Solved Y-Axis Issues

Had something strange happen today when printing a large object on my R1+. It is running a Smart LCD Controller, as well as Marlin RC8

Mattercontrol, by default, thinks that the bed is 228x254x200.

Using that setting, I attempted a print and ended up with a squished back-end.

Checked the Y-Axis mechanical parts first, found that the pulley on the stepper was down too far, and the belt would walk up the pulley, causing the whole system to bind (but not fail). Found that the double-setscrew gear's hole was undersize to the 5mm stepper shaft, and that they had pressed the damn thing on. Had to use a gear puller to remove it, then bore the hole to proper 5mm and reinstall at the proper height.

Still didn't fix it.

Manually commanded the tray around and found that it stopped at 236mm.. Far short of the advertised 10" Y-Axis.

Decided to check Marlin's configuration.h, and sure enough, the firmware is set to 220x236x230! While I'm not going to complain too much about 8mm on the X-Axis, 18mm on the Y-Axis definitely screws things up.

Setting the firmware temporarily to 254 on the Y, I checked the actual mechanical limit and found it to be 249mm (or 250, seemed like 249 began to bind). I then set the firmware to 245mm, and all is running nicely now.

245mm/9.64" I suppose isn't the end of the world, it is just not quite as advertised. However, the extra 30mm Z-height was nice!

I suppose this isn't so much a troubleshooting post as it is a post for posterity's sake. Hopefully this helps someone else in the future. For me, it cost 30 hours of printing time and about 80% of a pound of PLA.

Also, Robo3D, you guys might want to look at those pulleys. A double grubbed screw doesn't need a friggin' interference fit when the load is all radial. A fork-style height gauge between the stepper body and bottom of the gear would easily set the proper standoff height at manufacturing time, and not require it to be eyeballed by an operator on an arbor press.

 

@WheresWaldo - No worries. I've dialed my firmware in for the mechanics of my specific printer now. I should have known better than to trust the assumptions of any software, so I half blame myself.