# Spindle Goop



## NegativeK (Feb 19, 2021)

I was working on a mini pallet, and this just happened:



It's goop from the spindle of some kind. The machine is pretty new to me, and I've been adding spindle oil every time I've used it. Sometimes I get some extra drips, letting me know that I've added a little extra -- but this was like a dam burst, right in the middle of me countersinking a bunch of holes that I'd just drilled. The consistency is something similar to way oil. Definitely thicker than the spindle oil I've been using.

It's an Acra 2S (step pulley). Overall, the machine's in _really_ good shape.

Any thoughts? I'm getting some advice to pull the spindle just for inspection, which doesn't sound like too terrible of a weekend.


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## Cadillac (Feb 19, 2021)

How new to you? Did the previous owner have sealed bearings installed which would be greased once. No lube in spindle oil port. Would lead to liquefying the grease and getting something similitude to that?


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## NegativeK (Feb 19, 2021)

I've had it a few weeks. Since I'm a hobbyist just starting to set up a garage shop, it hasn't seen heavy use from me.

Previous owner had it in an auto shop, unused for at least a few years. I wasn't able to get detailed service history, so grease could definitely have happened but is still a question mark.


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## Cadillac (Feb 19, 2021)

Pop the spindle it will be obvious. Grease or not.


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## markba633csi (Feb 20, 2021)

Looks like some water mixed in there too-?  Yucko
-M


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## HD Bee (Feb 20, 2021)

It looks like it was greased and the oil thinned it out.
White lithium mixed with spindle oil
Just like a grease gun that leaks In the hot sun.

Older BPs had zerk fittings for the ways. They where for a oil gun. Some knuckleheads put grease instead.


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## NegativeK (Feb 20, 2021)

Well there's your (my) problem.




I'm a little concerned about what to do with the top sealed bearing, so I'll be doing research today. Starting with if sealed bearings keep out future oilings..


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## hman (Feb 20, 2021)

My gawd ... that's some groaty looking stuff ... and a very strange color!


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## Ken226 (Feb 20, 2021)

Usually that chocolate milk looking color indicates some water mixed with oil. 

I'm with @HD Bee   probably oil churned up really good with that grease. 


It didn't spend any time out in the rain did it?


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## Aukai (Feb 21, 2021)

Trying to quiet it down for sale maybe?


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## Canus (Feb 21, 2021)

Is this mess coming from the bearing shown or from above it?


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## Lo-Fi (Feb 21, 2021)

Ewww. It should not be a sealed bearing up there. The oilers are set up to wick onto a felt washer, which then drip feeds the top bearing and spindle bearings as the oil runs down. Pull the top of the head off and have a good look in there too, it could well be full of nasty schmoo. I doubt it's done much damage, though it's worth assessing whether the spindle bearings are holding up ok with lack of lube. If the shim tube between the outer races can be moved sideways easily, they're toast.


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## Cadillac (Feb 21, 2021)

Running grease through a bearing designed for oil just changed the tolerance of that bearing.


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## Lo-Fi (Feb 21, 2021)

Problem with running grease is there's no way to replenish it or run sealed bearings of the correct type in the Bridgeport spindle. I suspect the emulsion is due to condensation mixing in. That sealed bearing has created quite the trap.


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## Ken226 (Feb 21, 2021)

Those sealed bearings are designed for grease, but only for the grease that comes pre-packed inside the seal.  Not that red stuff everywhere.

As Lo-Fi pointed out,  there shouldn't be sealed bearings in there.

Milling machines of that type typically come with tapered roller bearings, or sometimes angular contact bearings.

Which begs the question, what type of bearings are those?  Because the performance of a milling machine can be severely diminished by poor bearing selection. 

If someone who had no idea what he was doing, replaced them with whatever was cheapest from Amazon, it would make for some pretty bad spindle performance.

The cheapest bearings available are typically p0 precision, c3 clearance deep groove radial ball bearings.  Designed for radial loads only, and with "extra" clearance built into the rollers.   Not good for the axial loads drilling produces.  Not good for anything else spindle related either.

The OP should replace those with some P5 tapered rollers or Angular Contact bearings ASAP.


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## Ken226 (Feb 21, 2021)

Your Acra 2s appears to be the same basic machine as the Grizzly G0796.  It has the same "M" on the column casting as the original Bridgeport model they copied,  the same dual drains in the base casting, and lots of other indicators.

The grizzly manual shows it to use the common 7207 (35mmx72x17mm)  angular contact bearing for both the upper and lower.  the pulley carrier takes the 6206zz deep groove shielded radial bearing.

The cheapo sealed radial bearings in that 35x72x17 size are 6207.   I wonder what the chances are, when you clean the grease off, those bearings say "6207-2rs c3" or similar

When you replace those, look for 7207 bearings with a 20ish degree contact angle and P5-P4 precision (abec5 to abec9) depending on your budget.


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## NegativeK (Feb 21, 2021)

Okay, I've gotten some clarity on what's going on and what I'm going to do next. Brace for wall of text.

Re. the state of the machine, I'm in Vegas -- so no condensation or rain. The machine's also in very, very good condition otherwise. No detectable wear in the lead screw, and the two gibs I pulled looked like the scraping was untouched. I'm pretty certain the seller didn't bone me and the machine was very occasionally used -- just dirty from being in an auto shop.

For the bearings, they're NTN 7207C and NSK 6206V. I actually got a thumbs up from Tom Lipton on Acras (he has the variable speed model and has worked with other models,) so I'm not too concerned about being cheaped out by the builder. More importantly, the runout I measured before the spindle gooping was in the low tenths. And even if it's worse when under load, I'm going to keep using the ones I have until I'm unhappy with them, and then I'll just order from H&W. I'm hoping to avoid spending that money, but I'm comfortable installing them if necessary.

As for the plan going forward.. I've finally pieced together the puzzle. The upper bearing is shielded, and the lower bearings definitely had some grease in them -- so the assembler (I don't think it was anyone else; the nose cap had the set screw in the only drilled spot on the threads) went with grease, not oil. This also explains why the spindle oiling cup that's mentioned in the manual was replaced with a grease zerk, and the grease zerk explains the Nutella that's all over the top bearing. The oil that's visible is likely from me adding more than I should, in hopes that I'd flush out any tire dust that had accumulated.

So given all of that blather, I'm going to clean clean clean, repack the bearings, clean the inside of the quill, and be a lot more gentle with the two remaining oil spots. I also figure I'll need to pull apart the top housing and degunk what's in there, but that's for future me to deal with. I'm not super thrilled about pulling the motor off without help.


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## Aukai (Feb 21, 2021)

Great report


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## Ken226 (Feb 21, 2021)

That's good info.  Im glad to hear there are no major issues.


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## NegativeK (Feb 24, 2021)

We're back!






The grease arrived today, all the bearings are packed, and reassembly went smoothly. Runout in the taper is at 0.0003", which is maybe a tenth or two more than what it was. Maybe some day I'll regrind the taper, but I really don't feel the need now.

I'm somewhat proud of fixing the problem in only a few days, but really I'm just happy that I didn't make things notably worse.


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## Aukai (Feb 24, 2021)

Good job


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## NegativeK (Feb 24, 2021)

Some last minute info in case other Acra 2S owners stumble here for info:

I posted the bearing info above, but you'll see that when you pull everything apart. I leaned heavily on 



 for the info -- the process is absolutely identical, with the exception that the lock washer was already pleasantly prebent. I also used Mobilgrease 28, based on a comment on Practical Machinist -- someoone had gotten advice from H&W on what they recommend.

Also, take everything I said with a grain of salt. I'm no pro. 

Thanks for all the comments and suggestions, everyone!


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## Norseman C.B. (Feb 24, 2021)

The vids from H&W were the greatest help when I went through the rescue/cleanup of my new to me
 Acra mill last fall,  ( My new shop baby in the Bridgeport & clones section ).
Unfortunately I will be needing to replace either the motor bearings or the upper spindle bearings
soon as one or the other set has started to make noise when its cold in the shop.
Hoping it isn't both, but with my luck ...........


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## Lo-Fi (Feb 24, 2021)

It's not unlikely to be the pulley bearings. Mine were worn enough to release the preload and were quite noisy. The motor bearings are probably fine.


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