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Needing a gear

Posted: Fri Jul 12, 2019 2:00 pm
by whateg0
I was chosen to take a look at my aunt's White Mountain ice cream maker. It' pretty old, and after taking the gearbox apart, I found quite a bit of wear. But they are expensive, so some fixing can be done. I'll bush the hole where one of the gears spins. The hole is worn and the gear is worn down too. There was enough wear to reduce the gear engagement and now the gear is stripped enough that even if I fix the hole, the engagement won't be sufficient to last. So, I need a new gear, too, and so far I've not had any luck. I have searched boston gear and SPI and haven't found it. I'm not finding what I need though. White Mountain will sell the whole motor assembly, but no thanks!

The gear is 12T, 24DP. I'm not sure of the PA yet. The end is mushroomed enough that I don't have a good view of the cross section. It's a little over 2-5/16" long with the ends turned down. It's pressed into the bigger gear.
20190712_134953-am.jpg
I don't have the gear cutter to make one, but could buy it if necessary. Not sure if it's worth the money to do so, though.

Also, every electric ice cream maker I have owned or used, or just been around uses gears and is noisy. The reduction on this appears to be around 160:1, so why don't they use a worm gear or belts? This one uses 3 reductions to get there. Belts would take more space, but geez! They would be a lot quieter!

Re: Needing a gear

Posted: Fri Jul 12, 2019 2:01 pm
by whateg0
Oh, this gear is steel. I'm not sure if brass would hold up or not. I haven't tried to see how hard it is.

Dave

Re: Needing a gear

Posted: Fri Jul 12, 2019 3:19 pm
by spro
I think they used gear cored tube or the proper name. You buy it to length from the larger industrial supply places. MSC and Graingers have /had a section. If the end wasn't so damaged, you could cut the proper length at the unused area and turn it around, weld it.

Re: Needing a gear

Posted: Fri Jul 12, 2019 3:45 pm
by tornitore45
You have a spare gear right there. Cut the gears free, re-bore and make a new shaft. Assemble with Loctite.

Re: Needing a gear

Posted: Fri Jul 12, 2019 4:36 pm
by whateg0
The "shaft" at the ends are part of the smaller gear, which is all pressed into the bigger gear. There's no shaft going through them. The small gear is the shaft.

I did consider making a shaft to press into the bigger gear as the existing small gear does now, then somehow drill/bore a section of the smaller gear to fit the shaft. This is the final drive, so it is where the forces are highest, though. I'm not sure how if loctite would be enough to hold that or not. And as I stated before, I don't know how hard the gear is. I need to check it this evening.

Dave

Re: Needing a gear

Posted: Fri Jul 12, 2019 4:37 pm
by whateg0
I'll check the gear cored tube thing out. I could shove that into the big gear and put a shaft through it all.

Dave

Re: Needing a gear

Posted: Fri Jul 12, 2019 5:02 pm
by TimTheGrim
Look for steel “Pinion Wire”. Maybe somebody makes a size you could work with. Brass as a 2nd option.

Re: Needing a gear

Posted: Fri Jul 12, 2019 7:30 pm
by spro
Gosh. The picture showed the small end of the pinion and it looked threaded. That and because there was so much unused gear teeth, I thought it would be cored that way. The big end obviously fit a bushing or bearing. Now, requires a different look at things.

Re: Needing a gear

Posted: Fri Jul 12, 2019 8:33 pm
by whateg0
I'm sorry about the bad picture. I was trying to get something posted before I went to bed. Here's a couple better pics.

I did start out looking for pinion wire, but wasn't finding what I needed. I just looked again and found brass 24DP, 14.5PA, 15T, in brass, so maybe it does exist somewhere.
20190712_202300-sm.jpg
20190712_202312-sm.jpg

Re: Needing a gear

Posted: Fri Jul 12, 2019 8:48 pm
by BigDumbDinosaur
whateg0 wrote:
Fri Jul 12, 2019 8:33 pm
I'm sorry about the bad picture. I was trying to get something posted before I went to bed. Here's a couple better pics.

I did start out looking for pinion wire, but wasn't finding what I needed. I just looked again and found brass 24DP, 14.5PA, 15T, in brass, so maybe it does exist somewhere.
Looks like 20° PA teeth to me. In machinery, 20° is more common than 14½°, as smoothness of conjugal action is of secondary importance to resistance to shock loads.

Re: Needing a gear

Posted: Fri Jul 12, 2019 8:58 pm
by whateg0
BigDumbDinosaur wrote:
Fri Jul 12, 2019 8:48 pm
Looks like 20° PA teeth to me. In machinery, 20° is more common than 14½°, as smoothness of conjugal action is of secondary importance to resistance to shock loads.
Makes sense considering the application is high torque.

Dave

Re: Needing a gear

Posted: Fri Jul 12, 2019 9:09 pm
by whateg0
Good grief!!! I went back to McMaster and was just looking for a 12T gear and found "Gear stock". I had searched for pinion wire before, but didn't search for just gears.

Thanks for the suggestions - and patience...

Dave