Thread: Bearing Headstock

Originally Posted by Auskart

What are peoples thoughts on using High Temperature Wheel Bearing Grease in the headstock bearings.

I was using it in the Sheraton but, I noticed that the grease makes the spindle drag ... it doesn't harm the bearings but the spindle takes more power to achieve its rpm compared to using oil .. I found that thin oil just runs out and goes all over everything , a mess . I compromised and use a thicker oil and it seems to work fine .


Mike

I suppose at the time when Hercus made the roller bearing headstock grease must of been dearer than oil.
All though grease nipples would of been cheaper than there oil pots.
With your oil running out and going over everything on the Sheraton you may need to change the bearing seals.

Originally Posted by pipeclay

With your oil running out and going over everything on the Sheraton you may need to change the bearing seals.

So are the tapered roller bearings on a Hercus supposed to have a seal or some sort of gasket, if so where?

Behind the end covers.

Thanks, are they gaskets , seals or O Rings ?

Originally Posted by Auskart

Thanks, are they gaskets , seals or O Rings ?

On the Hercus 260 there are only some centrifugal grooves to prevent the entry of metal dust ot small chips. But the bearings do not have seals as such.

It is a "total loss" oil lubrication system. You keep adding fresh clean spindle oil to the oil ports. There is a small volume reservoir or basin at the bottom of each bearing. When the spindle rotates, the rollers dip into the bottom basin and swirl the oil into the outer race, so no oil will flow out of the bearing as long as it is running. When the spindle is stopped, oil flows back to the basin and fills it. If there is too much oil in the bearing (when you fill it), it simply flows to waste past the centrifugal sealing grooves in the flanges. Too much oil would cause excessive friction and heat, the design described above ensures there can never be too much oil. It is a simplified version of what can see here on page 57:
igor.chudov.com/manuals/Timken-Bearings-Catalog.pdf

Why not grease, like in a car wheel? In a lathe spindle, the taper roller bearings must bee much more heavily preloaded. This is necessary to increase rigidity to avoid chatter and other problems. You can use grease, but you must be careful not to overfill the bearing. No more than about 1/3 of the total free volume inside the assembled bearing should be grease. Otherwise the bearing overheats in use, melting the oil out of the grease leaving useless gunk behind, then the rollin surfaces are quickly scored and the bearing is irreversibly degraded. There are smaller hobbylathes that use grease to lube taper roller spindles - filled for life or a few thousand running hours. Industrial grade lathes with roller bearings use oil (oil bath in geared head lathes, and total loss lubrication in smaller belt driven models). Chris

Thanks Chris, mine is a 9" are there any sort of seals or gaskets that need to be replaced in it.

Thanks Shane.

Hi Shane,

I've currently got my 9" atm in bits, there are no seals or gaskets. If you want to have a quick look, remove the chuck and then the spindle bearing cover plate which is held on by 4 socket head screws, you are straight into the bearing, no seals etc.

I would tend to go with light oil lubrication, the higher preload required may mean that grease could cause overheating. If you want to go with grease then I would buy some high speed spindle grease, most bearing shops supply it in a small tube a bit smaller than a toothpaste tube.

Shane,
You didn't say why you are considering grease. Do you have a problem with oil leakage? If so, maybe you are using too much oil, or it's too thin.
Chris

Hi Chris, it was just a question out of curiosity, I just aquired a bearing head and was wondering what people were using.

hi mate. interesting idea but I think the first choice for lubricating roller bearings should be oil.
oil. When present lubricates better than grease. the only advantage with grease is i think i would be longer before you have to replenish the supply to the bearing.
the thought of having wheel bearing grease oozing out of the head stock on my little hercus is just all wrong. besides that . i like oiling my lathe.

> interesting idea but I think the first choice for lubricating roller bearings should be oil.

Not only hobbylathes with cheap standard quality roller bearings use grease. There are also expensive industrial lathes that use grease to lubricate highest precision class spindle rolling bearings.

> oil. When present lubricates better than grease.

"when present" is the magic word. Grease is OIL with a thickener, to make it stick to where plain oil would not "be present" for long.

And also consider that synthetic oil, as used for high speed spindle grease, may in itself even be a better lubricant than plain mineral oil. Oils ain't oils...


The best recommendation is: stick to the lubraction system that the particular lathe at hand was designed for. Because it is not as easy as it seems to successfully convert from one to the other. Chris