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Extrusion Calibration Issue

Posted by johnkmitchell911 
Extrusion Calibration Issue
July 19, 2016 06:15PM
So I got my reprap up and running. I am using a direct drive setup. I calibrated the extrusion rate with a starting value of 250 and found that 245 would extrude 98 to 101 mm when told to extrude 100. That was yesterday. Today I seem to be getting all kinds of weird extrusion rates. With tension, temperature, and e-step settings the same, I tell the printer to extrude 100 mm, and I have gotten values ranging from 30 to 80 mm.

My assumption going into this was that once the tension is strong enough for the gear to grip the filament, I would get consistent extrusion rates. I could then adjust the e-steps to get accurate rates. But I seem to be unable to extrude filament at a constant rate. The effect is causing my test prints to have some layers that are under extruded and some over. I had plenty of slack in the filament during all tests.
Re: Extrusion Calibration Issue
July 30, 2016 09:49AM
Is your hotend attached to the extruder while you are doing this test? If so maybe you have a clogged hotend ? If it was fine yesterday but is problematic today and you said you made no changes, then maybe you should check that the filament is actually passing into the hotend. Either this or a clog would be my guess.
Re: Extrusion Calibration Issue
July 30, 2016 10:54AM
The hotend wasn't clogged. I could push filament through by hand. After a couple dozen extrusion tests, I changed the way that I was adjusting the filament tension. Now when I load the filament, I adjust the tension to the point that it stalls the motor. Then I back off one or two turns of an M3 screw. I've done tests at 220, 205, and 195. I'm getting within a mm of 100mm when I do an extrusion test. Thanks for the reply though, blahhh10.
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