Re: [CAD_CAM_EDM_DRO] More Info: Re: How do I stop a lubrication leak through a bearing?

washcomp wrote:

>Long story below, but problem is my Bridgeport (unique setup done by
>original re-fitters) uses an oil resevoir at the crossnut. It is
>designed so that the oil leaves it and follows the screws inside the
>bellows. It is leaking out at the micrometer dial. I took another
>look at the problem this morning. There are two potential leakage
>points. The first is they used a cloth covered rubber bellows over
>the shaft held to a flange on the casting (where the shaft leaves the
>table) with a "Jesus" clip. It sounds like that should be a pretty
>good seal (but I'm willing to be corrected). They then depend on a
>sealed ball bearing where the screw goes through the casting for
>their main seal to keep the lubricant in the system. I'm pretty sure
>that's where it's leaking.
>
>It may be leaking through the center where the shaft penetrates or
>around the edge of the bearing or through the seal plate of the
>bearing. Are these supposed to be a liquid tight barrier?
>

Generally, no. The only place I know of where bearing seals are used
to seal outside liquids are differential axle bearings.

My guess is that this system is so tight that air is being trapped in the
bellows and building up pressure when the screw spins through the nut,
and the bellows is collapsed like an accordion. You may need to put
some vents at the top of the bellows at each end. You could put cloth
over the vent to prevent chips from getting in.

> If so (or
>not), do "O" rings or trying to put sealant around the edge of the
>bearing or where the shaft penetrates it make sense? If so, what do
>you recommend that will hold up against the lubricant, but be
>removable if I have to take off the table or replace the bearing?
>
>I like the idea of the oil reservoir, but if it's going to leak like
>a sieve, I'll have to use the oil drip method onto the screw. If I
>use the drip, where should I place the spout in relation to the two
>axis?
>
>

I really don't think it is necessary to have big pools of oil in the
machine.
A few drops of oil every day should keep the screw lubricated. Big pools
can get contaminated with coolant and cause a major problem, too.

Jon