Quote Originally Posted by m_c View Post
I had just assumed it was the Z-rails...

Y the load should be spread over a larger pivot, however, it'll do far more movement than the Z, so any dirt ingress/lubrication issues could wear it out quicker.
No, I'm pretty sure Matt had 15mm rails on the Y-axis and 20mm on X & Z. This is why I'm surprised they have worn.
I've got a machine with 20mm Hi-win rails that I bought second-hand 15yrs ago so could be the best part of 20yrs old which have been completely utterly abused and neglected with hardly any maintenance on a machine that solely cuts Aluminium and still the rails are not excessively worn.

It takes a lot of abuse to wear these rails and even thou 15mm I'd still expect them to last 4yrs on a machine which I'm sure isn't working in a production environment.