I ask because on my Primo I need to re-square the trucks every single time, and I think it may be leading to other issues I’m having. Even if the machine working itself loose is an independent problem, it would be nice not to have to deal with it.
Also, if anyone has an LR3 going, how fast have you been cutting with it? 15mm/s? 20mm/s?
Most of us for the Primo either use dual endstops, or have a hard stop that we can hold the gantry against which will ensure that the machine starts up square.
The LowRider is no different. The LR3 has provisions for endstops built-in which you can set to square the machine when you home it. The Y axis will stay true to the machine, but hte X axis will need to be set everyt ime you power down the motors. This CAN be done with hard stops (Provisions for that are in there too) or with the endstops. The big issue with the LowRider is the Z axis though. There are 2 Z axis screws and they like to drop randomly when the motors are powered off, so those need to be squared up each time.
The LR2, many people used a cradle of some sort and powered the machine up from there. The cradle kept the X and Z axes square, so simply powering up the motors from there ensured that the machine would be square. Other people used blocks (Or I remember one person using food cans) which kept the Z axis square, but did not help the X axis. In those cases, they used separate hard stops for the wheels t keep the X axis square to the Y axis.
Both my LowRider and Primo use endstops, so they are square when the homing sequence ends.
yeah, I made some in Tinkercad. They just clamp on to the bars and align the machine then, I move .1mm either x or y and the machine is then locked.
Just whatever you do, do not forget them. They like to Fly if they are still on when you start printing 
I cannot take full credit, there are many models like this out there, but the ones I found were adjustable. I wanted them to be the same each time.
Shoot, I am soooo sorry. I saw Primo and did not read the Title. If you want I can delete. Not sure that this can/will work for lowrider, so sorry.
Oh, that’s a cool idea. I think I’ll cut a few up myself. Thanks again