blobs on direction change

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dylantep
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blobs on direction change

Post by dylantep » Fri Apr 21, 2017 8:42 pm

I'm using simplify3D and I've noticed that during solid infill when I change directions a large blob is made. I think this is a slicing issue because when it happens I watch the gear on the extruder jump forward. Anyone have an idea what this could be?

Picture: https://goo.gl/photos/V8wEdXVp6wUZoLpKA

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thingismith
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Re: blobs on direction change

Post by thingismith » Fri Apr 21, 2017 10:52 pm

Wow, I've never seen anything like that before. It could be your settings for extra restart distance and retraction vertical lift in the extruder tab... Maybe run a test halving the values for those settings. Is it like that anywhere else, or just in that one place?

IMBoring25
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Re: blobs on direction change

Post by IMBoring25 » Sat Apr 22, 2017 1:31 am

Does S3D have a setting like other slicers call Pressure Advance or Elasticity Compensation that tweaks the extruded volume up or down as speed changes? You could have an extremely inappropriate setting for that parameter, perhaps.

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KAS
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Re: blobs on direction change

Post by KAS » Sat Apr 22, 2017 8:01 am

Could be in your coast, wipe, and/or outline overlap %.

Attached a copy of your FFF file, I'll compare it to mine.

dylantep
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Re: blobs on direction change

Post by dylantep » Tue Apr 25, 2017 12:12 pm

The forum wont let me attach .fff
I am using a 0.8 nozzle which is why the blobs are so extreme, but I see this a effect with a 0.4 nozzle as well

My extra restart is -0.02, coasting is 0.05, and infill overlap is 15%

S3D does not have any pressure advanced setting that I know of.

Its strange because it happens on the direction change in solid infill so I don't think it has to do with retraction.

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Jimustanguitar
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Re: blobs on direction change

Post by Jimustanguitar » Tue Apr 25, 2017 12:46 pm

The nozzle diameter doesn't effect the volume of plastic that the machine is extruding, the extrusion width and layer height do.

Regardless of the setting that's to blame, it's because you're extruding more plastic than will "fit". I'd measure a thin wall calibration cube to check your extrusion steps per mm and multiplier. I think that'll tell the tale. It could also be an "extra extrude on restart" setting or something like that.

dylantep
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Re: blobs on direction change

Post by dylantep » Wed Apr 26, 2017 4:30 pm

I don't think its steps/mm or multiplier because the center looks fine. I also don't think its extra extrude on restart as thats currently set negative and the problem is happening in a place where there should't be a retraction. I think it may be a problem with S3D as I can watch the extruder gear jump forward every time the blobs happen.

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KAS
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Re: blobs on direction change

Post by KAS » Wed Apr 26, 2017 5:43 pm

With my .4mm nozzle, I have coast set to 1mm. ( see attached pic)

Don't run with Auto extrusion width, it's garbage. Calibrate with a thin-wall hallow cube and measure the wall thickness to adjust the extrusion multiplier.

Your .05 coast on a .8mm nozzle wont do much of anything. Also, again -.02 Extra Restart Distance is nothing on that size nozzle. ( also depends on your retract distance.)
What layer height are you printing at? It almost looks to squished for a .8 nozzle.

Coast is your pressure relief in S3D. If you have any back pressure with any bit of vertical lift, you'll see those extra blobs during lift movements.


I recommend taking it to the extremes with tons of coast and large retracts to see any differences. Don't mess with the extra restart distance until you tune the others in.
Coast further, retract more, and/or retract faster. Its just finding that combo that works to your expectations



FFF.png

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