Spindle Oil Seal Leak

[bluwolf]

I've got a Jet 8x30 mill similar to wquiles and gadgetlover. Recently I've started to get grease leaking from the the spindle oil seal. Is this something that can be replaced without disassembling the whole spindle assembly?

There appears to be a set screw at the base of the quill where it looks like a cover meets the spindle. I thought this might allow access to the seal.

I've never had to work on the spindle/head assembly and what is supposed to pass for a manual has nothing about it. Other than this leak, the head works very well. No noises or vibration.

If it matters it's a model JVM-830. But there is nothing online about this mill that I can find.

Mike

 

[precisionworks]

started to get grease leaking from the the spindle oil seal

I may be wrong, but almost no milling machine spindles have bearings running in oil. They typically have an upper bearing & a lower bearing, and the really nice machines (Bridgeport, Wells Index, etc.) use an ABEC-7 class bearing both upper & lower with adjustable preload. Less expensive mills use a conventional ABEC-1 bearing both upper & lower, without preload.

Most likely some grease has leaked from the lower bearing. I wouldn't be too concerned unless the bearing temp gets warm-hot, or the bearing sings the song of death :huh:

 

[gadget_lover]

I have a copy of the parts list. It includes an exploded diagram of the head.

I'll leave it on a web server till I remember to delete it.

http://home.earthlink.net/~dbsweb2/jet-jtm830parts.pdf

Daniel

 

[unterhausen]

my bridgeport leaks oil, I don't really think they intended for it not to leak.

 

[65535]

There shouldn't really be any large quantities of oil in any single area on a mill except in a luber. Like Barry said, nothing should be sitting in a pool of oil, lightly oiled, well everything should be lightly oiled.

 

[bluwolf]

I may be wrong, but almost no milling machine spindles have bearings running in oil. They typically have an upper bearing & a lower bearing, and the really nice machines (Bridgeport, Wells Index, etc.) use an ABEC-7 class bearing both upper & lower with adjustable preload. Less expensive mills use a conventional ABEC-1 bearing both upper & lower, without preload.

Most likely some grease has leaked from the lower bearing. I wouldn't be too concerned unless the bearing temp gets warm-hot, or the bearing sings the song of death :huh:

Sorry, I worded the subject line wrong. I should have said grease seal. The parts diagram says spindle oil seal. But you are correct, it is grease not oil. And I wouldn't be concerned except that it's enough that it slings it. I have two new shop-only shirts now.

I'm pretty sure it's to the point that I should do something before it starts to sing the song of death:shakehead

I have a copy of the parts list. It includes an exploded diagram of the head.

I'll leave it on a web server till I remember to delete it.

http://home.earthlink.net/~dbsweb2/jet-jtm830parts.pdf

Daniel

Thank you Daniel. I see yours says JTM830/Phoebus. I've got that one and the one that says JVM-830. But the parts diagrams are the same. It's part #7. Ever mess with that area on the spindle?

 

[gadget_lover]

Nope, I've not played with that area. I'm a little wary about messing it up

Dan

 

[precisionworks]

my bridgeport leaks oil,

Any machine with a pressurized oiling system will distribute the oil to all the different places in the machine (knee ways, table ways, quill housing, etc.). Once applied, there's no overflow reservoir, so it drips out or oozes out.

Some bearings run in thin oil, like the spindle bearings on a Dumore tool post grinder. At 30,000-50,000 rpm, grease is not a suitable lubricant. It does work well at most speeds under 4000 rpm, which covers most manual milling machines & lathes. Newer CNC machining centers, with spindles that run 20,000 rpm or more, use a variety of oiling systems, plus spindle temp compensation to help control the tool path.

 

[precisionworks]

it's to the point that I should do something before it starts to sing the song of death

You can approach that a couple of ways - fast, cheap & easy ... or slow, challenging & perhaps expensive 😀

If the bearing has not expelled a lot of grease, it will still run quietly & not get hot, although there are many degrees of warm that are OK. In that case, the Approved Redneck Machinist fix is to inject some type of grease using an automotive grease gun with a needle injector tip. Since you don't know the manufacturer of the bearing you can't be sure of the type of grease, but the typical ABEC-1 bearing (low precision with relatively loose fits) seems to do pretty well with automotive wheel bearing grease. If the bearing has a rubber seal, poke the needle through the seal & pump away. If it has metal shields, drill a 1/16" hole through the shield, insert needle & pump away. Drilling a hole through the shield guarantees that some metal shavings will get inside the bearing, so that is a temporary fix at best.

The correct method is to pull the spindle, remove the old bearings, and press in new bearings. This also allows upgrading to ABEC-3 bearings, which have much closer internal tolerance allowances. But it takes longer, costs more, and the machine is out of use until the job is done.

 

[bluwolf]

Thanks Barry,

As usual, good advice. My first problem is figuring out how to get at the bearing and/or seal. But also, as usual, I got more help here than I did on group dedicated to that type of mill. It would be funny if it wasn't such a shame.

Mike

 

[bluwolf]

Re: Spindle Oil Seal Leak - Update

I happened to be talking to Matt at Quality Machine. I was checking on delivery of my PM1236. I asked him if he had ever worked on the head of a similar mill.

He said he had and took the time to explain it to me. I called him 3 times at different stages of the disassembly because I was concerned about whatever it was that I was about to do next. He apologized once for not calling me right back (he called about an hour later) because he was out plowing snow so the trucks could get in to pick up machines. This was at 6:30 at night.

I ended up disassembling the quill and spindle, cleaning all the parts, re-packing the bearings, and reassembling the whole mess. It really wasn't too bad now that I look back. But it really helped to have Matt on the other end telling me it was no big deal and this is what you do next. He wasted a lot of time holding my hand. Probably 2 hours total.

So a shameless plug for Matt at Quality Machine Tool. Did I mention this was all going on over the weekend?

Mike

 

[gadget_lover]

Re: Spindle Oil Seal Leak - Update

That was awfully nice of him. He must be buttering Santa up. 🙂

So what key pointers did you get out of this? I may need to take apart my mill's head soon too.

Daniel

 

[wquiles]

+1 - that might come handy as I have never looked at my mill either, and I always wonder that preventive maintenance I should be doing before something goes boom

 

[bluwolf]

That was awfully nice of him. He must be buttering Santa up. 🙂

So what key pointers did you get out of this? I may need to take apart my mill's head soon too.

Daniel

I'm not sure what key pointers I got except that it wasn't as scary as I thought it would be. I will do it again when I have more time because I wasn't able to remove all the bearings. But I was able to deal with the pair at the bottom that was the major problem.

I'm expecting my new lathe today. So I didn't want to have to major projects going at once. I don't have the room for that much mess:laughing:

+1 - that might come handy as I have never looked at my mill either, and I always wonder that preventive maintenance I should be doing before something goes boom

I found this after the fact. It's an exploded view that is easier at least for me to understand than the drawing in the manual. It's from the Grizzly parts list of their new variable speed 8x30 that is basically the same as ours. When you look at it you realize there aren't that many parts involved.

http://www.grizzly.com/products/G0678/parts/2

Also the bearings on the bottom of the spindle are not press on. Yes, I know, doesn't sound impressive. But Matt said they weren't and he was right.

The other thing is that it was good to take it apart because all the parts involving the fine downfeed and the drill press handle downfeed looked as if they had never had any grease or oil on them and some had started to surface rust. So they needed to be cleaned and lubed. It all has a much nicer, tighter, smoother feel to it now.

Mike