• Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.

Big auction in October- Vancouver Island -Includes Modern BL-1340 Lathe, milling machine, laser, CNC stuff, etc...

Educate me here. Why would a ball screw ruin manual work vs ACME lead screw? I would have thought that to be an upgrade, particularly when climb milling!
 
garball said:
Educate me here. Why would a ball screw ruin manual work vs ACME lead screw? I would have thought that to be an upgrade, particularly when climb milling!
Click to expand...
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. :)
 
VicHobbyGuy said:
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. :)
Click to expand...
You've got it right.
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 said:
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. :)
Click to expand...

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.
 
Last edited:
This is manual machine with added CNC stuff that is not complete. Machine is fully manual capable from the pictures. Adding actual CNC may take some work.
 
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.
 
You must log in or register to reply here.
Back
Top