12" Atlas Reverse Tumbler Gear Stud

Yes. The Atlas part numbering system identified whatever type or size of machine a part was originally used on. At least up until the palace coup that changed the company name from Atlas back to Clausing, for the most part Atlas did not assign a new part number to an old part simply because the part was used on a different machine than what it started life being designed for. If you look at almost any parts list for any type machine, you will see examples of part numbers that do not match the machine that the part is being used on. So if a part number is 10-242, it is still 10-242 even though the machine it's being used on is a 12". If a table saw had needed a gear like that, the part number would still have been 10-242. Or to put it the other way around, if the part number isn't 10-242, then a 10-242 won't work there.
 
paul s said:
The too short one is hex head and is identical to the other one, but about 0.003" too short.
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Was that as measured compared to the other bolt, or as compared to the gear?

Just speculating, but the bolt may have been fine and the gear could have been the problem. You mentioned other gears suffering from "Zamac disease" or "Zinc pests" and one of the first symptoms of this is parts beginning to swell. It's possible you gear may have begun to swell a bit.
 
RobertB said:
Was that as measured compared to the other bolt, or as compared to the gear?

Just speculating, but the bolt may have been fine and the gear could have been the problem. You mentioned other gears suffering from "Zamac disease" or "Zinc pests" and one of the first symptoms of this is parts beginning to swell. It's possible you gear may have begun to swell a bit.
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Good point - that's estimating, just by looking at the gear/bolt combination assembled. I never did measure the two bolts, just skimmed the face of the "fat" gear on my other lathe.

So, am I sitting on a time bomb, as far as these gears falling apart? Or are they good for another 20 years?

Paul
 
The Suffix A gear hub lengths were 0.500". Probably +/- 0.005". Same is true of the early and late bushing lengths. Measure the hub length of the gear that you didn't modify and the one that you did.

As far as the Zinc Pest problem is concerned, it is generally thought that at this late date, if the parts haven't already failed, they aren't going to.
 
Well if it took 70 years for it to swell a few thousandths, I would expect many more years of service left in it.
 
I measured the bushing lengths at about 0.574" - each was within 0.001" of the other. I didn't measure the gears, mute point now.

I did order a backgear off of ebay, and made an offer on one of the spindle gears, as well. The only one I can't locate is the bull gear. I did call Clausing, just for the heck of it - they have a new bull gear, they quoted $202.95. All I see on ebay are entire headstocks or entire spindles. I may end up buying a whole spindle, taking the bull gear off it, and selling the rest.
 
Yeah. It is good that Clausing still offers some parts support for the Atlas machines. But unless they overstocked on a part 50 or 60 years ago, it is going to cost what it costs in 2019 dollars and wage scales, not 1940's or 50's. Just price a similar part for some newer US built machine (if there are any).
 
I've now got a backgear assembly and a 10-242 gear for the spindle.

Regarding the 10-242 gear: The teeth are noticeably smaller than the gear they mate with on the backgear. I'm assuming this is caused by wear, although the gear is so clean, it may have been media blasted. I'll attach some pics - is this going to cause problems? I've also noticed that the bronze sleeve that fits into the bore of the 10-242 is loose, which I also noticed on my original gear; a consequence of the Zamac swelling? It's essentially a slip fit - should I fixture it with some Loctite?

Just need to source the bull gear at this point.
P8222713.JPGP8222711.JPG
 
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Paul,

It would appear from your photo that the small spindle gear has been bead blasted. But I wouldn't worry about the slightly loose fit. It won't hurt anything.

The bushings are sintered bronze AFAIK, But the nature of the lubrication of the step pulley and small spindle gear bushings makes that less important than on some of the others. I would wash and dry the outside of it and use Lockwick primer and Locktite Bearing and Bushing Mount and let it cure a day or two before re-installing the spindle. I would be more inclined to blame the bead blasting for the loose bushing fit. I've not heard that bad Zamak castings swell appreciably but if they did and if that were a problem here, the ID would grow smaller, not larger.
 
That almost looks like the new gear is 20 deg. pressure angle and old gear is 14-1/2 deg. Where did you get the gear?
 
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