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Missing steps after extruder replacement and retracting

Posted by Parabolic 
Missing steps after extruder replacement and retracting
June 01, 2012 07:53PM
Ok, stay with me on this one.
Ive been running a Wades since I got into this in Oct. Its been fine - for the most part. This past weekend I had some filiment feeding issues. Which resulted in me assembling a Gregs extruder which I had printed out with herringbone gears. All went well on the rebuild except the hobbed bolt that I had for the wades wasnt enough grip for the Gregs. No issue, I ordered a VERY nice bolt from Ultimachine - which came today.
I assembled the extruder, but it wasnt putting out enough plastic. So I had to relearn how to calibrate and upload the firmware - no big deal. I finally got it extruding 30 for 30mm.
Great - now for a test print.
The print is great - nice fill and all. but as it starts layering up and the extruder has to retract, Im noticing that now its missing steps after it retracts. Like its taking too long to reload the plastic into the extruder.
Now im using slicer, and my extract was at 5mm at 30mm p/s so I lowered it to 2mm, but im still having the issue - better, but not as bad.
Any ideas on this? Anyone else had this issue?
Thanks!
Jeff
Re: Missing steps after extruder replacement and retracting
June 01, 2012 09:30PM
5mm sounds like alot for retraction. Most of what ive read and learned is that anywhere from .5 to 1.5 retraction distance is about average. My experience thus far with retraction is that you are kind of limited by the max speed and acceleration that your extruder motor can reverse without missing steps or causing filament to slip. I have no experince with a wades extruder style yet as i have been using a geared motor direct drive unit, the wades might need more retraction due to gear lash but still i wouldnt think it would need 5mm.
Re: Missing steps after extruder replacement and retracting
June 01, 2012 10:39PM
Try slowing down your retract speed or reducing your E axis acceleration, it sounds like your motor may be missing steps. 2mm of retraction should be plenty.


Cameron

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Re: Missing steps after extruder replacement and retracting
June 02, 2012 06:07AM
I did. I set it for 1mm of retraction and 10mm p/s speed. seemed to clear it up. Weird - It worked great like that with the wades. I think with this better gearset and recal that this is more precise.

Thanks for the help!
Jeff
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