Ultimate Extruder Calibration Test

by Starno, published

Ultimate Extruder Calibration Test by Starno Sep 18, 2011

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Ultimate Extruder Calibration Test by Starno is licensed under the GNU - GPL license.

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Flow rate and feed rate are no longer difficult to calibrate, thanks to stepper extruders. However, to really get your print quality to the next level, you will need to calibrate temperature and reversal settings for a given material. (and/or travel feed rate, depending on your machine) This is a fully parametric calibration test for both bridging and gap distances within the same part.

Bridging is a great test for temperature. If the bridge is too saggy, the temperature is too high. There are also some advantages to higher temperatures though, one of which is it makes the thermoplastic less viscous, creating less work for the motor. If your preference is printing really hot, a fan concentrating cool air on the extrudate can also be used to calibrate bridging.

Traversing large gaps is obviously a great test for reversal/travel speed settings. Set extra shells to 0 to avoid hiding any ooze behind inner perimeters. Make the infill very low to save printing time since you only care about spanning gaps for this test. Use a camera for feedback if you are extra picky about strings.

Good Luck.


To customize your test, open the script with OpenSCAD, and edit the variables labeled at the top. Once you are finished, select "Compile and Render" or press F6.

minimum reversal gap distance (mm)
maximum reversal gap distance (mm)
minimum bridging distance (mm)
maximum bridging distance (mm)
number of steps
total height of object (mm)

width of vertical tower (mm)
width of border on base plane (mm)
thickness of border on base plane (mm)
thickness of bridges (mm)

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Please best configuration ABS ? use simplify3d....davinci 1.0

cool. I just got my first printer and designed something like this last night to see how far I could push the spans. this looks like a very useful test.

Interesting, the perimeters of the bridges go flawlessly, but the infill in between, the printer just 'buzzes' or 'pulsates' and the line falls in between the perimeter lines of the bridge.

Maybe my X-belt isn't tensioned enough? The 'buzzing' obviously should be some kind of really short movement from left- to right to connect the zig-zag lines to the perimeters' bridge lines.

Don't worry about this issue too much, it is dependent of how intelligent the slicing software is. Whenever extruded filament attaches infill to a perimeter, the software is telling it to move just enough to contact the perimeter, and if that perimeter is dangling in the air, it doesn't have a very good chance of succeeding flawlessly. If the imperfections still bother you, you can adjust the infill angle to start at 180degrees and rotate 180degrees every layer. This will force the software to have bridging infill in the same direction as the bridge on all layers, and your problem will go away

Sounds like fun just to try that out and see if it works.

Imagine, if I would let the infill angle stay at this 180º setting, will I get into trouble with other prints? Or can I just configure my slic3r like that and leave it like that?

It's advantageous to rotate the angle of infill for most objects but not on the first few layers of bridges. Only change it if you want to verify that is your problem, but I wouldn't suggest using those settings all the time.

Okay, I'm also testing Cura at the moment and it doesn't even have any bridging settings! Weird.

Thanks for your reply.

My Prusa Air did this one succesfully, but I had to reduce the gap fill speed because those tight fills from the bridge were making the printing bed shake way too much.

Do you think we could set up a sort of benchmark for this? If so what criteria would we employ. I would like to know how we would best rate this print. Do we have a "perfect" print of this to compare to?

Printed this with reasonable success...all except the first line of bridging, which either retracted too far previously or didn't have enough space to attach the beginning of the line (and then started the first line of the bridge mid-air).

Have you found a fix for this? I've seen it a couple times on my own machine.

I resliced with a thicker layer width in Kisslicer and had better success.

its only on the perifery that this pyramid stands. It is Hollow. If it were a hive it there would bee.


I dont understand the question

Could people comment with the settings they ended up with after using this calibration tool? :-)

Every printer's different, that's why you have to calibrate them!

Hay, could someone please post what settings they found worked best for this? perhaps it would help others in the future calibrate their printers!

Can you tell me, what is the purpose of the non-bridging portion of the print?

Are you talking about the wall across from the bridging portion? That's for eliminating strings. It's oriented so that no matter what toolpath software is used, the shortest distances to traverse on each layer are the ones specified in the OpenSCAD file.

This was a big help in setting up the temperatures for my Thingomatic. Thanks!

Nice! This really gave my Prusa a workout. Orange ABS @ 220C with a heated bed. I can see the material change consistency due to temperature fluctuations when I look at the sides of the print. Time for PID temperature. Thanks!