
      > I stand corrected.
      > Chuck
      >
      > ----- Original Message -----
      > From: Tony Jeffree
      > To: taigtools
      > Sent: Monday, April 01, 2013 4:17 PM
      > Subject: Re: [taigtools] Lathe Cross slide backlash
      >
      >
      >
      > Chuck
      >
      > Don't confuse the direction of movement with the direction of the cutting
      > forces acting on the tool.
      >
      > When the tool is cutting metal there is always a component of the cutting
      > force that acts in the direcion of the operator, which takes up the
      > backlash in the cross-slide feed screw. The rest of the cutting force
      > acts
      > in the axis of tge leadscrew, either to the right if cutting on the left
      > flank of the tool, or to the left if cutting on the right flank. So cross
      > slide backlash is always taken up in one direction whereas the direction
      > that leadscrew backlash is taken up depends on which flank of the tool is
      > doing the cutting.
      >
      > Regards,
      > Tony
      > On 1 Apr 2013 20:37, "chuck" <chuckels@...> wrote:
      >
      > > Tony,
      > > I would think it would be more of an issue on the cross slide (X axis)
      > and
      > > not the lead screw (Z axis).
      > > when I have watched turning a profile on a piece of stock the Z axis is
      > > moving toward the chuck in one continuous motion while the X axis is
      > moving
      > > in and out reversing direction along the profile than backing away and
      > the
      > > Z moves back to the start to take another cut.
      > > this would make backlash more critical on the cross slide (X axis) I
      > would
      > > think. am I not correct?
      > > I have not done any cnc on a lathe yet but have watched others, it just
      > > seems right.
      > > feel free to correct me if I'm way off base.
      > > Chuck
      > >
      > > ----- Original Message -----
      > > From: Tony Jeffree
      > > To: taigtools
      > > Sent: Monday, April 01, 2013 2:19 PM
      > > Subject: Re: [taigtools] Lathe Cross slide backlash
      > >
      > >
      > >
      > > ...but only a problem on the leadscrew, not the cross-slide.
      > >
      > > Regards,
      > > Tony
      > > On 1 Apr 2013 18:03, "Ron Thompson" <ron@...> wrote:
      > >
      > > > CNC is capable of contour cuts, like in a chess pawn. So, yes,
      > backlash
      > > > can be a problem.
      > > >
      > > > On 4/1/2013 12:11 PM, Paul J. Ste. Marie wrote:
      > > > >
      > > > > On 3/31/2013 9:58 AM, Tony Jeffree wrote:
      > > > > > because going from
      > > > > > cutting up to a peak to cutting dowwn to a valley there is a
      > > reversal
      > > > in
      > > > > > the direction in which the leadscrew backlash is taken up.
      > > > >
      > > > > Are you talking about the carriage or the cross slide?
      > > > >
      > > > > Either way, on a lathe, I would expect the cutting force to always
      > > take
      > > > > up the backlash in the same direction. The exception would be in
      > the
      > > > > carriage if you went from a right-hand cut to left-hand cut, but
      > that
      > > > > would require a tool change and thus again backlash is a non-issue.
      > > > >
      > > > > Am I missing something here? Even with something like a recessed
      > > face on
      > > > > a flywheel, you still need to change the tool setup between the
      > > inside
      > > > > of the outer circumference and the outside of the hub.
      > > > >
      > > > >
      > > > >
      > > > > No virus found in this message.
      > > > > Checked by AVG - www.avg.com <http://www.avg.com>
      > > > > Version: 2012.0.2240 / Virus Database: 2641/5718 - Release Date:
      > > 04/01/13
      > > > >
      > > >
      > > >
      > > > --
      > > >
      > > >
      > > > Ron Thompson
      > > > On the Beautiful Florida Space Coast, right beside the Kennedy Space
      > > > Center, USA
      > > >
      > > > Think, Draw, Print. 3D printers ROCK!
      > > >
      > > > http://www.plansandprojects.com/My%20Machines/PrusaMendel2012-1/
      > > >
      > > > http://www.plansandprojects.com My hobby pages are here:
      > > > http://www.plansandprojects.com/My%20Machines/
      > > >
      > > > Visit the castinghobby FAQ:
      > > > http://castinghobbyfaq.bareboogerhost.com/
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > > [Non-text portions of this message have been removed]
      > > >
      > > >
      > > >
      > > > ------------------------------------
      > > >
      > > > To Post a message, send it to:
      > > > taigtools@yahoogroups.com
      > > >
      > > > To Unsubscribe, send a blank message to:
      > > > taigtools-unsubscribe@yahoogroups.com
      > > >
      > > > Let the chips fly!
      > > > Yahoo! Groups Links
      > > >
      > > >
      > > >
      > > >
      > >
      > > [Non-text portions of this message have been removed]
      > >
      > >
      > >
      > >
      > >
      > > [Non-text portions of this message have been removed]
      > >
      > >
      > >
      > > ------------------------------------
      > >
      > > To Post a message, send it to:
      > > taigtools@yahoogroups.com
      > >
      > > To Unsubscribe, send a blank message to:
      > > taigtools-unsubscribe@yahoogroups.com
      > >
      > > Let the chips fly!
      > > Yahoo! Groups Links
      > >
      > >
      > >
      > >
      >
      > [Non-text portions of this message have been removed]
      >
      >
      >
      >
      >
      > [Non-text portions of this message have been removed]
      >
      >
      >
      > ------------------------------------
      >
      > To Post a message, send it to:
      > taigtools@yahoogroups.com
      >
      > To Unsubscribe, send a blank message to:
      > taigtools-unsubscribe@yahoogroups.com
      >
      > Let the chips fly!
      > Yahoo! Groups Links
      >
      >
      >
      >


      [Non-text portions of this message have been removed]
    • Paul J. Ste. Marie
      ... Isn t the force from the lathe always pushing the tool away from the work? I ve never noticed any tendency for the tool to dig into the work running by
      Message 2 of 30 , Apr 3, 2013
      • 0 Attachment
        On 4/1/2013 10:03 AM, Ron Thompson wrote:
        > CNC is capable of contour cuts, like in a chess pawn. So, yes, backlash
        > can be a problem.

        Isn't the force from the lathe always pushing the tool away from the
        work? I've never noticed any tendency for the tool to dig into the work
        running by hand, although I haven't turned any brass on the lathe.

        Typical lathe tools only cut one way in Z, so lead screw backlash isn't
        usually going to be an issue, either.
      • Tony Jeffree
        Paul - See my posts earlier in this thread. You are right about the cross-slide backlash, and right about most plain turning operations, but if you were
        Message 3 of 30 , Apr 4, 2013
        • 0 Attachment
          Paul -

          See my posts earlier in this thread.

          You are right about the cross-slide backlash, and right about most plain
          turning operations, but if you were cutting a contour where the tool
          changes from cutting on one flank to cutting on the other (e.g., a chess
          piece), then although the Z travel would be all in one direction, the
          cutting force on the tool would change directions as the cutting action
          changes flanks. At the point where the direction of the cutting force
          reverses, the direction in which any leadscrew backlash is taken up also
          reverses. This is exactly the same problem you get with a milling machine
          when you try to mill a circular path and you have backlash in the X and/or
          Y feeds. The reason that it is not a problem with the cross slide is that
          (for obvious reasons) you never switch from cutting on the nose of the tool
          to cutting on its back end.

          Regards,
          Tony


          On 3 April 2013 18:21, Paul J. Ste. Marie <taig@...> wrote:

          > On 4/1/2013 10:03 AM, Ron Thompson wrote:
          > > CNC is capable of contour cuts, like in a chess pawn. So, yes, backlash
          > > can be a problem.
          >
          > Isn't the force from the lathe always pushing the tool away from the
          > work? I've never noticed any tendency for the tool to dig into the work
          > running by hand, although I haven't turned any brass on the lathe.
          >
          > Typical lathe tools only cut one way in Z, so lead screw backlash isn't
          > usually going to be an issue, either.
          >
          >
          >
          > ------------------------------------
          >
          > To Post a message, send it to:
          > taigtools@yahoogroups.com
          >
          > To Unsubscribe, send a blank message to:
          > taigtools-unsubscribe@yahoogroups.com
          >
          > Let the chips fly!
          > Yahoo! Groups Links
          >
          >
          >
          >


          [Non-text portions of this message have been removed]
        • Paul J. Ste. Marie
          ... How does that work? Tool with zero side rake? IIRC that s how Taig grinds their round v-nose tool, but my experiences with that tool have been less than
          Message 4 of 30 , Apr 5, 2013
          • 0 Attachment
            On 4/4/2013 5:06 AM, Tony Jeffree wrote:
            > if you were cutting a contour where the tool
            > changes from cutting on one flank to cutting on the other (e.g., a chess
            > piece), then although the Z travel would be all in one direction, the
            > cutting force on the tool would change directions as the cutting action
            > changes flanks.

            How does that work? Tool with zero side rake? IIRC that's how Taig
            grinds their round v-nose tool, but my experiences with that tool have
            been less than stellar.

            I haven't done any CNC on the lathe, but for something like the little
            flange under the head of a chess piece I'd expect to do two passes, one
            from the right, a second from the left, and switch out tools in between.
          • Tony Jeffree
            Use a V tool (e.g., a thread cutting tool). Regards, Tony ... [Non-text portions of this message have been removed]
            Message 5 of 30 , Apr 5, 2013
            • 0 Attachment
              Use a V tool (e.g., a thread cutting tool).

              Regards,
              Tony


              On 5 April 2013 18:44, Paul J. Ste. Marie <taig@...> wrote:

              > On 4/4/2013 5:06 AM, Tony Jeffree wrote:
              > > if you were cutting a contour where the tool
              > > changes from cutting on one flank to cutting on the other (e.g., a chess
              > > piece), then although the Z travel would be all in one direction, the
              > > cutting force on the tool would change directions as the cutting action
              > > changes flanks.
              >
              > How does that work? Tool with zero side rake? IIRC that's how Taig
              > grinds their round v-nose tool, but my experiences with that tool have
              > been less than stellar.
              >
              > I haven't done any CNC on the lathe, but for something like the little
              > flange under the head of a chess piece I'd expect to do two passes, one
              > from the right, a second from the left, and switch out tools in between.
              >
              >
              >
              > ------------------------------------
              >
              > To Post a message, send it to:
              > taigtools@yahoogroups.com
              >
              > To Unsubscribe, send a blank message to:
              > taigtools-unsubscribe@yahoogroups.com
              >
              > Let the chips fly!
              > Yahoo! Groups Links
              >
              >
              >
              >


              [Non-text portions of this message have been removed]
            Your message has been successfully submitted and would be delivered to recipients shortly.