Thread cutting in chinese ballscrew

[Neale]

Typically, the outside of these ballscrews is very hard, but the hardness is just a skin and the core is relatively soft. If you are talking about putting a thread on a plain end of a ready-machined ballscrew, then that would probably be OK (tough-ish steel but machinable) but I wonder why you would do this? Usually, this is where the pulley goes and you want that to be a close sliding fit on the ballscrew. A thread is most definitely not a good surface to bear on, and a thread cut by a die is very, very unlikely to be square to the shaft. OK for simple nut-and-bolt type work, but not if you are looking for accuracy/parallelism/concentricity, etc.

Some people talk about being able to turn the end of ballscrews with carbide tools and get under the hard skin; others soften the end first before machining. However, that is to turn the end down to the nominal 10mm or whatever, and if you are doing that then you would also be in a position to screwcut the thread on a lathe. A machine that justifies ballscrews justifies decent machining of those ballscrews or you are just throwing away accuracy.

But maybe you have something else in mind? Not sure what the real requirement is here.