Low Rider 3 y axis belt holder with adjustable endstop target

During stress testing I discovered that it was necessary to modify the y axis belt holder. With this new design, the belt is installed by wrapping the belt around the stationary pulley and pressing the cover onto the holder. If needed, table squaring could be fine tuned by about 24mm without needing to move the belt holder.


Looks neat, cheers for sharing. Curious what problem/behavior you were noticing that inspired the mod?

Personally created a remix of the Y tensioner block to help reduce time required to move my LR3 between different sizes tables (will update with link soon incase others have similar need).

Thank you! For a number of reasons I printed all parts in petg. The core and most parts were sufficiently rigid due to their thickness. However the y axis blocks were flexible and the nut traps did not prevent the hexagonal nut from rotating. During stress testing one of the belt holders popped off of the base resulting in a spectacular slow motion catastrophe. A temporary solution was to drive 3 inch wood screws through the top of the blocks. Subsequently I thought it would be better to redesign the y tensioner block and use the method of reinforcing printed parts with wood screws. I tested these redesigned blocks by pulling approximately 40lbs and they do not budge.

Also, when milling in the y direction the spindle would sometimes skip or bounce several times. After installing the new belt holders these resonances went away.

Mine were printed with PLA and popped off as well. Currently solving with 2 clamps but I’ll give these a go.


You may also want to look at an alternate x tensioner block, where the hex nut was replaced with a square nut trap. The issue I had with the x tensioner was that the screw could be tightened to the point where the tensioner was attached to the xz plate but the belt was not yet tight, then the nut started spinning in the trap. I had the same issue with the MPCNC - the belt tensioners would get stuck in the housing and the only way to remove the tensioner was to dremel off the screw.