1 Topic by Shotline

  • Shotline
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  • Registered: 2013-06-12
  • Posts: 79

Topic: DRV8825 Help please!

I have installed an E3D hot end and go the moire pattern that everyone talked about.  So, I ordered the DRV8825 (m20b) drivers and installed one on the extruder, doubled up the steps/mm and I still get the same moire pattern.  I have turned down the pot and then turned it up until the extruder ran smooth but again no change, still the same moire pattern.

What am I missing?

I noticed that the pinout on the DRV8825 does not exactly match the old driver, does that matter?

I also noticed that under the driver on the board there were three jumpers, do I need to remove one or some of them?

Please help.

2 Reply by 2n2r5

  • 2n2r5
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  • From: Frederick, MD
  • Registered: 2013-05-09
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Re: DRV8825 Help please!

Please note that you do NOT have to get a drv8825 to fix severe moire caused by the E3D. To get back to the original moire, you just have to adjust your current drivers.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

2n2r5's Website

3 Reply by Shotline (edited by Shotline 2013-08-31 23:40:38)

  • Shotline
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Re: DRV8825 Help please!

2n2r5 I am becoming convinced that you are right.  I had originally adjusted the vref just by sight (observing when the motor ran smooth) but that didn't seem to help.  I then adjusted vref to .388 v (as close to .384 as I could get) but still it didn't help.  Then after seeing your post I decided to adjust the vref again and the photo shows the results, perfection!  The vref is now at .191 v.  After examining the print closely there is still a very slight moire pattern present (I may continue to adjust vref).

After this adjustment I think it would be worthwhile to try vref adjustments before going to the drv8825 driver.  However since I have it and it is apperantly working correctly now I shall just leave it installed.

Thanks for the help.

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