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Re: Retraction Value

Thu Oct 17, 2013 7:01 pm

whodat....yes those are the little blobls i was getting. it takes a combination and tuning of all those settings to get that right. those blobs are the start and or stop of the line on each layer. a little extra material there that needs to be controlled. check out this thread. i finally got those under control by pg3.

dale, my torture test colums were smooth either way but one thing you mentioned that i didnt really check what how round they were. i think i will print that again. once with the g2 and once without and compare roundness side by side.

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Re: Retraction Value

Sat Oct 19, 2013 10:11 pm

whoDat wrote:Curious which "retraction value" you guys are talking about? In Creator 1.1.5, I see "Retraction Distance", "Extra Restart Distance", "Retraction Vertical Lift", and "Retraction Speed" all under the Retraction area. I am having problems with little dimples where the print head stops and starts, and thinking I need to adjust one of these settings?
Well, anybody can correct me if I'm wrong, but here's what I THINK they do:

Retraction Distance: This is how far to pull back the filament at the end of an extrusion move. This helps relieve the pressure in the nozzle to try to keep the filament from continuing to ooze out after the extrusion move is done, before starting a "rapid" (move with no extrusion, to a disconnected part of the layer, to go extrude there...). After the rapid is done, the filament is "un-retracted" back to where it was before the rapid.

Extra Restart Distance: This is how much further to push the filament on the "un-retract" described above. NOTE that this can be a positive or negative number. Some people have had great results (jimc, others) by putting a small negative number here to keep from pushing out a blob during this "un-retract".

Retraction Vertical Lift: This is how much to raise the Z (on an M2, lower the bed) before doing a rapid. This helps to avoid "clonking" into slightly high parts of the print while doing the rapid. The Z is returned to the original position after the rapid. The Z axis doesn't move very fast, so if you use Z-lift, you have a good chance of leaving a blob. The Tallhex.g that comes on the SD card with the M2 includes Z-lift, and you can see the Z lead screw knob do its back-and-forth dance during rapids.

Retraction Speed is how fast to retract (and return -- un-retract) the filament. Not the X/Y speed, as X/Y isn't moving during the retraction.

There's one more setting you should look at seriously for eliminating blobs, and that's the Coast Distance. When you do an X/Y move that is extruding, you can have the filament finish moving "early" -- This lets the built-up filament pressure in behind the nozzle ooze out as the move finishes, rather than AFTER the move finished. Note that if you use Coast, you'll see little "dashes" of lighter color on the Preview in Creator -- those are where the X/Y is still moving without extruding during the "coast" of the filament. Those dashes HOPEFULLY will be where the blobs USED TO BE!

I'm not sure EXACTLY how "Coast Distance" is defined, whether it's in terms of X/Y motion or filament extruder motion. But using this setting (at about 1 or 2 mm) helped me reduce blobs a lot. I hope jimc and ketil will chime in about their experiences with this setting as well -- I think they've done more detailed tuning than I have.

Hope I got all that right. I'm quite certain someone will correct me here if I'm wrong ;-) And good luck with the de-blobbing --- you'll learn a lot!


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Re: Retraction Value

Mon Oct 21, 2013 11:18 pm

Great explanations for each of those settings, Dale, thanks! I am just now tackling my blob issue again and will be trying some things based on your info.

Would be awesome if we had detailed explanations like that for all of the advanced settings. I noticed hovering over them (some, not all) gives a little information, but not much.


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