Oilite Bushing Grease or Oil??

While working on the rebuild of My hendey T&G lathe and have come across a vexing question.

Here's the situation,
In the feed/belt selector box there is a shaft that runs the belt part of the drive, that is running in Oilite bushings. This shaft runs at speeds up to 2500 rpm, and is, like the rest of the machine grease lubricated. Everything else on the lathe is either running in bronze or ball bearings, depending on the speed. This is the only "high" speed use of bronze.
The shaft that runs in these bushings has worn pretty badly and will be replaced. I have spoken to several other hendey owners and this is a "known" problem area.
The use of oilite is shown in a penciled in note on a drawing, date unknown.
My experience with oilite is that it is usually oiled, either by a drip cup or by an oil gun at regular intervals.

I was wondering is I might be better off using oil to lube this??

any comments?

thanks
Pete

Oilite is a sintered bronze made to have its pores filled with oil and used like that. The filling is usually done at an elevated tempeature. They are MADE for areas that do not ordinarily have a dedicated oil supply

If you are going to lubricate an Oilite bushing directly, prefer oil to grease. Especially avoid clay-thickened greases (which are not common these days). Lube reaching the bearing indirectly, for example migrating down a lubricated shaft, doesn't matter so much.

What oiling facilities are there for that bearing? (Git's cup, hole in the casting, zerk, etc.)

johnoder said:

Oilite is a sintered bronze made to have its pores filled with oil and used like that. The filling is usually done at an elevated tempeature. They are MADE for areas that do not ordinarily have a dedicated oil supply

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John's reply is spot on, as usual. Here's a quote excerpted from an Oilite bearing vendor's website:

"Re-oiling: after machining of the bearing, or following oil loss during storage, immerse in high quality mineral oil to ISO VG 60 or ISO VG 150 (SAE30 or SAE40) at 80°C to 100°C for 10 to 15 minutes and then cool in cold oil."

~TW~

Tommy said:

John's reply is spot on, as usual. Here's a quote excerpted from an Oilite bearing vendor's website:

"Re-oiling: after machining of the bearing, or following oil loss during storage, immerse in high quality mineral oil to ISO VG 60 or ISO VG 150 (SAE30 or SAE40) at 80°C to 100°C for 10 to 15 minutes and then cool in cold oil."

~TW~

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A former employer had an application that required replacement of the oil the oilite was originally made with. I can't remember how they removed the old oil, but the replacement was done via vacuum impregnation.

Any chance of substituting a Torrington needle bearing in its place? That would be my fix if the housing could be bored out a small amount. Peter

You need a hardened and ground inner race for a needle bearing. Oilite with drip should last a long time.

Not needed IF the shaft is hardened and ground. Peter

Thanks for the advise!!
I'm going to make a new shaft from 4130ph, and use oilite bushings as original. I will replace the current grease fittings with small oil cups and felt wicks. The mount for the grease fittings is about 1 1/4" above the bushings so the drilled hole will make a nice little oil well.


Cheers
Pete

SOOO many machines ruined by some lazy maintenance guy replacing oil cups with grease fittings. Logic goes like this, put grease fitting on it and it will require less attention and not drool oil. It works great. You put grease fittings on it and pack it full of grease. Now, you almost never have to grease it (like once every 50yrs, whether it needs it or not). It never leaks oil, especially once the grease hardens into a waxy wad of goo. Eventually, the grease turns to a hard black carbon substance that has to be removed from the oil grooves with a screwdriver or chisel and hammer. The shaft, as you discovered, gets worn very severely and usually has to be replaced, but think of how many extra hours of doing nothing the maintenance guy got away with.

shapeaholic said:

Thanks for the advise!!
I'm going to make a new shaft from 4130ph, and use oilite bushings as original. I will replace the current grease fittings with small oil cups and felt wicks. The mount for the grease fittings is about 1 1/4" above the bushings so the drilled hole will make a nice little oil well.

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Excellent reasoning, grease never has a place near an Oilite bushing at any RPM unless the designers screwed the pooch with a misapplication. If this isn't a 24-7-52 machine let the bearing be as installed.

If I have it right, grease is oil in a binding matrix that holds position. Nothing more.

There are various binders, soap, lithium, water proof, etc, It's important to select the correct type, but it's the oil that does the lubrication. (I would choose Lubriplate!)

The nice thing about grease, is that it does not run out. and like the oilite, actually supplies additional lubrication under pressure andheat. A true example of "The squeaking wheel getting the grease".

Of course, poor maintenance practices can screw anything up. The risk of oil only is that the oil will run out leaving the bearing dry. 'Disaster with hard bronze, and something that Oilite is good at preventing!

The risk with grease is that you will forget about a regular refresh. As mentioned.

I have a 3 hp GE electric motor in service as a RPC that runs on oilites with grease fittings. The motor turns 3450 and has over 3squir0 years in my service. I got it used, It must be over 50 years old. I give it a pump of grease about once a year or when it starts to make a little racket. The lubrication plate warns "DO NOT OVER GREASE". I'm sure the end bells are filled with dried out binder, but I am also sure there is fresh grease at the bearing surfaces.

IF I were refitting, and IF I planned to use and lubricate the machine "daily", then OIL.

If the use and maintenance will be infrequent, then grease would be my choice. 'less oil running out and making a mess.
Remember, with wicks and gravity at work, under some conditions, the oil put in the cups will flow out even when the machine is just sitting.

Which would be worse?

"The nice thing about grease, is that it does not run out."

And that's the worst thing about it. It doesn't run out, so essentially, the oil in the bearing never gets "changed". Any powdered metal from wear just stays in there and causes more wear, which adds more powdered metal, etc... All my plain bearing motors have oil cups with reservoirs and oiling rings in them. They do not drool oil, but the oil does get a chance to circulate and there is a huge quantity of it, compared to the tiny amount present in the clearance of a shaft and plain bearing.

Your example of a converter idler is the absolute lightest duty a motor could ever pull. There is no load on the shaft or motor whatsoever, so the only thing the bearings are asked to do is locate the shaft. I have never seen a constant duty plain bearing motor with factory grease fittings. I have a little 7,000rpm momentary duty motor that has the old screw down grease cups on it, but all other motors I have seen with grease fittings were ball bearing. Most of them had been fitted with sealed bearings, rendering the grease fittings useless.

Mike C. said:

"The nice thing about grease, is that it does not run out."

And that's the worst thing about it. It doesn't run out, so essentially, the oil in the bearing never gets "changed". Any powdered metal from wear just stays in there and causes more wear, which adds more powdered metal, etc... All my plain bearing motors have oil cups with reservoirs and oiling rings in them. They do not drool oil, but the oil does get a chance to circulate and there is a huge quantity of it, compared to the tiny amount present in the clearance of a shaft and plain bearing.

Your example of a converter idler is the absolute lightest duty a motor could ever pull. There is no load on the shaft or motor whatsoever, so the only thing the bearings are asked to do is locate the shaft. I have never seen a constant duty plain bearing motor with factory grease fittings. I have a little 7,000rpm momentary duty motor that has the old screw down grease cups on it, but all other motors I have seen with grease fittings were ball bearing. Most of them had been fitted with sealed bearings, rendering the grease fittings useless.

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I don't believe the OP intends to add a recirculating oiling scheme. And Do we have a clue regarding the OP application shaft loading? Only that the original parts were worn. (Those with specific knowledge of the lathe will know better)

Why would you need to "change the oil" in an application that is designed for Oilite bearings . There is a disconnect there, at least for me. One can always make improvements, But how many life times must a machine last?

Your motors and mine are different ;-)
I do know that I can change out the grease lubricated plane bearings at little cost and in short time. (I do have a set of adjustable electric motor reamers)

The point of changing the oil is a typical total loss cup or port on a typical bronze or oilite bearing. You put oil in and it slowly runs through. I have taken apart enough ruined machinery to know the damage caused by installing grease fittings where oil is supposed to be. If you want to run grease on your bearings instead of oil, have at it.

Tommy said:

"Re-oiling: after machining of the bearing, or following oil loss during storage, immerse in high quality mineral oil to ISO VG 60 or ISO VG 150 (SAE30 or SAE40) at 80°C to 100°C for 10 to 15 minutes and then cool in cold oil."

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If you just have the one bushing to do, plug the bottom with your thumb or palm, fill the bushing with oil, and apply pressure with your other thumb or palm until the oil weeps through the sides.

My Sheldon UM-56-B lathe (13x56) has oilite bearings installed from the factory, with grease fittings in place for lube. The lathe manual shows them as oilite, and they have inner grooves and a hole for grease to flow into. The entire underdrive is grease only. I'm rebuilding the underdrive now, and the oilite bearings are in much better shape than I thought, measuring .0015 over on ID. The needle bearings and large ball bearings ended up much worse after years and years of hard use.

I'm not saying grease is better...just saying that's how the factory built this Sheldon lathe and how it has worked well.

Does it specify grease for those fittings or have you just been using grease in oil zerks?

Mark Rand said:

Does it specify grease for those fittings or have you just been using grease in oil zerks?

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The grease fittings on the lathe in question are under a little cast iron door with the word GREASE cast into it.

--Doozer