Improving dimensional accuracy on Taz 4

I have had fairly good luck printing parts so far with my new Taz 4, but have noticed that everything seems to be over extruding a little bit. I’m getting good precision, the results are fairly predictable. Walls tend to be ~0.2-0.3mm thicker than designed, and holes tend to be ~0.2-0.5mm smaller than intended (worse for smaller holes). Since it’s been predictable I have been able to compensate for the error in parts that I have designed, but it does limit my ability to use an existing design when I’m able to find something that meets my needs. Screw holes are the real issue!

I seem to have had the best luck running the hotend at 180 degrees and the bed at 50 degrees (default for PLA). I took several measurements of my filament (purchased at Microcenter) diameter with a caliper and am using that value in Slic3r.

Should I be expecting to get better dimensional accuracy? I know this thing isn’t magical so it’s expected that there will be some tolerance that I have to design around. But if there’s something I can adjust that will make things better then I’d like to know how! I’ve considered telling it that the filament is thicker than it is, which in theory would result in it extruding less plastic per mm of commanded extrusion, but I’ve never been a big fan of arbitrary fudge factors without understanding the mechanics behind the decision. Is there a more elegant way to get at it? Preferably something I could calculate based on the known over extrusion!


You may want to further refine the extrusion calibration and slicer profile on your machine. The biggest variable that the stock profiles don’t have any way of taking into account is the actual width of the filliament itself. a 3.00mm filliament is almost never exactly 3.00mm. They not only tend to vary from roll to roll, they can also vary from section to section on the same roll as much as .05mm. You will want to measure your filliament in a few places before starting a print, and take the average for the slicer filliament diameter setting.

You can also further refine the calibration of the extruder head itself. The one from the factory should be pretty close though. Here are a few guides to get you started:’s_Calibration_Guide

What is interesting about Triffid Hunter’s Extruder Calibration method is that you calibrate the E-Steps without the Hot End.

I use separate Extruders for ABS and PLA and after finishing my PLA extruder, I couldn’t dial in appropriate E-Steps for the life of me. I then followed Triffid Hunter’s Calibration steps (without the Hot End) and my E-Steps ended up being 800, right on the default setting.

After finishing the other steps (with the Hot End attached), I settled for 820, although I could have just left it at 800.

When I tried to calibrate, pushing the filament through the Hot End, I was up in the high 900’s one time, then the next time it would under extrude, then after adjusting it would over extrude, and this kept going on and on and was one heck of a frustrating experience trying to get the extruder calibrated.