[j2sip]

I'm about to buy these (used) but is the 15mm rail size ok for the Z? And I'm afraid I can find more of these and be tempted to use 'em for all axis. This is my machine, cutting wood and maybe aluminum(when I get a more appropriate spindle)
DIY CNC router Build log

The Z will be replaced with aluminum when the linear bearing upgrade will come; Geck0 G540 will replace the hobbycnc driving 1/2-8 5 start Roton screws.

Is 20mm more suitable? 25mm are rare and doesn't come in long lengths.

Thank you in advance.

JOrdan

[ger21]

15mm are more than strong enough for that machine, for all axis. The only real issue with 15mm is that they are really small, and use very small bolts for mounting.
20mm can be easier to work with, mainly due to the larger bolt sizes.

[j2sip]

I just called the supplier and THK HSR15 are available. From reading in the zone these are better than the NSK LS15 or the THK SR15 as they can take loads from all direction. My cnc router is small anyway, so I guess I can live with the mounting problem. It needs just 40inch and 48inch rails.

Thanks for the quick reply, as always..

JOrdan