Machine limits?

bug2k22

Are the machine speed/acceleration limits in config.g hard limits that override any speed requests in gcode files? For example what I mean is that if I slice a model with gcode limits expecting 10,000mm/s2 acceleration and 500mm/s x/y movement and the machine is not capable of these as written in the config.g will it just print slower at the maximum speed configured in config.g or will it just skip steps and attempt to print at the speed in the gcode file?

I ask as I'm diagnosing an extrusion error with the duet magnetic filament monitor with insufficient movement detected. I've set the maximum extrusion rate in config.g to 2mm/s which it should easily be capable of (bondtech bmg/e3d v6) but am still getting the error.

dc42

@bug2k22 the M201 and M203 limits set in config.g should be hard limits. Unfortunately, some slicers generate these commands, even though there is IMO no good reason for them to do so. Some slicers (for example PrusaSlicer) give you the option of generating them or not.

I have it in mind in a future release to ignore but warn about any commands to change machine limits that are encountered in GCode job files.

bug2k22

Thanks for that, yes the slicer (orca) was putting M201 and M203 machine limits in the gcode file. This can be disabled in the printer profile settings within orca.

Removing these did not solve my issue, although now the machine is sticking to the limits in the config.g file.
I have limited the extrude speed to 1mm/s and still get the error when printing even at this very slow speed.
I have the following entries for the extruder:

M584 E0.0   ; set extruder mapping
M350 E16 I1 ; configure microstepping with interpolation
M92 E830    ; configure steps per mm
M566 E60    ; set maximum instantaneous speed changes (mm/min)
M203 E60   ; set maximum speeds (mm/min)
M201 E1   ; set accelerations (mm/s^2)

M591 D0 P3 C"io5.in" S1 ; filament monitor

The error:

Filament error on extruder 0: tooLittleMovement

Following the error M591 shows:

M591 D0
Duet3D magnetic filament monitor v4 on pin io5.in, enabled when SD printing, 28.80mm/rev, allow 60% to 160%, check printing moves every 3.0mm, mag 131 agc 54, measured 25.27mm/rev, min 52% max 105% over 561.8mm

If I disable the filament sensor it appears to print fine, but perhaps the issue is not severe enough to be visible.

The filament sensor was purchased pre assembled.

I've disassembled the extruder/hotend, changed the nozzle and heatbreak and replaced the ptfe tube. The filament spool sits on a steel shaft which is mounted on bearings and rotates freely.

Any ideas on anything else that I should check?

droftarts

@bug2k22 If you haven't already, I'd disassemble the filament monitor and check that the hobbed insert can rotate properly; perhaps it is rubbing. Also check that the PTFE tubes are have no movement, at the filament monitor end, and the hot end.

What is your extruder/filament sensor/hot end setup (Bowden or direct drive)? How far from the hot end and extruder is the filament sensor mounted?

Also see the filament monitoring troubleshooting section for other suggestions: https://docs.duet3d.com/en/User_manual/Connecting_hardware/Sensors_filament#troubleshooting

Ian

bug2k22

@droftarts I've dismantled the filament monitor and it looked fine. I think I may have found the issue, I have about 20cm length of ptfe tubing to route the filament from the side of the frame in to the top of the monitor which sits on top of the bondtech bmg extruder which sits directly on top of an e3d v6 hotend. The tubing is a very shallow 15cm or so radius curve and it feels like there is very little if any resistance. I printed a couple more test prints with the tubing removed and just unrolling and feeding it manually and the prints competed successfully.
This is strange as I have other printers using more ptfe tubing to route the filament with no issues. I played with the tension on the extruder and it seemed to make no difference.
Hopefully this was not just an anomoly, I'll make up a new filament holder above the extruder which should fix the issue.