Used ballscrews

[quant]

Hi there,

As you all are well aware off, it is possible lots of used precision ground ball screws on ebay. This all seems very interresting but are these still worth something. These screws were used in industrial machines, so i suppose they have been used quite a lot since industrial machines don't often run iddel..

Anyway do you think that the fact that they have been used could introduce backlash or any other drawbacks?
Have any of you bought and used such ball screw assembly?
And what about the precision bearing with support?

Thank you kindly,
Quentin

[NC_jimbo]

Boy there are loads of them from China/Singapore. I take the worse case assumption that these things wouldn't be pulled from a Chinese CNC until they are well worn out.

OTOH, it's possible that these are being pulled on scheduled refreshes and there could be some reasonable life left. I guess that would be the best case.

There's plenty of people buying them though and if your expectations are reasonable enough they probably will always be better than some homemade thingy and so if you get it at 5% of retail price, it probaly makes reasonable sense. I guess you could always do a ball refresh on them too. I'd love to hear from people who bought some. Tyically they are NSKs with C1-C7 ratings.

[RICHARD ZASTROW]

I suppose the used ballscrews could be re-ground and fitted with proper sized balls. If, after all additional expenses are included, that still results in a cost savings, why not? Be aware there are other "devils" in the details. Bent screws, either from your source or shipping, will need straightening. Do the ends fit your requirements? If not, what then? Modifications may be difficult (expensive) for the screw or the bearing housing(s). Still, being informed of those "devils" could result in a good buy. Buyer Beware. Good Luck

[Stepper Monkey]

I have had great luck in the many ballscrew purchases I've made so far. I've been able to pin down the origin of the used equipment I have bought, however, as I have gotten it from industrial surplus dealers - something you can't really do on Ebay.
It may cost more to go through brokers, sometimes even double or more, but in the end it still gets you equipment at pennies on the dollar and the lack of surprises and headaches actually makes it average out much cheaper in the long run. You can pick through WHY they have the equipment, and in some cases it is new or nearly new from anything from bankruptcies to changing production methods (ROHS put a lot of good fixtures out on the curb regardless of thier age). Also, they know what they are selling and can guarantee suitability to purpose, which is more than Ebay sellers can.

I would tend to agree that a lot of stuff coming from China or Singapore would probably have had every last bit of usefulness worn out of it if indeed it was running in a company over there, unless the sellers are simply recyclers breaking containerloads of US scrap and selling off the nice bits we didn't take the time to pull - which happens a LOT. I still wouldn't want to take the chance though.

[NC_jimbo]

"industrial surplus dealers" and "brokers"

Web based? Local places to you? Names?

[quant]

Ok, so from what I understand the china and singapoore sellers don't seem like a real good solution.. That was I though to.. too bad..

But what about your reseller??
Does anyone else has any experience with buying used, or greatly underprised, ball screws with any succes??

Grtz

[maxcontrol]

Hi all, I'm from Singapore. And had successfully built a 3 axis cnc machine using recycled THK KR33A. I tried to measure the backlash but off hand I only have a 10 micron resolution Mitutoyo digital dial gauge. I could not detect any backlash hence I think they are below 10 micron. I was able to physically view the parts before purchasing, and it was really worth it. At the price I purchased, I can't even make a new set of linear axis with proper LM guides and acme screw. If anyone is interested, I could help.