On 2/27/2016 8:04 AM, Dave Cole wrote: > The nut and screw are matched to each other and then they fit the nut to > the screw with the proper sized balls. > Usually they are purchased together as a set and you really don't want > to take them apart unless it is necessary. > You can have screws reground - I think that Thompson and Nook others do > that in the US. > I suspect that if you have a "standard" screw you might be able to fit a > new nut to it, but then if the nut is shot, generally the screw also > needs help. > So what usually needs to be done is that the nut and screw need to be > reconditioned as a set. > I worked on a machine that had a bad screw and they got a quote from > Thompson or Nook to have the screw and nut reconditioned and I think it > was about half what a new > set would have cost.
Some of them have every other ball slightly smaller as a spacer to reduce turning friction. Unfortunately that also cuts load capacity. What some rebuilders do is replace all the balls with ones of the full size, or if the screw has to be ground more than usual they'll install larger than original balls. If you have a screw with even wear along its length and a willingness to experiment, and precise way to measure ball diameter, you can buy new balls on eBay real cheap. Choose some just a smidge larger than what was in it and see if the screw tightens up, without binding. There's probably some formula to select the ball size required based on measuring backlash etc, but the balls are cheap enough to buy more than one size. What I'd like to see is a precision and accuracy test of a new ground ball screw VS a high grade rolled ball screw VS a rebuilt with full grind rolled ball screw. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
