I’m new here in the forums but already did a lot of reading and finally want to build my own MPCNC (even though that means making some space in my basement).
Big would be optimally 3,5"7" (100210cm), but I think I could do with something smaller (say 2"5" / 60cm150cm).
Tubing I would use 25mm OD and 2mm (0,079") wall thickness stainless steel.
There were big MPCNC builds, then the LR came, but now the Primo is here. I was thinking about using 1-3 support feet on the long side (drill a hole, put a nut trap in, screw the support foot/feet down to not just reduce sag but also vibration). Could even do one on one of the shorter sides, the other one would be nice to have open for loading it with material.
Wood is the maximum I would do with it, main goal is to cut through high-density fiberboards. But (hopefully) plenty of them, and the LR looks like it needs more constant readjustment than the Primo.
What are your thoughts, should I just go for the LR and let the Primo be or is it worth a shot?
The Primo has only been out two weeks and we only have 3-4 of them running. There’s no way this statement can be made at this time as we have no idea of the longevity of the Primo.
The truth is, the lowrider was designed to be used for larger cut sizes. The MPCNC was always designed for smaller. A 3.5’ x 7’ MPCNC would be way too big. Especially on the 7’ section. It’s not just the length of the side rails that causes the problem, but the weight on the center of the gantry. in the middle of the machine it would be sagging quite a bit causing your Z to be off. This would lead to a larger DOC in the center than along the edges causing all types of issues. I think 3’ x 3’ is the largest that Ryan recommends.
I would like have read these comment before, I have already built a PRIMO 8’ x 5’, at the moment everything seems to be rigth, but I have not tried any large cut, just medium size cuts.
Trying to avoid sagging I have put some levelers and I have filled 8’ axis with epoxic resin in order to gain some rigidity (I don’t know if I really gain something or not).
Let see how it goes. This week I’m going attempt to prove it with a complete plywood sheet.
Don’t worry Ryan, I have read every of that links where you suggest don’t go bigger with MPCNC, I’m not complaining, mine works great. I have done two large cuts today, 12 mm plywood, and was pretty good for what I need it.