Repairing Stripped Plastic Gear Teeth

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sleddriver

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I've been doing some research on this and wondered if anyone had been down this road before? This double-gear came out of an appliance. The small gear drives a larger one connected to the output. You can see where the teeth were shredded in the center section.

One method of repair suggested coating the damaged threads with a metal-reinforced 24hr epoxy, letting it set up, then using it in place with either wax paper, teflon tape, clear food wrap, etc. to keep the epoxy from sticking to it, to imprint new teeth.

Another cut out the damaged smaller section, slid in a new gear and trimmed it to length.

I spent some time in a hobby shop that carries cars & helo's looking through their selection of gears. No joy. Parts are no longer avail. from the manufacturer either.

Small gear: 11T; dia: 0.38"; Height: 0.37"
Large gear: 40T; dia: 1.225"; Height: 0.13"
Overall H: 0.5"
Tooth height: 0.045"

Any ideas?

Gear%20002_zpsnzc1tgyq.jpg


Gear%20003_zpsclrdmw3v.jpg
 
see if you can buy a used or broken version of same appliance (check ebay) and hope it's gear is in better condition-same strategy as going to junkyard for carparts
 
Last edited:
Originally Posted By: cptbarkey
3D Printer.


That. If you know how to use Autodesk or Blender you can have the part printed or laser-sintered in a material of your choice. Nylon is available.
 
nylon gear teeth cannot be properly repaired, period.

Go find a fresh new replacement and then take it from there.

Q.
 
I like the 3D printing item. Great excuse for a new toy...er, tool.

Seriously though, probably can even find a somewhat local place that does it.
 
By the time you get'er fix it will cost the same as buying a new one...how do I know? I do this all the time
laugh.gif
 
Sometimes it's not about the cost.

I can think of some reasons :
- Keep it out of landfill
- Burning desire for the challenge
- Irrational emotional attachment

..and..

- Sometimes the repair is actually cheaper
 
Also have a look why the gear stripped in the first place too. I had a gear of that type strip in my RC car 3 times before I really looked to see what was happening. The shaft the gear was riding on would flex under extreme load and let the gears partially unmesh, and zing, no more teeth.
 
This came out of a Krups ice cream maker. As the mix stiffens up, the motor will reverse, attempting to keep stirring. Overtime & use, this gear wears out. Further, it appears the gear itself has become softened due to the grease. As if they were incompatable. Odd that...

I've been unable to get to a local HW store to buy the Devcon slow epoxy recommended. Found no joy at a box store last night. However, I have found an unopened pkg of JB-Weld on hand! It takes about 15hrs to cure, which is what I'm looking for. So I'm going to go with it and see what happens. Unfortunately, the mixer is out of commission for Labor Day...

Backup plans include seeing if I can find a replacement from some outfit that carries A LOT of plastic gears, making a mold and pouring one, I like the 3D printer option, but don't know where to do this, (suggestions?), or firing up the Taig and making a new one from Delrin.
 
I am 100% sure an epoxy gear won't hold up under anything more than minimal torque. You need the part made from Nylon or similar, or from metal. If you go the 3D printing route, you need to design the part in 3D modeling software. Then you upload your file to shapeways.com or a similar site that will lasersinter or print the part for you in a material of your choice. They can do noble metals, steel stainless steel, bronze, brass, nylon, styrene etc. They can even print parts in wax so you can go have a lost wax casting made. Why don't you contact Krups for the part?
 
Originally Posted By: brzed
Why don't you contact Krups for the part?
Your answer is found in my OP.

I'll lookup shapeways...thanks.

Here's a video:
 
Originally Posted By: sleddriver
Originally Posted By: brzed
Why don't you contact Krups for the part?
Your answer is found in my OP.

I'll lookup shapeways...thanks.

Here's a video:



Honestly, from experience, I don't see it holding up under stress.
 
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