Fitting Oilite Bearings

[SteveT]

I'm just about ready to machine a crankcase to fit 3/8"x1/2"x5/8" oilite bearings. In my mind I seem to remember advice that the hole should be to size even though the O.D. & I.D. of the bearing are slightly oversize. The bearing is then force fitted into the hole and the oilite material 'crushes' down to leave a correctly sized I.D. in the bearing. Can anyone confirm that this is correct.
Many thanks,
Steve T

 

[Brian Rupnow]

Yes, you have it correct. Make the hole for the o.d. of the bushing "on size". The bearing will be a light press fit into place. This will yield the correct bushing i.d. after the bushing is pressed into place.

 

[SteveT]

Hi Brian,
Many thanks for replying.
Seems like I have not lost all my grey memory cells yet!
Stay Safe
Steve T

 

[alan.crawley1]

When I was an apprentice in the middle of the last century we were taught never to ream an oilite if it was a bit tight. The correct practice was to press a polished mandrel through it to achieve the exact size.

 

[popnrattle]

I chamfer the hole and file a bit of a lead-in before pressing so hole won't shear OD of brg.. Sometimes need to ream to size after pressing. The sizes are from Bunting website. These are the brgs I use. Hope this helps.

Later, Rick.
https://www.buntingbearings.com/index.html#

 

[Peter Twissell]

I understand the idea behind the 'no reaming' instruction was that reaming would close up the pores in the surface of the bearing, reducing its self-lubricating properties. Pressing a mandrel through would have the same effect.

 

[kquiggle]

Why not see what the people who make these have to say: 8 Tips for Machining Sintered Bronze Bar Stock - National Bronze Manufacturing

A few highlights:

• Tungsten Carbide tools are recommended because they retain a sharp cutting edge much longer.
• Sintered Bronze Bar Stock may be reamed without destroying porosity as long as a dead sharp cutting tool is used.
• Lapping compounds are not recommended due to the difficulty of later removing abrasive materials from the pores.
• Re-impregnation is recommending after machining. The bearings should be soaked in a bath of hot oil for 1 hour for thorough impregnation.
• It is very important to have the cutting surface highly polished to prevent adhesion of metal to the cutting tip.

I assume these recommendations are for use in a manufacturing environment, but they provide some help for working in the home shop.

 

[doc1955]

My father-in-law had a motor,generator,altenator and started repair shop and worked with sintered bronze bushings a lot. Most times he would bore them but says reaming is perfectly fine. He says your reamer would have to be mighty dull to close up pores enough to hurt anything. Lapping with a lapping compound is a no no. But when you are ready to install you do need to reload them with oil. Reloading them is a very simple process. Anyway I trust his judgement he has done this many years for a living and has the reputation as the go to guy for that type of work.

 

[SmithDoor]

I use press fit .001" to .003"
After installing simply team bore to size about .001 to .002 for most application. In some as little as .0002" .

Do not use oils like 3 in one or way lub. It will plug the poors of bearing. I use 30W oil

 

[stackerjack]

To load your bushes with oil, you can either submerse them in oil, then place in a vacuum chamber. As the air comes out, the pores will fill with oil.
An easier way is to submerse them in oil and heat up the oil. As it cools down, the bush will absorb oil.

 

[doc1955]

Depends on size for small bushings just set on top the palm of your hand fill with oil then press on the opp side with your thumb untill you see the oil come out of the pores in the bushing. Use a non detergent oil.

 

[SmithDoor]

I drill a hole to add oil.
If have the room I will add groove for more oil storage in bearing

To load your bushes with oil, you can either submerse them in oil, then place in a vacuum chamber. As the air comes out, the pores will fill with oil.
An easier way is to submerse them in oil and heat up the oil. As it cools down, the bush will absorb oil.

 

[WOB]

A simple way to effectively reoil a bearing is to drop it in a canning jar and cover it with 30W oil. Put a hose barb in the lid and connect it to your vacuum pump ( manual or electric). Pump until bubbles stop.

WOB

 

[teeleevs]

My father-in-law had a motor,generator,altenator and started repair shop and worked with sintered bronze bushings a lot. Most times he would bore them but says reaming is perfectly fine. He says your reamer would have to be mighty dull to close up pores enough to hurt anything. Lapping with a lapping compound is a no no. But when you are ready to install you do need to reload them with oil. Reloading them is a very simple process. Anyway I trust his judgement he has done this many years for a living and has the reputation as the go to guy for that type of work.

I used to do a lot starter motor work and to reload the bush was easy, just sit the bush on your thumb, fill it with oil, place the other thumb on top and press until the oil came out through the pores.

 

[doc1955]

I used to do a lot starter motor work and to reload the bush was easy, just sit the bush on your thumb, fill it with oil, place the other thumb on top and press until the oil came out through the pores.

Exactly for bigger put on palm of hand plus use a non detergent oil preferably 30 weight.

 

[Cogsy]

I like the vacuum idea and it would be an interesting experiment to try it on a bush that has been refilled using the thumb/palm pressure technique. My intuition suggests the vacuum method would find more trapped air in the bush and therefore get more oil into it. If I had some I'd give it a go myself.

 

[kquiggle]

Here's a simple method for re-oiling:

"After machining of the bearings or following loss of oil during storage, immerse in high quality mineral oil (SAE 30) at 140 degrees F to 160 degrees F for 10 to 15 minutes and then cool in cold oil."​

​

https://www.bronzebushings.com/blog/tips-for-using-oil-impregnated-bronze-bearings/​

 

[David Shealey]

Many years ago when I started work for a company, they were complaining that some oilite bushings were wearing out very fast on a piece of equipment, and wanted me to come up with a better bushing. I looked at the application, saw nothing wrong, went to the tool crib and looked at the stock. HA! They had about a hundred in stock, had been removed from shipping packs and put into a cardboard box! Of course all the oil was now in the cardboard instead of the bushings! Picked up a few at the local supplier, put them in, problem solved. Then vacuum oiled all the stock and put them in a plastic container. Bushings lasted so long equipment was still operating well a year later.

 

[SmithDoor]

Where live we 110 deg days so oilite woul have the oil running. The way fix was to add a oil hole.
It hard to find the heavy oil they use in oilite bearing.
But I found 30w to 60w gear oil would works great, oiling oilite bearing.

Dave

Many years ago when I started work for a company, they were complaining that some oilite bushings were wearing out very fast on a piece of equipment, and wanted me to come up with a better bushing. I looked at the application, saw nothing wrong, went to the tool crib and looked at the stock. HA! They had about a hundred in stock, had been removed from shipping packs and put into a cardboard box! Of course all the oil was now in the cardboard instead of the bushings! Picked up a few at the local supplier, put them in, problem solved. Then vacuum oiled all the stock and put them in a plastic container. Bushings lasted so long equipment was still operating well a year later.

 

[SmithDoor]

For oiling I use 1/16" copper tubing to bearing. I take most tubing to one location and use one oil port.

Dave