Need help with a gear.

T Bredehoft said:
What follows is an unanswerable question.

Why did the stronger/wider teeth strip? Why not the weaker/narrower ones?
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The narrow teeth power the drive wheels and the wide teeth drive the tiller tines. I hit a buried piece of very heavy, commercial, plastic edging and the rest is history. You would have thought that there should be shear pins on the tines.
 
38Bill said:
The narrow teeth power the drive wheels and the wide teeth drive the tiller tines. I hit a buried piece of very heavy, commercial, plastic edging and the rest is history. You would have thought that there should be shear pins on the tines.
Click to expand...
Huh, interesting! I've not seen a tiller without a shear pin, but they clearly knew that this was going to be an issue when designing this (which is why the tines have a bigger gear).

I'd offer to make it for materials (plus perhaps the gear-cutter I'd need for the chain teeth), but I have low confidence I could cut the splines accurately enough :/

I also couldn't guarantee any sort of turn-around time since it looks like it would require making at least 1 more shaper attachment to cut the splines.
 
splines.jpg
This splined coupling was indexed by first drilling the bolt circle on a dividing head. Then put in the vise and use 2 close fitting pins and leveling the holes. Holes were turned off when done.
 
mcostello said:
View attachment 328532This splined coupling was indexed by first drilling the bolt circle on a dividing head. Then put in the vise and use 2 close fitting pins and leveling the holes. Holes were turned off when done.
Click to expand...

Ah! I'd seen that when you posted it, but forgot about it! Thats a good idea. I'd definitely want to cut the outer-gear after the splines anyway, so this isn't an issue.

38Bill: Do you have any idea of the gear pitch on the outside? I doubt I have a cutter for it unfortunately, but it would determine if it is cost effective to buy a cutter. Though I guess, even with that, I could cut the profile in a flycutter blade and single-point it. No idea how accurate I could get with that though.
 
How about this? I weld up the end with the missing teeth. Then I use the good teeth on the other end to index the gear with the cutter head. Should be able to get close enough?
 
I think RandyWilson's suggestion will be the quickest and cheapest and then fit a shear pin somewhere in the system to avoid a repeat occurrence.
 
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