# Spindle drive gears on Atlas / Craftsman 12 x 36



## Bill1958 (Dec 1, 2021)

Hi....just joined up and my first post here.
I could really use some input here as to what type of gear drive setup this is on my lathe. Craftsman tag on the bed: 101.07403, 12 x 36.
Just picked it up about a week ago...but the seller didn't have any info on it. A renter skipped out on him in a hurry and left the big stuff behind...to cover the back rent I guess.
From what I can find on google images it looks as it should...except the spindle gear drive assembly. No one has an answer so far...so I'm hoping someone here can shed some light on this mystery.
Has anyone ever seen this setup on a lathe before?
I don't believe it's completely custom...as the outer support plate for the gear train is stamped steel and fairly thick.
The one gear has chipped teeth but it still ran quiet.
I've got it about half apart for inspection and then strip and paint. I'm not fixing it up to sell and I plan to use it.
Whatever lathe this gear drive is from...I'm pretty sure the speed and threading charts won't match up.

Any thoughts on this gear drive would help....as I am lost.
Thanks!
Bill


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## pdentrem (Dec 1, 2021)

First time I have seen this set up. There has been aftermarket makers of gear boxes as well as the units produced by Atlas. Maybe somebody has adapted from another company’s lathe.
Pierre


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## Bill1958 (Dec 1, 2021)

Hey thanks for your input Pierre! The plate is what made me think that it might be aftermarket. Hard to stamp that out at home.
I'm guessing it's an improvment of some sorts...otherwise why replace the original gear set with something that looks to be more expensive.
I don't know...just guessing. 
Thanks again for your input!
Bill


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## Orangetruckman (Dec 2, 2021)

That’s an interesting quick change gear setup. I’m only a couple year into the hobby, but I ain’t seen something like that. I’m sure the super knowledgeable Robert will be along shortly to hopefully help shed some light on your unique setup. Congratulations on the new to you lathe and welcome aboard Bill!


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## Bill1958 (Dec 2, 2021)

Thanks OTM! I'm pretty new too...got my feet wet restoring and learning on an old Unimat. I've got it bolted down to a granite inspection block to help with the vibration. It was good to learn the basics on...now I'm hooked : )
When I spoke with Mr. Davis (from Davis Machining) he told me for threading I can do the math on the gear train, which sounds like a nightmare, or just make test pieces with each setting and then measure the threads with a gauge and make my own chart from that. Probably what I will do this spring...after I paint it and get it back together.
I'm glad to be here and I'm sure I'm going to learn a lot.


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## markba633csi (Dec 2, 2021)

It looks like a completely homemade quick change arrangement.  Probably works just fine as is, you'll want to cut some test threads to check it.
-Mark


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## epanzella (Dec 2, 2021)

Never saw a setup like that. I would guess that some one bought this lathe used and there was missing change gears so he set up his own. Use your threading chart and pick some random threads coarse, medium and fine. Compare the difference between your thread chart and the actual threads you cut.  There may be a simple conversion factor you can use to make an accurate threading chart.


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## Orangetruckman (Dec 2, 2021)

You’re very welcome. Another idea, aside from cutting threads, would be to setup a dial indicator against the carriage. Then, manually rotate the spindle one time and record how much movement you get from the carriage for each gear position. Maybe then a method can be developed by correlating the amount of carriage movement using the change gear/quick change gear charts provided by the folks that have done all that math stuff. No need to reinvent the wheel, ya know


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## Bill1958 (Dec 3, 2021)

epanzella said:


> Never saw a setup like that. I would guess that some one bought this lathe used and there was missing change gears so he set up his own. Use your threading chart and pick some random threads coarse, medium and fine. Compare the difference between your thread chart and the actual threads you cut.  There may be a simple conversion factor you can use to make an accurate threading chart.


Thanks for your input Epan....a lot of good suggestion here. I was a little stressed about it at first but not now. A lot of good ideas!


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## Bill1958 (Dec 3, 2021)

Orangetruckman said:


> You’re very welcome. Another idea, aside from cutting threads, would be to setup a dial indicator against the carriage. Then, manually rotate the spindle one time and record how much movement you get from the carriage for each gear position. Maybe then a method can be developed by correlating the amount of carriage movement using the change gear/quick change gear charts provided by the folks that have done all that math stuff. No need to reinvent the wheel, ya know


I'm a pretty smart fella....I have thoughts I haven't even thunk yet. But I don't think I would have came up with that one.
That is a simple and great way to get some answers on the threading. Thanks!


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## Bill1958 (Dec 3, 2021)

markba633csi said:


> It looks like a completely homemade quick change arrangement.  Probably works just fine as is, you'll want to cut some test threads to check it.
> -Mark


Thanks for your input Mark....I'm hoping for the best. As a last resort I could always hunt around for the stock setup and just put it back to original.
I'm thinking that it won't be necessary....time will tell.


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## wa5cab (Dec 4, 2021)

Sorry to be a bit late to the party.  Once I get behind, it takes me forever to catch up.

I am inclined to agree with several others that it is a one-off done by someone.  Totally different concept to the factory QCGB and the couple of after-market ones that preceded it.  There is no front view photo of the headstock so part of this has to be a guess but the two shafts sticking out in the photo of the left end  make me guess that the gear box is in the IN position and changing to the OUT position would result in the entire visible assembly sliding out, covering most of the exposed ends of the shafts.

The threading chart riveted to the inside of the  gear guard  is the original change gear chart and is not used.  The other chart pictured is similar to the factory chart except for three things.  On the factory chart, the coarsest pitch setting is shown on the left edge of the chart instead of one increment in from the left edge (this made me think for a few seconds that the GB would not cut 32 TPI!).

The factory chart only shows a single column of pitches for the "IN" sliding gear position.

And the bottom row of the chart is marked in TPI like the rest of the chart whereas on the factory one, the finest pitch numbers are in thousandths of an inch feed instead of in TPI.

At a guess, the original lathe was a very early 101.07403.  This is based upon the presence of the individual gear guard over the bull gear.  And the lack of a belt cover/gear guard covering the top of the headstock.  Possibly the PO had removed that guard, as the earliest known parts list shows both individual gear guards and the one piece guard.  Some time after introduction of the 101.07403, the two individual gear guards were dropped from the parts list.  In any case, the serial number should still be found stamped into the right end of the front way.


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## Bill1958 (Dec 5, 2021)

Thank you for all your input and observations! The reason I was leaning away from "home made or one-off" was the outer support for the gear train is fairly thick and I was told by a machinist with 55 years of experience that the support was stamped metal.
But after reading your post I'm starting to believe that it most likely is a one-off. The stamped metal support still throws me...I don't know. The only thing that really matters though is that it works.
I took a better look at the chart on the QCGB....when you enlarge it you can see that it looks to be hand stamped and etched with a scribe....custom.
It might work well...and the chart on the QCGB might be accurate. Won't know till I get it back together in early spring and make some chips.
For some reason the Lord wanted me to end up with this one-of-a-kind...so I ain't gona argue with Him : )


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## Orangetruckman (Dec 6, 2021)

Bill1958 said:


> I'm a pretty smart fella....I have thoughts I haven't even thunk yet. But I don't think I would have came up with that one.
> That is a simple and great way to get some answers on the threading. Thanks!


I have no doubts you’re smart, I mean you joined this forum after all :> I can’t take credit for all of that. Mr. Pete’s YouTube videos gave me the idea on measuring the carriage movement with a dial indicator. I wish you continued fun with your new toy!


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## Bill1958 (Dec 6, 2021)

I'll have to check out Mr. Pete on youTube...one can only watch so much of the Three Stooges.
I've got it stripped down to just the headstock on the bed and will try to get the spindle apart today.
I'll have to hunt around on here and seen what's recommended as far as bearing replacements.
So far the only video I've looked at says not to spend the extra $$$ on class 3 bearings. That it would be overkill due to the machine's short comings. What do you think?
The only complaints I've read about the A/C's is that the power cross feed could be a little slower and that the longer beds are a little "springie".
I thought about a 2' x 6' x 2" granite slab with a support in the middle of the bed bolting it to the slab...added support and to damped vibrations.
The granite helped to cut down the vibrations on my little Unimat. Any thoughts.....all are welcome!


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## pdentrem (Dec 6, 2021)

Mass will dampen vibrations, that is for sure. When I had mine, it was bolted down to a wooden bench. See photo. There was a lot of steel etc in the drawers under the machine!
Yes the power crossfeed is a little quick and it can be tamed by using a larger gear than the 64s that were included. The older lathes had 96s but not the 16/32 stud gear behind the spindle. Order a similar gear or 3D printed one to reduce the feed rate. I believe that the slowest feed was 0.0017”, but don’t quote me on that!
Pierre


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## Orangetruckman (Dec 6, 2021)

If you look around on the forum, I swear there’s a thread about the bearings recommended by others more knowledgeable. And my understanding is that the power cross-feed advances at the same amount of movement the carriage is set for. The lead screw powers both the carriage and the cross-feed, just not at the same time. 
As for a/c lathes being less than stout, anything to add rigidity would be a big PLUS. For the bench, I’m not the person you want to get input from. I’ve got my lathe mounted on a rolling cart


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## Bill1958 (Dec 7, 2021)

pdentrem said:


> Mass will dampen vibrations, that is for sure. When I had mine, it was bolted down to a wooden bench. See photo. There was a lot of steel etc in the drawers under the machine!
> Yes the power crossfeed is a little quick and it can be tamed by using a larger gear than the 64s that were included. The older lathes had 96s but not the 16/32 stud gear behind the spindle. Order a similar gear or 3D printed one to reduce the feed rate. I believe that the slowest feed was 0.0017”, but don’t quote me on that!
> Pierre
> 
> View attachment 387587


That's a nice lookin machine Pierre....good job.


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## Bill1958 (Dec 7, 2021)

Orangetruckman said:


> If you look around on the forum, I swear there’s a thread about the bearings recommended by others more knowledgeable. And my understanding is that the power cross-feed advances at the same amount of movement the carriage is set for. The lead screw powers both the carriage and the cross-feed, just not at the same time.
> As for a/c lathes being less than stout, anything to add rigidity would be a big PLUS. For the bench, I’m not the person you want to get input from. I’ve got my lathe mounted on a rolling cart


I'm gona forget about mounting it on a granite slab. I just ordered the bearings and races - 16150 / 16284B and 14125 / 14276B.
I'll be lucky to afford to mount it on a bed sheet from Goodwill. The bearings weren't that expensive but the "B" races with the flange on them...wow!


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## Bill1958 (Dec 7, 2021)

Here's a few pics of the spindle...looks pretty good but I've still got to measure it. The bearings were scribed with the date of 
2 - 9 - 40. Eighty years...that a pretty good run. The races or cups weren't pitted but were just starting to show signs of wear at the inboard and outboard edges. Here's the link if anyone is having trouble finding them (I sure did):   https://www.radwell.com/en-US/Search/?q=timken+16284B
   $150 for the 16284B and $60 for the 14276B. I found them at other sites for about the same price...but the photos weren't accurate...no flange...so I didn't want to take the chance. Radwell took the time to list the correct photo so I went with them. Gona try and find some dry ice when it comes time to install them. Freezer might be good enough...


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## pdentrem (Dec 7, 2021)

Pretty good shape! No real wear marks.
Pierre


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## Bill1958 (Dec 9, 2021)

Could you tell me what type of paint you used on your lathe? Looks like it's holding up good.
I'm not ready to paint anything yet...still have to strip the old paint off. I picked up an air needle scaler from HF after watching a few youtubes.
I've never seen one before but from the videos it looks to work great on paint and rust in hard to reach areas...like inside corners.


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## pdentrem (Dec 9, 2021)

Rustoleum oil paint. Cleaned everywhere with mineral spirits first.


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## Bill1958 (Dec 9, 2021)

pdentrem said:


> Rustoleum oil paint. Cleaned everywhere with mineral spirits first.


Thanks!


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## Bill1958 (Dec 26, 2021)

Bill1958 said:


> Hi....just joined up and my first post here.
> I could really use some input here as to what type of gear drive setup this is on my lathe. Craftsman tag on the bed: 101.07403, 12 x 36.
> Just picked it up about a week ago...but the seller didn't have any info on it. A renter skipped out on him in a hurry and left the big stuff behind...to cover the back rent I guess.
> From what I can find on google images it looks as it should...except the spindle gear drive assembly. No one has an answer so far...so I'm hoping someone here can shed some light on this mystery.
> ...


Hope everyone had a safe and merry Christmas!
I decided to get the parts needed to put the lathe back to stock...and keep the custom gear drive and QCGB as another option.
I searched images of QCGB's and could not find another one like it...searching other machines as well. I'll upload a few pics of it a little later.
I figured it might be best to just restore it back to the stock setup and see how she runs.

I have 2 questions, first : The change gear bracket L3-58M (banjo) I picked up came with the gear case L3-27 and stud L3-52A and 5 gears.
Where the screw gear was installed there was a 96T gear (?).
I haven't been able to find a reference to a 96 tooth gear being used...nothing on the gear chart. 
Any thoughts?
Second : I picked up the reverse tumbler assembly. It was listed as a L6-21...but when I got it I had to take a hard look (paint was thick) and found that the "6" was a "3". So it's an L3-21. I've seen several listed as L6 and the photos show the "L3" right on the part they are selling.
So....is this the same part with an updated part # ? It seems to fit......but it looks like it's missing a spacer or something on the stud L3-47A.
Where the stud screws into the Headstock...there is a nut to lock it in place......but that leaves a gap between the nut and the tumbler assembly .....where the assembly is free to slide on the stud towards the Headstock. If I try to screw the stud further into the Headstock to take up the gap / play.....then the selector pin ends up to the right of the position holes.
When I look at the parts diagram for a 101.07403 it doesn't show the nut or a spacer on the stud - between the tumbler and the Headstock.
Any thoughts or ideas? 
I was thinking of just using a double nut instead of just the single one.......or am I missing something here?
Thanks!
Bill


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## epanzella (Dec 26, 2021)

You have a lathe now. You can make any spacers and bushings you need to take up play and align gears. As long as all your gears mesh (same pitch) you're golden. Have some fun!


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## pdentrem (Dec 27, 2021)

The 96 tooth were used on earlier machines. You should have 2 64s and a what is called a stud gear 16/32 set behind the spindle gear.

This topic may not reflect accurately your lathe!








						Change Gears for 10D and F series lathes
					

This listing is a work in progress. I owned a 10D that had been converted sometime in it's history to 10F. This listing will allow the user to make Imperial and Metric threads This may not be correct for the 12" lathes towards the end of production like the 3996.  These are the required gears...




					www.hobby-machinist.com


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## Bill1958 (Dec 27, 2021)

epanzella said:


> You have a lathe now. You can make any spacers and bushings you need to take up play and align gears. As long as all your gears mesh (same pitch) you're golden. Have some fun!


She won't be up and running for a few months yet...got it all apart and stripping the paint now. Right now I'm just trying to make sure I have all the correct parts I'll need to put her back to original...except for the motor. I picked up a 2.5hp treadmill motor and controller and wanted to give that a try. I thought 2.5hp was a bit of overkill...but I've read that when you go from AC to a DC motor you need at least double the HP due to the torque differences.
I'm having fun doing the restoration work...but I can't wait to start making chips! I still have my old Unimat which works great for making small bushings and such.


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## Bill1958 (Dec 27, 2021)

pdentrem said:


> The 96 tooth were used on earlier machines. You should have 2 64s and a what is called a stud gear 16/32 set behind the spindle gear.
> 
> This topic may not reflect accurately your lathe!
> 
> ...


Thanks! I'll check it out for sure.
I've got the 2 64s. The "stud gear"...I'm not clear on. Is that the bottom combination gears on the reverse tumbler? If it is...I've got a 20/32 there and a 24 and 20 above that on the tumbler.
Looking at the threading chart the only gear I don't have that's listed is the 16T. All the gears I have are Zamak...can you run the new plastic gears with the old Zamak ones?
I did see a listing for a 50T and a 60T Zamak gears suppose to be used for metric threads and used with the QCGB on the later A/C's.
$70 bucks seemed a little high.


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## Bill1958 (Dec 27, 2021)

Bill1958 said:


> Thanks! I'll check it out for sure.
> I've got the 2 64s. The "stud gear"...I'm not clear on. Is that the bottom combination gears on the reverse tumbler? If it is...I've got a 20/32 there and a 24 and 20 above that on the tumbler.
> Looking at the threading chart the only gear I don't have that's listed is the 16T. All the gears I have are Zamak...can you run the new plastic gears with the old Zamak ones?
> I did see a listing for a 50T and a 60T Zamak gears suppose to be used for metric threads and used with the QCGB on the later A/C's.
> $70 bucks seemed a little high.


Just viewed the photo in the link you provided. Now I know what a stud gear is : )


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## pdentrem (Dec 27, 2021)

The stud gear is shown on the chart on the cover door. It is the combo below the tumbers. The first gear on the banjo uses either the 32 or 16 tooth to change the feeds. The far right column shows 32 or 16.


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## Bill1958 (Dec 27, 2021)

pdentrem said:


> The stud gear is shown on the chart on the cover door. It is the combo below the tumbers. The first gear on the banjo uses either the 32 or 16 tooth to change the feeds. The far right column shows 32 or 16.


Thanks! I got it. Hey...I'm not the sharpest pen in the box.


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## Bill1958 (Jun 25, 2022)

pdentrem said:


> Mass will dampen vibrations, that is for sure. When I had mine, it was bolted down to a wooden bench. See photo. There was a lot of steel etc in the drawers under the machine!
> Yes the power crossfeed is a little quick and it can be tamed by using a larger gear than the 64s that were included. The older lathes had 96s but not the 16/32 stud gear behind the spindle. Order a similar gear or 3D printed one to reduce the feed rate. I believe that the slowest feed was 0.0017”, but don’t quote me on that!
> Pierre
> 
> View attachment 387587


Hi Pierre....haven't been on here in months and the project has been on hold. Just started working on it again a few weeks ago.
Got the lathe bed stripped down and soda blasted it and ready for primer now.
Been thinking about you guys up there and my heart and prayers are with you all. Watched the videos of the truckers convoy in Ottawa...better days ARE coming my friend. We have about the same mess down here. Fear not - God wins!
Hope you and your family are doing well.
Bill


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