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Mori Seiki MV55 gearbox blowing oil mist?

ferrretcatcher

Aluminum
Joined
Feb 27, 2019
I just bought a 1986 Mori Seiki MV55 VMC. It runs great but there is a oil mist almost like smoke coming out from under the tool changer cylinder. It is also coming out from under the front cover where a brass elbow vent is located too. Wondering if anybody has seen this happen before? And is there a way to correct it? I have the pressure intensifier and the drawbar cylinder taken off and I'm down to the top of the gearbox. I'm assuming the spindle is all below the gearbox? And the top of the gearbox is not tied into the spindle? I have some manuals for the machine and they show the spindle-gearbox assembly but I see no seal up above the gears in the parts manual. Having trouble with the top gearbox nut too, I put spanner wrenches on it and it didn't move at all. I have taken the set screws loose and there's copper pushers under them to not damage the threads that might be seizing it up? It's been a while since I've torn apart anything this precision.
 

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I've never been in any of my MV's that far, but I have had the oil mist problem.

My MV45 drips from the top of the headstock if I fill the sump to the full mark. When it's low it's fine, no leaks. It's a different design that the 55/65 headstocks though.

My MV65B would spray a lot of mist when I first got it. She was pretty rough when I got her and I didn't want to waste time/money if she was a dud so I ran her pretty hard for a few jobs and the oil misting just stopped after a few weeks. She was blowing oil mist out of all over like a vent was clogged, but I never found it. Also would drip through the center of the spindle.

I find these machines are happiest with rapids at 100%, RPM about 500 below max and 100% spindle load. Run them there all day and worry about where to put all the chips. Take it easy on them or let them sit and they get cranky.
 
That's a bummer cause mine's going to sit a lot. I don't do a lot of machining, mostly heavy equipment repairs and welding. I need a mill though for the occasional odd equipment repairs though.

I got to tearing into it tonight. The big nut on top had some hammer chisel marks on it so I figured I couldn't do much more damage to it. It came loose with a few chisel hits. I worked my way down through the nuts and pulled up the large washer like thingy to find out its a sleeve washer seal thingy. The outer large stationary ring with 4 bolts holding it down is a mirror like image of the washer seal thingy that seals with a oil ring arrangement. Oil gets pumped up into the stationary ring between them and I'm guessing makes a liquid oil ring seal. In one picture the 2 set screws plug the outer end of the oil passages. I think it's just dirty and maybe I need a oil change or flush. Going to blow out the passages too to see if there's an obstruction of oil flow. Oil gets pumped up there to lube the top gearbox bearing also. Hopefully this helps someone in the future.
 

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Another update, Got it all back together and it was a real pain. The tool clamp pressure intensifier was awful! I got everything back together and couldn't get the drawbar to activate. Low pressure on the intensifier. Tried bleeding per the manual instructions and every other way I could think of for 2 days to no avail. Finally got pissed and hooked the porta power up to the very top bleeder and pressurized it till the drawbar was released and the cylinder was down. Left it unclamped and reassembled it all and that all works great now. Fired it back up and it was still doing the oil mist thing so I was bummed about that. Decided to drain the chiller oil tank and only mud came out. Pulled the tank which was a real pain, and found about 2 inches of crud in the bottom of the tank. Spent a few days cleaning and fixing the hole under the mud in the tank. Refilled the tank with about 10 gallons of ISO32 and it took care of the mist problem. Now the machine works great and have made a few parts on it so far. Next will be to clean the tool changer as I have a issue with a few pots. It's a great machine, just hasn't been deep cleaned in a decade.
 








 
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