Hi everyone, here I am, a french man living in Egypt ready to join the mpcnc club!
First question (I guess a lot more to come!), as stainless steel pipes are very expensive there, and the steel one are …hummm…almost round, I was thinking to use 1’ OD ppr tubing with midpoint support?
Is it a good idea? anyone tried it before?
Thanks for your help!
Hi,
I’m not an expert on these particular plastic pipes, but do work in the plumbing industry and have some experience with that material.
Other than the obvious accelerated wear from the bearings as it is a much softer material(though reasonably tough as plastics go), biggest problem I guess is flex, even with mid span support I think it would be a lot and in the x/y sections, would almost certainly be unusable.
Plus the general idea is to turn the pipe when wear occurs, I think the supports would have to be bolted to the pipe so not long until you have more holes than pipe.
Can you get a piece of PVC pipe in Egypt to just experiment with, like the US sch40 for example, that is generally very cheap and is both stiffer and harder than polyprop?
A 600-1000mm length clamped over 2 feet with the roller installed would be enough for you to experiment with and cost should be (at least I hope) minimal.
It would be interesting to see exactly what you could achieve, what would happen with plastic long term, but I guess that is easy to say when someone else has to pay for the materials 
The bearings can deform stainless tube, plastic won’t stand a chance. Also like someblokefromtheinternet said, they’re too flexible.