The reason i said that the 20mm profiled rail is most likely an overkill, was based on the design of the machine and what he is machining.
This is just an estimation because no real data is available, but the the basic loading of the BRH15 is 850kgf (dynamic) and the BHF20 is 1450kgf.


How much load will machining small pieces of ali impose on the bearing?

I cant imagine it is anyware near what the bearings is capable of?



Quote Originally Posted by Kip View Post
How is it overkill to use 20mm rail....As far as using a single carriage...forget the notion......Check the spec sheets for details/differences between manufacturers parts.

Bearing in mind that cutting forces have to go somewhere and the bearing surface on linear bearings is very small compared to oilite bushes and dovetails......