Craftsman/Atlas change gear question

ARC-170

ARC-170

Jeff L.
H-M Lifetime Diamond Member
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I have a Craftsman 101.07403 lathe that did not come with a set of change gears. Do the Atlas 618 and Craftsman 101 use the same gear set? There are many sets on Ebay and I want to make sure I'm looking at the correct ones. They don't all have the exact set of gears I need, but they are close. Some have too many, some have all except one. I don't want to buy a set and then find out they won't fit. The sellers don't always put the number of teeth or the hole size, either.

For example:
https://www.ebay.com/itm/9-Pc-Craft...h=item2cdf8ae585:g:GG4AAOSwe9Fb8f3p:rk:4:pf:0
 
Yes they are the same. The 10" and 12" lathe gears are different and have a larger bore
 
Correction or clarification - The Atlas and Craftsman 6" lathes use the same change gears. And the Atlas 10" and Craftsman 12" use the same change gears in the same years. The 6" gears are smaller than those on the 10"/12" and don't interchange with either version of the 10" and 12" lathes.

The Atlas 9" and 10" up through 10D use the same gears as the Craftsman 9", 101.07360, 101.07380, 101.07400, 101.07361, 101.07381 and 101.07401.

At Atlas 10F and Craftsman 101.07362, 101.07382, 101.07402 the gears were changed. All of the later gears are suffix A. Both gear sets have a 3/8" face or gear tooth width. The early gears have a 3/8" hub length (same as the face). The later suffix A gears have a 1/2" hub length (wider than the face). The later gears can be modified to the earlier spec by facing off 1/16" from each side. But the later gear set does not include a 96T gear. However, you do have the two 96T gears on the machine, so that shouldn't be a problem. The same "A" suffix gears were used on all later Atlas 10" and 12" and Craftsman 12" lathes up through March, 1981 when production ceased.
 
wa5cab said:
Correction or clarification - The Atlas and Craftsman 6" lathes use the same change gears. And the Atlas 10" and Craftsman 12" use the same change gears in the same years. The 6" gears are smaller than those on the 10"/12" and don't interchange with either version of the 10" and 12" lathes.

The Atlas 9" and 10" up through 10D use the same gears as the Craftsman 9", 101.07360, 101.07380, 101.07400, 101.07361, 101.07381 and 101.07401.

At Atlas 10F and Craftsman 101.07362, 101.07382, 101.07402 the gears were changed. All of the later gears are suffix A. Both gear sets have a 3/8" face or gear tooth width. The early gears have a 3/8" hub length (same as the face). The later suffix A gears have a 1/2" hub length (wider than the face). The later gears can be modified to the earlier spec by facing off 1/16" from each side. But the later gear set does not include a 96T gear. However, you do have the two 96T gears on the machine, so that shouldn't be a problem. The same "A" suffix gears were used on all later Atlas 10" and 12" and Craftsman 12" lathes up through March, 1981 when production ceased.
Click to expand...

1. Just out of curiosity, what is not interchangeable? The axle hole diameter, the keyways, the number of teeth, or...?

2. I didn't see my 101.07403 listed in your post. I found a set of change gears that was listed as fitting a Craftsman/Atlas lathe. The teeth count matched what I needed and the holes had the 2 keyway notches. My part list has the "A" suffix on the gear part # and the ones I bought match that.

3. I don't have a 96 tooth gear, either. Where would that be? I don't see one listed on the parts diagram.
 
1. The early and late 10" and 12" gear sets are not interchangeable and the double-keyed bushings and bolts are not because the distance through the keyed mounting hole (the length of the hub) is 0.375" on the early set and 0.500" on the later. You can use either complete set of parts on either lathe, although the nut securing the screw gear won't have will not fit exactly right. However, if you use the later gears and other parts on the earlier lathes using the earlier threading chart, you will lose the threads on the chart where the chart calls for 96T. If you use the later chart, on the early 10" you must modify the headstock using the template that came with the 1570 QCGB kit (which we have a drawing of) or you will loose those threads calling for using the 16T half of the 16/32T compound gear. So on both lathe sizes, you must also purchase the 16/32T compound stud gear and stud. But you cannot mix-n-match the two sets.

2. The 101.07403 isn't on my list because it uses the "A" suffix gears. You lucked out that the set of gears you bought were "A" suffix as the seller, which is quite common on eBay, didn't know his product.

3. The 96T gear is not a part of the "A" suffix set. Just as the 16/32T compound gear is tot a part of the early set. The later 10" and 12" lathes added the 16/32T compound gear and dropped the 96T (and the later 12" dropped one 32T gear). When Atlas ceased production of the 3/8" hub "no suffix" or "non-A" gears, for a few years they continued production of the 96T only.
 
1. If all that is different is the thickness of the hub, couldn't one just turn them down on each side OR use washers to add thickness to match, then they would work? I suppose the bushing would have to be modified as well.

2. I knew I was looking for ones with the thicker hubs. It's hard to tell from images, though. This is the set I bought (seller's picture from Ebay). They look like the narrower ones now that I look at them again. I guess I'll find out when I get them. Might even be mixed and matched.
change gears i bought.jpg

3. Good to know I don't need it.
 
1. Yes, "All" that it takes is two 0.063" thick spacers for each gear that's actually mounted. Worst case probably 6. The kicker, however, is that the spacers must be double-keyed, which significantly increases the difficulty of making them. The bushings and bolts should already be on hand. Or at least two of them. According to the later threading chart, the only threads or feeds requiring three are 80 and 96 TPI and 0.0071" feed. There are probably some more on the odd feeds and metric threads charts in the MOLO. But in any case, the bushing. bolt, washer and nut are still available from Clausing.

2. The gears that you bought do look like the 3/8" hub early ones. The odd one in the back row certainly is.
 
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As a rule of thumb, a gear tooth gauge for primitive use can be made with a piece of sheet metal. Cut a "notch" of 3.14 inches (Pi inches) and lay around the gear. The number of exposed teeth indicates the "DP" or diametrical pitch of the gear. Modulus gears can be compared this way, but as they are calcolated differently a solid number cannot be obtained.

With an older Atlas, or Craftsman 101 series machine, the gears will probably be made of Zamak (Zamac), a zinc and aluminium alloy. The DP will be different for different sized machines. I have a 101.27440(12X36), which has 16DP gears. Pressure angle is 14 degrees which is likely the same throughout the line.

Different widths and shaft sizes with different models and years. If they mesh otherwise, they can be trimmed or shimmed as necessary to use them. Different tooth widths can be run together, although not having the best appearance or wear pattern. So long as they are the same DP.

Worst case (and what I have done) is to make the appropriate gear out of aluminium. It's a PITA, but I did do it several years back. I later found a set of manual change wheels that provided most of the gear setups I was looking for. BTW, the 27440 has a threading QC box. I was looking for odd sizes for coil winding, not threading.

I had a couple more pointers and then got distracted and forgot what I was talking about. Sorry...

Bill Hudson​
 
I got the gears. They are wrong:
gears pic.jpg
The one on the left is what I need. The one on the right is what I got. It was hard to tell from the images on Ebay how big the holes and gear teeth are. I just counted teeth. A few of them are marked with an "M6". This was NOT indicated in the description. It just said for Craftsman 101/Atlas lathes.

Measurements:
LEFT GEAR
Hole dia: 0.749"
notches: 0.188" wide.
gear thickness: 0.350"
hub thickness: 0.499"

RIGHT GEAR
Hole dia: 0.500"
notches: 0.123" wide.
gear thickness: 0.356"
hub thickness: 0.364"

I'll sell the whole set (64, 64, 56, 54, 52, 48, 46, 44, 40, 36, 32, 24) for $150 shipped CONUS if anyone wants them. PM me id you want more details, pictures, etc.
 
Yes, as I've commented in the past, most eBay sellers know little or nothing about what they are selling. And Murphy's law can usually be counted upon. Plus when they finally went to illustrated parts lists, Atlas didn't do owners or collectors any favors by not including some sort of note under the drawing of the "change gear set" to remind one that the total change gear count includes the ones that originally came installed on the lathe.

Just to spell out the situation, the gears that Jeff has and can't use fit the Atlas and Atlas/Craftsman 6" including the MK2. And I'm told also fit the AA built 109 models.
 
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