Lube for vertical spindle bearings

[Pete O]

One of the jobs I have been wanting to do for ages is to renew the spindle bearings in the vertical attachment of my Victoria U2 mill. Whenever I have used it, the bearings have run quite hot and the grease has oozed down the outside of the spindle and sprayed everywhere plus dripped onto the work. I dismantled it last week and ordered new bearings, picked them up yesterday and began reassembling.
There is no actual seal at the bottom end of the spindle, just what appears to be an O-ring groove enabling an O-ring to run on the rotating spindle, this seems all wrong to me but it's the only thing I can figure the groove is for.
Here's the spindle sitting in the housing as viewed from below without the lower cover. The shiny surface is where the O-ring will run.

  spindle lower bearing.jpg (Size: 22.66 KB / Downloads: 81)
This is the lower cover, I have fitted an O-ring into the groove.
   
The lower cover in place with the spindle out of the way.
   
I would love to be able to machine the cover out to take a proper lipped seal but this photo shows how there is not sufficient wall thickness on one side to do that.
   
The housing has a grease (or oil) nipple for each bearing.
   

I pulled this vertical attachment apart and cleaned out the ancient grease when I first got the machine, I repacked it with wheel bearing grease and installed an O-ring that I had in stock, the O-ring was a bit of a loose fit. I knew that the bearings were not in great condition but decided to see how they went. As mentioned, grease has just run right out of the thing whenever it got warm. Hopefully the new bearings will run at a cooler temperature, also I have sourced an O-ring that is a more snug fit. I have been trying to source some NGLI 3 grease to pack the thing with so that it has less tendency to drip out but have so far been unable to find it in less than 20kg.
I'm very uncomfortable with the idea of an O-ring as a seal on a rotating shaft, just can't see that it will work. I'm open to suggestions on how to solve this problem, I'd like to keep the vertical attachment in place most of the time now that I have the power Z-axis feed working.

[Mayhem]

Have a chat to your local bearing supplier. When I did my Kondia, I was lucky enough to chat to a guy in QLD who use to be a service tech for them. He advised me to get a tube of appropriate lube from the bearing supplier, specific to the task (comes in a little toothpaste tube). He also told me to not to put any more lube in than 30% of the capacity of the bearing. The reason he gave was that excessive lube actually causes increased temperatures and premature failure.

It wouldn't hurt to have a chat to the people that you get the bearings from, as you will have to buy decent bearings (otherwise you'll end up with a cheap drill press!).

[f350ca]

I agree with Darren, find the correct lube, it may only call for a heavy oil. Wheel bearing grease may me too heavy and have fillers that aren't compatible with the speed the spindle runs at. A truck wheel only turns at 4 or 500 rpm (if faster warning lights show in your mirrors) your spindle I would guess is a few thousand. Over packing the bearings can cause the rollers to slide rather than roll.
My vertical mill has no lower seals either, guessing its  to let the oil circulate out as you relube  and would be a problem with cuttings getting under the lip.

[Pete O]

That's good info, thankyou. I was considering making a housing to hold a seal at the bottom end of the spindle but I'll see what I can find out from Timken before I go any further. The maximum speed of the spindle is about 1400 rpm, not particularly fast but I hadn't considered that it is much faster than wheel bearings typically run. I have a manual for the mill but it shows a different vertical attachment to what I have (it shows the type with a quill). It specifies a #3 grease for the vertical spindle bearings with 2-3 shots monthly only. Interestingly it calls the lube points on the vertical spindle "grease nipples" whereas every other lube point on the machine is referred to as an "oil nipple".

[Mayhem]

(03-02-2017, 05:07 PM)Pete O Wrote: ...It specifies a #3 grease for the vertical spindle bearings with 2-3 shots monthly only. Interestingly it calls the lube points on the vertical spindle "grease nipples" whereas every other lube point on the machine is referred to as an "oil nipple".

That is correct - grease into the grease nipple and oil into the oil nipples. The problems begin when people squeeze grease into both

The Americans call them zerks, as nipples are obviously too raunchy for them

[Pete O]

I made an enquiry via the Timken website tech support email proforma, will see whether they respond. I find most of those things seem to be perpetually ignored, here's hoping they might be an exception.