Why am I having to run with an extrusion multiplier of 60%?

Avatar

By deckingman 20 October 2016 16:17

Member · 796 comments

Sorry to post this here but I'm running out of ideas and wondering if there is something in the firmware (or my settings that I haven't spotted) that is causing my problems.

So I'm getting my machine pretty well dialled in and am producing some nice prints. However, it's taken a while 'cos I have been fighting a severe over extrusion problem. Basically I'm having to extrude at a factor of around 60%. I have to go below 50% before I see definite signs of under extrusion. It's a Diamond hot end but I get the same results on each of the 3 extruders when run separately as well as when mixing.

I've done all the obvious stuff. I'm using E3D titan extruders. Initially I set the steps/mm to what E3D recommend as a default which goes like this. 1.8 degree stepper, 16 times microstepping, 3 times gear ratio and effective hob diameter of 7.3 mm so 200x16 x 3 / (7.3X3.142) = 418.5. Then I measured what was actually extruded which was a bit on the low side and ended up with steps/mm of 424 to give me true 100mm when I asked for 100mm. I tried it with the Bowden tubes disconnected and with them connected but the hot end heated and got more or less the same.

I've measured the filament and it's about right (1.74 to 1.75). I've checked everything in Slic3R and it's the same as I've always used for 1.75mm PLA with a 0.5mm nozzle.

Yet to get anything like a decent print, I have to make drastic changes and set the extrusion multiplier to around 60%. 

AFAIK I'm the only one who is using a mixing hot end on a CoreXY. Sorry to ask the question but is there any possibility that there is something in firmware that is causing this?

The other thing that occurred to me is that the nozzle diameter might be slightly more than 0.5 mm (I'm waiting for delivery of some  micro size drill bits to confirm this) so it could be that the extrusion is out by a factor of 2, which is s nice round number.

Config.g as follows:-

; Configuration file for Duet WiFi
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool on Fri Sep 09 2016 09:45:21 GMT+0100 (GMT Standard Time)

; General preferences
M111 S0 ; Debugging off
G21 ; Work in millimetres
G90 ; Send absolute coordinates...
M83 ; ...but relative extruder moves
M555 P2 ; Set firmware compatibility to look like Marlin

M667 S1 ; Select CoreXY mode
M208 X0 Y0 Z0 S1 ; Set axis minima
M208 X325 Y330 Z740 S0 ; Set axis maxima

; Endstops
M574 Z0 S0 ; Define active low and unused microswitches
M574 X1 Y1 S1 ; Define active high microswitches
M558 P1 X0 Y0 Z1 H5 F120 T6000 ; Set Z probe type to modulated, the axes for which it is used and the probe + travel speeds
G31 P500 X0 Y0 Z2.35 ; Set Z probe trigger value, offset and trigger height. Use 1.49 for sandblasted, 1.88 for smooth, 2.11 for Kapton, 2.3 for blue tape


; Drives
M569 P0 S0 ; Drive 0 goes backwards
M569 P1 S1 ; Drive 1 goes forwards
M569 P2 S1 ; Drive 2 goes forwards
M569 P3 S0 ; Drive 3 goes backwards
M569 P4 S0 ; Drive 4 goes backwards
M569 P5 S0 ; Drive 5 goes backwards
;M350 X16 X16 X16 X16 X16 X16 I0 ; Configure microstepping without interpolation - this is what the configuator generated and is wrong
M350 X16 Y16 Z16 E16:16:16 I1; Configure XYZ and 3 extruders microstepping with interpolation
M92 X80 Y80 Z3200 E424:424:424 ; Set steps per mm
M566 X800 Y800 Z10 E120:120:120 ; Set maximum instantaneous speed changes (mm/min)
M203 X70000 Y45000 Z240 E1200:1200:1200 ; Set maximum speeds (mm/min)
M201 X800 Y800 Z10 E250:250:250 ; Set accelerations (mm/s^2)
M906 X1800 Y1800 Z1800 E300:300:300 I20 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Heaters
M143 S260 ; Set maximum heater temperature to 260C
M570 S240 ; Set maximum heating time to 240s
;M305 P0 T10000 B3988 C0 R4700 L0 H0 ; Set thermistor + ADC parameters for heater 0
;M305 P1 T100000 B4138 C0 R4700 L0 H0 ; Set thermistor + ADC parameters for heater 1
M305 P0 X200 ; Set Bed to use PT 100 (1st channel is 200)
M305 P1 X201 ;Set Hot end to use PT 100 (2nd channel is 201)
; use the following with 0.5mm diamond hot end and new heater cartridge
M307 H1 A409.0 C211.4 D4.4 B0; Derived from auto tune 13/09/16 A=gain, C=time constant, D=deda time, B0 switch on PID mode.
; use the following for 0.9mm diamond hot end and aged heater cartridge
; M307 H1 A361.7 C236 D15.6 B0; Derived from auto tune 29/09/16

M307 H0 A198.7 C1205.5 D30 B0; Derived from auto tune 14/09/16 M303 H0 P0.5 S140
; dead time was calculated at 4.8 seconds but gves a slow heater fault error.

; Tools
M563 P0 D0:1:2 H1 ; Define tool 0
G10 P0 X0 Y0 ; Set tool 0 axis offsets
G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C
M568 P0 S1 ; Enable mixing for tool 0
M567 P0 E1:0:0 ; Set mixing ratios for tool 0
M563 P1 D0:1:2 H1 ; Define tool 1
G10 P1 X0 Y0 ; Set tool 1 axis offsets
G10 P1 R0 S0 ; Set initial tool 1 active and standby temperatures to 0C
M568 P1 S1 ; Enable mixing for tool 1
M567 P1 E0:1:0 ; Set mixing ratios for tool 1
M563 P2 D0:1:2 H1 ; Define tool 2
G10 P2 X0 Y0 ; Set tool 2 axis offsets
G10 P2 R0 S0 ; Set initial tool 2 active and standby temperatures to 0C
M568 P2 S1 ; Enable mixing for tool 2
M567 P2 E0:0:1 ; Set mixing ratios for tool 2
M563 P3 D0:1:2 H1 ; Define tool 3
G10 P3 X0 Y0 ; Set tool 3 axis offsets
G10 P3 R0 S0 ; Set initial tool 3 active and standby temperatures to 0C
M568 P3 S1 ; Enable mixing for tool 3
M567 P3 E0.34:0.33:0.33 ; Set mixing ratios for tool 3
T0 ; Select first tool

; Network
M550 PTall CoreXY ; Set machine name
M552 P0.0.0.0 S1 ; Enable network and acquire dynamic address via DHCP

; Fans
M106 P0 S0.0 I0 F10 H-1 ; Set print cooling fan (0) value, PWM signal inversion (off)and frequency (10 hz). Thermostatic control is turned off
M106 P1 S255 I0 F500 H1 T45; Set hot end fan (1) value, PWM signal inversion(off) and frequency. Thermostatic control is turned on
M106 P2 S1 I0 F500 H-1 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned off

; Custom settings
M207 S3.0 F2400 ;set firmware retraction S=amount in mm, F=Feed rate mm/min(/60 to get mm/sec), R = additional length, Z = additional Z lift in mm
M572 D0 S0.10 ; set pressure advance coefficient
M572 D1 S0.10
M572 D2 S0.10


; Emergency stops
M581 E0 S1 T0 C0 ; E0 is emergency stop button, S1 = rising edge, T0 is emergency stop like M112, C0 means any time
M581 E1 S1 T0 C0 ; E1 is axes limits


Avatar

By DjDemonD 20 October 2016 16:32

Member · 481 comments

What diameter is your filament extruded into free air? That will normally be 20% larger than your nozzle width, as die swell is usually expected to be 20%, hence the default 0.48mm extrusion width setting with a 0.4mm nozzle.

Is the printing the same with pressure advance off?

Last edited by DjDemonD (20 October 2016 16:33)

Avatar

By piankoc 20 October 2016 16:45

Member · 20 comments

I am having a similar issue as well, also using dual titan extruders on a kossel type delta with a chimera hot end. doing the 100mm check i had to lower to around a 400 steps per mm and need an extrusion multiplier of around .80 to make it not over extrude and to pass the extrusion width test when printing a vase. Seeing that we both have titans, could it be a titan issue?

Avatar

By deckingman 20 October 2016 16:48

Member · 796 comments

It's about 0.6mm which is constant with a 0.5mm nozzle. Pressure advance makes no difference.

For info, the filament and the filament settings in Slic3R are the same that I've always used with the same Diamond hot end fitted to an ageing RRP Mendel.


Avatar

By DjDemonD 20 October 2016 16:48

Member · 481 comments

I have a two titans using 1.75mm and I don't run my steps/mm anywhere near 400. 290 more like.

Avatar

By deckingman 20 October 2016 16:51

Member · 796 comments
piankoc wrote

I am having a similar issue as well, also using dual titan extruders on a kossel type delta with a chimera hot end. doing the 100mm check i had to lower to around a 400 steps per mm and need an extrusion multiplier of around .80 to make it not over extrude and to pass the extrusion width test when printing a vase. Seeing that we both have titans, could it be a titan issue?

Could be but I can't see why. If you ask to push 100mm in and set it to do exactly that, then why do we have to reduce it by 60% to get a decent print?


Avatar

By deckingman 20 October 2016 16:53

Member · 796 comments
DjDemonD wrote

I have a two titans using 1.75mm and I don't run my steps/mm anywhere near 400. 290 more like.

Well that would do the job but when you calibrate the steps per mm, do you still get 100mm of filament when you ask for 100mm?

Edit, because I have to set mine to 424 to achieve that.

Last edited by deckingman (20 October 2016 16:54)


Avatar

By piankoc 20 October 2016 16:54

Member · 20 comments

have you done a 100mm test with hotend on and pushing filament through? I havent thinking maybe the pressure causes issues or something. Ohter issue i am running into which may or may not be related are weak infil. I have the extrusion multiplier down to .8 to stop over extrusion on the outside but need 150% infil extrusion width just to get ok infil.

Avatar

By deckingman 20 October 2016 16:57

Member · 796 comments
piankoc wrote

have you done a 100mm test with hotend on and pushing filament through?

Yes, said that in my first post.


Avatar

By piankoc 20 October 2016 17:04

Member · 20 comments

sorry, missed that I guess. I was always assuming this was a slicer issue in simplify3d as that is what i am using, but if you are using Slic3r that doesnt appear to be the issue...

Avatar

By Bobblejot 20 October 2016 17:05

Member · 24 comments

I also have a couple of titans and run them at the suggested 419 steps per mm on two different machines both running 1.75mm filament with no issues at all. Both my titans have bog standard 1.8° 1.68A Nema 17s.

I also run E3d V6 hotends with 0.4mm Nozzles and use simplify 3d with a 0.4mm fixed extrusion width and an extrusion multiplier of 1.

@DjDemonD 290 seems extremely low.

I don't have mixing hotends though so cant comment on that.

Have you tried setting the extruders only to non-interpolated microstepping and trying again? it shouldn't make a difference but you never know.

Avatar

By DjDemonD 20 October 2016 19:36

Member · 481 comments

It might be low but its not under-extruding, my objects print with extrusion multiplier in slic3r at 1.00.

I am using pancake 20mm 1.8 deg nema 17's, but this shouldn't make a difference to the steps/mm or gearing of the extruder.

Avatar

By Dougal1957 20 October 2016 20:03

Member · 284 comments

I am also using a Titan with 20mm Pancake motor and have no under/over extrusion my S3D is set at 1.0 ext factor with a 0.48mm default width (0.4mm nozzle E3D Hotend) and step's/mm is approx 414 IIRC (would have to switch Printer on and check it)

Doug

Avatar

By piankoc 20 October 2016 20:23

Member · 20 comments

DjDemonD, if your steps per mm is around 290 with an extrusion multiplier of 1 would that be the same as the 419 steps per mm suggested with an extrusion multiplier of .7?

Did you set your steps per mm by printing objects and adjusting or by extruding 100mm and measuring the distance?

Avatar

By deckingman 20 October 2016 20:51

Member · 796 comments
DjDemonD wrote

It might be low but its not under-extruding, my objects print with extrusion multiplier in slic3r at 1.00.

I am using pancake 20mm 1.8 deg nema 17's, but this shouldn't make a difference to the steps/mm or gearing of the extruder.

So it seems to me that we effectively have the same setting, In my case it's steps of 424 with extrusion multiplier of 0.7, and in your case it's steps per mm of 290 with extrusion multiplier of 1.00. Others are getting good results with std E3D settings of around 419 steps per mm and extrusion multiplier of around 1.00. What's the common thread? Mine is a CoreXY is yours?


Avatar

By deckingman 20 October 2016 20:52

Member · 796 comments
Dougal1957 wrote

I am also using a Titan with 20mm Pancake motor and have no under/over extrusion my S3D is set at 1.0 ext factor with a 0.48mm default width (0.4mm nozzle E3D Hotend) and step's/mm is approx 414 IIRC (would have to switch Printer on and check it)

Doug

Doug. Just out of curiosity, is yours CoreXY?


Avatar

By Bobblejot 20 October 2016 20:55

Member · 24 comments

The two machines i use with the E3D titans are both deltas with bowdens. Not that it should matter i wouldn't have thought.

Normally an extrusion multiplier of 0.92 or thereabouts is for PLA and 1.0 is for ABS. Materials like colorfab xt are normally higher 1.05 or so. But to be fair it depends on the brand of filament more than anything else.

Avatar

By deckingman 20 October 2016 21:29

Member · 796 comments
Bobblejot wrote

The two machines i use with the E3D titans are both deltas with bowdens. Not that it should matter i wouldn't have thought.

Normally an extrusion multiplier of 0.92 or thereabouts is for PLA and 1.0 is for ABS. Materials like colorfab xt are normally higher 1.05 or so. But to be fair it depends on the brand of filament more than anything else.

For sure I've only ever had to use similar extrusion multipliers on my old RRP Mendel and then only to suit different rolls of filament. Admittedly they weren't E3D titan extruders but similar geared design.

What I can't get my head around is why I have to use such a large number for printing when I've set the steps per mm to give me an accurate extruded length when "static". I just have this nagging feeling that it's something to do with CoreXY or the way Slic3R works with CoreXY or something that the firmware is doing. What's bugging me is that CoreXY works differently in that one motor will make the hot end move diagonally. To get X or Y axis movement, you have to drive both motors and in one case, one motor forwards and the other backwards. As far as a slicer is concerned, the volume to extrude is purely a function of axis travel so is the fact that on a CoreXY both motors are driven for pure X movement screwing things up?

I'm clutching at straws here but if everyone with CoreXY and Slic3R has to set a really low extrusion multiplier, then I may be on to something. Is there anyone out there getting good results on a CoreXY, using Slic3R with "normal" extrusion settings? If so, that'll blow one theory out of the water.

Last edited by deckingman (20 October 2016 21:31)


Avatar

By DjDemonD 20 October 2016 21:34

Member · 481 comments

I have a corexy not using Duet but ramps, I use Slic3r and I have a flex3drive extruder which at 1/8th microstepping needs to be set to 1600 steps/mm. Which it is. And it extrudes normally extrusion multiplier 1.00.

Are you providing enough power to the machine (I suspect you have a massive PSU on that bad boy) is the motor current correct for the extruders?

My understanding of corexy kinematics is that whilst two motors have to turn for x or y movements and only one turns for diagonal movements this has no bearing on syncing extrusion moves, if you ask for 10mm movement in whatever direction and 10mm extrusion whilst you do it thats what you get.

I checked the steps/mm on my titans, one is set to 250 and the other to 333 both printers extruding normally with extrusion multipliers set to 1.00. I can't explain this difference. Its not filament either as I regular swap filaments between machines and get very similar results. Maybe one extruder has a different drive gear to the other.

Last edited by DjDemonD (20 October 2016 21:38)

Avatar

By deckingman 20 October 2016 22:50

Member · 796 comments

PSU is 24V 15 Amp (350Watt) but it's only doing the steppers and hot end heater and Duet. The bed is 240V via a SSR. Main motors (X,Y and Z) are 2 amp but I'm running them at 1.8. Extruder motors are the next size up to the pancake ones. 0,4 Amp but I'm running them at 0.3. No sign of any skipped steps. Current draw with everything running is about 7 amps max from the PSU so plenty of spare capacity.

I agree about the CoreXY kinematics and that if you ask for 10mm of movement and 10mm of extrusion, that's what you should get but for whatever reason, it seems I'm getting 30% more.

I've just printed your test pieces that I found on Thingiverse. Started at 100% extrusion multiplier. Then reduced it to 90% and printed another, and so on down to 60%. I need daylight to see properly but 100% is way too much and 60% is a bit too little. Crazy......


Avatar

By DjDemonD 20 October 2016 23:34

Member · 481 comments

Well all I can say is that the steps/mm calculated for this extruder and what it actually needs to be set to are not the same. Unless you want to be running with a 0.6 extrusion multiplier all the time. It doesn't really matter though how you set it, there are a lot of different ways of adjusting the amount of material extruded flow, steps/mm, multiplier they all do the same thing. As long as the amount you get out matches the amount you need you're there. I'd change your steps/mm to a corrected value and set your multiplier to 1.

I've always set the steps/mm fairly arbitrarily then adjusted based on calibration objects. When I first got a titan I figured since I was running around 100 steps/mm on a mk8 which was not geared and the titan was 3:1 I'd try 300 and see how I got on. On the mini kossel I nudged it down to 250. On the large kossel I started at 250 and went up to 330. Now that I can't explain but the large kossel has been nothing but trouble, at the moment its a genuine e3d v6 jamming (with abs!) if I even look at it funny. Might send it back.

Avatar

By Dougal1957 21 October 2016 01:07

Member · 284 comments

Mine is a Delta and something that maybe of interest is that the first batch of Titans towards the end of that first run had the hobbing tool wear which caused the drive gear to be the wrong size.

Myself and a few others that I know had this issue and in my case caused horrendous stripping issues.

E3D Swapped them out FOC as indeed they should have done all it needed was to send them a photo of the drive gear.

When you calculate your steps/mm you are measuring the amount of filament going into the extruder arn't you and not the length coming out of the nozzle tho I doubt you are making that mistake but stranger things have happened.

Doug

Avatar

By piankoc 21 October 2016 01:26

Member · 20 comments

DjDemon, I just don't understand why if you're using the same extruders you have that much variability in the steps per mm. If they are the same extruder it should be the same steps per mm. If i am pushing 100mm into my hotend it should print correctly or close to it with an extrusion multiplier of 1. I understand that a bowden setup could cause some slack in that but didn't think it would be a difference of 30%. But how does the same extruder have such different values and once dialed in to push 100mm through it? if the amount of plastic going into the nozzle is the same it expects why do i have to drop it 30%?

Avatar

By deckingman 21 October 2016 08:34

Member · 796 comments
Dougal1957 wrote

Mine is a Delta and something that maybe of interest is that the first batch of Titans towards the end of that first run had the hobbing tool wear which caused the drive gear to be the wrong size.

Myself and a few others that I know had this issue and in my case caused horrendous stripping issues.

E3D Swapped them out FOC as indeed they should have done all it needed was to send them a photo of the drive gear.

When you calculate your steps/mm you are measuring the amount of filament going into the extruder arn't you and not the length coming out of the nozzle tho I doubt you are making that mistake but stranger things have happened.

Doug

Hi Doug,

Yes, I'm aware of the bad hobbed bolt issue and I was extra careful to check mine when I got them - they are a later batch and look fine. In any case, if it was stripping the filament, I'd be getting under extrusion issues, not over extrusion.

Yes, I am measuring the filament going in to the nozzle and not what comes out. I'm reassured that my settings are about right because they are very close to the theoretical value that E3D state (the theoretical value is 418.5 and I need 424).

I'm getting good quality prints but it's bugging me that I have to use such wild extrusion factors to achieve them.  I'll continue my investigations.

Ian


Avatar

By DjDemonD 21 October 2016 08:51

Member · 481 comments

Okay so the first titan I bought was an early one (May 2016) but, and here's another anomaly, it feeds filament very well, no stripping. The second one I bought about a month ago and it strips filament and feeds less well albeit into the v6 hotend I have been having a lot of problems with. Both hobbed drive gears look the same and feel the same.

I understand the accepted calibration procedure perfectly well, measure filament going in and adjust steps/mm to get the exact amount fed in mm that you requested. However If, as is clearly the case when printing (which after all is what this is about) you need only 70% of that amount of filament to make good objects, then either this process is incorrect, or there is some titan related oddness going on, or there is a firmware issue here.

Having so many variables to modify to basically determine the number of step pulses that get sent for each 1mm of filament to be extruded is not necessarily helpful.

Has anyone actually counted the teeth on the gears to check it really is 3:1? That would throw the calculation off.

As for why one of my titans prints beautifully with 250 steps/mm and the other with 330 steps/mm - its interesting sure and I will try to find out why if I get the opportunity, but when its printing well I am not going to take it apart to satisfy scientific curiosity.

Last edited by DjDemonD (21 October 2016 08:51)