Extruder woes (not extruding correct amount under pressure) April 17, 2019 05:04AM |
Admin Registered: 11 years ago Posts: 3,096 |
100mm extrude WHITE ReForm FormFutura PLA 1.75mm 210ºC Old stepper driver: 93.73 98.65 96.10 Maybe the stepper driver is broken and it's missing steps? New stepper driver: 96.78 96.38 96.08 96.00 94.28 97.14 96.38 97.10 Results seem the same on both stepper drivers, varying equally. After removing the hotend's cooler airflow guide: 80.15 88.70 Maybe the filament plugs up in the hotend now? After hot & cold pulls to remove potential blockage in hotend, nothing was blocking it and I have 100% surely cleaned the entire hotend (multiple times): 66.99 97.42 No improvement. Without hotend connected, free extrusion in the air (I had previously set the steps/mm while extruding filament through the hotend, so I had to raise the steps/mm to get the correct extrusion length, but without any backpressure, suddenly it extrudes too much): 108.85 109.68 109.30 109.18 Adjusted steps/mm to correct value again After setting correct values in free extrusion: 100MM YES Now try extruding through hot hotend again to see if it still extrudes 100mm: 89.78 89.33 87.90 81.73 85.00 NOPE. Maybe try a different kind of filament? BLACK Premium FormFutura PLA 1.75mm 210ºC 89.32 88.81 Same results...
Re: Extruder woes (not extruding correct amount under pressure) April 17, 2019 06:07AM |
Registered: 9 years ago Posts: 752 |
Re: Extruder woes (not extruding correct amount under pressure) April 17, 2019 01:34PM |
Admin Registered: 11 years ago Posts: 3,096 |
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imqqmi
Maybe the nozzle is partially blocked? Did you try heating up the hotend while pulling the filament out before it reaches the temperature? This will pull out all the filament including particles that may have collected in there. If you don't use your 3D printer for longer periods, it may collect dust on the filament spool and draw it into the nozzle. I had something similar with older filament. Also try new filament, maybe the softeners in the plastic have gone bad. Also check the filament where the hobbed bolt latches onto the filament. Does it show any tear out?
Is the temperature stable during printing, when it does infill is the temperature dropping? Do you use a part cooling fan, is it directed at the nozzle/heater block?
Re: Extruder woes (not extruding correct amount under pressure) April 17, 2019 03:50PM |
Registered: 6 years ago Posts: 23 |
Re: Extruder woes (not extruding correct amount under pressure) April 17, 2019 04:01PM |
Registered: 9 years ago Posts: 752 |
Re: Extruder woes (not extruding correct amount under pressure) April 17, 2019 04:24PM |
Admin Registered: 11 years ago Posts: 3,096 |
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G3DBuilder
I had a similar problem today. I replaced the nozzle (.4mm) Direct drive Mk8 Extruder. Pushing the filament through by hand I noticed slight puffing of the extruded filament. My experience tells me that puffing filament has some moisture in it. Slight moisture can cause steaming inside the nozzle and cause the pressure to build up and as the filament is pushed through, and the pressure is relieved randomly. (Puffs) excess nozzle pressure will cause the filament to slip on the drive sprocket thus giving random extrusion. I changed to another filament and now the extrusion rate is more consistent.
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imqqmi
Ok, it's just to rule out the basics since you didn't tell us (everything) what you tried/checked already . So without feeding filament into the nozzle it extrudes the right amount, and with it feeding through the nozzle (under pressure) it will be 10% short?
I love a mystery, so thanks for sharing
Did you check motor current? Replace the stepstick? Check voltage stability under load? Replace the ramps board? Does the extruder feedrate have any influence on the amount extruded? Is the hobbed bolt or gears slipping?
Do you use a bowden tube? Some pre tensioning is needed (extra length fed) before the requested length translates into extruded length.
Re: Extruder woes (not extruding correct amount under pressure) April 18, 2019 03:53AM |
Admin Registered: 11 years ago Posts: 3,096 |
Re: Extruder woes (not extruding correct amount under pressure) April 18, 2019 08:46AM |
Registered: 9 years ago Posts: 752 |
Re: Extruder woes (not extruding correct amount under pressure) April 18, 2019 10:33AM |
Registered: 5 years ago Posts: 10 |
Re: Extruder woes (not extruding correct amount under pressure) April 18, 2019 10:42AM |
Admin Registered: 11 years ago Posts: 3,096 |
Quote
imqqmi
Did you try feeding filament manually through the nozzle to see if it runs smoothly and doesn't take too much force to push it through? Did you check the nozzle temperature with an external thermocouple that's proven to be within about 2 degrees C accurate? Put it into the hot end all the way down.
If you use a Bowden the tube adds significant amount of springiness (though 1.75mm maybe less so than 2.85/3mm). It needs to build up back pressure. Did you try extruding some, then immediately extrude the set 100mm amount? This would account for the pre-tensioning of the filemant. Did you measure the filament going into the hobbed bolt vs the amount coming out of it, at the end or at the start of the bowden tube?
Did you try printing a test object to see if extrusion is correct? So far you only tried calibrating the e steps per mm (as far as I know).
For example, I need to extrude about 6mm before starting a print due to my 600mm 3mm diameter bowden tube to pre tension the filament or the first layer isn't going to start properly.
If you put pressure on the filament coming out of the cold end manually, does it show the same results of shorter than requested length of filament? Could you feel the motor slipping, skipping etc?
Is there any change in method when you extrude 100mm without nozzle and with nozzle on? If you use gcode scrips could there be a difference, maybe gcode that changes the extrusion rate that's not in the non nozzle script?
If none of the above, is there any way you could measure the number of step pulses on the step stick? If you've got an oscilloscope you could try to see if the actual amount of steps are sent to the step pin of the extruder stepstick.
Did you try a ramps firmware reset to factory defaults? Did you do any recent updates? Older versions?
Re: Extruder woes (not extruding correct amount under pressure) April 19, 2019 05:51AM |
Admin Registered: 11 years ago Posts: 3,096 |
Re: Extruder woes (not extruding correct amount under pressure) April 19, 2019 10:24AM |
Registered: 7 years ago Posts: 619 |
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Ohmarinus
Okay I've tried 3 different hotends (J-head, Merlin and E3D v6), 2 extruder motors (both new), rebuilt the extruder twice (no slippage, no filled up teeth, no loss of compression and consistent extrusion), completely changed the motherboard (replaced both Ramps 1.4 and the Arduino Mega), replaced the stepper driver 3 times on both Ramps, tried 3 versions of Marlin firmware (the first one I ran on for years from 2014, one from 2016 and the newest Marlin) and now I'm lost.
Lubricated the bowden cable, inspected every inch.
Right now I have put on the E3D V6 hotend that was supposed to be for my new printer, still no reliable extrusion. I have no clue what's wrong. It now extrudes a little more than 88mm, around 91~92mm but still not the 100mm I get when I run the extruder freely.
I have used 2 pieces of software to give the extrusion command, tried two different computers with USB, tried to put the extrusion command on an SD card in a gcode file.. I can't find the issue.
Can it be the PSU? I have tried two differens PSU's, no difference. I think the machine is haunted.
Oh and 3 different types of filament, different brands, etc. All stored in a good way, low humidity, no offgassing when extruding.
Re: Extruder woes (not extruding correct amount under pressure) April 20, 2019 03:09AM |
Admin Registered: 11 years ago Posts: 3,096 |
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dlc60
Quote
Ohmarinus
Okay I've tried 3 different hotends (J-head, Merlin and E3D v6), 2 extruder motors (both new), rebuilt the extruder twice (no slippage, no filled up teeth, no loss of compression and consistent extrusion), completely changed the motherboard (replaced both Ramps 1.4 and the Arduino Mega), replaced the stepper driver 3 times on both Ramps, tried 3 versions of Marlin firmware (the first one I ran on for years from 2014, one from 2016 and the newest Marlin) and now I'm lost.
Lubricated the bowden cable, inspected every inch.
Right now I have put on the E3D V6 hotend that was supposed to be for my new printer, still no reliable extrusion. I have no clue what's wrong. It now extrudes a little more than 88mm, around 91~92mm but still not the 100mm I get when I run the extruder freely.
I have used 2 pieces of software to give the extrusion command, tried two different computers with USB, tried to put the extrusion command on an SD card in a gcode file.. I can't find the issue.
Can it be the PSU? I have tried two differens PSU's, no difference. I think the machine is haunted.
Oh and 3 different types of filament, different brands, etc. All stored in a good way, low humidity, no offgassing when extruding.
Sigh. I have a heavily modified Anet A8 that was absolutely perfect for about a year. Then (poof!) I have the same problems you have. Irregular extrusions, weird first layer, poor quality prints. I have tried all that you have too. Still, my perfect printer will not do well anymore. I am down to looking at bearings to see if the movements are putting the hot end in a bad place. It has gotten so bad that I am considering scrapping the whole printer and starting over. I work in the tech industry and over the years have seen several "possessed" devices that will not work even after replacing everything in the box. They become the home of Maxwell's Demon and cannot be reclaimed...
I feel your pain, I really liked this printer. I think that I'll tear mine down into its component pieces and rebuild from the bottom up. Maybe "Max" will move on if left homeless for a while.
DLC
Last G29 after squaring the frame and leveling the bed: Bilinear Leveling Grid: 0 1 2 0 +0.033 -0.045 -0.062 1 +0.014 +0.058 -0.013 2 +0.054 +0.068 -0.019
Re: Extruder woes (not extruding correct amount under pressure) May 30, 2019 06:42AM |
Registered: 7 years ago Posts: 7 |