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Forestgnome
02-13-2012, 04:25 PM
I came across a description of an interesting bearing design, and was wondering if anyone has seen one or knows where to find more info on it. It's a bronze bearing that has a parallel bore for a shaft, and has a tapered od and is split lengthwise. The idea is that the outer bore for the bearing is also tapered, which allows you to adjust the clearance to the shaft by squeezing the bearing via the taper. When I search for tapered bronze bearings all I get is cone bearing info.

claudev
02-13-2012, 05:01 PM
In the late 1950's / early 1960's, I had an old Sears lathe with a bearing like the one you describe. I remember because I bought a new bearing and spindle from Sears and replaced it. This was a small lathe of about 4-6 inch size with about a 3/4 inch shaft diameter with a very small bore. I did not keep it long.

I don't remember whether it was Craftsman or Dunlap brand. Sorry but that is all the info I have. You might find some information on an Atlas site.

topct
02-13-2012, 05:24 PM
A great design for a small low speed spindle. A hardened shaft running in a proper alloy of bronze can be run at a very close tolerance. Easily adjusted for wear.

kitno455
02-13-2012, 05:39 PM
A great design for a small low speed spindle. A hardened shaft running in a proper alloy of bronze can be run at a very close tolerance. Easily adjusted for wear.

Lots of older machines were this way, particularly Hendey, both lathes and millers.

allan

RussZHC
02-13-2012, 05:44 PM
Not doubting you but I am wondering about the taper...am I missing something? What is the need to have a taper (of course if the part/casting around the "sleeve" is tapered, it makes sense the bearing is as well, but...).

The idea of squeezing a split bronze bearing and so adjusting clearance is/was pretty common for a whole bunch of lathe manufacturers, many decades ago but as far as I know, they were not tapered on the exterior. OTOH, I am making an assumption, since I have never completely removed one out of its housing (my Sheldon lathe is this way and I wish it weren't but rather a true bearing cap style)

lynnl
02-13-2012, 06:33 PM
But as it's adjusted, the radius of curvature of the bearing ID would need to change in order to remain perfectly concentric with the OD of the shaft ...would it not?

Or is the idea that the difference is so miniscule as to be insignificant?

Forestgnome
02-13-2012, 06:36 PM
This is where it is used:

http://www.youtube.com/watch?v=d-woPRV_lac

duckman
02-13-2012, 06:42 PM
The ones I'm familiar with have a dove tail milled in the slot, and a threaded nut on the small end, loosen up the dove tail nuts then adjust the bearing and the snug up the dove tail nuts, then run it and check to see if you got it right, not to tight and not running hot. One thing I forgot to add was they use square threads so the angle of the thread does not squeeze the bearing in.

David Powell
02-13-2012, 06:42 PM
I owned an ancient IXL lathe made in Germany. That had this type of bearings. It was very worn and the adjustment was tricky, but once correct the lathe worked well and would part off smoothly. Regards David Powell.

Hopefuldave
02-13-2012, 07:28 PM
It's used on Holbrook lathe spindles (those that aren't the roller bearing ones, of course), a large adjusting nut presses the outside-tapered bearing into a tapered housing in the headstock, adjust until tight then tighten the wedge in the gap to establish clearance - works very well indeed, can run up to 2000 RPM (more if pushed) with barely measurable runout, no cyclic roller noise - with a properly sharpened tool they can take cuts that look like cylindrical grinding, though the rigidity of the machine probably helps!

One word of advice if trying this at home - Holbrook recommended ISO-5 hydraulic oil for the spindle bearings, which is mighty thin stuff, and had pumped lubrication for the spindle...

Dave H. (the other one)

ulav8r
02-13-2012, 08:53 PM
This type of bearing was also used on various Brown and Sharpe grinders. The bearings could be tightened to take up wear. In the mid 1990's I worked in a shop that had several Brown and Sharpes, one of which was alt least 90 years old. We ran 10 and 12 inch diameter diamond wheels on them at about 2800 rpms. We had to have the bearings on one of them scraped because of scoring. After that it ran fine until the company closed.

RussZHC
02-13-2012, 09:09 PM
This idea fascinates me...with one exception (that may not have been as "miller" was not specified...) the spindles have been horizontal in orientation.
Is there any reason, a vertical spindle of a similar design would come to grief?
Or would any issue be more based on keeping it properly lubricated? [I am thinking bath/near immersion as opposed to pressurized from a pump]

Full disclosure: right at this moment one of the things going around in my brain is a vertical head for an Atlas milling machine and it appears to me that its the $$$ bearings that account for a goodly portion of the bill...

J Tiers
02-13-2012, 09:21 PM
The biggest issue is the necessary slot, which would leak oil continually..... you would need to come up with an oiling scheme that would contain the oil and possibly recirculate it via a simple scoop arrangement, etc.

The small Sears lathe referred to above is the "109", of which at least the 109.20630 has the exact setup described. I line-reamed one to very good performance (of the bearing) many years ago, and then got rid of it.

In those the issue was not "egging" of the bore, but "bell-mouthing". no amount of tightening fixes that, you have to line-ream/line bore the bearing to size.

Don Young
02-13-2012, 09:23 PM
This type of bearing was used in the horizontal mill arbor supports made by Cincinnati and by Kearney and Trecker.

Suitable ball or roller bearings in a vertical head for an Atlas milling machine should be available at very reasonable prices. The big expense comes with large high precision bearings used in much larger and more capable machines.

gzig5
02-13-2012, 09:47 PM
The early Rockwell Toolmaker surface grinders use a large tapered bronze bearing in the front. There is a oil pond below the spindle that a slinger ring rides in to pick up oil. The spindle speed with the standard 1725 rpm motor was 3200 and 4200 rpm, so they can handle some speed with the right oil. Mine runs smooth and quiet and was not too difficult to clean up the bearing surfaces.

john hobdeclipe
02-13-2012, 09:47 PM
Interesting discussion...

I've been thinking about using the same bearing design on a project, too. I first saw it on the Craftsman "109" lathes built by Double A in the 1940's and 50's. I'm pleased to learn that the design has also been used on other, more robust machines with success.

On the little Craftsman lathes the large part of the taper is to the outside, and the large face of the bearing also serves as the thrust face. The adjusting nut is on the inside of the headstock housing, next to the bull gear.

I think that if the bearing had, say, 4 slits cut into it, with one of them cut all the way through at the big end, then as you tightened it the bore would remain cylindrical.

Andrew_D
02-13-2012, 11:32 PM
Very interesting...

What would the taper be on something like this? I'm guessing fairly shallow to allow for easier adjustment???

Andrew

J Tiers
02-14-2012, 12:04 AM
I think that if the bearing had, say, 4 slits cut into it, with one of them cut all the way through at the big end, then as you tightened it the bore would remain cylindrical.

IIRC the AA machine was made with at least 2 and possibly 4 slots. Anyone who has one (and will admit to it) can look and see.

WCPenney
02-14-2012, 12:09 AM
I have an old Pratt Whitney & Co pattern makers lathe with tapered bearings and a straight spindle.

The bearings are tapered and pull into the matching tapers in the headstock uprights. There are two threaded locking rings for each bearing. One on either side of the uprights. The bearings are threaded on parts of the O.D. Very thick, and when adjusted, they are also very very smooth.

Edit: Found one picture. Somewhere there are pictures of the bearings themselves out of the headstock but I can't seem to find them. I'd go take some more shots, but the machine is all covered up out in the shop and it's cold out there.

https://lh5.googleusercontent.com/-kZV9ydlwChk/TzmxPnxxnuI/AAAAAAAAAQM/Xp__3eJb3yQ/s200/IMG_1324.JPG

To the left of the headstock on the bench are several of the rings. The far outboard ring is much heavier, bell shaped, and threaded inside for a thrust adjusting screw that acts on the end of the spindle. It looks as though there may have also been some other gizmos that attached there long before I got it.

Forestgnome
02-14-2012, 03:22 AM
Very interesting...

What would the taper be on something like this? I'm guessing fairly shallow to allow for easier adjustment???

Andrew
I was thinking along the lines of a tapered collet, like a DA or double taper. That would avoid a locking effect like a Morse would cause. You'ld need to be able to loosen it if it was getting too warm.

J Tiers
02-14-2012, 08:08 AM
I have an old Pratt Whitney & Co pattern makers lathe with tapered bearings and a straight spindle.


The Rivett 608 headstock has a watchmaker's lathe double angle nose bearing, but the tail bearing is a tapered OD bronze bearing which has a single slot for adjustment. The tail bearing journal is cylindrical, so that portion is exactly the sort of thing being discussed here.

dian
02-14-2012, 08:39 AM
this is my spindle.

http://i973.photobucket.com/albums/ae218/romandian/CCF14022012_00000.jpg

(5) is the adjustment screw. can anybody explain, how it works? i wouldnt have thought it is split though.

J Tiers
02-14-2012, 08:56 AM
In your case it appears to be the reverse of the type we are discussing... Your taper is on the spindle, and the headstock housing is straight.

What we are talking about is the taper on the housing and a straight spindle. As the bearing is drawn into the taper, it closes down on the spindle rather like a collet.

In your case, the housing is straight, and the taper is on the spindle. No need for any split.

So I presume that the adjustment moves the tapered bearing towards the nose of the spindle. The 'correct" adjustment would be when the taper clearance is such as to just leave room for oil, while at the same time some other feature (not shown) which takes thrust against the spindle also has only oil clearance against a "shoulder" of some sort.

Essentially it sets the "position" of the spindle, instead of a clearance.

I presume that part "M" is the locking collar for spindle attachments such as chucks, etc.

dian
02-14-2012, 09:22 AM
m is the locking collar and what you are saying makes sence, but it is hard to imagine, how the bearing gets moved. i cant believe the screw just grabs the bearing in one spot and pulls it forward.

Doozer
02-14-2012, 09:29 AM
Think old Cataract and Hardinge style.
Like a big old cast iron ER collet.

--Doozer

Forestgnome
02-14-2012, 09:36 AM
Another taper option would be to use a long taper with an adjusting nut on one end and a stop nut on the other. Similiar to the tapered gib setup on some crossfeeds. That way you can still tighten and loosen. In the grinder application it would probably mean a full length bearing. Otherwise you need two bearings and an open shaft in between.

Barrington
02-14-2012, 12:59 PM
This is just guesswork, but I read the drawing as below:-

http://i564.photobucket.com/albums/ss82/MrBarrington/taper.jpg

I see the adjustment shaft (blue) as being geared at the far end, meshing with a ring (green).

This ring is threaded onto the tapered bearing (orange dots) and so can push the bearing against the shaft taper when turned.

The ring acts against a further ring (red) secured by slotted (?) screws (pink), one of which is shown at the top.

As I say, just a guess.

Cheers

.

Hopefuldave
02-14-2012, 03:25 PM
[QUOTE=J Tiers]

The biggest issue is the necessary slot, which would leak oil continually..... you would need to come up with an oiling scheme that would contain the oil and possibly recirculate it via a simple scoop arrangement, etc.

QUOTE]

Yep, says a Holbrook user... "Leak oil continually" is about right - an understatement, possibly!

Ideally you want a pumped oil feed and a sump to collect the leakage - a filter's a *very* good idea, too. The Holbrook uses a surprisingly small pump and the oil that doesn't escape behind the chuck is drained from the headstock sump into a gallon? tank, then pumped through a mesh/magnetic-labyrinth filter - and there's a sight glass to show the oil's flowing, also a Very Good Idea! Extra pipes with metering jets take oil to the headstock gears and the spindle-pulley roller bearings.

The pump's driven by a worm on the spindle pulley, not the spindle itself so:
It can be pumped up without [drive to / wear on] the spindle at start-of-the-working-day by disengaging the spindle drive and running for a few minutes;
It gets the same rate of oil pumped in back-gear so the heavier bearing load on heavy cuts sort of gets compensated for;
The higher the spindle speed, the faster/higher pressure the oil flow :)

Dave H. (the other one)

RussZHC
02-14-2012, 04:24 PM
J Tiers and Doozer beat me to it but my "Eureka!" moment last night lying in bed was, "Its like a big ER collet".

So, going with the spindle being cylindrical and the bearing exterior and housing interior surfaces being tapered, "it" should still require the need of some method of locating the spindle longitudinally, right?
I'm thinking thrust bearing, but could one make use of the "edge" of the tapered bearing to say push against a thrust bearing/shoulder...or is this unnecessary or best done a different way (i.e. making one thing too complicated when two simpler ways would be best)?
If one were to use this taper idea from either end, could it be enough to locate the spindle longitudinally and accurately enough?

p.s. I value this discussion and not to put a damper on it but I suspect this to be "re-invention" of old technology, but given the benefits, why would the method have slowed/ceased? Too costly versus "modern" roller element bearings?

john hobdeclipe
02-14-2012, 05:13 PM
p.s. I value this discussion and not to put a damper on it but I suspect this to be "re-invention" of old technology, but given the benefits, why would the method have slowed/ceased? Too costly versus "modern" roller element bearings?

Good question, I've wondered about that too.

********************

Although the OP was asking about bearings with the taper on the outside diameter, we seem to have digressed a bit, into the realm of bearings with the taper on the inside diameter. So here is a pic of the spindle, etc. from an old Delta Toolmaker grinder. In this design, the large bearing is captive in the housing. Axial play is controlled by the smaller bronze washer. The nut to the right of it threads into the end of the large bearing, holding the flat face of the washer against the flat face at the large end of the spindle taper. A ball bearing goes at the drive end of the spindle.

http://www.auldooly.com/imagehost/P7230027-0.jpg

Forestgnome
02-14-2012, 05:34 PM
I value this discussion and not to put a damper on it but I suspect this to be "re-invention" of old technology, but given the benefits, why would the method have slowed/ceased? Too costly versus "modern" roller element bearings?
I was thinking the same thing. As we discuss the places where bronze bearing are used and the benefits of using said bearings the question of development trends comes to the forefront. I have been enjoying the rediscovery of old technology. It's one of the reasons so many of us revere old machinery. The designs are timeless. I think sometimes engineering developments continue on a forward path without taking the time to reflect on where we've been.

Rustybolt
02-14-2012, 05:52 PM
Brown and Sharpe screw machines used tapered bronze bushings

topct
02-14-2012, 06:38 PM
Aren't the high speed spindles used on CNC circuit board drilling machines using plain bearings? Rather than using an oil film to keep the elements from contacting one another they use air pressure. Oil will let you get so close but air can let you get even closer.

The basic rules are still in place.

dian
02-15-2012, 04:18 AM
thanks for that, barrington. what i find weird is the small contact area of the bearing.

Barrington
02-15-2012, 05:12 AM
Dian - I suspect that the drawing is just showing the cross section through a couple of longitudinal oil grooves, the rest of the 'cone' being intact.

dian
02-15-2012, 05:19 AM
i see, that makes sence.

Doozer
02-15-2012, 07:13 AM
http://www.lathes.co.uk/cataract/img102.jpg
http://www.lathes.co.uk/cataract/img111.jpg

Cast iron Hardinge spindle bearings tapered on the OD.

--Doozer

Forestgnome
02-23-2012, 04:21 PM
Found some interesting info on another type of bronze bearing, the floating bush bearing.

http://www.rodyn-inc.com/ISCORMA3_Gunter%26Chen_TurbochargerVer2.pdf