As an engineer, my first prob with the build was the extrusion, 2020 and the carriage (aka: cheap skates). There were tough spots that the were not to my liking that were cyclycal relative to the 625ZZ bearings and the polymer (plastic) wheels. Having several of my machinists look at the matter, they suggested putting them on the lathe and recutting them.
After pondering the situation and a few beers I found the root cause of the problem.
The press fit of the bearing to the (plastic) tread was done by a six year old in China.
This induced wobble to the carriage and tough spots that may affect print quality.
As Chuck The Average Idiot I found a cheap solution to tweak this problem.
Get a washer with an OD bigger than the plastic tread. Get a pack of washers that fit the outer race of the bearing.
You can do this while the wheel is on the carriage or rail, but not recommended. Simply use the big washer to back up the plastic tread (make sure it is flat/straight). Then use the small washers to press the outer portion of the bearing (race) with the existing nut. Hand tighten and the nut a quarter turn +/-. Then torque it.
IMPORTANT: Get a hand torque feel for this, as you will have to this 18 times, grab a beer and watch TV and get into autoproduction mode.
Turn the Wheel/Bearing over and do the same, effectively repressing/re-aligning the bearing to make it not wooble and not have rough spots on the extrusion. Repeat for the other 17 sides of the wheels. The hard quarter turn press from both sides of the carriage wheel/bearing will true it up as best as possible.
Of course, you can spend lots of money on linear rails, but try this first. Patience is the key. Get the hardware solid first, then you can’t blame the software.
Also, I am getting wave springs and torque prevailing nuts (ESNA) to preload the outer race of the carriage wheels.
Chuck the Average Idiot
chuckalfa@aol.com
