Saturday, February 28, 2015

3d Printer Part 17


I had a bunch of trouble today. My calculations assumed I was using 16 microsteps per axis so my printer suffered numerous head crashes. Belts and gears don't like that. The printer thought it was 16 times larger than it was so it was trying to traverse the axis' that much. It is a scary sound when your printer tries to destroy itself. I may have peed a little. Anywho! I searched the firmware, the slicer software settings, and the printer interface software settings for microstep settings. Several internet searches later, I found they are set with jumpers under the stepper motor controllers on the RAMPS board. Anyone care for a tall glass of RTFM? I set my x and y axis' to 1/4 micro steps and adjusted the firmware config accordingly.

Shortly after, my x belt kept jumping and skipping teeth. That was freakin awesome. The jumping could be dealt with pretty easily but skipping teeth makes it so the center moves while it's printing like in this cropped version of the image I posted before:

You can see it drifting to the left in a star shaped coil. Nice. On closer inspection with a magnifrier, I discovered the belt doesn't mate perfectly to the gear. I posted the picture before out of anger and walked away from the thing a awhile thinking I was going to have to rebuild the x axis.

When I came back to it and started taking it apart, I saw the mounting screw was binding the tensioning pulley. I loosened it up and made a little guide to keep the belt from being thrown and viola!

I could then adjust my x so it and the y could make square objects. This took some trial and error since I don't really know the pitch of the x belt. The result seems within about 5% error.



As one can see in that video, it wouldn't be hard to actually make this a working plotter or cnc machine or laser cutter..


I would also like to note that with microstepping working, the motors are considerably quieter.

Note to selfdude:

Code:
 jumper   Yes/No  step size
 1     2    3
 no   no    no    full step
 yes  no    no    half step
 no   yes   no    1/4 step
 yes  yes   no    1/8 step
 yes  yes   yes   1/16 step

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