Super simple preloaded ballscrew design - It Works!

[jimjovan]

After looking at the other pre-loaded ballscrew designs out there, I think I've found an easier solution.

Just thought I'd post my design for making a simple preloaded ballscrew. There is only one part to machine, five wave washers (from McMaster), and a SHCS to keep the nut from rotating.

The only drawback I've found is that it's hard to near impossible to align both nuts so that their ball returns are on the same side. In most cases, I don't think it will matter.

As for seals, I used the hot glue and lubed shaft trick I learned about on this site.

For the X-axis I combined the ballscrew preload into the X-axis mount and tapped the mount for a future lubrication system (should have taken a photo, sorry).

I've learned a lot lurking on this site and I thought I should at least contribute (I hope the attached photos work).

Thanks,

Jim

[sendkeys]

nice job Kind of wish my ballnuts weren't round hehe

[Bubba]

Jim,
I did basically the same thing except I added one more part. I have an "adjuster nut" on the trailing ballnut and use a sockethead screw through the adjuster nut into the rectangular socket. My wave washers are captured between the rectangular socket and the lead nut. Then the trailing ballnut is run up to the whole sandwich (just snug and lined up), the adjuster nut is then tightend to the proper spec and "pinned" by running a socket head screw through the adjuster nut into the rectangular nut and then a setscrew is tightened into the trailing nut so it won't back out. A picture can be seen on my web site noted below.

Bubba

[ViperTX]

There is a recommended orientation for the ball return tubes...checkout the THK site.

[jimjovan]

Yes, I know they should be oriented so the returns are on the bottom, but with the Z axis it's irrelevant.

[JFettig]

I had a few ballnuts laying around, now on the screw that I will soon be using for my lathe, to preload them I took a 3/4" thick chunk of aluminum, threaded it and screwed both of them into it and put it on the screw. Aluminum has set screws in it too and other holes for mounting. Basicly I just rotate the nut untill I like the amount of preaload and I tighten the setscrew. Its really not the best way to do it, but it works.

I like your way a little better, but it was what I had at the time, wanted to try it without spending a lot of money on it. Is there a reason one of the nuts doesnt have the threaded part on it still? did you mill/turn it off?

I have been using the hot glue wipers for a while and like them a lot, although one of them fell off its still going good(its on the X axis under the table, no chips so its good still.)

Jon

[FLUTE HEAD]

couldn't the wave washers be excluded? What if both ballnuts sandwhiched a single plate, with one side of plate being slotted as you have shown. Then tighten to your liking. Maybe i'm thinkin about this wrong but heres a .bmp to comment on.

[jceg]

Originally Posted by FLUTE HEAD couldn't the wave washers be excluded? What if both ballnuts sandwhiched a single plate, with one side of plate being slotted as you have shown. Then tighten to your liking. Maybe i'm thinkin about this wrong but heres a .bmp to comment on.

Is the point of the washers to add the pre-load to the two ballnuts in opposite directions on the ballscrew? Im a total newbie to ballscrews, but Ive been doing research on them for a refurbish of an old army rockwell/delta mill I recently bought.

Jimjova: Could you possibly post a simple cross section of your design? Im trying to wrap my brain around it and not quite getting it.

[balsaman]

The washers are to add a preload and also account for any imperfection in the rolled ball screw pitch thoughout the length.

Eric

Originally Posted by jceg Is the point of the washers to add the pre-load to the two ballnuts in opposite directions on the ballscrew? Im a total newbie to ballscrews, but Ive been doing research on them for a refurbish of an old army rockwell/delta mill I recently bought. Jimjova: Could you possibly post a simple cross section of your design? Im trying to wrap my brain around it and not quite getting it.

[FLUTE HEAD]

Let me think about this on a simple example. If I take a threaded rod and sandwich a nut on both sides of a plate and snug them up, now I would assume zero backlash without wave washers. If I were to add wave washers to that same assembly, I assume it would make tightening the two nuts much easier. I'm just thinking out-loud. Any comments? Oh, by-the way, on my previous design the ballnut on the right side needs to be reversed so that it threads into the housing, to hold the assembly centered.