[wildwestpat]

Hi Michael

The housing for 5xxx bearings is simple as they do not require to be press fitted. The tolerance on the bore of the housing and the shaft are H6 and h6 respectively which means that a tight slip fit and some Locktite would be OK. Here is a GA of the mount I have been using which is a bit more elaborate on a small mill. The estimated load is arround 50Kg. The bearings I am using in these mounts are the sealed RS type.

Keeping it simple the alternatives are flanged deep row ball bearings bearings using a threaded shaft to trap / pre-load the bearings into a simple bore. Then there are a number of improvements right through to matched pairs of high pecision angular contact bearings.

But please do work back from the tolerance requirements of the finished product through the various sources that add errors. Then look at the bearing specs and consider price.

Hope this helps. Regards - Pat

[michaelthomas]

Yes....that was helpful. Thank you.

[CarbideBob]

I view the ball screw support bearings as part of system where tolerances stack up. Axial clearances of the ball screw/nut, support bearings, flex in mounts, backlash in any gears or belts, stretch in belts, ball screw lead error etc. Each contributing to the total error.
Dick Z

Excellent comment, and all items adding a different type of error to the system.

Since we don't know what the OP is building it's impossible to give a good answer.
There is a world of design difference between a wood router and a 5 millionths grinder.

I do miss NC Cams , he was quite a character with a ton of knowledge.
Bob

[michaelthomas]

We do know that the OP said he was OK with C7 grade screws, but got the C3's at a good deal. I think that probably rules out the worry of microns.

[RP Designs]

We do know that the OP said he was OK with C7 grade screws, but got the C3's at a good deal. I think that probably rules out the worry of microns.

Yeah, microns isn't an issue with this machine. It is a Smithy machine that I am trying to make into a useful lathe. I found a 14mm NSK ballscrew on ebay brand new in the package which I won for $79 delivered. best part is that it has machined ends and is pretty much a perfect fit for my machine. Considering I won't have to pay for any additional machining I think it was a great deal! Motion industries sells this ballscrew for $1500. I found the NSK fixed end nut to match this ballscrew for $80+ shipping and I will make the floating end since the bearing for that side are nothing special. The fixed end nut sells for $480 on MI as well so overall I am pretty happy with the purchase.