On Monday, 24 May 2021 at 20:13:55 UTC+1, Murmansk wrote:
I have a circular saw jig which I made myself and it uses bits of aluminium which are L shaped in cross section for the saw to run in.

I'd like to make a better one with longer "rails" and rather than using the L shaped strips, which tend to sag, I'd like to use tubing and I know you can get some things that run along tubing and probably have ball bearing in, but I can't remember what they're called.

Can anyone tell me what these are called please so I can look them up online

Linear bearings.

https://www.automotioncomponents.co....rom-automotion

Tons and tons on ebay and ALiExpress, etc.

You might find you need to use solid rather than tube - but that is way down the line!