Extruder Calibration

[PowderLab Drew]

Hi Everyone,

First off, I did search for this topic and found some that looked like they were going to cover what I was going to ask but didn't quite cover it.

Basically I have 2 questions- I have a 3 week old Max V2

1. EXTRUSION AMOUNT TEST- What is the best way to make sure when I send the command to extrude 100mm it actually does 100mm? I tried marking the filament with a start and 100mm mark and lining it up to the top of the Bowden connector and hitting the +100. The thing that surprises me is that it only moves through less than HALF of the 100mm mark. Is that right? My coworker has a different style printer and he tried to do the same test and his was only ~1mm off. I thought maybe it was collecting in the extruder itself so I did one test with the extruder totally empty and one with it totally full- none of which yielded a 100mm extrusion.

2. FREE AIR EXTRUSION TEST- The Max V2 comes with a .5 tip right? When I let the filament free air extrude, I let it harden and snap it off. I then measure the filament with my caliper at numerous points and its measuring .69-.77. Is that normal? From everything I can read it should be pretty close to what the tip size is ~.5 or so. Is that right? If it is, why is the filament so much bigger?

Thanks in advance!
Drew

[Jimustanguitar]

1. EXTRUSION AMOUNT TEST- What is the best way to make sure when I send the command to extrude 100mm it actually does 100mm? I tried marking the filament with a start and 100mm mark and lining it up to the top of the Bowden connector and hitting the +100. The thing that surprises me is that it only moves through less than HALF of the 100mm mark. Is that right? My coworker has a different style printer and he tried to do the same test and his was only ~1mm off. I thought maybe it was collecting in the extruder itself so I did one test with the extruder totally empty and one with it totally full- none of which yielded a 100mm extrusion.

I measure out a meter of filament and mark it at 100mm increments by nicking the surface with a razor blade and putting a dot on it with a marker. (the cut mark is very sharp and precise, and the dot makes it visible). Then extrude various amounts that add up to 100mm and guestimate how far off you are to adjust the steps per mm. After a few times through this, you should have enough of your meter left to test 2-300mm at once for final fine tuning.

2. FREE AIR EXTRUSION TEST- The Max V2 comes with a .5 tip right? When I let the filament free air extrude, I let it harden and snap it off. I then measure the filament with my caliper at numerous points and its measuring .69-.77. Is that normal? From everything I can read it should be pretty close to what the tip size is ~.5 or so. Is that right? If it is, why is the filament so much bigger?

What you're measuring is more useful for identifying which size nozzle you're using than it is for calibration. This measurement will vary depending on how much "squirt" is hanging down from the nozzle. The longer the amount that's hanging, the thinner gravity will draw the string of plastic. You should be printing a thin wall test cube to measure wall thickness to gauge accuracy instead.

[PowderLab Drew]

1. EXTRUSION AMOUNT TEST- What is the best way to make sure when I send the command to extrude 100mm it actually does 100mm? I tried marking the filament with a start and 100mm mark and lining it up to the top of the Bowden connector and hitting the +100. The thing that surprises me is that it only moves through less than HALF of the 100mm mark. Is that right? My coworker has a different style printer and he tried to do the same test and his was only ~1mm off. I thought maybe it was collecting in the extruder itself so I did one test with the extruder totally empty and one with it totally full- none of which yielded a 100mm extrusion.

I measure out a meter of filament and mark it at 100mm increments by nicking the surface with a razor blade and putting a dot on it with a marker. (the cut mark is very sharp and precise, and the dot makes it visible). Then extrude various amounts that add up to 100mm and guestimate how far off you are to adjust the steps per mm. After a few times through this, you should have enough of your meter left to test 2-300mm at once for final fine tuning.

2. FREE AIR EXTRUSION TEST- The Max V2 comes with a .5 tip right? When I let the filament free air extrude, I let it harden and snap it off. I then measure the filament with my caliper at numerous points and its measuring .69-.77. Is that normal? From everything I can read it should be pretty close to what the tip size is ~.5 or so. Is that right? If it is, why is the filament so much bigger?

What you're measuring is more useful for identifying which size nozzle you're using than it is for calibration. This measurement will vary depending on how much "squirt" is hanging down from the nozzle. The longer the amount that's hanging, the thinner gravity will draw the string of plastic. You should be printing a thin wall test cube to measure wall thickness to gauge accuracy instead.

Hi,

Thanks for the reply- for the 100mm test, when I say its not close- its REALLY not close.. more like less than half of the marked 100mm distance. Like 35-40mm when clicking the 100mm extrude in Mattercontrol. Is that really how far off my extrusion is? When I print things its definitely not perfect, but it really doesn't look like its missing half of the filament.

For #2, that is kind of what I wanted to test- what size nozzle is really on there. I understood that it came with a .5 nozzle, but I cant get any filament to extrude and hang at less than .65, most are closer to .75.

[rampeh]

#1. Have you changed your firmware since you bought the rostock? It could be the default steps_per_mm for extruder is wrong somehow, I know I have an old rostock which only has 1/8 microstepping so i had to reduce my steps per mm by a half. You may have the opposite problem.

#2. The nozzle will usually extrude a larger bead when in free air, due to the plastic expanding after leaving the nozzle (die swell). This won't affect your print as it will behave differently when printing a thin wall cube, since it will be constrained by pressing against the bed. I don't think there's any good way to exactly measure out your nozzle diameter based on free air extrude, but I might be wrong.

[PowderLab Drew]

Hi Rampeh,

Yes, I followed the manual to a tee and installed the latest firmware, i think .91? Something like that.

I have continued to mess with the settings and actually think i have got it pretty good! Kinda hard to see the layers in this Glow in the Dark filament, but it really does look nice.

[img]http://imagizer.imageshack.us/v2/150x100q90/539/a51c6e.jpg[/img] [img]http://imagizer.imageshack.us/v2/150x100q90/536/e01c4c.jpg[/img]

Drew