New Owner, New To Forum, Many Questions.

Hello All,
New to the forum and to craftsman atlas lathes. I was recently given a model 101.07381 12" by my father, serial # 4583s. It is in fair condition, operating at the moment. I was trying to date the lathe and had a few questions.
First question. the change gear cover case has a threading chart as almost all do, but this one is showing diagrams for 96 tooth gears. The diagram also show instead of them going through a stud gear to the 2 fwd rev gears that it would be connected straight to the spindle.? the MOLO I have for craftsman is the 21st edition and shows the fwd rev gear selector. The lathe does have a fwd rev lever and does work, but I am missing both the 96 tooth gears.
If I were to follow the threading chart in the manual I would not need them for the threads I would like to cut, would this still work as designed, and am I missing something when looking at the original threading chart on the machine?

Fast (please sign your posts or set up your Signature),

First, the 101.07381 only appeared in the 1937 Craftsman Power Tools catalog. So yours was made in late 1936 or 1937. We don't have enough examples of that model to have a feel for how many Sears sold or what the beginning and ending serial numbers were. the 101.07381 was replaced in the 1938 catalog by the 101.07382, which did not use the two 96T gears.

Read the instructions above for using the H-M DOWNLOADS, then go to the Atlas section and download the Part 7 - Threading PDF for the early version MOLO. It will match your machine except that the threading chart calls the 32T tumbler gear the Spindle gear, because the chart was actually written for the Atlas 10D and earlier, which do not have a tumbler. Three of the differences between your machine and the later 12" ones are that (1) the gear on the pivot point of the tumbler is a single 32T gear whereas that gear on the later machines is a compound gear, 16T/32T, (2) your machine uses up to two 96T gears for some threads and feeds whereas the later machines only use up to 64T gears, and (3) the change gears on your machine have 3/8" thick or wide hubs, whereas all later gears have 1/2" hubs.

More later....

Thank you for the response. I understand where my confusion was in the wording of the threading chart on my machine verses the MOLO I have. Correct me if Im wrong but if I were to obtain the correct toothed gears that were 3/8" thick I could follow either the old version or the newer version of the threading chart depending what it was asking me to run for a tumbler, either 16t or 32t.
Thanks again,

Sorry, but no. Of importance to your problem, there are three differences between the change gear drive components on the 101.07360 through 101.07401 (which includes the 101.07381) and the 101.07362 through 101.07403 or the relatively uncommon change gear models of the later 1/2" bed machines. The first is that your change gear bracket (banjo) only has two slots, so no position "D". The second is that your tumbler pivot gear is a standard (early) 32T change gear instead of a 16/32T compound gear. The third is that the later machines all use 1/2" long hub gears instead of the early 3/8". The compound tumbler gear is a total of 1" thick, instead of 3/4". So assuming that you have all of the other gears, you can cut threads between 4 tpi and 32 tpi, using setups as shown in the threading chart's Figures 1, 2 and 3.

They didn't make a 16T change gear (not enough diameter to cut the double keyways in), so you don't have one of those. So you can't make up a 3/4" thick 16/32T compound gear. It is possible that you could buy a 10-101-16A compound gear and face off 1/16" from each face and be able to cut the threads that have a setup as shown in Figures 4 or 6. But it wouldn't do any good to buy a 16T gear and modify it to fit the tumbler pivot stud because the FWD and REV tumbler gears wouldn't mesh with it.

Your best bet is to try to find two of the 96T gears. Unfortunately, Atlas didn't make a 96T gear with a 1/2" hub, so you don't have the possibility of buying one of those and modifying it. Another option would be to acquire all of the necessary gears and parts and convert the machine to use the later gear train. But that would be quite expensive, because besides the gears, you would have to get all of the bushings and studs, and the bracket..

While reviewing the setup I noticed the banjo bracket has 3 slots. Giving it a position d. Either craftsman was using up parts or someone has already tried to convert this. The gears measure 3/8" thick across teeth and hub looks the same.
I attached a file with picture of gear train but dont know if I was successful?

Sean
Welcome to the site! I don't see a file or picture, but wonder if it has to do with a minimum number of posts to attach stuff...maybe Robert can confirm or deny that for us.

The owner recently stated that working links were suppressed for new members with 3 or fewer posts to cut down on businesses having someone join just to post links to their business web site. He didn't say explicitly but that may also apply to uploading files including photos. Sean, try the UPLOAD A FILE button next to the POST REPLY button, if you can see it. Also, some of the status or permission updates don't happen automatically but have to be done manually by an Administrator, of which there are only two. So sometimes there is a lag between the time a member's post count passes one of the few thresholds and when the permissions change actually happens.

Back to the banjo/change gear bracket question, I think that the answer may actually be a matter of production lag or schedules. We have noticed a few times that as-found machines with earlier model numbers that "officially" should have one version of a part actually have the later one. While it's always possible that the swap may have been done by a PO, there is enough evidence to say that some of the changes were done on the production line. One of the cases is the third slot with Position D on the banjo. The one "official" photo we have found of the parts in a 101.07381 shows the two-slot banjo. But the one "official" threading chart shows the 3-slot, but doesn't mention or use it. Since the rest of the banjo is the same on both versions, it works OK with the 96T gear set.

1938 appears to be the year that the change from 3/8" hub to 1/2" hub change gears occurred. My guess is that the 3-slot banjos and drawings or artwork for the threading charts were ready before the gears and maybe bushings were so they started installing the later banjo.

Anyway, that changes your options to get the machine up and running for all threads and feeds. If you can't come up with two 96T gears, you can instead locate a 10-101-16A compound tumbler gear with 10-264 bearing, and the L3-47A stud that goes with it. Face 1/16" off of both sides of the gear. If the bearing is loose (not pressed into the gear), shorten it by 1/8". And face the (I think 1/2" diameter) part of the stud back 1/8" to match the shortened gear. Or alternatively, you could make a 1/2" ID by 1/8" thick spacer to put between the gear and the S8-88 Washer. See the headstock page in the 101.07383 parts manual (in DOWNLOADS) for what the parts look like.

This is by far one of the most helpful sites I have been to for newbies. Thank you. I will continue my research and post another question when I get lunch break.

We try.

ok so now that I have a better understanding of the change gear information and the dating I will say that the lathe has 1 major flaw, the Babbitt bearings are pretty shot and the shim packs have already been removed. There is quite a bit of vertical and horizontal play in the spindle along with some serious score marks on the spindle itself. the chattering it made along with run out was proof pos that something had to be done. The good news is that I found a headstock unit on ebay that is from a newer model 12" with Timken bearings. it is on its way! In the meantime I need to get it mounted. I have a pretty sturdy work bench that I have recovered with 3/4" plywood and bolted to the wall of my garage. It is not yet perfectly level due to my floor. The lathe when bolted to the bench shows no signs of being twisted when using set up guide of the MOLO.
1) how important is it to be at true level
2) I do not have a machinist square so should I wait and purchase 1 before moving forward.
3) I know that the spindle threads on the new headstock are the same 1 1/2 x 8, can I put any correct sized chuck for this or is there a specific taper I will need.

I don't mean to jump around, I have limited internet usage during the night because I work and during the day I try to keep my son busy in the shop with me. Just looking for small things to do until I can start making chips again