Design question regarding ballscrew and bearings

Hi

This is my second post, including the welcome post :)
I have been reading the forums alot, especially the huge post the one user made to explain ballscrews. I can't find the URL now

I am designing a machine and I was wondering if the ballscrew shaft needs to sit flush with the BK bearing or is 1mm distance fine? I would prefer 1mm distance, because I don't know if the rest of the machine will be cut, from t-slot aluminium, as perfectly as the shaft

The pictures might explain better what I mean

In this image the shaft has been machined in the recommended way by the supplier. The shaft goes from 20mm down to 15mm down to 12mm. My question is, does the 20mm part of the shaft need to touch the bearing inside the housing?
Attachment 213212

This is the image zoomed in a bit
Attachment 213214

Thank you

Well I'm hardly an expert, but I can tell you my experience. I purchased my ball screws and supports from Misumi. Included was a sleeve that went in between the (in your case) 20mm and the bearing in the support. And then on the opposite side of the bearings is another sleeve and then a lock nut to capture the ball screw in the bearings.

I hope this makes sense. Here is a link to the ball screws I got from Misumi.
Rolled Ball Screw - Thread Diameter 15- Lead 5,10 or 20 - Precision Grade C7 or C10?MISUMI?Product Specifications

Rick

Cool. So if there is a gap after assembly I might just print something like a sleeve or a big washer to fill the gap

That would make sense to me.