Lathe spindle bearing help

So I've looked everywhere (yes, including our board), and have yet to get a good answer. Is it possible to replace bronze bushings for roller or needle bearings for a lathe spindle. I'm aware a lot depends on the lathe. Mine is the Atlas/Craftsman 101.07301. There's not much room for a regular tapered roller bearing without adding material to the headstock, which is cast, and I'm crap as welding cast, so I thought a needle bearing might work. Otherwise, I'll just rebuild the whole headstock to build it up the way I want it.

I would check the radial load rating on a needle bearing small enough to fit in your headstock. I am thinking that the capacity would be too low.

My first inclination is just as above, but slightly different. Determine which bearing size and class at least meet present specification [of original part]. Then fabricate a housing to work within constraints of headstock over all. Terribly simplistic description, yes it's more about a concept. General spindle bearings are probably 3 or 4 times in rank of precision compared to good off the shelf parts. Both lathes and mills have loading, speed, fit, and thrust issues multiple that of a plain shaft. Highest quality spindle grade I know of is ABEC 7. Likely higher than you'd need, it would not pay to use anything lower than what equals original.
Then again, many old lathes worldwide run their original bronze or babbit sleeves and remain amazingly accurate, just lower RPM ranges. Just tend the oilers regularly. When I first started machine work, my favorite lathe was 1910 era; smooth, quiet, accurate, powerful. No surprise nearly 50 years hence, it was American Tool Works too. I don't know what swing it was, lol. Everyone called it 'The 20', but faceplate was 26". Maybe it was on risers. I don't think it ever spun with a chuck on the spindle, sometimes a flat-back was clamped to the faceplate, but...

Don't consider needle bearings for a lathe spindle. They have plenty of load capability in sizes to fit a small lathe spindle. But you can't easily adjust the internal clearances as you can with preloaded ball bearings and tapered rollers. And needle bearings don't like high speeds. Also they can't handle thrust loads like from cutting tool loading; so you will need to fit a separate thrust bearing for both axial directions. I recommend repairing the existing bronze bearing setup.
If you must convert then go with ball bearings of outside diamteter that can be easily fitted to the existing headstock casting and machine a new smaller diameter shaft. The trickiest part of this will be fitting a special sleeve needed to adapt your current stock of chucks, faceplates, etc and likely require you to find other uses for your collets. This all will require a compromise in how you use the lathe. Specifically go easy on loading your cutting tools, expecially on interrupted cuts.
If you are an ameteur like me you already do mostly light cuts anyway. I've always been a half assed hobby machinist. But my work was mechanical engineering and my specialty for a few years was high speed centrifuge drives. The kind that were in the same class as the ones used to separate uranium oxide gas into stuff used to build bombs. But that's another story.

I am familiar with those little lathes, as my grandfather and myself have had a couple of them. They were made for a specific duty. That was light machining of small parts. They were somewhat troublesome when they were in good condition. As I recall, they didn't have a lot of meat around the spindle casting. Any time you apply needle bearings, remember that the shaft has to be hardened to run with the needles in the bearings. I don't think the spindles on these little lathes were RC 55-60. Don't ruin your little treasure by trying to push it beyond it's limits. Find some new Oilite bushings and install them. If they are to loose for your standards, make your own bushings and use a heavy (high pressure) spindle oil. Good luck, and take care of your piece of history.

Determine the Id and OD the bearing will need to be then visit your local industrial bearing supply company.
Don't feel bashful about needing to install as many as 3 4 or 5 bearings in the casting where the bronze bearing was angular contact bearings can tolerate slight amounts of side thrust as well as radial. I would consider using a combination of angular contact and radial ball bearings additionally you will require a flat thrust bearing.
By stacking angular contact bearings back to back or front to front of each other you can situate them to have a preload

Tmoore - If you've gotten deep enough into your lathe headstock can you give us some idea of the dimensions (OD, ID, amd length) of each headstock bearing. On this lathe I doubt if the bearing ID is tapered since it's knda new for that type of construction but be aware of that possibility. Also take note if their are any lubricating grooves otn bearing ID's or on the ends of the bearing that take thrust from a shoulder on the shaft. I don't think oilite or sintered bronze will be the best choice. But they may be cheaper that bearing bronze bar or tube (bearing bronze has some soft metals like lead in its composition). Don't use common 360 brass bar for this job. It's a lousy bearing material for friction and wear even if lubricated. Ed Weldon

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Originally Posted by tmoore4748

So I've looked everywhere (yes, including our board), and have yet to get a good answer. Is it possible to replace bronze bushings for roller or needle bearings for a lathe spindle. I'm aware a lot depends on the lathe. Mine is the Atlas/Craftsman 101.07301. There's not much room for a regular tapered roller bearing without adding material to the headstock, which is cast, and I'm crap as welding cast, so I thought a needle bearing might work. Otherwise, I'll just rebuild the whole headstock to build it up the way I want it.

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I believe the lathe you're referencing is a 6" Atlas - I don't know if this would work for you, but about 10 years ago the bronze head stock bearings in my 1930's era Atlas 10" went south. I noticed that later model Atlas lathes had tapered roller bearings for the spindle. I too, had trouble with an attempt to fit bearings in the head stock, but was lucky enough to find a complete later model head stock with spindle on fleebay for not much more the the cost of the bearings. -Good Luck!

This later roller bwearing Atlas hedstock is probably the most sensible solution unless you are really tight for money and are a pretty decent machinist. In that case go hunt up some bearing bronze bar stock pieces that you don't need to pay market price for (scary that) and have at it. Scout eBay (patiently) for bearing bronze and try to find someone with a small piece that is the right size and price.
Keep in mind that it is completely practical in this situation to solder two or more pieces of bearing bronze (not oilite) together to get a usable size machining block or even in the worst possible situation melt and cast a blank in a simple mold. But do a little research on casting techniques first. I'm thinking here of a plaster mold (well dried of course) and make yourself a nice little heating/ pouring ladle. You might even want to learn a little about copper alloy metalurgy and mix up your own recipe for bearing bronze.

Bearings, schmearings.

My vote goes to Ed Weldon's posts and my hint towards continuing with genuine bearing bronze/ oil-lite.

Most horizontal mills under #4 and all the old ones ran bronze in outboard supports. Certainly side and thrust loads from a arbor loaded with straddle cutters is more severe than ANY single point turning tool generates.
I wish you all well, but decent made bronzes will outlive most any reading this. So there...

Nice ones are split, tapered and adjusted with a take-up nut. I think with a little creative fixturing a large premade oil-lite bushing [as 'raw' stock] could be bored, turned, threaded, and tapered. Likely the proportions are sufficient to have a hub/ flange to face with a thrust washer [chuck side] and long enough for a separate one inboard. If the headstock has bearing caps, they could be align-bored easily; press fit could be too, just more involved set up.

Well into the machine age, bronzes were bored in lathes fitted with lignum-vitae. Every advancement in machine tools was supported by older means [I abhor misuse of term 'technology' in such instances] until wide-spread enough to prevail on it's own.
By the way, companies are STILL in business propagating lignum-vitae.
https://www.google.com/search?q=lign...nt=firefox-b-1

I vote for the bronze approach. Surely adequate and a cleaner fix. As said bronze and Babbitt built our country. I am still running a pre 1900 lathe with Babbitt and bronze regularly
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I don't know whether this is the right size for a 101 Atlas plain bearing headstock. But if it is with some finishing to size then the price looks reasonable. Remember if you press fit it the ID will be reduced about 80% of the press (common old rule of thumb).
Bunting Bearings CB162006 Cast Bronze Sleeve Bearing 1" ID 1-1/4" OD 3/4" Length; eBay item number: 292047574584
A close fitting brass or steel sleeve on the OD will allow you to fit it to a larger housing bore. Loctite can hold the steel sleeve and bronze bearing together. Don't forget the oil holes.
Ed Weldon

Owen, thanks for the advice, it's much the same as my father gave me. I've looked into every option for pre-made bushings, and they're all really expensive, so, looks like I'm making my own. Thanks to this board, I also know how to do the oil impregnation myself! I can use the same vacuum chamber I use for my epoxy work, it'll just take longer.