Does firmware 1.19 handle extruder rate limiting any differently?

burtoogle

OK, thanks for trying. You only need print up to the 13th layer, it should misbehave by then.

dc42

I tried it without pressure advance - still no problem.

Can you isolate a short section of gcode that exhibits the issue when run by itself?

burtoogle

I think I may have something…

Here's some gcode from the region where the stepper is noisier that normal:

G0 F18000 X2.749 Y8.39
G1 F2250 X2.747 Y8.39 E0.00008
G1 F1800 E-5

And here's the debug output:

DDA: start=[6.274000 9.103000 2.650000] end=[2.749000 8.390000 2.650000] d=3.596386 vec=[-0.980151 -0.198254 0.000000 0.000000 0.000000]
a=1000.000000 reqv=300.000031 topv=61.352169 startv=8.162012 endv=16.394712
daccel=1.848735 ddecel=1.747651 cks=92013
DMX: dir=F steps=168 next=1 rev=169 interval=2111 sstcda=7651 acmadtcdts=21615 tstcdapdsc=107382 2dtstc2diva=6557935337
hmz0sK=7302429 minusAaPlusBbTimesKs=4366961 dSquaredMinusAsquaredMinusBsquared=53317988253696
2c2mmsdak=42915 asdsk=75724 dsdsk=75724 mmstcdts=195592
DMY: dir=B steps=112 next=1 rev=113 interval=3139 sstcda=7651 acmadtcdts=21615 tstcdapdsc=107382 2dtstc2diva=6557935337
hmz0sK=7556800 minusAaPlusBbTimesKs=-2870198 dSquaredMinusAsquaredMinusBsquared=57112973541376
2c2mmsdak=42915 asdsk=75724 dsdsk=75724 mmstcdts=195592
DMZ: dir=B steps=22 next=1 rev=23 interval=11934 sstcda=7651 acmadtcdts=21615 tstcdapdsc=107382 2dtstc2diva=6557935337
hmz0sK=7744420 minusAaPlusBbTimesKs=-519354 dSquaredMinusAsquaredMinusBsquared=59983966240768
2c2mmsdak=42915 asdsk=75724 dsdsk=75724 mmstcdts=195592
Transformed 3.05 3.05 2.65 to 14766 15005 15092
DDA: start=[2.749000 8.390000 2.650000] end=[2.747000 8.390000 2.650000] d=0.002000 vec=[-1.000000 0.000000 0.000000 -2499.883057 0.000000]
a=1.200056 reqv=0.500000 topv=0.049408 startv=0.006400 endv=0.006400
daccel=0.001000 ddecel=0.001000 cks=67196
DM0: dir=B steps=3215 next=1 rev=3216 interval=90 sstcda=5000 acmadtcdts=14623 tstcdapdsc=72196 2dtstc2diva=2954649380
accelStopStep=1608 decelStartStep=1608 2CsqtMmPerStepDivA=911254
mmPerStepTimesCdivtopSpeed=12087 fmsdmtstdca2=0

If i'm interpreting this correctly (a big assumption!) it looks like the small extrude and the following retract have somehow become combined because the DDA line shows a distance of 0.002 (rather than 5.000 which it shows for other retract/primes) and low velocities but then the DM0 line shows 5mm worth of steps. Is that right?

dc42

Looks like the first G1 command has been thrown away because it results in zero steps on all motors. Then the G1 E-5 line has been processed, but because there is some XY movement left over, the feed rate in that command has been applied to the XY movement instead of the E movement. This will cause the E speed to be the maximum you allow in the M203 command. If that is higher than the extruder drive is capable of, that could explain the behaviour you are seeing.

I will investigate this and implement a firmware fix if my diagnosis is correct, but there isn't time to do this before the 1.19.1 release. Your workaround is to set the E speed to an achievable value in M203, for example 1800.

Edit: according to your config.g it already is, so there must be something else going on.

burtoogle

OK, thanks. My workaround is currently not allowing the slicer to emit any extrudes less than 5um long. That appears to stop the problem occurring.

dc42

I'm going to try to put a fix in 1.18.1, if you will be able to run another test today. Which Duet do you have?

burtoogle

Sorry, I've only just seen the above question, I have a Wifi Duet. Please post the link to the test. Thanks.

dc42

See https://www.duet3d.com/forum/thread.php?pid=23326#p23326.