Where\how to enable Pressure Advance?
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@deckingman
Thanks, i'll give that a try again.
I was looking to reduce the "Z scar" on prints, that bulge where the nozzle stops. I've been using a 20mm cube with a half circle on one side to help spot any changes, good or bad, but haven't seen anything, the bulge is still there. Can you recommend any shapes or models that i can print that will easily show a difference?
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I find that pressure advance is very dependant on the filament. I have some PLA that works best with s0.05 and some with s0.01, or some PETG that works best with s0.07. It really depends on how stringy and gooey the filament is. This may also vary with temperature.
The best way I have found to tune the value is to create a set of macros each with a different S value, that way you can quickly adjust it while printing and immediately see the result it has on the print. Print a long narrow rectangle, during the solid fill sections you will be able to see the effect pressure advance has most noticeably at the ends of the lines where the solid fill comes in contact with the perimeter walls. If the S value is too low, you will see the line blob out a bit. If the value is too high, you will see a gap between the solid fill and the walls. Adjust the value up and down until the line endings look clean and there are no gaps or holes left behind.
To save you some time, here are the macros I use.
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@phaedrux
Thanks!
I'm up to S0.5 now and have yet to see any difference at all. From what i've read around the forum, a setting that high should do something to the print right? Maybe it is my filament, this stuff i have is pretty stringy, i use 6mm of retraction on a 550mm bowden tube to combat stringiness. -
A bowden tube setup will require a higher value to begin with. My values are for a geared direct drive extruder.
In your case, try modifying the macro files to start at S0.1 rather than S0.01 and increase it by 0.05 each step.
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@phaedrux
Yeah, the wiki says S0.2 for a long bowden tube, I'm up to S0.5. I know its doing something, i can hear my extruder working overtime with retractions during top and bottom layers and various other areas where it would normally just continue smoothly but i notice no difference in quality, corners still bulge. I need a good but simple model that this can be demonstrated on. Any suggestions?
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@juice As I said above, I use a rectangle to watch the solid fill lines. You can also watch the corners of a hollow square for bulge.
Scale it to suit your needs.
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@phaedrux
That simple eh? I'll give it a go, thanks again. -
So, I've really tried to get pressure advance to benefit my print quality, but so far, no setting from 0.01 to 0.5 will produce anything different for me. I've even tried lowering extrusion and temperature, but each print looks the same as without pressure advance. All i get when i go as high as 0.5 is a creaky extruder. Maybe its this filament, maybe its this extruder (knockoff titan) . I've printed over 20 test pieces so far and its getting frustrating having zero results (good or bad). I'm gonna leave it at 0.1 for now and move on to other things. Thanks for the help!
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I've never used it with a Bowden setup but with a long tube the effect could be far less noticeable. Perhaps someone with more experience with a long Bowden setup could chime in with their settings.
Have you also reduced retraction amount since less should be needed with pressure advance? That might help ease the load on the extruder.
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Pressure Advance interacts with jerk and acceleration of the extruder. My way to adjust is printing two cubes with facing seams whilst changing parameters (jerk, speed, acc., pressure advace) on the fly and looking attentive to the ongoing print with a magnifier. It is very subtile to adjust pressure advance on my printer but it is worth it.
Gruß
Niko -
@heapstar said in Where\how to enable Pressure Advance?:
Pressure Advance interacts with jerk and acceleration of the extruder. My way to adjust is printing two cubes with facing seams whilst changing parameters (jerk, speed, acc., pressure advace) on the fly and looking attentive to the ongoing print with a magnifier. It is very subtile to adjust pressure advance on my printer but it is worth it.
+1
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@heapstar
Does your printer have a long bowden tube? If so, would you be able to share your accel and jerk settings? -
My bowden tube is about 200mm long. It ist a flying extruder thing.
