Boley "Reform" Lathe Headstock bushing - damaged

[Sansuisteve]

Hello Friends,
Just picked up a nice Boley lathe and was checking the spindle endplay (+/- 0.001") and detected a bit of a sticky spot on the rotation. I pushed out the spindle and when examining the front bushing saw some damage. Looks like the brass is showing about halfway down the cylinder and there are some ridges. Any chance there is a source for a replacement bushing?

 

[Nickelsilver]

That lathe has (had?) hardened steel double cone bearings front and back. Could you post some pics? My gut says put it back together and run it with some ISO 10 spindle oil for some hours, then have a look inside again, it will probably look better. There were many thousands of machines used industrially in the watch industry in both the U.S. and Switzerland (and elsewhere), which ran for 10s of thousands of hours, with the same bearing arrangement, without wearing out. They might show some wear, but they remained accurate dependable machines. Some might have used bronze bearings, but even those can go many thousands of hours before needing adjustment much less rescraping or replacing.

It is possible to lap the hard steel bearings to the spindle, but that's really something someone with experience in such work should do.

There just isn't much chance of a watchmaker lathe ever getting run enough to actually wear out. To show some wear, usually due to lack of lubrication for its occasional use, that happens. But isn't really an issue.

 

[dave-b]

I have a Boley headstock that appears to have a brazed repair to the spindle bearing area. To me its inexplicable how such damage could happen. The previous owner said it came from somewhere in India. Obviously it's scrap, yet the bearings feel ok when assembled.

 

[Sansuisteve]

I will post some pictures today, thanks for the replies....

 

[Sansuisteve]

See images

 

[Betzel]

Looks good to me and .001' is Sherline's tolerance for a brand new spindle. These float in thin oil and do not have to look like a chronometer balance staff to deliver great results over a lifetime. Here's how they were made: Boley headstock bearings

None of us have this kind of equipment, it was a one-time process, and unfortunately there are no cost-effective options for replacement parts, as modern machines all use ball/roller bearings. Be forewarned: removing material often ends up making things worse. And, it's all hard to measure repeatably at this scale.

So, if it were mine I would stop right here and leave it alone. Maybe it was run too tight, or with thick oil, etc. and the discoloration is from heat, which is permanent. It happens, but is usually not 100% fatal. Straw is better than violet, way better.

What did the binding feel like? What kind of oil are you using, how fast are you going, and how tight is your split-nut adjustment?

I like the idea of letting it break itself in again, micro wear from use is intentional and it can tighten back up and run fine with no regrets

 

[dave-b]

Looks good to me and .001' is Sherline's tolerance for a brand new spindle. These float in thin oil and do not have to look like a chronometer balance staff to deliver great results over a lifetime. Here's how they were made: Boley headstock bearings

None of us have this kind of equipment, it was a one-time process, and unfortunately there are no cost-effective options for replacement parts, as modern machines all use ball/roller bearings. Be forewarned: removing material often ends up making things worse. And, it's all hard to measure repeatably at this scale.

So, if it were mine I would stop right here and leave it alone. Maybe it was run too tight, or with thick oil, etc. and the discoloration is from heat, which is permanent. It happens, but is usually not 100% fatal. Straw is better than violet, way better.

What did the binding feel like? What kind of oil are you using, how fast are you going, and how tight is your split-nut adjustment?

I like the idea of letting it break itself in again, micro wear from use is intentional and it can tighten back up and run fine with no regrets

Looks good to me and .001' is Sherline's tolerance for a brand new spindle. These float in thin oil and do not have to look like a chronometer balance staff to deliver great results over a lifetime. Here's how they were made: Boley headstock bearings

None of us have this kind of equipment, it was a one-time process, and unfortunately there are no cost-effective options for replacement parts, as modern machines all use ball/roller bearings. Be forewarned: removing material often ends up making things worse. And, it's all hard to measure repeatably at this scale.

So, if it were mine I would stop right here and leave it alone. Maybe it was run too tight, or with thick oil, etc. and the discoloration is from heat, which is permanent. It happens, but is usually not 100% fatal. Straw is better than violet, way better.

What did the binding feel like? What kind of oil are you using, how fast are you going, and how tight is your split-nut adjustment?

I like the idea of letting it break itself in again, micro wear from use is intentional and it can tighten back up and run fine with no regrets

Hello Friends,
Just picked up a nice Boley lathe and was checking the spindle endplay (+/- 0.001") and detected a bit of a sticky spot on the rotation. I pushed out the spindle and when examining the front bushing saw some damage. Looks like the brass is showing about halfway down the cylinder and there are some ridges. Any chance there is a source for a replacement bushing?

Steve, there are many differing views on repairing spindle/bearing wear. (just "search" this site ) Personally, from what I see, I have no hesitation in recommending hand lapping with "timesaver" green.
dave.

 

[Betzel]

That's fair. At least the compound breaks down. But, there's a lot posted here, so it's not easy to quickly extract what we might call the best bits.

Call me chicken-poop, but there's nothing wrong with going very straight and very slow, and stopping as early as possible. For me, without both cones mounted close (it's a PITA, I know) it's hard to stay on center to knock off just one high spot at either end. The "total loss" cone bearings are designed to leak. But pretty slowly, flushing contaminants as part of that slow flow. How fast does any lathe leak it's oil right now?

If you want to know:

Buy a small bottle of spindle oil ($5 / eBay) and guesstimate the oil loss rate "before" and "after" the reconditioning? You may not be able to get the exact oil G. Boley (or Lorch) specified, but you'll get close. After break-in, when the oil runs clear again on a white rag, and your split nut is adjusted "right" and running at the same general (800 RPM?) speed, if the oil drains out faster than it did before, you'll understand my hesitation. OTOH, if it really holds thin oil longer, runs cool at high speed, and reads within .001" how awesome will that feel? I hope this is everyone's experience!

PdsDetailsPage

The Mobil Velocite™ Oil Numbered Series oils are premium performance products primarily designed for the lubrication of high-speed spindles in machine tools. They are also used in some critical hydraulic, circulation systems and air line oilers where the appropriate viscosity grade is selected.

www.mobil.com

 

[karlmansson]

The "brass" that is showing is probably really resin formed oil and dirt. If you scrape at it with a sharpened piece fo brass or aluminium is should scrape off. But I agree, there is some striping and wear on you spindle. Nothing excessive at a first glance though. I think you will find that your collets can be a much greater source of runout. I notice that you write that you measure some movement in the endplay. This is adjusted with the nuts behind the rear cone bearing. The tricky part is finding just the right tension on these, where you can't feel any movement but the spindle isn't binding up. This requires a very clean bearing condition to be reliable.

 

[Sansuisteve]

All,
First of all, Thank you very much for generously sharing your knowledge and experience. I will elaborate on several points.

1. I just got this box set of Boley lathes and accessories and am in the process of cleaning and inspecting. There was some "resin" and old lubrication on the spindles and bearings. I disassembled, cleaned, re-lubricated and ran the spindles for several minutes until the spindle oil ran clear-ish. Upon reinspecting the bearings I noticed the issues that generated this thread. I have two lathes in the set and this is the only headstock bearing where I noticed any discoloration. As I rotated the spindle with my fingers the binding felt like a "high spot" of interference between the spindle bearing surface and the bearing. As was suggested this may go away with some "burn in" operation and I am inclined to do that before any lapping or scraping. Call me chicken but this seems like the best progression of a "do no harm" paradigm.

2. I am using Moly-cote DX as assembly lube and Mobil Velocite #10 on the spindle bearings. There is no real noticeable oil discharge from the bearings so far during the spindle operation but consider that I have only run them for several minutes.

3. I do not have a way to measure RPM yet so guesstimating between 500-1500 rpm as I have a DC brushless motor setup with a continuously variable motor controller. I ordered a optical digital tachometer this morning.

4. I mispoke on my characterization of "endplay". To define terms: endplay is the motion of the spindle along its axis if the spindle is pushed back and forth while mounted in its bearing with the endplay adjusting split nut set to some prescribed location. What I measured was the endplay during lathe operation. So the way I see it there is some asymmetry during operation that is moving the spindle back and forth as it rotates. I have two lathes in this box set and the other one was "dead bang" zero for the same measurement and its bearing and spindle surfaces looked pristine.

5. I surely need to get better at using the "search" feature on this forum, but initial efforts were unsuccessful at finding good reference information on the issue. I will endeavor to spend more time at getting familiar with the operation of the search capability.

6. I will do some research on " hand lapping with "timesaver" green" as that process is new to me.

7. I had forgotten about UK Lathes site and the wealth of information it has in reproduction manuals on Boley lathe products. Thanks for the reminder....

8. I have included images of the box set for reference and any comments on the lathes vintage or model would be greatly appreciated!

 

[Betzel]

Okay. This is a Leinen (a.k.a. Boley & Leinen, not G. Boley) 8mm Reform lathe, likely from the 1950's (ish) and it appears pretty complete, in an original box. Nicaraguans are nice, though I prefer Dominicans, but the cigar boxes are all good for this kind of stuff. And the nickel and blueing are pretty good on all the components you've displayed here. Hope you're happy? Looks like a nice setup.

If you are into it, read up on the naming issues here Leinen lathes and just know that the two families were rivals --and all is fair in love and war. Both were extremely good quality, and this is a watchmaker's lathe. You may have sensed it, but I believe that they were far better at this craft then than than we are today. If your oil leaks out slowly, at any speed, it's fine. Keep it that way.

My advice is to be conservative; unpack and explore, but do not be in any hurry to remove any original material to "improve" things until you are good and ready. Also, know that your tailstock runner is 7.50 mm in diameter. No other runners were made in this size.

 

[Sansuisteve]

Betzel,
Thanks for the info, I will update this thread with some data on how the headstock performs going forward.

 

[karlmansson]

Beautiful lathe!

Measure inside the collet seat of the spindle with a DTI instead, that is what is important for concentricit. If there is longitudinal movement in the spindle during use it could be due to either a bent spindle (or debris on the spindles bearing surface) or simply due to a ding in the material. on the spindle nose. The latter will probably not require adressing. So long as you intend you use the spindle cone for seating workholding equipment agains you'll be fine.

Be sure that the problem can be, and needs to be, adressed by lapping before attempting that. You risk ruining the lathe in the process. Lots of factors involved, not the least cutting forces. If you just roll the spindle with your palm for instance you will wear the bearings downwards and create an oval bearing surface. For this degree of precision you really need to consider all forces, prerequisite work and resulting work.

I would start by looking at why you are not getting any oil out of your bearings. Probably clogged up oil channels. Which leads me to again suspect that the browning you see in your bearings is resin formed oil and that is also the reason for the sensation of resistance at certain points of rotating the spindle.

 

[dave-b]

Steve, I forgot to mention my first " go-to " test on these bearings. Firmly push on the nose or the pulley of the spindle while turning it (as though to push the spindle into the bearings. Quite often this will tend to seize up the bearings. If so, it tells you that the steep angle of the bearings has worn more than the shallow angle, overcoming any oil clearances. Lapping cures this.
dave.

 

[Sansuisteve]

Karl, Dave,
Thanks! I will do some more testing and analysis and post the results....

 

[Betzel]

As mentioned, cleanliness is key and the size of the oil film bath is really thin. So, the tolerances are not measurably close. If it binds as Dave describes, then a correction for weird wear is in order, but the amount of a corrective adjustment will be super small. A little goes a long way!

The thickness of a drop of oil on water is probably too thin, but it suggests how close it all is

 

[dave-b]

Betzel, I wouldnt call it weird wear, as about 30 percent of watchmakers lathes I see for sale fail this test to some degree. Probably due to different surface areas of bearing faces. You are right about small corrections though. We are in the micron area.

 

[Sansuisteve]

I have not forgotten about this thread. Been doing some infrastructure upgrades to the shop and bench. Hope to get more info out next week...

 

[Betzel]

Heh. No worries.

You likely noticed on disassembly the Leinen back cone is a very tight press fit onto the shaft? You may have also noticed the rear part of the spindle is soft, so a hasty reassembly can introduce error. You have your assembly sauce, but unless you have a factory press with jigs (who does?) hot and cold parts may help. Deferral of action can be a good thing...

I'm a broken record, I know, but agreeing with previous posts here and elsewhere, for any nice hard cone spindle (not yet "pooched" via neglect, abuse, or well-meant modifications) sub-microns of improvement come best via gentle cleaning (decontamination, but no removal of material) and another proper break-in, with a series of ridiculously closer adjustment(s) of the rear split nut (without deforming it!) using spindle oil (at least at speed) and the patience to run it slow at first to knock off the old (and new) high spots with a good out-flow of break-in contaminants, as it tightens itself up again. If all that goes well, you will eventually be able to run it crazy fast floating in a thin film of thin oil, and it will stay cool, tight and and true under appropriate load. Finally, these have great oil channels cut into the outer bearings. Watch the oil level in the cups while running and overnight. If they stay fairly level, weeping slowly and only slightly gray onto a white cloth, it's a good result, so amazingly accurate and a pleasure to own.

After sitting around in the box, or overnight with the weight of a large chuck or tension from a belt, the oil film gets displaced, so it's metal-on-metal. A few turns by hand get it freely floating again and it's ready to go. The ones that are not nice (partially pooched?) are worth a shot to repair, with real intervention(s), but may never return to their original glory.

Take your time?

 

[dave-b]

Betzel, I have to ask - how do you define "pooched" ?
dave.

 

[Betzel]

Heh. Fair question, Dave.

I have to give credit where due. The cute term was (IIRC) loosely coined on this board by measuretwice in other threads. He's a mechanical engineer, whose work I admire with a garage full of machining equipment that most of us only dream about, used as intended/needed for all sorts of fun. If he's not totally covered in snow, maybe he'll chime in.

There are a number of destruction routes for these old "hard as glass" steel spindles that were once tight, and ran cool at high speed with low rates of intended "total" oil loss weeping out the cracks and low total indicated runout. They are the survivors, the rest are pooched or somewhere in-between. There are probably recoverable semi-poochings, but the way out at this small scale and precision isn't easy. Just winging it:

Pooched #1: bearings got too hot and softened the glass-hard steel (wrong/no oil, too tight, etc.) You can't re-harden these.

Pooched #2: bearings are worn egg-shaped due to abuse (mal-adjusted too loose) these shift on a cut and leak.

Pooched #3 bearings were accidentally lapped against each other to distorted gaps (exposed to contamination like diamond, carbide, or hard steel, silicone oxide dust, etc.) if it's caught early on you might recover, but with fabulous factory-cut oil channels (I really admire the Leinen's which get and keep everything wet with channels fed by oil cups topside to keep the whole shebang floating) there's very little room for corrections without hitting these channels.

Pooched #4 It was dropped or a cleaning went bad due to disassembly/reassembly distortion (the spindle rear is soft) so it's now bent and rubs/sticks when rotated and tight.

Pooched #5 A repair went bad trying to lap out cosmetic imperfections that had no real effect on good operation because we expected the surfaces to look like a chronometer pinion.

- - -

So, there is some (?) debate about lapping two mating surfaces against each other. IMHO, it does not work --beyond knocking off a few glaring high spots that would just heat things up during the break-in, but it's just my opinion. There are a few ugly-looking spindles out there that will actually work great for another generation or two if they are just cleaned, maintained and used correctly. But, this is not widely understood or appreciated.

There may be other "pooch" scenarios, but these are the most common. I've seen 1-4 from auction purchases and personally committed #5, so I'm like a former smoker now: trying to save others. One or two very light push/turns with timesaver green is probably okay to knock off anything egregious, if it exists, and if the back cone comes off and back on the spindle easily, the bend is likely to be minimal. The rest are impactful.

I won't fight disagreement, but that's my 50 cents

Some older threads here show the German lathe makers (prior to their going out of business due to quartz technology) declaring that just using the wrong oil would "pooch" their near-pefect hard steel cone bearings and void the warranty. Those spindles (60's to early 70's, around the time things went toward ball-bearings) were exceptionally tight and probably looked fabulous when they left the factory at the end of that period. So, the other pooch-options (being far more severe) just take things up several more notches.

My thinking is if you love these old things (I do) and the spindle itself is not pooched, you can cut and press in hard bronze for the outers (undersized) then grind the spindle to fit the smaller bore of these soft bearings. Yes, the glass-hard steel was better, but for a repair, even bronze is not cost effective if you paid someone to do it. Labor of love / restoration. The big machines use bronze and it works great. Ultimately unpooched?

 

[dave-b]

Thanks for that.Now I have a much better understanding where you are coming from. ( I share your admiration of these old things )
dave.

 

[Sansuisteve]

Agree, many thanks for the detail.

 

[dave-b]

Betzel, re your pooched no. 5 - Do not expect lapped surfaces to be shiny bright. They should be an even matte grey. The shine comes after much careful progressive "running in"
dave.

 

[Betzel]

Yep, a proper break-in sometimes shows candy-cane striping / wear patterns on an even grey after a rebuild. So, it's really half-microns. Light belt tension during break-in is also key, along with serious patience. Daniels liked oiled leather: a full pull with almost no tension...

I've never seen new bearings, but I know the older (post WWII, nickel-plated) G. Boley's were "lapped in" (scarequotes mine) with fine oilstone powder after being precision ground on their jigs. I have no experience with timesaver green, but suspect it would produce a similar finish in a similar way, but be far easier to clean out, and less risky. Ignoring the Chinese, Bergeon still make these. So, someone over (up?) there knows what today's bearings look like on first assembly!

 

[measuretwice]

Heh. Fair question, Dave.

I have to give credit where due. The cute term was (IIRC) loosely coined on this board by measuretwice in other threads. He's a mechanical engineer, whose work I admire with a garage full of machining equipment that most of us only dream about, used as intended/needed for all sorts of fun. If he's not totally covered in snow, maybe he'll chime in.

haha, thank you for the generous compliments!! I'm not an engineer, only play one on the internet, but work with them all day, have an engineering business of sorts, have been machining for 30 years and have pursued and written extensively on reconditioning machine tools. So the subject is near and dear and has had me puzzling over it for some time. Always hoping these muses smoke out the silver bullet to this problem....because I don't have it.... here's why.....

Pooched is a technical term meaning "%$#F%^$, why did I ever think I could fix this" or in other words its scrap.

I'm not adverse to trying the time saver, kind of the of farmer's kill or cure approach to a very sick animal. Can't make it any worse.....however, lapping tapers with a taper is verboten in the mechanical and machine work world. No one would do so because it creates rings and ridges vs nice straight lines to the taper's cross section profile. The lap must travel across the work surface so there is averaging....that doesn't happen with a taper as it can't move in and out. The laps or grinding points used in a taper's manufacture are cylindrical and held at an angle to the the work, so they are played in and out and hence work very well. That is the objection to lapping a taper with a taper. Also, lapping is almost always done with a lap, vs work on work. This gives you control, its a bit shade tree (a bad thing, but this side of pooched) lapping work on work.

In my opinion, the double or biconical taper is the most challenging of machining jobs. It is about impossible to do without special fixturers to machine and measure it. Why? How do you know where a taper is along a shaft? Short of a CMM, you need to put a precision ball in it and measure its distance from the end. That holds it own challenges while the work is mounted in the lathe, now do so with two tapers. Then do so with the mating part also with two tapers, male this time so the ball thing doesn't work, and after it all it has to end up sub thou mating! And the two tapers are so different, a tenth of a thou difference laterally along one = a thou on the other other. Enough to drive a man to drink.

It is an amazing well engineered bearing that easily lasts 100 years or more....until some meat head runs it without oil. Bare bones lathes are cheap enough, if the headstock bearings are "pooched", get another one. There is no way I'm aware of rectify this in workman like manner, i.e. bring it back to its intended performance and life span with committing any sins. Garnet lapping (timesavers) MAY make is usable but all you are doing is rounding off corners and creating a bit of slop. May do so and use a thicker oil? Still, its in the catatory of a dodge than might work vs a way to fix these bearings (and no grief from me for trying).

Here's a fairly detailed account, although only 90% complete, of my spindle reconditioning (and everything else) of a a plane bearing Schaublin 70. It has the distinct advantage that I could use bronze, and that it was big enough to scrape the bearing (no fun at all in non-split beating, let me tell you!). Look in the Headstock chapter.

Reconditioning a Schaublin 70 - Metallum

Reconditioning a Schaublin 70 Return to Projects Intro With our North American approach to things, satisfying the masses is what drives most activity. In business, and in engineering, the expression “good enough, is, good enough” is quite correct. Making it better than it needs to be just...

www.metallum.shop

There, after machining the bearing and regrinding the shaft, I scraped the bearing using this shaft as a pattern. Very difficult, weeks of tedium weakening the resolve. As a final step I did use some of the finest yellow timesaver (for soft material). This worked because it had no effect on the hardned steel shaft and was so fine it just knocked the worst of the high points off the brozne. You don't have the dynamic or possibility of that with a watchmakers lathe where both bearing and steel are the same hardness.

Who wants to go through that or has time, equipment and ablity? I did end up with factory new performance, but I won't do it again. Its not worth it. Yet thats what it took, and that was much easier (for reasons noted above) than a watchmakers lathe.

What would be a lot less work is 1) buy another bare bones lathe or 2) mimic a Levin lathe and simply make a new headstock using P4 AC's, the old spindle shaft and a block of durabar (cast iron). FAR easiler than what I did to the Schaublin. Use the old spindle. loctite some steel in place and grind to fit the AC's. Fit a block of durabar and scrape into alignment with the tailstock. Not a weekend's work, but a far more realistic project than repairing damage double taper hardened steel bearings. Lets you use the hardened spindle and drawbar, which would be the tougher bits to make

 

[Sansuisteve]

Friends,
Finally got the infrastructure stuff under control. New lights, power, etc. Everything is up and running and I'm getting work done. Thanks for all your insight and advice.

Steve

 

[dave-b]

haha, thank you for the generous compliments!! I'm not an engineer, only play one on the internet, but work with them all day, have an engineering business of sorts, have been machining for 30 years and have pursued and written extensively on reconditioning machine tools. So the subject is near and dear and has had me puzzling over it for some time. Always hoping these muses smoke out the silver bullet to this problem....because I don't have it.... here's why.....

Pooched is a technical term meaning "%$#F%^$, why did I ever think I could fix this" or in other words its scrap.

I'm not adverse to trying the time saver, kind of the of farmer's kill or cure approach to a very sick animal. Can't make it any worse.....however, lapping tapers with a taper is verboten in the mechanical and machine work world. No one would do so because it creates rings and ridges vs nice straight lines to the taper's cross section profile. The lap must travel across the work surface so there is averaging....that doesn't happen with a taper as it can't move in and out. The laps or grinding points used in a taper's manufacture are cylindrical and held at an angle to the the work, so they are played in and out and hence work very well. That is the objection to lapping a taper with a taper. Also, lapping is almost always done with a lap, vs work on work. This gives you control, its a bit shade tree (a bad thing, but this side of pooched) lapping work on work.

In my opinion, the double or biconical taper is the most challenging of machining jobs. It is about impossible to do without special fixturers to machine and measure it. Why? How do you know where a taper is along a shaft? Short of a CMM, you need to put a precision ball in it and measure its distance from the end. That holds it own challenges while the work is mounted in the lathe, now do so with two tapers. Then do so with the mating part also with two tapers, male this time so the ball thing doesn't work, and after it all it has to end up sub thou mating! And the two tapers are so different, a tenth of a thou difference laterally along one = a thou on the other other. Enough to drive a man to drink.

It is an amazing well engineered bearing that easily lasts 100 years or more....until some meat head runs it without oil. Bare bones lathes are cheap enough, if the headstock bearings are "pooched", get another one. There is no way I'm aware of rectify this in workman like manner, i.e. bring it back to its intended performance and life span with committing any sins. Garnet lapping (timesavers) MAY make is usable but all you are doing is rounding off corners and creating a bit of slop. May do so and use a thicker oil? Still, its in the catatory of a dodge than might work vs a way to fix these bearings (and no grief from me for trying).

Here's a fairly detailed account, although only 90% complete, of my spindle reconditioning (and everything else) of a a plane bearing Schaublin 70. It has the distinct advantage that I could use bronze, and that it was big enough to scrape the bearing (no fun at all in non-split beating, let me tell you!). Look in the Headstock chapter.

Reconditioning a Schaublin 70 - Metallum

Reconditioning a Schaublin 70 Return to Projects Intro With our North American approach to things, satisfying the masses is what drives most activity. In business, and in engineering, the expression “good enough, is, good enough” is quite correct. Making it better than it needs to be just...

www.metallum.shop

There, after machining the bearing and regrinding the shaft, I scraped the bearing using this shaft as a pattern. Very difficult, weeks of tedium weakening the resolve. As a final step I did use some of the finest yellow timesaver (for soft material). This worked because it had no effect on the hardned steel shaft and was so fine it just knocked the worst of the high points off the brozne. You don't have the dynamic or possibility of that with a watchmakers lathe where both bearing and steel are the same hardness.

Who wants to go through that or has time, equipment and ablity? I did end up with factory new performance, but I won't do it again. Its not worth it. Yet thats what it took, and that was much easier (for reasons noted above) than a watchmakers lathe.

What would be a lot less work is 1) buy another bare bones lathe or 2) mimic a Levin lathe and simply make a new headstock using P4 AC's, the old spindle shaft and a block of durabar (cast iron). FAR easiler than what I did to the Schaublin. Use the old spindle. loctite some steel in place and grind to fit the AC's. Fit a block of durabar and scrape into alignment with the tailstock. Not a weekend's work, but a far more realistic project than repairing damage double taper hardened steel bearings. Lets you use the hardened spindle and drawbar, which would be the tougher bits to make


View attachment 745490

I doubt you are right that lapping work on work is agricultural. I think that is exactky how it was originally done. You are right in saying it has no place in the mechanical (powered) world, though. It has to be done by hand methods, ie half turn back and forth rotations from varying positions. We know Rivett had a specialised lapping department.

 

[measuretwice]

I doubt you are right that lapping work on work is agricultural. I think that is exactky how it was originally done.

What information do you have that would cause you to think that? Please explain, I"d love to know more about how they were made.

They were lapped, however as general principal part on part is not how lapping is done, its dodgy in anything and verboten on tapers. Having said that, if you are just trying to remove some minor imperfections and use garnet it can work (I did so on an double taper bearing after scraping it in as essentially a way to debur for example). It's not clear how doing so by hand, part on part, would over come the reasons why its not done (no relative motion, you get rings).

What you can do is use a lap reciprocated in and out of the taper along an axis that is at the taper's angle to the spindle's axis. It's the same set up I've used for grinding a taper, except obviously a charge lap (NOT the mating part!) produces a finer finish and the (huge) added complication that the whole headstock has to revolve (if done insitu) as per the Boley photo kicking about.

 

[dave-b]

I have a set of new (as ground) bearings and spindlle for a Pultra 10 lathe , sadly missing the rear bearing outer. The front bearing wedges on the shallow taper about 0.0012" from the steep taper. this was roughly measured with a cigarette paper. They are clearly factory made and await lapping. I estimate about rwo microns lapped off the shallow taper would allow both tapers to be in intimate contact for hand lapping (hand taper lapping is regularly done grinding in car engine valves, and high vacuum glass stopcocks without ridges forming) If these bearings were intended for machine lapping, why not do it when they were set up for grinding?

 

[Betzel]

Dave-b, curiosity springs eternal. Start a new thread with it!

If not, and you have a minute, would you please post your Pultra's images? And, when do you think they were made? Sorry for your rear ring loss. Wonder what the front one sounds like if you ping it, gently (a zildjian cymbal)? Bronze might be a decent replacement, or are you going to do one up in steel? Also, I wonder how a blued-up contact trace would look, if you could get them centered (ha) for a good smear, or get them apart again

 

[measuretwice]

I have a set of new (as ground) bearings and spindlle for a Pultra 10 lathe , sadly missing the rear bearing outer. The front bearing wedges on the shallow taper about 0.0012" from the steep taper. this was roughly measured with a cigarette paper. They are clearly factory made and await lapping. I estimate about rwo microns lapped off the shallow taper would allow both tapers to be in intmate contact for hand lapping (hand taper lapping is regularly done grinding in car engine valves, and high vacuum glass stopcocks without ridges forming)

The car valve or stop cocks instances are not comparable, its not a bearing, the parts aren't rotating. All that is required is a seal.

I thought you might have had some insight as to how they were actually made.

What If these bearings were intended for machine lapping, why not do it when they were set up for grinding?

How do you know they weren't? You'd lap following grinding simply for finish, (potentially) on the same setup and machine. Have a look here ( Boley headstock bearings ) and you can see Boley most certainly did this operation under power.

It makes sense that bearings were carefully fit to an individual spindle shaft (it's very large challenge to get two tapers in the right position relatively so fitting is logical), however it would not have been lapped with the spindle shaft (its not how to make precision fitting tapers).

Besides, except for the case of MRO type jobs, done with garnet, a lap mst be softer than the the work. If both the same, such as the hardened steel of a watch lathe bearing and shaft, you'd end up with abrasive embedded in the work, leading to rapid wear.

I've made several high precision spindles, reground spindles, made double taper bearings for spindles, ground tapers and in 35 years of being familiar with, reading, doing and hanging around people doing this sort of metal working I have never seen anyone knowledgeable promote lapping part on part for a taper, or any else that I recall...lapping is done with a lap which is a cutting tool charged with abrasive. That of course doesn't mean I'm mean I'm right, but as your claim is so contrary to my experience on the subject, I hope for some real knowledge and/or and science on it so I could learn.

 

[dave-b]

Measuretwice, car valves and stopcocks are examples of taper lapping part on part, which you think is a no-no. With all your experience, have you actually tried what I suggested? if so, how did it go? Lapping in this case is for fit, not appearance. It should leave a matt grey look.

 

[dave-b]

Betzel, I will think about a new thread ( I thought I had already posted images somewhere, but not yet found them) Re the rear ring, when I need them I will have to see how the old one it's replacing looks.

 

[Betzel]

OK, well I would love to see a new thread and vicariously experience your progress. Though I have a ball bearing WW headstock, I've always been fascinated to know exactly how these hard cone tapers were made. Not counting the Chinese, surely some old timers at Levin and a few at Bergeon (who still make these today) know for sure.

I am not operating at the same caliber as "real" engineers, I just try to figure it out as I go. So, I think perhaps both of the engineering ideas expressed here are right, but each for a different purpose. It's guesswork (I admit it) but I wonder if the G. Boley cones made before the war were ground in situ and then (not lapped in the strict sense) but a light oilstone paste was used to knock off the high spots and get the parts to fit/mate without binding. Being ground "fat" makes sense to me for a final finish. Why I asked about the date of the Pultra parts you have. This does not mean surfaces were finished to perfection in those days, just close enough to be run for a while, and then they cut the register for the nose and delivered them. These older models were not as tight, leaked oil and ran better at slower speeds. I think the old Boley jigs in the photo were from those days, but it's a guess.

After the war, and reconstruction, etc. all the good makers benefited from modern and more precise grinding and lapping operations which improved (reduced the microscopic error) of these surfaces and how they were mated to each other prior to cutting the nose register. No pictures survive from this era (that I know of). So, either method will work, but at different levels of precision.

If the older machines were not really lapped, but just fit better than the grinding of the time would allow, it all worked, but as technology improved, better ways of doing this operation produced finer tolerances, and we see manufacturers from the early 50's insisting on spindle oil to keep the warranty, because users were used to the old school way of using whatever oil they could find (bad habits, etc.) and these newer spindles (after break-in) were way tighter, and could scream at high speed with the right oil and did not leak nearly as much. So, my guess is you can choose from a pre-war or a post-war method of finishing the grinding job, getting very different results from each operation. Both work, but one produces a finer fit.

This is just a guess. I still think it would be very difficult to make these (even pre-war) in a home or small shop and impossible to do the same kind of work as done in the 50's without specialized equipment today. Once made correctly, most repairs will make things worse, taking you back to the 1930's and 1940's. This works for me at slow speed, but I can't run anything old at crazy speed.

Most of us do not need the speed anyway, right? Good luck either way you go!

 

[dave-b]

Measuretwice, I have put up a photo of a Boley bearing lapped taper-on-taper on "Pultra bearings" thread. There are no signs of rings forming.
dave
.

 

[Betzel]

Totally true.

The rings evolve over time after the initial taper-on-taper fit-up after grinding, which is how older lathes were made. Abuse just speeds it up. Look closely at the variations emerging in Steve's bearings in post #5 above. These are not so bad; I've seen rings that will catch your fingernail. When like that (but not pooched) minimally scrape or grind, grey them up (like you've done) and if the work is good it starts all over again. This is covered in the Perkins book, and works fine for most of us.

Don't know how the newer ones were made, or how to get anything to that level of precision. To your point, we may never know.

 

[dave-b]

To repeat, I thik grinding and lapping as described would give a "perfect" beaing , equal to the originals. Wear woud affect the steep taper more, simply because it is about 1/10th the bearing area of the shallow taper This reveals as a wedging action on the shallow taper, and restricts oil circulation. The purpose of my push test is to show this up, and the purpose of lapping a worn bearing is to cure it.
dave

 

[Betzel]

Ah. Now I understand the "push" test

When you're done, turn any inner dust seal cracks to 6:00 and remove the outer covers. Put in some real spindle oil and fire it up. If there's no heat or quick loss of oil after 8-10 minutes it's perfect. If not, but they still run okay on sewing machine oil slowly without too much loss, they're still very usable. The Pultra and Boley came like this, so they'd actually be as good as original. Still, not bad work.

All the best!

 

[dave-b]

Betzel, yes, but only after careful running-in.
dave

 

[measuretwice]

You mentioned PM (I know the crowd there well, have been there for decades with thousands of posts, many very knowledgeable people), did you ask about lapping tapers or lapping part on part?

As I said, i may work for very minor corrections in a kill or cure scenario, but as a way to manufacture or finish bearing surfaces it is "agricultural" as you say (although somewhat derogatory to farmers lol)

Measuretwice, I have put up a photo of a Boley bearing lapped taper-on-taper on "Pultra bearings" thread. There are no signs of rings forming.
dave
.

Glad you feel its worked out for you. I doubt you did anything. It takes a bit of work to remove a few microns of hardened steel with fine lapping compound, not just a few hand turns and cigarrete paper isn't exactly exact. If you did did something its not clear how you held your lap/shaft parallel to the axis. In any event, given your convictions its not worth more time to post about it. If you're happy with it, great.

 

[dave-b]

Small confession - my memory let me down. My query re.factory grinding practice was on The Home shop Machiist site, not PM.
ps. I am surprised you appear to think my convictions are more rigid than yours!

 

[dave-b]

Sorry to drag this out, but I feel these couple of criticisms need answering. The lathe itself does a first class job of holding alignment during lapping.A little ingenuity , together with the bearing outers remaining in their original positions, and the tapers being self-aligning make things easy.
I agree it takes more than a few turns to lap a couple of microns. I estimate 150 part turns. ( don't forget, 1 micron off the surface = 2 microns off the diameter )
You soon get into a routine, apply slurry, apply 4 or 5 part turns, separate, turn to a new position and repeat. Do this 25- 30 times until satisfied. This should take about 10 minutes.
dave.

 

[Betzel]

FWIW, my hare-brained reconditioning method does not work "perfectly," but it's the best way I have thought of to keep "everything in line" while greying up a set of cones against their mating outers for interchangeable (all components made at 50.00mm center height) systems (such as Leinen, Boley, WW sets, etc.) You'll need at least an extra tailstock (preferably one that holds collets) and a long bed known/scraped flat.

Make an on-center plug for the rear of the spindle to be worked, drilled with a 60 degree dead center with a witness mark to align with the keyway. Then, get or make a male cone collet to fit right up into the nose register of the spindle that will also fit your collet holding tailstock. A high quality "live" center collet may work. Then, fit the two tailstock points (oiled) into each end of the naked spindle, true and tight-ish between centers and lock it all down.

With a loose belt turning the spindle, you can test runout with a DTI and then shave off any deep ring high spots on the steep (outer) cones using a very sharp carbide graver at low speed with good light and optics, no coffee, etc. I do this by hand using a tool rest. Same for the rings in the headstock outers using a rag on the bench. Sometimes a crazy sharp scraper blade works better for me than the graver. I try to remove as little material as possible, do not alter any angles and try not to touch the shallow tapers at all. But if I do, it's just at the narrowest end where the oil will leak out and I go very lightly if there are rings using the scraper flat-on, to avoid shallowing.

Then, I remove the naked spindle from between centers and lock the headstock to be worked in the center, assemble the spindle in it's stock with .5mm axial play/shake between the cones using my slurry / timesaver green. I refit the spindle (now in it's headstock) between the same two tailstock centers. With the belt, and at low speed I unlock the two tailstock runners and apply axial pressure (left and right) sliding the spindle cones "straight in" and out of their mating components with some oil to keep things flowing. At least it helps keep everything aligned while the abrasive procedure is going on. Makes me feel better ;-)

These repairs I think are the lesser of many evils, but still leak spindle oil out quickly after a second break-in. But, they don't run hot and usually don't impact truth at the register. So, good enough for government work, but the best spindles were far better. Beyond my ability to measure --which is essentially the speed at which true spindle oil escapes at speed. Another reason I love the ones with the nice cups. This would be hard on a bar lathe, or the old WW's with matched head/tail pairs. Maybe not worth the fuss, but I'm fussy

 

[dave-b]

Hello Friends,
Just picked up a nice Boley lathe and was checking the spindle endplay (+/- 0.001") and detected a bit of a sticky spot on the rotation. I pushed out the spindle and when examining the front bushing saw some damage. Looks like the brass is showing about halfway down the cylinder and there are some ridges. Any chance there is a source for a replacement bushing?

Steve, any progress to report yet?
dave.