[ack1]

Anyone done this ?
Im running rexroth ones and the machine is 20 years old soon so I thought id replace the blocks or perhaps just replace the balls since the blocks are in good condition. Perhaps a slight preload too.

Bad idea ?

[firepong]

I have done this with some knock-off Hiwin rails. Usually, the bearings are what goes out first instead of the rails (Unless the rails are not hardened). I know the rexroth are hardened rails, so you should be relatively fine trying a bearing replacement.

What you need to do is pull the blocks apart and take a mic to all the balls in that block. Get an average size from them and then search the web for the correct size needed.

Instead of ordering enough to do them all at once, order enough for one block and try them out. Depending on how much slop is in each block, you might have to get varying sizes. Just a heads up though, you can only go as big as the bearing channels of the block, and even then, you do have to have enough clearance for the bearings to move freely without hindrance.

In my 15mm rails, instead of getting stainless steel bearings (at a size of 3.15mm), I went ahead and got some ceramic coated bearings in the same size. Made a hell of a difference on the machine use wise. Stiffened the blocks up a lot (and very noticeable) compared to the previous bearings. I don't know how long they will last because ceramic is nearly 3x harder than stainless steel, possibly putting more wear on the rails. If that is true though, I can always buy more rails and blocks when they wear more than what is acceptable. I have made my money back on them, so it is fine in my book.

[ack1]

Thanks for the reply. I think might order 1 block with some preload and then have a local ballscrew company compare and replace the balls in the others to match.They have that stuff in stock.
Im not sure, its a production machine so i might just be overly cheap by not just ordering new ones. But man its 12 of them..
Ill sleep on it.

Thanks