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Lee in Texas
07-08-2007, 12:48 AM
While getting some nuts/bolts/threaded rod, etc, I saw a bin with bronze bearings. I picked a flanged pair for future use on a Heron steam engine. These bearings look rough, like they're cast. Is it oilite? Do I need to add oil? They don't seem to be "leaking". Once in place, do I need to add oil?

Thanks, Lee

dp
07-08-2007, 12:57 AM
http://www.oilitebearings.com/

oldtiffie
07-08-2007, 04:33 AM
Deleted/erased-out

Your Old Dog
07-08-2007, 07:14 AM
As old tiffe says, you shouldn't machine these bearings as it supposedly closes up the pores and ruins the self lubricating action. But in going to the site DP mentioned I read this on the first page:

Machining
We also specialize in machining Oilite self-lubricating bearings to meet individual specifications and tolerances. This maintains the performance characteristics and physical properties which are the prerequisite of these components.

I wonder what they know that the rest of us don't? Is it possible to machine these with good sharp tooling and flood cooling/washing and not damage the pores?

John Stevenson
07-08-2007, 08:06 AM
If you can't machine it why is it sold in stick form ?

.

Lee in Texas
07-08-2007, 08:30 AM
Can it be soldered? I got a flanged bearing and I want it to go on/in a copper sphere. The sphere is spun, so it's relatively thin walled sheet metal.

DR
07-08-2007, 09:19 AM
If you can't machine it why is it sold in stick form ?

.

We machine it all the time, a customer likes to use it for large, special purpose thrust bearing......nasty stuff to work with.

Turning isn't so bad, except it weeps oil. Do it on a manual machine and expect to get oil in your face.

Milling is something else.....even totally immersed with flood coolant it smokes and burns.

Band sawing and drilling are almost as bad as milling.

Depending on the manufacturer the sticks John mentioned come in cast form with an obvious parting line on the OD, these are bad since the diameter varies so much you can't hold them in a collet. Other makers supply the sticks premachined with the OD about .050" larger in diameter than nominal. I never know which the customer will supply.

I believe the flanged type the OP mentioned are made under size in the bore, after pressing into place, they need reaming to size.

A.K. Boomer
07-08-2007, 10:07 AM
Can it be soldered? I got a flanged bearing and I want it to go on/in a copper sphere. The sphere is spun, so it's relatively thin walled sheet metal.


Thats a damn good question, I think you would play hell getting all the oil out first but maybe with tons of brake cleaner and then a couple pre-heats you could solder it --- on thing about it though is I believe it would defeat the purpose of the oil light, all those hungry pores would imediatly fill up with tin so you would lose the effect of what the bearing material was designed for...

As far as machining --- Same thing DR said, extremely sharp endmills will cut down on the smoke some but its nasty, Iv never had to turn it on a lathe but I imagine all the oil flinging out of it esp. when it starts to heat would be a PITA, I had to cut a ton of it up on the band saw it was 1/2" sheet --- do yourself a favor and wear some nitril gloves if you have to handle it much, It will stain your hands for days...

oldtiffie
07-08-2007, 11:23 AM
Deleted/erased-out

Tin Falcon
07-08-2007, 11:48 AM
OK here is my humble understanding of oilite.
it is porouse and satuated with oil when made
Adding a little oil to replace what is lost and to keep it lubed is a good thing . regular plain bearing need an oil hole and or groove too allow for oil flow .
This is not needed with oil lite since it is porous.
Of course it can be machined the manufacturur is not going to make a forming mold for ever possible size. And like John said why sell sticks or rods if it can not be machined.
If the oil is being slung out while machining the rpm is too fast.
Soldering is done with clean surfaces free from oil . press fit oil lite.
Do not under any circumstances try to lapp oil lite the abrasive will get in the poors and never come out.
I see no reason not to use it on a steam engine espesialy if keeping it oiled.
Tin's Humble opinion Always follow manufacturers recomendations. And sound shop practice.

lazlo
07-08-2007, 11:49 AM
If you can't machine it why is it sold in stick form ?

You can machine Oilite, but you have to use a razor-sharp tool. If you use a tool that isn't very sharp, or if you have your speeds/feeds wrong, you'll smear the porosity of the bearing, and the oil won't leak out like it's supposed to.

I also had problems pressing in Oilite bearings in an interference fit -- if the hole has a sharp edge (like most press-fit holes), you can scar the outside of the Oilite, and again, no oil comes out.

A.K. Boomer
07-08-2007, 12:28 PM
Adding a little oil to replace what is lost and to keep it lubed is a good thing . regular plain bearing need an oil hole and or groove too allow for oil flow .
.


Adding to this --- many designs that are of permanent assembly or limited access utilize a hefty peice of felt behind the oilite, this will keep the bearing lubed, It has a remarkable action even when it starts to dry out, the bearing will then see a little heat, the heat will disipate to the felt, the oil in the felt will be attracted to the sintered bronze in a "wicking action"
It is why in so many cases you will hear a dry bearing start to act up and then the sound goes away with more use, I had a few heater fans in cars that drove me crazy like this --- but they drove me crazy for years because they would never sieze up either...

Mcgyver
07-08-2007, 01:39 PM
I also had problems pressing in Oilite bearings in an interference fit -- if the hole has a sharp edge (like most press-fit holes), you can scar the outside of the Oilite, and again, no oil comes out.

Lazlo, don't understand that part - the outside gets smeared by press fit action but why would it matter, the outside, between bearing and press fit hole is not where you need the oil....l or what am i missing??

my $.02 on sintered bronze bearings (oilite is i believe just a brand, there are many others); the OD is slightly oversized, such that when press fit in a reamed hole, it closes up the ID to a set amount of clearance. Machinery's handbook iirc will talks about this calculation for sintered bearings if you want to alter the clearance. I machine them all the time and find them easy to machine. i avoid machining the ID for the obvious reasons mentioned but keep a stock of a bunch of different sizes so that i can machine to length or occasionally to OD as required. they're convenient but don't have anywhere near the tensile strength of bronze if the application is heavy duty.

bhjones
07-08-2007, 03:04 PM
I'm glad I ran across this post. I'm about to order some SAE 841 Oil-Impregnated Bronze from McMaster Carr. I'm ordering the ID's that I need with the intention of turning the OD and parting to the lengths needed. My concern is that McMaster Carr's discription lists the ID as "undersized to allow for finishing".

Assuming the ID is .010 or less undersized (I'm guessing here), how should I open up the ID.

This material will be used for some of the gearing within the apron of a Craftsman 12" lathe, so I'm worried about clogging the pores.

Thanks.

Lee in Texas
07-08-2007, 05:32 PM
I chucked one up in my little Sherline lathe and spun it at top speed. No oil slung out. I'm now wondering if this is just some cheap Ace Hardware Made In China junk piece of cast bronze.

The Heron Steam Engine would have fairly loose tolerances, so I'm not worried too much about solder clogging up the pores in the vicinity of the flange. Heck I didn't even even know oilite existed until a few days ago. I was planning to just turn a couple of flange bearings from bronze barstock.

Thanks, it's great to pick the minds of people who have more experience.

BTW I'm working on Sherline tools right now, but I have a Bridgeport mill and small South Bend lathe in my garage. They need a little cleanup before use, though. It will be a while, since I'm working away from home and I only go back on some weekends.

lazlo
07-08-2007, 05:41 PM
McGyvver, the Oilite application notes tell you that you need to change the oil an Oilite bearing every 1,000 hours of use, or once a year, whichever comes first.

The easiest way to do that is to cut a little oil reservoir pocket around the bearing, like AK was talking about. The idea is the new oil leaches down into the spongy Oilite material, and refreshes the oil.

If you burnish the OD of the Oilite bushing when you press fit it, it's hard to get new oil into it. The application notes say something like "make sure to break sharp edges on the hole", but that's not always practical.

I replaced the bronze change gear selector bearings on my lathe with Oilite, and the first time I press fit the bearings, I got a lot of oil ooze, and sure enough when I pulled it back out, I had scored/smeared the OD.

So when I tried again, I made a little sleeve out of nylon, and that worked great.

By the way, I got my Oilite from McMaster too. It's not Oilite brand, but it seems well made.

Mcostello
07-08-2007, 10:36 PM
2 other hints, don't carry around in a shirt pocket, and don't lay it down on a needed peice of paper. Don't ask....

J. R. Williams
07-08-2007, 11:07 PM
I ususally install Oilite bushings by making a piloted punch to size and install the bushing. The pilot end is made to the desired or measured shaft size and the OD of the bushing turned to a couple thousandths over the bore and press the bushing in place.

JRW

rbregn
07-09-2007, 10:52 PM
I would machine it how ever you want, besides lapping for obvious reasons. If your worried about the pores closing when you machine it, why would they not close up in operation with a shaft burnishing the inside when it is operation. :confused:

You can try to close them pores up the best you can, when it gets warm, oil will weep out anyway. Otherwise you could just machine the surface you want to solder and not worry about oil contamination.

Don't over engineer!

bhjones
07-12-2007, 01:46 AM
My bronze material order from McMaster arrived today. I turned the OD and bored the ID, and 15 minutes later while sitting on the bench I noticed it was weeping oil.

I'd ordered 3 8" lengths in 3 ID sizes (3/8, 1/2 and 3/4). They were listed as over sized on the OD and undersized on the ID. What I got was no where near listed dimensions. The 1/2" ID length was at least .020 over the listed .500. The 3/8" length was bent on one end. I didn't measure it, but I must have been out close to .100. Fortunately I'm able to make use of this stuff, it's definitely not meant to be used with a quick ream to size in the ID.

YankeeMetallic
07-12-2007, 08:55 PM
I've machined Oilite many times for bearings in refurbishing Glass Blowing Lathes (Litton's).
I first tried using a mist coolant on the lathe. The samll pieces turned off created a strong glue that covered my lathe when it dried. You can easily turn it as lower speeds without coolant as it has enough lubricant in it that it will smoke a little.
I have never had any problem with machining the pores closed so it is not effective in passing lube through. I have dipped them in acid baths to open the pores after machining by doing the following:
Machine to size, use a degreaser and let soak to leach out the lubricant. Let dry then place in an acid bath for 2 minutes max!. The acid will eat away the thin metal pushed over the pores first, thus opening them. Flush with water thoroughly and let dry for a day. Relube by simply warming to approx 130 degrees F. and then soaking in the lube required.