Thread: Inserting a grease line into a set of bearings

Hi Bob, would you be better of trying to get bearings that are sealed on one side so that the grease will get in, as I think the seals will possibly prevent the grease from getting in effectively. Get in touch with a bearing place for their recommendation.
In regards to the vertical hole, I would do it on the flat, as it would be a lot easier to start.
Regards
Kryn

Originally Posted by KBs PensNmore

Hi Bob, would you be better of trying to get bearings that are sealed on one side so that the grease will get in, as I think the seals will possibly prevent the grease from getting in effectively. Get in touch with a bearing place for their recommendation.

I though with bearings that were greased via a grease duct the bearings should be open on both sides so that the fresh grease would flus the dirty grease away?a

In regards to the vertical hole, I would do it on the flat, as it would be a lot easier to start.

Thanks

Originally Posted by BobL

I though with bearings that were greased via a grease duct the bearings should be open on both sides so that the fresh grease would flus the dirty grease away?a


Thanks

Hi Bob,
Sorry I didn't realise that the bearings you were talking about were of that type. In a pillow block bearing, the bearings have seals on both sides that allow the grease out, not in. These bearings have a small hole/s that line up with a groove in the housing, that allow the grease to travel around into the hole. I am talking about the self aligning bearings that have a curve to allow for self alignment.
Kryn

Originally Posted by KBs PensNmore

Hi Bob,
Sorry I didn't realise that the bearings you were talking about were of that type. In a pillow block bearing, the bearings have seals on both sides that allow the grease out, not in. These bearings have a small hole/s that line up with a groove in the housing, that allow the grease to travel around into the hole. I am talking about the self aligning bearings that have a curve to allow for self alignment.
Kryn

OK I know what you mean.

Both bearings should have a single grease shield fitted to the outer faces, this is to retain the grease and reduce the water ingress. There is no need for an escape route for B2. Give them a SMALL shot of grease before and after using the mill.

The biggest problem you'll have is preventing the grease shield from being forced out by hydraulic action, hence the SMALL shot only.

Is it possible to fit lip seals outboard of the bearings instead? It seems the biggest problem is water getting in, if you can fit a suplimentary seal here you can run normal sealed bearings. This is the normal way to protect bearings that can be submerged in use.

Hi Bob,
could you drill a small hole down the centre of the 1/2" bolt then another at right angles to feed the grease between the two bearings.
A grease nipple could then be put into the end of the bolt.

Phil

Thanks for all the feedback fellas - much appreciated .

Originally Posted by Steamwhisperer

Hi Bob,
could you drill a small hole down the centre of the 1/2" bolt then another at right angles to feed the grease between the two bearings.
A grease nipple could then be put into the end of the bolt. l

I like this because if I bugger it up I can just buy a new bolt and start again.
I'm going to give this one a go.

The trick will be to use a small enough hole not to weaken the bolt but large enough so I don'''t have to drill a long hole with a small bit in tensile steel.
The hole will need to be, bolt head depth +15mm to get past down to the start of B2 +10mm to get past B2 so at ~ 35 mm long.
How about a 3 mm hole?

QUOTE=Chief Tiff;1865239]Both bearings should have a single grease shield fitted to the outer faces, this is to retain the grease and reduce the water ingress. There is no need for an escape route for B2.[/QUOTE]
So how will the old grease get out?

Give them a SMALL shot of grease before and after using the mill.

The advice from one of the best sawmill manufacturers is to grease these bearings every 4 hours of use.

The biggest problem you'll have is preventing the grease shield from being forced out by hydraulic action, hence the SMALL shot only.

I was considering not using any grease shields at all so the grease could flush out the old grease.
Should I leave the outwards facing grease shield on B1 and just drill some small holes in it?

Is it possible to fit lip seals outboard of the bearings instead? It seems the biggest problem is water getting in, if you can fit a suplimentary seal here you can run normal sealed bearings. This is the normal way to protect bearings that can be submerged in use.

The problem is not just water as sawdust can be incredibly fine like clay, and there is a heap of it so it seems to find its way in there.
The previous bearings were sealed but were full of dirty grease and the outer ones were seized.
I will take a look at extra sealing but I will be more comfortable with an easily greaseable system

Lots of work. What about using bearings with two lip seals (suffix RS for Rubber Seal, greased for life) as inside bearing. And ZZ bearings with shields on the outside. The ZZ you could grease with a cheap tool that looks on one side like a syringe needle, on the other side it has a grease nipple:
grease-syringe.jpg

Following Bills suggestion, how does this look?
The blue spacer/stand off allows the bolt to remain fixed, this was not shown in the previous diagrams

I was going to us a (orange line) spacer between the bearings but then the grease won't be able to get to the bearings.
If I move it to the green lines will that be OK or will the side loads be too high?
.

Should I drill the hole right through the bolt at the grease cavity?

Originally Posted by cba_melbourne

Lots of work. What about using bearings with two lip seals (suffix RS for Rubber Seal, greased for life) as inside bearing. And ZZ bearings with shields on the outside. The ZZ you could grease with a cheap tool that looks on one side like a syringe needle, on the other side it has a grease nipple:

Thanks for that suggestion but access to the outside bearing is significantly restricted by the mill frame.

There is a gap of about 10 mm (see recent drawing) between the mill frame and the bearing which fills with muddy sawdust (i.e. outer bearing swims in this stuff) but it would still be very difficult to get any sort of syringe into the gap. I could drill holes in the mill frame for better access but they would block up quick smart and then I'd have to clear the crud and thread the syringe through every time I wanted to apply grease

It may be more work initially but Bill's grease though the bolt solution appears to be the easiest to service in the long term.

Hi Bob,

Why not keep three bearings and go with option C?

Stuart

p.s. how do you stop the bearing becoming 100% fill?

Originally Posted by Stustoys

Hi Bob,
Why not keep three bearings and go with option C?

Another good idea worthy of consideration - I'm I didn't see that option - another reason why these forums

One reason I like the idea of applying the grease through the bolt is that if I break a bit in the bolt I chuck the whole bolt and bit out, if I break it in the roller - err....... another hole?
Also the hole in the bolt can be done easily on the lathe, and it maintains roller balance.
At 7000 rpm balance might be significant - I dunno maybe someone with more experience can comment on this?
A way around balance issues might be to install two diametrically opposite nipples on each roller - more chances for bit breakage?

p.s. how do you stop the bearing becoming 100% fill?

Just like all filled greased bearings prevent themselves from becoming 100% fill.

One thing for sure is the bearings don't get hot as there is water spraying everywhere over the blade and roller.

Given that they are guide rollers, does the bolt need to be high tensile or will something like an 8.8 do?

Michael

(Psst - it was Phil not Bill)

Hi Bob,

The suggestions I made were based on the idea of deliberately keeping contaminants out of the bearings, not regularly replenishing the lubricant. The grease in sealed ball bearings will last for years; I've known massive electric motors that have run practically flat out for over twenty years on their original sealed bearings. With that in mind your B2 bearing would be protected from water/dirt ingress simply by its position inside the pulley and the small shot of grease at the start and finish of work is more about flushing crap out and not relubricating.

I'm kicking myself for not spotting the ideal grease path is through the shaft/bolt but I'm going to console myself with the excuse that you failed to include it in the sketch!

Sticking with the two bearing idea you have to keep the spacer between the inner races, seeing as you have a lathe you can knock up a lantern ring really easily that will provide the path for lubrication and act as the spacer.

Now that you have stated your priority is to flush grease and contaminants out regularly why not take it one step further and fit an auto greaser? Instead of a grease nipple screwed into the bolt screw on a greaser; low tech would be a Stauffer cap where you just give the cap a turn every so often, or fit a spring loaded Stauffer that you just charge with a grease gun at the start, thus providing a constant trickle of grease. Top of the range would be an SKF lubricator which uses a tiny battery operated gas generator to constantly pressurize the greaser and provide constant lubrication feed. These have an adjustable flow rate and can be switched on and off so you're not greasing stopped machinery if you don't need to.