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I'm using a CraftBot original to print PLA, but some of the filament has become stuck in the teeth of the extruder gear on its way into the hot end. I'm having issues with the gear becoming stuck and "clicking" instead of turning, and I suspect it is because of the clogged teeth. I haven't changed materials in a long time. I've cleared several print head clogs, but each time the gear gets back around to the one spot, it seems to get stuck again.

Are there any good ways to clean this gear? I was thinking of putting it in a toaster oven and trying to melt the PLA off it, ideally without setting my house on fire in the process. Anyone have better ideas?

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  • $\begingroup$ If you hear a clicking sound, it might be as well not enough power that is delivered to the motor, so that it loses steps. You can increase the current limit given (most likely by your pololu compatible stepper drivers). $\endgroup$
    – kamuro
    Jun 21, 2016 at 6:44

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I mostly use a tooth brush for that kind of problem

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  • $\begingroup$ My coworkers got to the gear before I did, and used a tooth brush and alcohol to clean it off. We have a new print job running now, and it appears to be working so far. $\endgroup$
    – emackey
    Jun 20, 2016 at 18:49
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If your gear skips at the same place each time I have found on my machine that the gear does not fit the motor shaft properly and has a larger gap between the gear and the idler roller.

Check to see if there is a thicker buildup on one side of the gear than the other.

On my machine what I had to do was to use a spare motor cable and watch the gear as it turned, and at one point on the gear it would slip and shave off a small amount of filament.

If that turns out to be your problem use a good caliper to measure your motor shaft, and the inner diameter of the gear.

Sometimes the minimum shaft diameter and the maximum bore diameter of the gear are just enough to allow that small variance in the outer rotation diameter of the gear.

Sometimes just replacing the gear will solve the problem, and sometimes it will require a new motor and/or gear.

As an alternative you can clean the gear using Acetone and a toothbrush, but that will be required often and you will have buildup in the chamber below the gear which can also cause feed problems, and you must make sure that all Acetone has dried before using the extruder again.

I suggest starting with changing gears since they are the cheapest and using the Caliper to find the closet fit possible.

You can get gears on e-bay at very reasonable prices. and I bought several to get the best fit possible.

Good luck and consider if you want to make a more permanent repair or temporary repair when making your choice. I chose the more permanent one because the slippage was affecting some of my prints.

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If you are able to remove the gear, as I suspect you can, a useful tool is the file card. It resembles a flat hair brush but the bristles are short wire, very stiff. In traditional use, it removes metal shavings from conventional metal files. It will easily remove plastic from between the gear teeth. If you are unable to remove the gear, but can access a portion of the exposed teeth, a suitably named dental pick can remove slowly the clogged material.

Cooking the gear may not cause a fire, but could carbonize the plastic onto the teeth, perhaps creating a greater problem.

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  • $\begingroup$ I've also used the small brush for my razor. Just about the perfect size. $\endgroup$
    – tbm0115
    Jun 17, 2016 at 22:32
  • $\begingroup$ I got the impression, although normally I don't do impressions, that the OP was having difficulty removing the plastic. If it's simple powdering getting stuck in the teeth, your razor brush is a good idea. They are also stiff and reasonably short bristled. It's less likely the OP will set the house afire using a razor cleaning brush. $\endgroup$
    – fred_dot_u
    Jun 18, 2016 at 0:38
  • $\begingroup$ Thanks. The plastic feels fairly well stuck in the gear teeth, but I'm going to acquire a file card brush and give that a try. I'll let you know if it works. $\endgroup$
    – emackey
    Jun 18, 2016 at 14:25
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I use an air bulb to clean dust out of teeth, but the clicking sounds like the stepper has too much mechanical load so i am guessing there is something solid stuck at that point. Poke it off with something sharp.

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  • $\begingroup$ Yep, it's not dust, it's hardened bits of PLA that seem fused to the gear teeth. The teeth are meant to dig into the incoming filament a bit, but they can't when they're full of old plastic, so the incoming filament can't move past the gear, and the stepper motor strains. $\endgroup$
    – emackey
    Jun 18, 2016 at 14:28

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