Non-Linear Extrusion
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Can someone double check my math? Using this modified macro with M592 D0 A0 B0
Non-linear extrusion script from Duet forum. Used to adjust A and B parameters in M592. ; G28 G1 X0 Y0 Z100 F5000 M83 G1 E5 F600 M400 M291 S3 R"Extrusion test" P"Press OK to start test" G1 X100 E100 F60 M400 M291 S3 R"Measure extrusion" P"Measure filament taken at 1mm/sec extrusion, then press OK" G1 X0 E100 F120 M400 M291 S3 R"Measure extrusion" P"Measure filament taken at 2mm/sec extrusion, then press OK" G1 X100 E100 F180 M400 M291 S3 R"Measure extrusion" P"Measure filament taken at 3mm/sec extrusion, then press OK" G1 X0 E100 F240 M400 M291 S3 R"Measure extrusion" P"Measure filament taken at 4mm/sec extrusion, then press OK" G1 X100 E100 F300 M400 M291 S3 R"Measure extrusion" P"Measure filament taken at 5mm/sec extrusion, then press OK" G1 X0 E100 F360 M400 M291 S3 R"Measure extrusion" P"Measure filament taken at 6mm/sec extrusion, then press OK" G28I get the following with PETG:
1mm/s = 98.9mm
2mm/s = 97.1mm
3mm/s = 94.5mm
4mm/s = 92mm
5mm/s = 88mm
6mm/s = 82mmSo I come up with
M592 D0 A-0.0593 B0.475Running the macro again:
1mm/s = aprox 118mm (went too far to measure accurately)
2mm/s = (Again too far to measure)
3mm/s = 111.8mm
4mm/s = 107.5mm
5mm/s = 101.7mm
6mm/s = 95.7mmSo obviously my math is flawed or it isn't working correctly.
I am using a Nimble Extruder with 2660 steps/mm
Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
Firmware Electronics: Duet WiFi 1.0 or 1.01
Firmware Version: 2.01beta2(RTOS) (2018-07-14b5)
WiFi Server Version: 1.21
Web Interface Version: 1.21.2-b2;Zesty Nimble PETG ; Communication and general M111 S0 ; Debug off M550 K250 ; Machine name and Netbios name (can be anything you like) M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xEF ; MAC Address ;*** Wifi Networking M552 S1 ; Enable WiFi M555 P2 ; Set output to look like Marlin M575 P1 B57600 S1 ; Comms parameters for PanelDue G21 ; Work in millimetres G90 ; Send absolute coordinates... M83 ; ...but relative extruder moves ; Axis and motor configuration M569 P0 S1 ; Drive 0 M569 P1 S1 ; Drive 1 M569 P2 S1 ; Drive 2 M569 P3 S0 ; Drive 3 M569 P4 S1 ; Drive 4 M574 X2 Y2 Z2 S1 ; set endstop configuration ; (all endstops at high end, active high) ; delta radius, diagonal rod length, printable radius and homed height M665 R169.784 L330.0 B120 H559.049 X0.079 Y-0.271 Z0.000 M666 X0.69 Y-0.26 Z-0.43 ; endstop adjustments M350 X16 Y16 Z16 I1 ; Stepper mode (I1 only works with 16) M92 X160 Y160 Z160 ; Set axis steps/mm M906 X1000 Y1000 Z1000 E500 ; Set motor currents (mA) M201 X1000 Y1000 Z1000 E120 ; Accelerations (mm/s^2) M203 X30000 Y30000 Z30000 E1000 ; Maximum speeds (mm/min) M566 X600 Y600 Z600 E40 ; Maximum instant speed changes mm/minute (Jerk) ; Fans M106 P1 T50 S255 H1 ; hotend heatsink FAN1 M106 P2 T50 S35 H1 ; extruder motor FAN2 ; Thermistors M305 P0 T100000 B3950 R4700 ;L54 H-97 ; Bed thermistor ADC correction M305 P1 T100000 B4388 R4700 ;L54 H-97 ; First nozzle thermistor ADC correction M143 S285 ; set the maximum temperature of the hot-end to 285°C M143 H0 S120 ; set the maximum bed temperature to 120C M570 H0 P5 T10 ;Hnnn Heater number H0 is bed, H1 is 1st hot end M570 H1 P5 T10 ;Pnnn Time in seconds for which a temperature anomaly must persist ;on this heater before raising a heater fault (default 5 seconds) ;Tnnn Permitted temperature excursion from the setpoint for this heater ;(default 10C) ; PID / B1 = bit bang B0 = PID M307 H0 A180.3 C557.9 D2.5 B0 ; Bed M307 H1 A617.2 C254 D4.5 B0 ; Hot End 1 ; Tool definitions M563 P0 D0 H1 ; Define tool 0 G10 P0 S0 R0 ; Set tool 0 operating and standby temperatures M92 E2660 ; Set extruder steps per mm (PETG) M350 E16 I1 ; Stepper mode (I1 only works with 16) ;M572 D0 S0.04 ; Pressure advance non Kisslicer M572 D0 S0.0 ; No Pressure advance with Kisslicer ; Z probe and compensation definition M558 P4 X0 Y0 Z0 H3 I0 ; Z probe is a switch and is not used for homing any axes G31 X0 Y0 Z-0.08 P500 ; Z value is trigger point, so a -Z closer to 0 = more smooshed M556 S78 X0 Y0 Z0 ; Axis compensation here M557 R75 S20 ; Define Grid For Mesh Height M592 D0 A-0.0593 B0.475 ; Non Linear Extrusion Orange PETG 230C M208 S1 Z-0.25 ; set minimum Z T0 ; select first hot end -
M592 D0 A-0.0593 B0.475
If your extruder behaves anything like mine, then the A value should never need to be negative, and the B value should be much smaller than you have it.
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Obviously I was plotting the wrong data.
What do I need to plot and find the trend line for?
Perhaps the additional amount needed like so?
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Last time I ran the correction I calibrated my extruder steps per mm at 1mm/s. That would bring your first value to 0 correction which may effect the results the spreadsheet software gives. It shouldn't in an ideal world as the curve remanis the same, just altering the point at which the y-axis of the graph crosses the plot.
Edit: Sorry missed last post. Yes, you are plotting the additional correction required. So if you need to multiply your current extrusion by 1.2 for a specific speed the the value you'd plot would be 0.2.
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@alexander-mundy
If you multiply 98,9 * 1,011122346 you get 100, so this is correct.
Also if you look at the formula for M592 1 + min(L, Av + Bv^2), you can see that you get that exactly. -
Thanks guys, cleared A & B and corrected my steps/mm to give correct extrusion at 1mm/s and ran the 100mm macro and the trend line gave A=0.0088 and B=0.0022 so I used those values and got the following results
After thinking about this for a bit it made me wonder if the correction should be recursive since you are not actually going to get the corrected amount but the corrected amount minus a % under due to the effect it is correcting? Anyway I don't have more time right now to mess with it but will mull that over.
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Yes I gree with that. While you have got data points for the right amount of extrusion it is not necessarily at the right speed. Or at least that was the case the way I did it.
I'll check mine next time around but at the moment this needs to be with the head moving so non-linear extrusion is used. Be aware that with these moves the feed rate is soley referring to the motion axis and the extrusion is paced to complete within the move.
Other option is to alter the extrusion amount at each speed amount until you get a target extrusion length and calculate the required correction from that, rather than calculating the correction required to reach the target. Guess this would be more accurate.
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I made a recursive spreadsheet that sums 6 iterations (yes way overkill, 3 would probably be sufficient) and set A & B back to 0 and started from scratch. The real life results are very good and probably within my measuring tolerance. Since there isn't a "c" in M592 I also had the spreadsheet correct the steps/mm based on the average of the real life results with M592 values in place.
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@alexander-mundy That's great. Could you share your excel file?
I don't suppose you could post a picture of an actual extrusion pattern before and after the calibration to show the under extrusion at higher speeds and the corrected extrusion afterwards?
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Edit (Here was the wrong results I removed)
If this works, here is the spreadsheet
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Actually that was the correct results.
Here is a non recursive
And the real world results from the non recursive
Note that I dropped the 6mm/s from the newest one because I think I might have been getting some lost steps at that speed and I hadn't corrected steps/mm to extrude correctly at 1mm/s
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