Anybody know where to buy a coarse-pitch spur gear?

[Showmedata]

I'm going to improve my Landpride snowblower and I would prefer to find a spur gear to match the pitch of the stock ring, rather than motorizing the big worm drive. I can't seem to find a source for spur gears with such a large pitch. Does anybody know where I should look?

Thanks.

 

[PoTreeBoy]

I'm going to improve my Landpride snowblower and I would prefer to find a spur gear to match the pitch of the stock ring, rather than motorizing the big worm drive. I can't seem to find a source for spur gears with such a large pitch. Does anybody know where I should look?

Thanks. View attachment 86020
View attachment 86021

Maybe make one? Similar to the one on the right below. Take 2 disks, drill holes around the edge for drive pins, one in the center. Mock it up in wood or foam first.

 

[JohnDB]

@Showmedata That doesn't look like a spur gear profile to me but maybe it would work. In addition to PoTreeBoy's idea, places to research if you want a spur gear would include as a starting point: SAE standard profile, or AGMA https://www.agma.org/. If you can't find a stock gear, then look for engineering firms that specialise in profile cutting using CNC plasma cutting machines. You supply the profile, they draw it into their system and the machine cuts it. They can get very accurate (not as accurate as CNC machining but good enough for low speed applications), and not hugely expensive. Make a template first so you know for sure that your profile will fit.

I assume you have worked out the difference in drive ratio of a spur gear compared to worm drive.

 

[Yooper]

Its not the gear but the worm pitch that you are after. You can use the same gear if you can find or make a worm with half the pitch of the current one. Going to start looking like a Bendix drive. Worm drives are known for being high ratio by their nature. Might want to think outside the box a bit. Maybe the existing setup with a gear increaser?

 

[chim]

When I had a snow blower I went with a cable wrapped around the chute and a shaft that turned with a small 12V motor. Worked well.

 

[Showmedata]

@chim that's clever. I can't tell from the photo - how does it return to rotate the chute CCW? Does the cable wrap on the drum shaft in two locations?

 

[Showmedata]

@Showmedata That doesn't look like a spur gear profile to me but maybe it would work. In addition to PoTreeBoy's idea, places to research if you want a spur gear would include as a starting point: SAE standard profile, or AGMA https://www.agma.org/. If you can't find a stock gear, then look for engineering firms that specialise in profile cutting using CNC plasma cutting machines. You supply the profile, they draw it into their system and the machine cuts it. They can get very accurate (not as accurate as CNC machining but good enough for low speed applications), and not hugely expensive. Make a template first so you know for sure that your profile will fit.

I assume you have worked out the difference in drive ratio of a spur gear compared to worm drive.

Thanks. I can draw up a gear profile and have it cut (plasma or laser), this is super easy now with online brokers like Xometry. I assumed it would be easy enough to find a catalog item to match the ring that Landpride put on there, but maybe not.
I'll probably have someone print a plastic gear first if I go this route.
And yes, I understand the ratio effects of gears and worms.

 

[chim]

@chim that's clever. I can't tell from the photo - how does it return to rotate the chute CCW? Does the cable wrap on the drum shaft in two locations?

Someone had something similar that I copied.

The cable wrapped around the chute and was fastened to it. The pipe on the side seen in the picture had the ends of the cable fastened to it through holes and a few wraps The cable ends on the pipe were wrapped in opposite directions. Turning the pipe one way wrapped one cable end and paid out cable on the other. The reversing motor was run in the other rotation to make the chute go the other way.