[ahren]

Hi all,
I haven't seen any threads on this in the recent past, so I'll go ahead and ask. I'm building a new machine and just got some rolled ball screws off of ebay for cheap. They don't have anything in the way of end machining. While I have access to a lathe, it isn't a very good one, so I'm trying to figure a way to avoid turning down the hardened screw. My crap lathe does do one thing pretty well, which is drill concentric holes.

So, I was thinking about making a rigid coupler ~3" long that basically converts from the 16mm ballscrew outer diameter (about 2" of the coupler would be this size), to a 1/2" hole. I would run a 1/2" precision shoulder bolt through from the ballscrew side, using the 1/2" deep groove bearings I already have, and the thread from the shoulder bolt to install a nut and wave washer for a light preload. I'd use a bunch of set screws to clamp everything together.

Has anyone ever done anything like this before? I'm not looking for uber accuracy out of these screws (as you can probably tell by my lack of angular contact bearings) -- I got them mostly for the increased efficiency over the 1/2-10 ACME I'm currently using (higher pitch and less friction, hopefully). I have attached a diagram to try and show what I'm talking about below. Your thoughts are greatly appreciated!

[chuckknigh]

I remember a thread about this, either here or on DIY-CNC. The gist of it, is that instead of machining the ends of the screws, the person made a sleeve that could be fixed to the *outside* of the ballscrew, which acted as a coupler.

I believe it worked quite well.

-- Chuck Knight

[ViperTX]

Yes, Home Shop Machinist's Roland Friedstad has had several articles where he described that as the method he prefers.

[mlaws1172]

You don't have to turn the ends as hardened steel. Heat up the end red hot and let cool natural. Don't cool with awet rag or anything else. Now it is turnable.
mike