. .
Page 1 of 2 12 LastLast
  1. I have a Denford Easiturn and recently when taking a cut near the chuck instead of the cut being flat... it is wavey. The ballscrew is 25.. diameter x 5mm pitch and the cut mimicks the ballscrew e.g. it goes in for 5mm and the out for 5mm (or it get larger in diameter for 5mm then smaller in diamter for 5mm).

    Click image for larger version. 

Name:	lathecut.jpg 
Views:	65 
Size:	14.7 KB 
ID:	30298


    Has anyone any idea what causes this? Worn ballscrew? Worn bearings?

    thanks
    Every time I am wrong - the World makes a little less sense.

  2. #2
    AndyCD's Avatar
    Lives in Northampton, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 1-2 years. Has a total post count of 6.
    Have you tested to see if there's any vertical movement on the cutting tool? looks like something you might see if the tool was moving away from the center of the workpiece.

  3. Quote Originally Posted by AndyCD View Post
    Have you tested to see if there's any vertical movement on the cutting tool? looks like something you might see if the tool was moving away from the center of the workpiece.
    Hi, thanks for the reply. Sort of... I can't see any movement as such with a dial gauge, however I perhaps should have mentioned this only happens for the first 40mm (ish) from the chuck face. If I use a thicker bar with a tailstock and make a cut 70mm from the chuck face the cut is as smooth as a babies bottom - which why I was thinking worn ballscrew (coupled with the ballscreww being 5mm and the tramlines also being 5mm.

    thanks again for th reply.
    Every time I am wrong - the World makes a little less sense.

  4. #4
    AndyCD's Avatar
    Lives in Northampton, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 1-2 years. Has a total post count of 6.
    do you see the same behaviour (moving in & out from the workpiece) if you mount a DTI to your cross slide?
    just trying to rule out spindle play as well

  5. Hi, no the cross cuts are perfect.

    thanks again
    Every time I am wrong - the World makes a little less sense.

  6. #6
    AndyCD's Avatar
    Lives in Northampton, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 1-2 years. Has a total post count of 6.
    apologies, I meant run a dti down the length of your workpiece, as though you were taking a length cut
    I'm just trying to see if the behaviour is coming from the z screw or from forces being applied to the spindle

  7. Ah - cracking idea - will do.

    thank you
    Every time I am wrong - the World makes a little less sense.

  8. #8
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 18 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,745. Received thanks 331 times, giving thanks to others 8 times.
    If the carriage assembly is tight on the ways, then the ballscrew shouldn't affect the cut in that way.

    I'd be putting a DTI on the main carriage, and giving it a good lever to check for play.

    I can't think of the exact setup on the Easiturn, but it could be something like a slight wobble in the ballscrew, which combined with play, is enough to move the carriage on the ways.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  9. Yes, it moves with a clock on the main z-axis... going to check the main carraige and the fixing to it next.

    Every time I am wrong - the World makes a little less sense.

  10. #10
    You have wear in your ways close to the chuck, this kind of artefact is common in worn manual lathes.
    You think that's too expensive? You're not a Model Engineer are you? :D

Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Help on fault finding on a C3-31 Hammer combination machine
    By OMLCNC in forum Workshop & Equipment
    Replies: 49
    Last Post: 18-12-2017, 11:58 AM
  2. Opto isolated Bob and drivers causing a strange fault.
    By lucan07 in forum General Electronics
    Replies: 2
    Last Post: 02-05-2016, 08:28 PM
  3. Plasma cutting fault diagnoses....
    By Davek0974 in forum Plasma Table Machines
    Replies: 15
    Last Post: 01-04-2014, 06:04 PM
  4. CNC style lathe home brew Lathe for drilling and cutting.
    By Bodge in forum Lathes, Lathe Rebuilding & Conversions
    Replies: 9
    Last Post: 18-04-2012, 09:45 AM
  5. Looking for Lathe Cutting Tools
    By Zeeshan in forum Tool & Tooling Technology
    Replies: 2
    Last Post: 06-09-2011, 08:50 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •