I'm installing the Micro Swiss direct drive kit for my Ender 3 Pro and I encountered two problems:
- The drive gear on my machine is pressed onto the stepper motor rather than held in place with a set screw.
- The stepper motor shaft is round and does not have a flat keyway. The Micro Swiss kit depends on the shaft having a flat spot on it for the new gear.
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| Ender 3 Pro extruder stepper motor with pressed-on brass gear. (note a drop of penetrating oil in the center) |
Creality Press-Fit Extruder Gear Removal
I read at least one claim that this gear easily pulls off with a pair of pliers; unfortunately I found that to not be the case with my motor and gear.Here is how I got the little gear off:
- Apply a little penetrating oil to the interface between the gear and the shaft. I used PB Blaster, WD-40 will work fine as well.
- Heat the gear with a MAP gas torch (the same kind used for soldering plumbing joints). You could probably use one of those little butane torches used for lighting cigars as well. Brass expands quite a bit when heated, so to increase your chances of success, heat the brass gear heavily and avoid applying heat anywhere else on the drive gear.
- Clamp the gear into a bench vice, and position a couple of wrenches as in the picture below:
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| Using a couple of wrenches to pop the brass gear off of the motor. (My vice was frosty -- it was in the negative teens here in Michigan this morning!) |
- Gently tap the end of the wrench in the photo (see red arrow) with another wench. The metal-to-metal impact should jar the heated brass gear loose. This is a precision stepper motor, so do not use a hammer!
- Be careful, this is not the correct way to remove this gear. The correct way to do this is with a tiny bearing puller like this one as it will not apply any force to the internals of the motor. Rather, the bearing puller will only apply force inward to the end of the shaft and an equivalent force outward to both sides of brass gear. The method shown here will transfer whatever force you apply to the gear to the entire length of the drive shaft as well as the internals of the motor. Proceed with caution and at your own risk.
- If you choose not to heat the gear, it will be harder to remove and you could increase the risk of motor damage. Apply heat to the brass gear and use light, gentle taps; the impact force should knock it loose.
Add Missing Flat to Drive Shaft
When you install the new Micro Swiss direct drive gearset, the included gear has a small set screw that is intended to sit onto the flat portion of the shaft. From the Micro Swiss installation instructions:
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| Step 14 of Micro Swiss direct drive installation instructions |
Since my machine does not have a flat part of the drive shaft, I had to add one as follows:
- Follow the Micro Swiss installation instructions for aligning the new filament drive gears.
- Proceed to tighten down the set screw *as if* there were a flat spot in the shaft. This step will make a tiny witness mark (scratch) in the shaft that you will use to determine where to grind the shaft down
- Release the set screw and remove the Micro Swiss drive gear.
- Use a magnifying glass, if necessary, to examine the surface of the shaft; you should see a tiny witness mark where the set screw was tightened down. (The shaft is hard steel and it may be hard to see this mark!)
- Use an abrasive wheel (I used a cut-off disc) to gently grind an area away on the shaft where the witness mark was. I went several millimeters on either side of the witness mark. See below:
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| Creating a flat in the stepper motor drive shaft for Micro Swiss gear installation. |
- Follow the Micro Swiss installation instructions for gear alignment *again* but make sure the set screw is directly over the new flat spot that you just made.
- Tighten the set screw down against the new flat spot once you are satisfied with drive gear alignment.
I hope this helps you with your Micro Swiss direct drive installation.
