View Full Version : Atlas reverse gear box repair, cheaper and better than oem parts!

the kid
12-07-2014, 06:31 PM
Well it's been a while but I finally got to fixing my lathe, the original discussion is here http://bbs.homeshopmachinist.net/threads/59800-Broken-gear-teeth/page1

I measured the teeth as best as I could then found the closest gear I could, I think it's exactly the same and my measure was off slightly, possibly due to wear, I machined off the teeth just leaving the clutch dogs, fyi you end up with 1" dia then bored the gear to slip on, not super tight as there needed to be a little space, then Used red loctite to secure it on to the stub, the other gear I simply machined to match the old as there was enough metal there to do so. I took some film and put it on YouTube, bear with me as I just recently started really making videos, there are 3 parts, and I tend to ramble a good bit, the part numbers for the gears are in the second video. I also intended to show a bit more in the 3rd part but accidentally deleted a few clips.




12-07-2014, 07:14 PM
Excellent fix! Thanks very much for sharing!

Can you post up the info on the gears you got and where you got them? While I do have a qcgb on my atlas 10" I do have the original fwd/rev box that has the same gears that are bad and I would like to fix it.

the kid
12-07-2014, 08:23 PM
No problem, I purchased mine on eBay from an outfit called nri industrial who sells industrial surplus, but McMaster and Boston gear also have it, though I got mine for about half price, they got here 3 days early too! On the idler I used a Boston L127Y which has a 1/2" bore, and I used a Boston L102Y which had a 3/4" bore for the input, Just so I needed to bore it out less, one could easily use 2 L127Y gears but the 3/4 bore won't work for the idler you need the 1/2, the gear is an 18t 12dp with a 20 degree pressure angle. I expect one day I'll need to replace the other gear in there as well, one could even convert the box to use helical bevel gears if replacing all 3, though I don't know why anyone would, I would probably do that to the back gears though if I ever needed to fix them, just a thought.

12-07-2014, 08:53 PM
Thank you very much!

I did a quick search on ebay and found the l127y for $27

Good stuff! Thanks again for the awesome videos and info!

the kid
12-08-2014, 10:01 PM
No problem, the oem parts suck and are about 100 bucks each if they can be found, so I hope this fix will help to get a lot of these back in service and at a reasonable cost with better parts. I probably should have just replaced all 3 gears but I'm going to be cheap, I'll take it all apart in a year or so and see how things are holding up, and I'll replace the 3rd gear if I detect any excessive wear.

12-08-2014, 10:05 PM
Well if ever there is a jamb up again either like you pointed out the locktite will break free or the one remaining zamak gear in the gearbox. Shouldn't ever harm the new steel gears.

Luckily (I guess) the one time I had a "crash" I only broke a 44 tooth change gear. I was doing either a long cut or just cutting by the tailstock with power feed and had a lapse and let the carriage run into the lead screw support. :(

12-08-2014, 10:12 PM
Most leadscrew end supports have a grease nipple if a plain bearing, I suppose a sealed roller bearing would be much better
Nice job, looks like it grew there

the kid
12-08-2014, 10:43 PM
On the bearing I made I haven't decided what I wanted to do about oil, I of course oiled it before I put it together bit I think I've got a spare gitz cup laying about and when I find it I'm going to put a bushing in and install the gitz oiler and a wick, the block is held on the mounting plate via 2 6-32 screws from the back, so I'm hoping should something happen they break free, I'm considering taking one out to weaken it more, any thoughts?

12-09-2014, 07:11 AM
I wouldn't worry about the tailstock leadscrew support to much. While the original may have been designed to break away in the event something happens mine didn't when I believe it should have.

12-10-2014, 10:04 AM
A lead screw needs thrust bearings, and not so much radial support,
so needle or ball thrust type bearings are the thing to use, in combination
with plain old bronze oilite bushings.
I did watch the video. Super good idea and nice fix. Well done.


George Seal
12-10-2014, 05:50 PM

New Atlas's don't break away. They have a clutch on the lead screw. Book even tells how to adjust & test

12-10-2014, 07:28 PM

New Atlas's don't break away. They have a clutch on the lead screw. Book even tells how to adjust & test

Very well could, I honestly am not sure and have to take your word for it.

However the OP's lathe and mine are of the 1940's era and have no clutches.

the kid
12-11-2014, 05:57 PM
That's a good point about the thrust bearings, I didn't take that in to consideration, there's steel washers on it now that have been there since I got the machine, I'm going to take it back apart soon though and adress the situation, I'm thinking of just using hard leather, my old canedy Otto has leather thrust bearings in the quill and they've held up quite well over the years (see mini camelback on my you tube channel) One of my clients is a shoe repair shop so I'll ask them for a few scraps of soul leather next time I'm there, they are usually quite helpfull when I need any help on any leather problem or need a scrap for a project. Anyone got any other ideas? I really don't feel like going and finding a correct size ball thrust bearing(s) and in a lite lathe such as this I think may be a bit overkill, I can make the leather ones in short order and they are nice because they will always hold oil. I can't seem to find that gitz cup I was searching for, might try the old hardware store to see if they've got any, they carrey a lot of the harder to find things like that, otherwise I'll just drill a small hole as the original had and call it good

12-11-2014, 06:05 PM
My 10" has steel "thrust" washers as well on both sides which I believe are stock/original. There isn't that much side load on the screw. Even taking an extreme (.020 on an atlas lol) there isn't a whole lot of pressure.

12-11-2014, 06:28 PM
Nice job on the fix. A friend of mine had a bunch of busted gears in the forward/reverse geabox, I was agble to get the whole gearbox including gears of ebay, used but in good shape. I've got some videos on my youtube site if your interested in some of the things I have done to revive the lathe. I still have a bit more worrk to do on it and a couple more videos.

Thanks for sharing your vids.