First run for my printer, anyway: :)

Just got the CoreXY mechanism working. This is just the right motor, but I also checked the left motor and it moved the carriage the other way. I think I’ll need to put endstops on the rods to constrain motion so that (for instance) the hotend doesn’t slam into the motors; that should be a fairly simple design. (I’m thinking printed rings clamped to the rods with screws, as I plan on using stall detection in the TMC2130 drivers in place of endstop switches on X and Y.)

Right now, I’m driving one motor at a time with a DRV8825 stepstick and a Teensy 2.0 on a breadboard. Maybe it’s time to finish wiring the electronics. :)

For the first time, I printed this tolerance test and got all of the inserts to spin. 0.1 mm took a little bit of persuasion, but I was able to break it loose with my fingers. Previously, I was lucky if I could break 0.2 mm loose at all, and I’d frequently need tools to break gaps smaller than 0.3 mm loose.

What changed? I’m calculating flow percentages for my filament, according to this page I ran across recently:

https://filament2print.com/gb/blog/33_What-is-the-flow-of-3D-printing.html

I also usually set the first-layer horizontal expansion to something like -0.1 mm to combat elephant foot. That and overextrusion from the default 100% flow rate (I’d sometimes punch in 95% for PLA if I remembered, but the rolls I’ve tested so far have come back at 90-92%) were the likely culprits of previous tolerance tests that got stuck.

Bottom line: high precision (by 3D-printer standards, anyway) is achievable, even with the A8. :)

(This is the tolerance test I’m using:: https://www.thingiverse.com/thing:2375342)