VicHobbyGuy
Ultra Member
https://bid.ableauctions.ca/VANCOUVER-ISLAND-ON-SITE-AUCTION_as84587_p7?
Location TBA but looks like up-island?
Location TBA but looks like up-island?
Big auction in October- Vancouver Island -Includes Modern BL-1340 Lathe, milling machine, laser, CNC stuff, etc...
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VicHobbyGuy
Ultra Member
So possibly ruined for manual work because the leadscrews were replaced with ball-type screws?
VicHobbyGuy
Ultra Member
I'm not fit to educate anybody about machining but I have read that ball screw mods to lathe cross slides have so little friction that without a stepper motor actng as a 'lock' on the end, the slide won't keep a setting....the weight of a standard handle will turn the screw. When I read that, it sounded like something a gib adjustment would correct, but I don't know.
I did pose the comment as a question, after all..but that didn't elicit an answer or explanation.
You've got it right.I'm not fit to educate anybody about machining but I have read that ball screw mods to lathe cross slides have so little friction that without a stepper motor actng as a 'lock' on the end, the slide won't keep a setting....the weight of a standard handle will turn the screw. When I read that, it sounded like something a gib adjustment would correct, but I don't know.
I did pose the comment as a question, after all..but that didn't elicit an answer or explanation.
On my CNC router with the steppers disengaged I can move all axis easily by hand. When they are powered up there's no moving them.
VicHobbyGuy
Ultra Member
Thanks, David.
I'm not fit to educate anybody about machining but I have read that ball screw mods to lathe cross slides have so little friction that without a stepper motor actng as a 'lock' on the end, the slide won't keep a setting....the weight of a standard handle will turn the screw. When I read that, it sounded like something a gib adjustment would correct, but I don't know.
I did pose the comment as a question, after all..but that didn't elicit an answer or explanation.
I saw your question and didn't reply because I am not really qualified to render an experienced response. But seeing how few have replied, I'll admit that I strongly considered putting ball screws into my Bridgeport before I sold it. I even priced kits to do it.
I read in many places that the low friction could be a problem. The handle weight is easily fixed by installing the x's 180 degrees from each other and balancing the Y handle as appropriate.
I found it hard to swallow (and still do) that low friction would be a serious issue. Lots of ways to use that to advantage and lots of ways to increase friction when/if it's required.
I never did hear a compelling reason not to. But I'm open to changing my view given solid advice to the contrary.
In the absence of that, I am still of the view that I would install ball screws on my Hartford Clone if the backlash ever became unacceptable.
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VicHobbyGuy
Ultra Member
Good to know; thanks...though machines like those are definitely 'out of my league'.
Its all about the pitch of the screw. My mill has 5.08mm/0.200" pitch ballscrews and backdriving the screws from cutting forces is not really a problem. You just have to be aware of it when coming up to a dimension. In those circumstances i use the table locks. It sure is nice to operate. Very smooth and zero backlash. On a lathe, I think it would be a pain in the ass, but, you now have a lathe. Build a new acme screw.....
I will second that . . . Darren.
After designing a few pipe corrugators with Ballscrew Drives to position the mould size tooling carriages . . . the PITCH of the screw will dictate whether you experience backdriving.
Plus, you are going to have a saddle and table with very little friction in the ways before you experience backdriving.
I used THOMSON Linear Bushings with hardened & ground guide shafts to ensure that the X and Y axis were maintained.
After designing a few pipe corrugators with Ballscrew Drives to position the mould size tooling carriages . . . the PITCH of the screw will dictate whether you experience backdriving.
Plus, you are going to have a saddle and table with very little friction in the ways before you experience backdriving.
I used THOMSON Linear Bushings with hardened & ground guide shafts to ensure that the X and Y axis were maintained.