# Excessive Spindle Play Fixed (newbie Error — I Didn't Need New Bearings)



## Rex Walters (Jul 20, 2015)

Embarrassing as this was, I'm posting this in the hopes that it might help someone else.

Tl;dr version: 

My rear spindle nut was nowhere near tight enough, so the spindle assembly wasn't under sufficient tension. After making a dedicated tool to tighten the nut, I was able to reduce about +/- 0.005" of play at the front of the spindle to +/- 0.0004" (better than a 10x improvement).

Long version:

I bought my first (and only) lathe a couple years ago (11" Montgomery Wards/Logan PowerKraft 2130 circa 1941). As with any new hobby, there was a pretty significant learning curve, and I learned a ridiculous amount just correcting my various mistakes. I learned that nine times out of ten any problems I experienced were due to something I'd done wrong (dull tools, tool not at center, poor tool grinding angles for the material, poor work-holding, whatever).

Ten times out of ten I'd blame the tools first, of course.

Anyway, as I gained experience I was becoming increasingly frustrated with the amount of chatter when parting, boring, or taking heavy turning cuts. I became fairly skilled at taking light cuts and playing with speeds and feeds — I made plenty of parts accurately, if slowly, and with a fair amount of cursing along the way.

Parting was a particular headache. I spent a _lot_ of time sharpening and honing,  tightening gibs, minimizing tool and part hang-out, carefully squaring my tool, carefully checking that it's just a smidge below center height, and adjusting speeds and feeds. Still, most of the time I was getting excessive chatter, even with soft stuff like aluminum and bronze. I'd break out in a victory dance on the rare occasion that I was able to part smoothly.

The problem was particularly bad when using my large (heavy) 6-jaw chuck. Quite a while back I decided to replace the spindle bearings in the hope that that was the problem. In my defense, I relish every opportunity to take apart and learn more about my lathe (I'd never pulled the spindle before).

I ended up removing and replacing the spindle multiple times as I made various bone-headed mistakes (only a complete idiot would put the spindle back on before putting on the new serpentine belt he purchased expressly for the opportunity). I noticed that when I first took out the bearings, the front (tail-stock side) bearing took quite a bit of force to press out of the headstock, but on the final re-assembly (after two or three remove/re-install cycles) I could actually push it back into place with just finger force (significant finger pressure to be sure, but quite a bit looser than originally).

The new bearings *did* seem to help, but it was only a modest improvement. I still had to baby my cuts.

Finally I got smart and decided to measure things. I took off the chuck, and put a fairly hefty (3/4") drill with a morse taper shank directly into the MT3 spindle (I did need a MT2-to-MT3 adapter). Then I measured the deflection right at the tip of the spindle nose as I pushed and pulled on the drill bit (with a fair amount of force). 

I could easily get plus or minus 0.005" deflection without undue pressure. This sure _seemed_ like a lot, especially compared to tool and part stiffness, but with so little experience and such an old lathe I wasn't sure if it was excessive. I did know that chatter means something isn't sufficiently rigid.

Jim Sehr was kind enough to measure his lathe and he only saw a few tenths of deflection at the nose. Now I knew for certain that I had a problem, but I wasn't sure if it was something I could fix. I was worried that I had a clapped out lathe and that removing/inserting the spindle so many times scraped enough metal in the headstock to cause the play. If that was the problem, the only "solution" I could imagine was brazing on some more material into the headstock, and re-boring the holes for the bearings — a far larger task than I was comfortable tackling.

Fortunately, I read somewhere that the spindle is supposed to be in tension (I wish I could remember where I saw this — I'd like to thank whoever mentioned it). 

The nut at the rear end of the spindle is just a ring with a hole for a pin-spanner: 
	

		
			
		

		
	




I don't remember exactly how I removed that nut or re-tightened it when I first removed the spindle. I remember that I had to jury-rig something because the pin-spanners I owned all had a pin too large for that hole. Somebody on this forum or on the Logan lathe mailing list periodically suggests making a dedicated collar with a grub screw to remove/tighten this nut when removing the spindle. I don't remember whot it was, but thank you whoever you are!

It certainly _seemed_ tight, but I wondered if I could tighten it further. So I built this tool out of some scrap aluminum:




I turned down the end of the grub screw so it fit into the pin-hole on the nut. The flats on the back of the tool let me use a big adjustable wrench to crank the nut tight. Aluminum is pretty soft for this purpose, but it sufficed for one-time use (the grub screw had wallowed out the tapped hole a bit after I used it).

Here it is on the nut, with the grub screw engaged:




I was surprised to discover that I could get a bit more than one full turn on the nut with this tool (I'm pretty sure it is now tighter than it was when I originally received the lathe, before I replaced the bearings). I was _extremely _ happy to discover that tightening this nut reduced the amount of play at the nose quite significantly (by a factor of ten).

I haven't done a lot of work yet since making the adjustment (just a few bits of aluminum) but so far I've had no chatter whatsoever, even with _very _heavy boring-bar cuts. What an improvement!

I don't quite understand the physics of why this should make such a difference. The rear (left, headstock-end) bearing on a Logan is a close-tolerance slip-fit. The front bearing is a press-fit. All I can figure is that cranking down on the nut locks the rear bearing to the rest of the spindle better. I suppose it's like bolt-on legs on a table, unless you really crank down on the bolts all the little micro-slippages add up to a wobbly table. Welded on legs are infinitely more rigid than bolt-on legs no matter how much you tighten the bolts.

If anyone has a better explanation, I'd love to hear it.

Anyway, I hope this might help someone else in the future.
-- 
Rex


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## Redlineman (Jul 20, 2015)

Har;

Your candor is embarrassing, funny, and resonant with every noob who has walked the path.

My project lathe don't quite run yet, but I think I'll go down and lean on my spindle nut a bit.


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## Rex Walters (Jul 20, 2015)

Heh. Well, the funniest part to me was when I referred to it as "my first lathe."

I introduce my wife that way sometimes.... She never seems to be amused.
-- 
Rex


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## wa5cab (Jul 20, 2015)

If I hadn't been told a year or two ago that you couldn't do that on a Logan, I would think that you had preloaded the spindle bearings.


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## Rex Walters (Jul 20, 2015)

wa5cab said:


> If I hadn't been told a year or two ago that you couldn't do that on a Logan, I would think that you had preloaded the spindle bearings.



Okay, here's where I really show my ignorance. I know almost nothing about bearings, and barely understand (probably _don't _understand) what "preload" means. I thought it was mostly about taking up radial clearance around the bearing — I still don't quite get what _axial _pre-load is for.

Here's a chicken-scratch drawing of my spindle assembly (minus a few spacers, _etc_.). The spindle is inserted into the headstock from the right (tailstock) side. The front bearing has to be pressed onto the spindle, and seats against a wider diameter "collar" turned on the spindle shaft. The rear bearing is a (tight) slip fit but has nothing to locate it axially on the spindle or within the headstock housing.




The front (right, tailstock-side) bearing locates axially with a retaining clip-ring that surrounds the bearing (the outer race of the bearing has a groove for the clip-ring). That ring mechanically seats on the outside of the headstock housing. The belleville washer presses against the bearing as the bearing-cap screws are tightened. When the bearing-cap screws are fully tightened, the bearing cap seats against the housing, the belleville washer flattens, and the front bearing is pushed axially to the left with the clip-ring seating against the headstock housing.

I _think_ the belleville washer is "pre-loading" the front bearing both axially (pushing to the left) and *radially *(pushing the outer race outward, taking up some slack in the bored hole in the headstock housing).

Correct me if I'm wrong, but I don't think the take-up nut has any affect on the front bearing "pre-load." The front bearing is trapped between the headstock casting on the left and the bearing cap on the right. Tightening the take up nut does seem to put the spindle in tension (it takes all the slack out between the various spacers, cone pulley, and gears along the shaft) but if the bearing cap were removed with the take-up nut still fully tightened, the whole assembly could still shift to the right in the headstock.

I'm thinking that tightening the take-up nut effectively "pre-loaded" the rear bearing somehow. 

My guess is that when there were small gaps between the various sliding parts along the spindle, the rear bearing was able to slip and move a bit (about +/- 0.005") — probably because it was just a slip fit on the shaft so it had room to cant left and right slightly. Once I snugged up the take-up nut and eliminated all the gaps, the rear bearing was better retained in a perpendicular orientation to the spindle (no longer able to cant left or right).

At least that's the only explanation I can come up with. It wouldn't surprise me at all if I'm utterly misunderstanding something, though. I'd love to hear any corrections or better explanations.

Regards,
-- 
Rex


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## wa5cab (Jul 21, 2015)

First, the Belleville Washer as drawn doesn't do anything that couldn't just as well have been done by the bearing cap if properly machined.  The only thing that it accomplishes is to allow an axial force against the bearing outer race as you tighten the screws holding the cap onto the headstock.  The washer cannot exert any significant radial force on the outer race.  And turned the way that it is shown in your sketch, it cannot exert any axial force on the bearing inner race.  The only Operator and Parts manual that we have is one on the 200 Series.  It clearly shows a shoulder on the spindle close to the left end but inside of the headstock.  A spacer abutts this and keeps the step pulley more or less from having axial motion on the spindle.  The left bearing pulls up tight against the spacer.  And then the gear and nut bear against the bearing.


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## Rex Walters (Jul 21, 2015)

Well, I plead ignorance. My engineering education was mostly in imaginary things like semiconductors and software. This mechanical stuff I'm figuring out as I go along. ;-)

My memory is also even worse than my drawing skills. I tried to draw the assembly from memory (it's been a while since I pulled the spindle). The only major error was that I thought the front bearing pressed on from the right (the short end). I showed the shoulder on the spindle on the wrong side of the front bearing (the front bearing presses on from the left — the long side). I also left out the take-up nut for the front bearing (to the left of the bearing).

[I suspect it might be possible to tighten that front take-up nut further as well, but with the press fit I doubt it would make much difference, and I don't want to pull the spindle again to find out.]

For the record, here is the relevant diagram from the manual I ordered for $25 from Logan Actuator company:



That's a terribly confusing diagram, though, as it doesn't actually show how things are assembled (the line of parts in the middle are interspersed among the line of parts on top).

So here's my corrected drawing (if I ever pull the spindle again, I'm going to make a real measured drawing and maybe even a sketchup model).




At least I think that's correct. The front bearing presses from the left onto a slightly larger diameter portion of the spindle until it butts up against the shoulder. (The right face of the shoulder is actually what the chuck registers against). Then a take up nut  prevents the front bearing from moving to the left along the spindle.

Between the press-fit, shoulder to the right, and take-up nut to the left, the front bearing is effectively welded to the spindle at that location. It can't move axially along the spindle left or right *at all*.

All other parts, including the rear bearing, are slip fits and can slide left and right along the spindle until they hit either of the take up nuts (or the headstock casting). The bull gear, of course, transfers



wa5cab said:


> First, the Belleville Washer as drawn doesn't do anything that couldn't just as well have been done by the bearing cap if properly machined.  The only thing that it accomplishes is to allow an axial force against the bearing outer race as you tighten the screws holding the cap onto the headstock.  The washer cannot exert any significant radial force on the outer race.  And turned the way that it is shown in your sketch, it cannot exert any axial force on the bearing inner race.



It's possible I put the belleville washer in backwards when I reassembled, but I still think I'm showing it in the correct orientation.

My (apparently faulty) thinking was that since the diameter of a belleville washer increases as it flattens, I thought it effectively provides a force vector that pushes outward slightly along the outer edge — so I thought it was supposed to bear on the _outer_ race. The only way that any outward radial force could be transferred is through friction, though, so my thinking appears to be pretty fuzzy. I now think a belleville washer is just a glorified spring and is only intended to apply an axial force.

You seem to be saying that the belleville washer should be oriented the other way and bear on the inner race, but it isn't possible to bear on the inner race — it's blocked by the shoulder on the spindle. The inside diameter of the washer also registers on a lip on the inside face of the bearing cap. If the washer were oriented the other way, it would be almost impossible to get the registration right during assembly. All indications appear to be that I've shown the orientation correctly.

That front bearing isn't going anywhere along the spindle for the reasons I described above, and the entire spindle is prevented from moving left by the headstock casting and the clip ring. So I'm a bit puzzled as to the purpose of the belleville washer.

My only guess is that it's there to provide constant pressure (forcing the spindle assembly into the headstock) but still allow some axial movement due to heat expansion in the spindle assembly itself.  That is, if the bearing cap was bearing directly on the bearing, then any expansion due to heat might cause distortion and inaccuracy. The belleville washer provides enough force to keep the entire spindle assembly located against the headstock, but with sufficient give to allow heat expansion.

At least that's currently my best guess, but I could be completely off base. What do you think? How hot do the bearings and spindle get in heavy operation?



wa5cab said:


> The only Operator and Parts manual that we have is one on the 200 Series.  It clearly shows a shoulder on the spindle close to the left end but inside of the headstock.  A spacer abutts this and keeps the step pulley more or less from having axial motion on the spindle.  The left bearing pulls up tight against the spacer.  And then the gear and nut bear against the bearing.



You're right. I didn't have my spindle out, so I forgot about the step on the left end of the spindle. I searched for a photo of a disassembled Logan spindle, and RedlineMan had a good one with the front bearing still in place: see the fourth photo in comment #4 of this thread.

The inner spacer bears against this step. So when I tightened the rear take-up nut, I squeezed the spindle-gear, outside spacer, rear-bearing, and inside spacer (in that order) against that step. That makes much more sense than squeezing the entire series of parts along the shaft together, since the cone-pulley has to be able to rotate on the shaft when using back-gears.

But I'm back to my original question and confusion. How did tightening the rear take-up nut remove radial spindle play for me? I don't see any way that the rear nut could affect anything at the front bearing. It could affect the rear bearing (snugging it up between the two spacers on either side) but I'm not at all clear on how that cleared up my radial play unless it prevented left/right canting of the rear bearing as I suggested earlier.

I'm going with that explanation unless someone has a better theory.

Regards,
--
Rex


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## hvontres (Jul 21, 2015)

I think what is going on here is that by tightening up the rear take up nut, you removed the remaining INTERAL clearance in the bearing. I was going to do a long writeup, but I figured the bearing guys are better at explaining this kind of stuff:
http://www.nmbtc.com/bearings/engineering/preload/
http://www.bardenbearings.co.uk/ind...//www.nmbtc.com/bearings/engineering/preload/
http://www.engineerlive.com/content/23694
http://www.nskamericas.com/cps/rde/xbcr/na_en/Preload.pdf

Hope this helps to clear things up a little.


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## Rex Walters (Jul 21, 2015)

hvontres said:


> Hope this helps to clear things up a little.



Thanks, Henry! Very helpful. That's a lot of content. I'll spend some time trying to understand it. I'm still unclear on precisely what is flexing/stiffening and in what way such that it removes clearance (internal or external). Hopefully those docs will clear it up for me. I saw diagrams there. Diagrams are good. I need gorilla logic. ;-)

Cheers!
-- 
Rex


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## Redlineman (Jul 21, 2015)

Hey;

Here is the image you are looking for.




You would assume that the tightening of that nut added no preload to any part of the spindle. Whether it stabilized, in some fashion, the rear bearing (drive side) or not by jamming it more tightly between the spacers and into the first shoulder machined in the spindle is an interesting notion, and perhaps covered in those linked documents. If I feel brave, I might dip a toe in. Tech stuff tends to make my head spin.


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## Redlineman (Jul 21, 2015)

And...




With all the pieces. Gets a little confusing, but it shows much more clearly where/how everything sits... once you get used to what you are looking at!


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## wa5cab (Jul 21, 2015)

Rex,

I'm also an EE, first Aerospace and then for much longer, NDT in the Oil Patch.

Although I still don't see what advantage there was to complicating the design, I agree that the Belleville washer is installed correctly.  And that assuming that the left bearing is free to slip in the hole bored through the headstock, it doesn't put an axial load on the right bearing.  However, if you were able to turn LA-259 Nut a full turn, that is 0.050", almost a sixteenth.  So the several components on the left end of the spindle were as loose as geese.

I also agree that the illustrated parts drawing of the 11" (and the 10", which is the same except for a couple of parts) was poorly done.  The two rows of parts are not shown in the order that they actually exist on the spindle.  The draftsman who drew it must have been drunk and the engineer who approved it high as a kite.


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## Rex Walters (Jul 21, 2015)

Redlineman said:


> And... With all the pieces.



Beauty! (As Bob and Doug McKenzie would say.) Many, many thanks! (Just a tiny bit more useful than my chicken scratches. ;-)

That colorized diagram is wonderful. It clarifies the assembly tremendously, and now I can see precisely whats bearing against what.

When I torqued the red take-up nut, it pressed against the green spindle gear, which bears on the left spacer (dark blue), which bears on the yellow rear bearing, which bears against the right dark blue spacer, which bears against the step to the 1.225" diameter portion of the spindle. Whew.

The surprising thing is that this means the right spacer must locate the left edge of the rear bearing such that it slightly overhangs (or at worst lines up with) the step from 1.1233" diameter to 1.1806" diameter (otherwise the left spacer can't bear against the inner race of the bearing).

I think Robert is right, things were seriously loose on the rear of the spindle. In fact, since the rear bearing must be close to that leftmost groove (1.098" diameter) I think my explanation of the rear bearing canting is almost certainly correct. Once I snugged it up it was better registered on the shaft and (presumably) in the bore of the headstock.

This weird thread taught me way more about my lathe than I expected! Thanks to all.
-- 
Rex


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## Redlineman (Jul 22, 2015)

Interestingly;

The Belleville washer was not used on the early versions, and as such was not depicted in the drawing as you can see. Neither my lathe (early #15235) nor the later headstock I bought for parts had one. My guess it that it was put there simply to take up space. The end cover at the main bearing does not load the spindle at all, but has a relief inside, matching one in the headstock, that the washer easily fits into. Perhaps that gap allowed the spindle to pull to Starboard under repeated heavy cutting? We'll never know, but it is interesting to speculate.

For a company to get into the lathe business that never made that sort of equipment might be reflected in some of the things they did that do not seem normal, or might be deemed sub standard. Yet, all things considered, they did a pretty good job and made a nice little machine.


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## Rex Walters (Jul 22, 2015)

Redlineman said:


> The Belleville washer was not used on the early versions, and as such was not depicted in the drawing as you can see. Neither my lathe (early #15235) nor the later headstock I bought for parts had one. My guess it that it was put there simply to take up space. The end cover at the main bearing does not load the spindle at all, but has a relief inside, matching one in the headstock, that the washer easily fits into. Perhaps that gap allowed the spindle to pull to Starboard under repeated heavy cutting? We'll never know, but it is interesting to speculate.



Actually, I think my lathe pre-dates yours slightly (mine is a Wards 2130, s/n 3124A, circa 1941) and definitely had the belleville washer. The diagram from my manual (posted above) still shows the washer (part LA-247). 

Logan's serial number table says they started making lathes in May of 1940. You must be more familiar with their history than me, I just found their history page on the wayback machine (the page on the Logan Actuator site seems to have gone missing).

Interesting that they'd get rid of the washer but leave the relief in the end cap. I can see the relief in the colored diagram — I guess since there was enough bearing surface there was no reason to re-design the part, but I'm surprised they didn't bother to eliminate a machining process step.

I don't know enough about mechanical engineering to have an opinion on the quality of Logan's design, but I definitely prefer my lathe to the Atlas lathes that it was competing with back in the day!

Also, I just now realized I've been incorrectly referring to my lathe as an 11" model. It's actually a 10" model! I just measured and it's just a bit over 5 1/4" from center to the flat part of the ways.

Lastly, I think I'm going to laminate that colored diagram and stick it into the inside of my the belt cover on the headstock! Love that diagram.
-- 
Rex


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## Redlineman (Jul 22, 2015)

Indeed;

I AM speculating, which is all that is left to us in many cases. The early section view drawing does not show/list the LA-247 Belleville washer. Neither my '42 (what I call a "coffin" horizontal emblem early model, still using a lot of MW parts), nor the later headstock I bought (what I call a "tombstone" vertical emblem "series production version) had it. The later exploded diagram shows it, and your earlier MW has it. Did mine disappear? Was yours added? Who knows, eh? Always fun to play sleuth though.

Given that the drive end bearing is not blocked against the headstock in any axial sense, I'm not sure what LA-247 is supposed to do?

Guesswork.


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## Rex Walters (Jul 22, 2015)

Redlineman said:


> Given that the drive end bearing is not blocked against the headstock in any axial sense, I'm not sure what LA-247 is supposed to do?



I'm not sure what you mean about the bearing not being blocked against the headstock. The snap-ring and groove in the bearing blocks mine from moving farther to the left (axially) into the headstock bore.

[Whoops. Now I see what you wrote -- the *drive* end bearing in the rear. It's not located axially. Apologies.]

I think the belleville washer was there to provide constant pressure. It pushes the front-bearing to the left with relatively  constant force (pushing the snap-ring into the headstock casting) while still allowing some expansion to the right if things heat up. Without the belleville washer (spring) there is no give. On a hobbyist machine I doubt it makes any difference, but that's the only explanation that makes any sense to me.

Regards,
--
Rex


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## wa5cab (Jul 23, 2015)

Well, now that we know that you have a 10". I understand why the illustrated parts list .looked just like the later one in the 200 Series manual (which is the only manual that we have in Downloads).  The earlier 200 does not have the Belleville washer.  As I said earlier, I'm an EE by profession, not an ME.  But given that the left spindle bearing is free to move axially relative to the headstock, I can't see any valid reason for the Belleville washer to have been added.  It neither added nor eliminated any machining step  But it's there on later production.

I don't want to start any discussion that often degenerates into a fight over the pros and cons of Atlas versus Logan or any other US badges.  But I have to say that there can be no doubt that tapered roller bearings of adequate spec are superior to ball bearings for lathe and milling machine spindles.  And flat belts were already quite obsolete by 1940.  Those are two of the reasons that 35 odd years ago I bought a new Atlas instead of a Logan or a South Bend.  Even that long ago, I already had a decade of design experience with small and large machines using both types of bearings and both types of belts.


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## Rex Walters (Jul 23, 2015)

Shoot, I still can't believe that Sears (the pre-Kmart Sears) isn't around any longer. I suspect I'd have gone new as well if they were.

I'm still not 100% confident that I understand what pre-loading is or does, though. Please validate if my understanding jibes with yours.

If I understand correctly what you and the engineerlive.com article that Henry provided are saying (a very big "if") then the normal way to spring pre-load this type of rotating spindle would be to have shoulders on the spindle or some other mechanical way to prevent the two bearings from moving toward each other axially. The shoulders would bear on the inside faces of the inner races, and springs (or Belleville washers) would bear on the outer faces of the outside races. This would cause the inside and outside races of each bearing to offset minutely, apparently taking up internal clearance between the balls and the races. This is what the nmbtc article refers to as "duplex face-to-face" preload.

I'm basing this understanding on your comment about not seeing a valid reason for the Belleville washer in my lathe since the rear bearing floats axially, and from the following two sentences from the engineeringlive.com article:



> For mounting, the spring is normally applied to the non-rotating part of the bearing, typically the outer ring.



and



> Axial adjustment calls for the mounting of at least two bearings in opposition, so that inner and outer rings of each bearing are offset axially.



Here's what I think I was missing:

I'd always visualized bearings as having the balls running on flat races, but if  I understand correctly (that "if" again) the balls actually ride in a curved groove in the races. So when the inner and outer races are offset axially, the balls are more tightly squeezed in the races (both axially and radially!).

If I've got it right, then "pre-loading" bearings just means minutely offsetting the inner and outer races of a bearing axially to remove internal clearances. This works because the ball bearings ride in groove, not on flat races.

Visually, here is what I think pre-loading means (a cross-section looking at a bearing on edge). Please let me know if I've got it right (finally!).




If this is correct, then I understand your comment that the Belleville washer in my lathe must be there for some reason other than pre-loading. Because both the solid stop (the clip-ring) and the spring (Belleville) bear on the outer race, the inner and outer races aren't being offset.

Sorry for prolonging this thread so long, but I figure if I'm this confused by the term "pre-loading" then I'm probably not alone. The conversation has improved my understanding of my lathe immensely. I hope it's useful for others.

On a sadder note, while the play at the spindle itself was greatly reduced, I'm still getting a few thou of play at the chuck jaws. I'm still getting a lot of chatter when parting a chucked piece (but parting with collets works a treat). It's more than possible I'm still doing something wrong, but several thou of play at the chuck jaws can't be helping.

Regards,
--
Rex


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## Redlineman (Jul 23, 2015)

Gad no;

Play at the chuck will never come out in the wash. The trick is identifying it. I've got an old plain bearing lathe that moves many 10ths of an inch axially. Not 10ths of a thou, 10ths of an INCH. Now... THAT machine is an adventure! The only way I can get a decent surface finish - or most of the time a close tolerance - is to use a FILE for the last few 10ths.

I think you have the preload thing pretty well figgerd. Look at MBFrontier's rehab thread and reference his preload mod on his spindle. This mod coming from another enterprising machinist named "JST" who ran into these issues and has some real brain skillz.


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## Rex Walters (Jul 23, 2015)

Thank you, John! Fantastically helpful info there (and you guys are eventually going to shame me into painting my lathe!). Both of you will end up with machines almost too pretty to use.

I'm new to the forum and I'm still catching up on all the great content here. I've just spent some time reading posts you mentioned: MBFrontier's rehab thread, your rescue thread, and JST's posts on the practicalmachinist site (especially this one).

[Off topic, but from the photo in comment #157 on your thread it appears you have flat, scraped ways? My Wards 2130 has vee-ways as well as flat that don't appear to have ever been scraped. Did you do the scraping?]

Earlier today, I spent some time carefully measuring the radial movement when I pull on the spindle (or on a chuck with the spindle) with a reasonably measurable amount of force (I used a hook type luggage weight scale to pull on the bar). I'd post photos, but I just loaned my son my phone with the pictures on them (he's visiting from overseas).

Unsurprisingly, there was more movement with a chuck than with a morse-taper drill bit stuck directly into the spindle. With about 40 lbs of pulling on a 3/4" bar about six inches from the spindle (a pretty heavy lean backwards, imagine hefting a suitcase weighing just under most airline's weight limits) I could get up to 0.0008" of deflection at the spindle. Interestingly, I noticed that with my 6-jaw chuck I got a _lot _more deflection when I measured the bar deflection right at the jaws (about 0.005") than when I measured on the outside of the chuck itself (which showed the same 0.0008" deflection as at the spindle). Clearly there is some internal movement of the jaws at work — this was enlightening.

*BUT* I did this measuring with the mag base on the cross-slide (hey, I have all this nice flat cast iron back there now, I want to use it!). I just read that the proper way to measure this deflection is with the mag base on the headstock casting itself, because the ways themselves can actually twist/warp slightly with this kind of pulling (makes sense to me).

Also, I'm unsure, but it sounds as if the new front bearing I bought from Logan Actuator is actually a "a double row internally preloaded ball bearing." Per JST, "[internally preloaded] means it was made with zero to negative 'clearance', and there was no 'rattle space' as there often is in a standard ball bearing." Yet more reason why the Belleville washer at the front is unnecessary.

Amazing how much I'm learning on this site. 

More updates soon as I continue my investigation, but I'm increasingly confident that I'll get things stiff enough to eliminate the chatter, even if I have to resort to JST's pre-load mods (which looks to be a pretty big job). From his posts, by the way, JST definitely sounds like someone I'd enjoy spending a few afternoons with — he really seems to know his stuff.

Since I only have one lathe, it's kinda like re-building a plane as you're flying along. Without another lathe to refer to, I'm unsure what's "normal" and I'm loathe to tear apart my lathe again because I can at least turn parts on it now, chatter or no!

Regards,
-- 
Rex


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## Redlineman (Jul 23, 2015)

Ha!

What you lack in direct Logan experience you more than make up for in candor and bravery!! Most of us are in the same boat on here; just groping along with no real experience to draw on. We get by on what we read elsewhere, and the hard won wisdom we share here, to a large extent. I have no real machine experience, but a lot of peripheral related experience with mechanical things, metal, welding, fabricating, etc. Others have definite technical skills that I do not. Some are just bold and brave. All tolled, between the lot of us, we might add up to one great machinist if we're lucky!


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## wa5cab (Jul 24, 2015)

Rex,

I think that all of your most recent comments WRT preload are correct.  I will add that the concept of taking out axial and radial play by preloading a pair of ball bearings is somewhat iffy as you drawings with exaggerated clearances illustrate.  But with two opposing ball bearings deliberately preloaded, you do reduce the possible axial and radial float.

However, as the drawings (especially those produced by Redlineman) show, you cannot reliably preload the spindle bearings in at least the 10" logan (the only one that we have seen drawings of).  The left hand spindle bearing's inner race is in fact locked in place on the spindle.  But the only thing resisting axial movement of the outer race is friction between the bearing outer race and the bore in the headstock.  There are no shoulders for the outer race to bear against.

Back to the Belleville washer that was added to the 200 prior to 1947, the only that that I can see it doing is taking out the clearance between the snap ring (circlip) and the groove it fits in on the bearing outer race.  However, this a several thousandths improvement in limiting axial movement.  It has no effect on radial movement, though.

On the right spindle bearing, this is a double row bearing.  I have read quite a few discussions on the subject of whether or not the current bearings as supplied by Logan still have the built in preload between the two rows.  Apparently vintage Logan advertising claimed built-in preload between the two races.  Or at least so it has been written here.


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## Rex Walters (Jul 24, 2015)

Thanks, Robert. That's helpful and makes total sense to me. I hadn't thought about the (axial) clearance in the snap ring groove.

The only thing I didn't understand was:



wa5cab said:


> I will add that the concept of taking out axial and radial play by preloading a pair of ball bearings is somewhat iffy as your drawings with exaggerated clearances illustrate.  But with two opposing ball bearings deliberately preloaded, you do reduce the possible axial and radial float.



I'm not following. When I read that it sounds like the second sentence says the exact opposite of the first. Could you clarify?

Thanks!
--
Rex


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## wa5cab (Jul 25, 2015)

Rex,

What I meant was that if you are dealing with two radial contact (the most common type) ball bearings, pushing the outer races toward each other (or away from each other) will eliminate essentially all of the end float but only reduce the radial float   The reason is that the inner diameter of the outer race and the inner diameter of the inner race do not overlap.  So if you drew a line through the contact points between a ball and its inner and outer race, it would not be far enough off of a line parallel to (in this specific case)  the spindle axis.  So it is relatively stable parallel to the spindle axis but unstable at right angles to that.  For bearing preload of a ball bearing pair to approach the effectiveness of a tapered roller bearing pair, you have to be using a special type of ball bearing called an angular contact type.  In these, the contact angle is typically 45 degrees, so they are stable (resist motion) in both the axial and the radial directions.  See crude drawing (made from your drawing because I can't draw circles worth a flip).




Two of these, back to back and properly pre-loaded against each other, are stable.  For relatively light duty applications, they are a reasonable substitute for a pair of Timken bearings.


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## MBfrontier (Jul 25, 2015)

In my correspondence with JST, the OP of the rear bearing mod that I used, I learned that he had converted his lathe to 3 phase power in addition to the rear bearing mod and asked him the following question:

_If you were to rate the improvement of the rear bearing mod and converting to three phase power what percentage improvement would you assign to each of these two changes to eliminate chatter? 
_
His response was:

_For me, the bearing preload mod made it useful again.  As good as it was before.  I don't know how you rate a change from "Scrap that POS", to "Hey, I can USE this".


The 3 phase made it much MORE useful, it made it fully "industrial" for me.  Chatter is totally manageable by standard remedies, the belts slip less, and a slip does NOT end with the belt coming off as it ALWAYS did before.

In neither case was there any comparison between before and after.... it was miles better._

 After my rear bearing mod there was a noticeable improvement. I could take a .020 cut on mild steel without the lathe chattering and got a nice finish. However, parting is still an impossible task on this lathe. I have been able to make several parts that turned out with a nice finish but use my band saw for cutting and face the part on the lathe. 

I have never had an issue with the belt coming off.

 I have been considering converting my lathe to 3 phase power using these items from Automation Direct:

GS2-21P0
GS2 1.0 HP AC DRIVE 230V 1/3 PH IN 3 PH OUT

GS-21P0-FKIT-1P  
FUSE KIT FOR GS1/GS2/GS3-21P0 1-PHASE (FUSES INCL)

MTR-P75-3BD18  
AC MOTOR 0.75HP 1800RPM 56C 208-230/ 460VAC 3-PH ROLLED STEEL

LR-21P0  
LINE REACTOR 230V 1HP 3PH DRIVE INPUT OR OUTPUT, 3% IMPEDANCE

GS-CBL2-3L  
CABLE GS KEYPAD TO DRIVE 3m (9.9ft) FOR REMOTE KEYPAD MOUNT

The above items total $425.00 so I've been staying away from my lathe for a while as I consider whether to spend more money on this project. I may have to do it to see how much better 3 phase vs. single phase is on my machine. However, I know it won't transform it into a one ton lathe.

Anyway, I think I'll get away from this computer before my wallet gets $425.00 lighter.


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## Rex Walters (Jul 25, 2015)

wa5cab said:


> In these, the contact angle is typically 45 degrees, so they are stable (resist motion) in both the axial and the radial directions.



Awesome. I finally understand what an angular contact bearing is (and your drawing was what let the penny drop for me).

Am I correct in assuming they should be oriented on the shaft correctly (not flipped left-for-right)? Seems like the single bearing you've drawn would be better able to resist axial spindle thrust to the left  than it would thrust to the right. I can see why a pre-loaded back-to-back pair would be stable and resist axial thrust in either direction.

Remember I started off completely clueless about bearings!  Are "Timken bearings" shorthand for tapered roller bearing (like "Kleenex" for tissues) or does that manufacturer just make particularly high quality bearings? Timken appears to manufacture all kinds of different bearings.


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## Rex Walters (Jul 25, 2015)

MBfrontier said:


> I think I'll get away from this computer before my wallet gets $425.00 lighter.



Thanks, Mike. I understand that concern! <laugh>

3-phase motors are nice, but if you've got a reasonably quiet and vibration free single phase motor, I wouldn't change it. I'm probably missing something, but for a belt driven lathe I can't see it making much difference (at least with respect to chatter, but even for power transfer it seems like belt-driven is belt-driven). In my case, changing from a leather clip-lace belt to an automotive serpentine belt was a huge win (quieter and far less slippage) that was a lot cheaper (and I believe more meaningful) than a motor change. (That said, I did replace my motor with a new one but mostly due to filth and concerns with the rotted out wiring.)

I think JST's spindle play was much worse than mine before he made his mod, so his lathe was completely unusable without it. It sounds like he got replacement bearings that absolutely needed to be pre-loaded to provide any kind of accuracy, so his mod was necessary. It appears the new bearings I got from Logan Actuator don't have that problem, so I've no plans to make the mod.

Regards,
-- 
Rex


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## MBfrontier (Jul 25, 2015)

Rex.

Like Redlineman, my lathe was made in 1942 and there was no Belleville washer utilized in that vintage by the factory. I spoke with Scott Logan before I ordered my new bearings and he said the bearing cap should have .001 to .002 clearance between the spindle cap and headstock after the spindle cap is tightened to insure that axial play is eliminated. I achieved that by using shim stock  instead of milling my spindle cap.

After looking at your drawing which shows your Belleville washer I was thinking I could have tried to preload the front bearing by reversing the washer orientation and installing it between the take-up-nut and the bearing. Perhaps multiple washers (if there is room) would have accomplished the same outcome on my lathe without  adding the extra bearing. I'm not sure there is enough room on my spindle to do that and I won't be taking the spindle out to find out.

I'll have to remember these ideas if I ever restore another Logan 200 Lathe but I'm thinking once was enough. It has been fun though.

Good luck with working on your lathe and I'll be interested to see how you make out with yours as you progress.


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## wa5cab (Jul 25, 2015)

Rex Walters said:


> Awesome. I finally understand what an angular contact bearing is (and your drawing was what let the penny drop for me).
> 
> Am I correct in assuming they should be oriented on the shaft correctly (not flipped left-for-right)? Seems like the single bearing you've drawn would be better able to resist axial spindle thrust to the left  than it would thrust to the right. I can see why a pre-loaded back-to-back pair would be stable and resist axial thrust in either direction.
> 
> Remember I started off completely clueless about bearings!  Are "Timken bearings" shorthand for tapered roller bearing (like "Kleenex" for tissues) or does that manufacturer just make particularly high quality bearings? Timken appears to manufacture all kinds of different bearings.



Rex,

The bearing that I crudely drew would in fact only work as one of a pair, with the second one flipped over and installed to the left of the one drawn.  The one drawn will take axial thrust from the right but not from the left.  Unlike radial contact (or just "radial") ball bearings, it is possible to manufacture an angular contact ball bearing with the inner and outer races separable.  I don't recall ever using any and don't know whether the balls would normally remain in the inner or the outer race but would guess the inner.  

Yes, "Timken" was used like "Kleenex" to mean tapered roller bearings.  Timken has for nearly a century manufactured high quality tapered roller bearings.  And in fact I can't ever recall seeing or using any bearing made by them that wasn't a tapered roller type.  In any case, that's where they made their reputation.  They don't (or at least claim not to) sell ANSI-ABMA Class 4 bearings.


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## wa5cab (Jul 25, 2015)

Mike,

As a practical matter, you cannot preload by axial forces a single bearing.  

On the subject of single-phase versus 3-phase motors and torque ripple, it is a fact that the torque ripple in a 3-phase motor is much smaller than with a single phase one.  And the frequency is higher.  If your purpose in going to 3-phase is only ripple reduction and not variable speed, there is an intermediate solution.  A single-phase capacitor-start capacitor-run motor has less torque ripple than the more common capacitor-start one.  The run capacitor drives the armature approximately in quadrature to the run winding.  Whether it would solve a chatter problem or not could only be determined by trying it, though.


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