1 Topic by PheonixSD3 (edited by PheonixSD3 2015-02-22 14:47:19)

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Topic: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

[solved] - see post #10 =  http://www.soliforum.com/post/86633/#p86633

Hey guys, I could use a little help on this one because it's about to drive me mad trying to solve it.  I get what appear to be very regular extruder pulses causing diagonal lines in my prints.  I'm using a RUMBA at 1/32 microstepping on 8825's and originally got it to help solve this issue similar hoping to get something similar to Ian's results (http://www.soliforum.com/post/33357/#p33357) - but no such luck.

I would consider the rest of my printer pretty highly tuned and the regularity makes me think it's either a slicer issue (Slic3r 1.1.7) or something in the Gcode.

Pictures attached of 20x20x50 shells - how do I get rid of this?

*I suggest opening the images in a new tab for superior zoom

http://i.imgur.com/yOpkmUG.jpg

http://i.imgur.com/Wu7T9KW.jpg

http://i.imgur.com/F107ynj.jpg

Thanks

SD3, RUMBA, 360W power, ABS: Glass bed + Aquanet Extra Super Hold Hairspray, Anti-backlash Z spanner, Repetier Host + Slic3r

2 Reply by jagowilson

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

you need to turn down the trimpot on your 8825s. it's the small knob on the driver. i don't recommend using a conductive screwdriver. i use DRV8825s at 1/32 and have no problems

3 Reply by shields1.as

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

Just curious. How does one adjust those tri pots correctly. I haven't figured that out on my sd2 yet either. Is right more left less or opposite. Is it also kinda a trial and error thing?


jagowilson wrote:

you need to turn down the trimpot on your 8825s. it's the small knob on the driver. i don't recommend using a conductive screwdriver. i use DRV8825s at 1/32 and have no problems

4 Reply by AZERATE

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

Use a non-conductive screwdriver like the ceramic one that comes with the RUMBA.
And you are right. Turning clockwise is more, left is less. Adjusting them can by done with a voltmeter, but most people just do it by ear. A tiny turn can have drastic effects, so keep that in mind.

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5 Reply by wardjr

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

I would agree that you need to adjust the VREF.  That is definitely Moire caused improper adjustment of the stepper driver.  It could either be too high or too low of voltage though.
Turning it clockwise will increase the voltage (counter clockwise to decrease).  With the extruder it is easy to call for say 100mm's and slow it way down.  This way you can see (a mark on the drive gear helps) the pulses.  You will also be able to hear them as well.  If I can't quite get it perfect that way I hold the motor shaft between my thumb and finger to feel the pulses.
The trick is to find that sweet spot where the motor sounds smooth and produces enough torque.
Too little voltage and it will skip easily.  Too much voltage and the motor will groan and sound rough.  Being out of adjustment either way and the motor will generate excess heat.

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6 Reply by PheonixSD3

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

Thanks guys - I'm heating up currently and will go through the tuning.  I never really could figure out how to tune vref in the past unless it was actually sounding rough.  It never really occurred to me to send manual gcode to ran at really slow rates so that I would have time to adjust without wasting filament of running out of room.  Will report back with results - may be tomorrow - sudden bad headache.

SD3, RUMBA, 360W power, ABS: Glass bed + Aquanet Extra Super Hold Hairspray, Anti-backlash Z spanner, Repetier Host + Slic3r

7 Reply by wardjr

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

You can just do it in the manual screen of RH.  Set it to 100 or 200 mm's and turn the speed down to say 30 then click extrude.  And yes you can adjust it with out filament.  No need to enter G-code commands.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
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8 Reply by PheonixSD3

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

wardjr wrote:

You can just do it in the manual screen of RH.  Set it to 100 or 200 mm's and turn the speed down to say 30 then click extrude.  And yes you can adjust it with out filament.  No need to enter G-code commands.

Yep, just did that - found the first point in turning the vref pot (starting full left then turning clockwise) that I could squeeze the extruder shaft and not fear it would miss steps.  It does sound much better.  Heating the bed for a print.

AZERATE wrote:

A tiny turn can have drastic effects

noticed!

SD3, RUMBA, 360W power, ABS: Glass bed + Aquanet Extra Super Hold Hairspray, Anti-backlash Z spanner, Repetier Host + Slic3r

9 Reply by PheonixSD3 (edited by PheonixSD3 2015-02-22 05:32:29)

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

On a side note - you'll notice in the first picture I posted that the change in X or Y in my Gcode doesn't seem to match the true dimensions (20mm) of the object.  Whats the reason for this?

Edit: figured out that the X or Y movement can't be full length or else when the layer is extruded and squished out it will be over dimension - makes sense, just took me a minute since this was about my first time looking this close at these parts of the Gcode.

(On looking back - it should have been easy to tell that the moire wasn't a Gcode issue)

SD3, RUMBA, 360W power, ABS: Glass bed + Aquanet Extra Super Hold Hairspray, Anti-backlash Z spanner, Repetier Host + Slic3r

10 Reply by PheonixSD3

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

Many Thanks.

Well, I'm totally stunned.  The recommendations just nailed it and truly fixed my issue.  This could be the most perfect print from my machine yet.  Also of note: I just switched to 2.963 layer heights per the prusa calculator recommendations (and on my stock 5/16" Z screw to boot).

Guys, I'm speechless.  Headache is also miraculously gone (several ibuprofen and a few glasses of water later).  Tomorrow will be a day of printing many things.

Picture attached:

http://i.imgur.com/OAzNR33.jpg

SD3, RUMBA, 360W power, ABS: Glass bed + Aquanet Extra Super Hold Hairspray, Anti-backlash Z spanner, Repetier Host + Slic3r

11 Reply by wardjr

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

Glad we could help yeah .2963 layer height sorry I forgot to mention that.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
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Thanks to all for your contributions

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12 Reply by lukie80 (edited by lukie80 2016-02-21 15:32:05)

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Re: Extruder pulse moire at 1/32 microstepping causing diagonal lines?

Sorry for digging out the old post, but this post very relevant with respect to moire and stepping errors and I want to add another possibility for sharp-lined moire as a help for others. Too slow decay setting of the stepper driver might also introduce moire if extrusion speed is low. Most drivers don't have a trimpot for decay so careful soldering is required. Here are the infos: http://forums.reprap.org/read.php?249,388795.

I've attached a picture with the impact of current, mircrostep setting, driver type and decay on the print quality. These moire lines may accumulate in complex models leading to a horrible look.
http://www.soliforum.com/misc.php?action=pun_attachment&item=9701&download=0

[Edit: Forgot to attach the picture. Added inline picture.]

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