I am part of a small group building our first MPCNC, and while we thought things were going well, we’ve run into an issue where not all of the 4 Roller parts, have all their 5 bearings engaged which provides slop between the left and right rollers on an axis.
I’ve tightened up all combinations of the 5 bolts and nuts (actually all 7 when the motor piece is on it). Now we have cracked (3) some of the Rollers starting on the side with the two lower bearing positions, usually closer to the middle but sometimes a bit more to the left or right. The cracks must have been caused by some stress in the triangle of bearings, but even when glued in a clamp, there is a gap on one or more bearings on the conduit. I’m really at a loss as to what is going on.
I thought the gantry X&Y beams might be pulling the rollers and causing the issue, but that doesn’t make sense, when all 5 bearings are engaged nothing is going to knock it off the rails.
Lastly, I was able to make a part with it yesterday, which came out pretty good, but then I had seen the cracks in the rollers and noticed some jerkiness on the X axis so took out the 3 cracked rollers, glued them with CA clamped over night, tested this this morning with a short amount of conduit, they were all fine, all bearings engaged, but then when putting them back on the machine, I have rollers with loose bearings.
Lastly, today it started binding badly, steps were missed (on the Y axis), which is a new symptom, I moved the rails by hand and experienced the binding, but could not find the cause of it. Took the belts off the Y axis… rolls very freely and smooth, no binding, still not 100% engagement of the bearings… but it felt very good.
Specs of our machine;
3’ x 3’
6.5" spindle collet to table Z Axis
3/4Inch Canadian Conduit
X and Y Dual steppers are wired in series
Any thing else I’ve missed to provide please ask, looking for pointers here… before I start taking the whole thing apart.
Oh… and I’m printing a PETG roller right now… just to see…