Quote Originally Posted by JAZZCNC View Post
TBI are decent enough linear rails and I still wouldn't expect them to wear out like this, also those cutting parameters while at the limit of the spindle shouldn't be anywhere near affecting the linear rails.
If the machine cannot handle 2.2Kw or 3Kw spindle then it certainly won't handle a 6.6Kw HSK63 spindle and just fitting larger rails may not be enough. I would look carefully at the machine to see if can find any other cause for the rails wearing out in that manner because I'm pretty sure it's not just because you have moved the ball-screw position. That large spindle will quickly find any weak areas and you could be back to square one chasing issues.
If the machine is using this design - http://www.mycncuk.com/threads/10118...2769#post82769 I'd say it'll be putting quite a lot of leverage on the rails through cutting forces.
Looking at the diagrams, it must be verging on a 2:1 leverage between the lower trucks and the upper trucks, which I'd guess will be pushing 15mm rail to their limits.
However I'd probably look at doubling up the 15mm rails, rather upsizing given the design.