3D Printing Blog

Choosing a 36mm extruder motor

NEMA14 36mm round steppers are becoming increasingly popular extruder stepper motors due to their small weight and high torque. I have tested LDO-36STH17-1004AHG, LDO-36STH20-1004AHG, and Moons’ 36mm 20mm steppers, and I will share my thoughts on them.

NEMA14 36mm round steppers

Orbiter and Sherpa Mini were the first popular extruders to use these motors, and recently even Voron Clockwork 2 extruder switched to this type of stepper. There are also Sailfin, HextrudORT, LGX Lite, and many more designs using these motors.

The first one I got was LDO-36STH17-1004AHG about a year ago. I used it to build Orbiter 1.0 extruder, and it works for me to this day, although it now powers Sailfin. It’s a great little extruder with only one issue: it runs very hot. I had to lower the run current to 0.35A to get it to a more reasonable temperature (about 60C). Technically it’s designed to run at high temperatures, and it should be just fine, but I didn’t feel comfortable as it could melt plastic parts around it. The lower current does reduce its torque, but it still has enough to keep up with 300mm/s printing.

When I was building my Voron 2.4, I chose to build a Galileo extruder (Orbiter adaptation for Voron printers) and got LDO-36STH20-1004AHG to power it. The number difference in the model name refers to a slightly longer body length of 20mm vs. 17mm. It’s also a newer motor with a lot lower internal resistance (2.1Ω vs. 10Ω), which means it runs a lot cooler. You can run it at 0.85A without issues. I’ve been using it for over 6 months now, and I think it’s a great choice.

Recently suppliers started carrying Moons 36mm 20mm stepper motors, and I decided to pick one up for my next build. Looking at the datasheet, it has even better internal resistance (1.9Ω) and lower rotor inertia. I’ve put it in my Galileo extruder, and it performs just as well as the 20mm LDO motor. I had it only for a couple of weeks, but I will update this post with a longer-term review.

LDO-36STH17-1004AHG LDO-36STH20-1004AHG Moons’ 36mm 20mm
Body length 17mm 20mm 20mm
Weight 70g 82g 81g
Peak current 1.0A 1.0 A 1.0A
Run current 0.35A RMS* 0.85A RMS 0.85A RMS

* LDO-36STH17-1004AHG could technically run at a higher current, but it gets very hot, and at over 0.35A RMS it could melt plastic parts around it.

LDO-36STH17-1004AHG LDO-36STH20-1004AHG Moons' 36mm 20mm

Which one to get?

I recommend getting one of the newer 20mm body steppers: LDO-36STH20-1004AHG or Moons 36mm 20mm. They are both excellent choices and perform very similarly. They also usually come at the same price point, but if you find a deal on one, that could be the reason to lean one way or the other. Finally, the slight weight savings you would get with the 17mm model are not worth it due to heat issues.

P.S. I would like to design a test to compare them in a quantifiable way. Stay tuned for an update to this post.

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