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Mazak QT15 Turrent Removal

Pete Deal

Stainless
Joined
Apr 10, 2007
Location
Morgantown, WV
I need to allign my turret. I am tired of having little nibs in the middle when facing off. I have read as many posts as I can find on here. I tried to put a big bar in and still can't get it to center (after loosening the curvic coupling bolts). I took one of the plugs out of the front of the turret and it appears to have the pins in the curvic coupling so I figured I would remove those and then try. How to get the big black oxide nut off the center shaft? I took all the bolts out of the ring around it and unclamped the turret and still can't get it to move with tools at hand. Make a spanner wrench?

 
I have not done a QT15, but I assume it like other Mazaks.

The screws you took out of the ring are a type of wedge/cone arrangement. The purpose of that is to allow the turret to move relative to the splines behind that black nut. It should not have to be adjusted if the turret was indexing properly. I think you can put those screws back in.

You need to get that nut off. It looks like it's split. You took the screws out that lock it by pinching the split. That's fine.

If you don't have the right spanner wrench, you can use the maintenance man's trick, the hammer and punch. It would be easier to get the nut off with the turret unclamped but it should work like it is. Once the nut is off you should be able to pull the turret.

Once you get it off you can knock out the pin in the curvic coupling and then you should be able to knock it back into alignment. Just a warning, getting that spline back on is a real bitch.
 
you have to be either unclamped or power down. you can use the slotted spit to pound the the nut loose with a drift or chisel.
 
The curvic coupling bolts are located in the face of the turret inside the stick tooling pockets. It does not look like you touched those bolts yet.

That's correct I have not touched them this time around. I did try to center the turret some time ago by loosening them though, putting a big bar in a pocket, and lifting up on it with power off and was not able to get it to move. My plan this time is to just take the whole thing off, do some cleaning, etc and take the pins out while it is off.
 
Loosen the bolt that pinches the center nut. Using the soft key on your controller, unclamp the turret. Loosen the center nut about a turn, then using your soft key, clamp the turret. This should pop it loose and allow you to remove it once you remove the center nut. Taper pins hold the curvic coupling in place. They have a tapped hole on the end to facilitate their removal with a slide hammer. Chances are that they are bent and their respective holes are damaged. Toss them and don't worry about replacing. Loosen the bolts connecting the curvic coupling to the turret. Now, gently beat the shit out of the turret until it is centered. We usually use a coaxial indicator and a boring bar holder mounted on the turret to check for center.
 
Thank you all. I made a wrench so I would not have to beat on the nut. Worked pretty well. I opted to take the whole thing off to look it over and clean it all up. Looked pretty good I think. I took the curvic coupling off the turret and cleaned everything out. I was afraid if I put it back together without doing this maybe it would have been rusted in place. I sprayed it with open gear lube before bolting the coupling back to the back of the turret.



 
While you've got the turret off, I would replace the seals on the brass coolant plunger.

The QT15's, and several other 80's/90's Mazak lathes have the coolant plunger inside the turret casting, and it can only be accessed by removing the turret tool plate like you've done. What a pain when the o-rings around the plunger start to leak!

Later Mazaks had the plunger in a separate black box that you could unbolt from the front of the turret box, making it an easy job to change the coolant seals.

Actually I've machined some improved coolant plungers, whose sliding seal is internal to the body of the plunger. This design eliminates the Mazak design of trying to seal the sliding plunger inside the hole in the cast iron turret body itself.

The stainless body is secured inside the turret housing with a set screw, while the brass plunger has 2 polyurethane o-rings that seal inside the stainless body.

Notice the Mazak plunger on be right, with the o-ring groove near the bottom - that is all that seals the sliding plunger from leaking coolant.

a56a0f36a6b5c48353ec07af2d0f7bd4.jpg



ToolCat Greg
 
Well that's good information thanks for that. I went out there and looked at it. How does that plunger come out? I can only see the end of it. Also, While I have things apart I am going to take the way covers off and look things over. They at least need new seals.
 
Pete, the coolant plunger is held in place by a set screw seen from the front of the machine. There could be a second set screw under the first, so make sure you can see the brass plunger through the hole before trying to remove.

Once the set screw(s) is out, the plunger should slide out easily. Sometimes it can be tricky to get out, use some penetrating fluid if necessary.

You can gently tap the plunger in a little deeper to help get it moving too.

Worst case I've had to use vice grips to grab the end and work it out.

There is a spring behind the plunger that will come out as well.

The main sliding seal is a metric "U-cup" type, and thus may be difficult to source anywhere but Mazak

I made a couple extra of my custom plungers, PM if you're interested.


ToolCat Greg
 
Well Greg I took the set screw out but can't get the thing to move. I can see the brass 'v' where the screw seats so I know there is not another screw. I put channel locks and even vise grips on it, tapped it backwards won't budge. The face moves back in but the body won't. I could maybe tap the thing and make a little puller but that would probably trash it. What did you do to replace that face seal where it mates with the tool plate? That looks like it would have to be a mazak part.
 
Mazak has the face seals. They are made from a hard rubber-plastic type material. You could make your own if you have a workable material.

Those plungers are hell to get out. If it wasn't leaking very much, you could just leave it alone, because yes, getting them out will trash them pretty bad. You can see in my photo above the vice grip marks I made on the plunger trying to get it out. It was trashed afterwards, as the end was out of round.


ToolCat Greg
 
your right.
a tap job on center hole (seems like maybe 3/8-16 works) then a slide hammer pops it right out
 
Fast forward 3-1/2 years-

My turret coolant became a trickle. I took the pipe plug off on the front of the turret and had lots of coolant there but practically none at the tools. Took it all apart thinking it was the plunger seal. We found a good way to remove this plunger assy. without damaging it is to remove the face seal and tap the brass piece 3/8-16 (hole diameter is about .317"). Use this to pull the plunger. Worked very well because we could not get it to budge without doing this. And no did not need to tear it up getting it out.

Our problem turned out to be that the passage up to the plunger seal was plugged up with crap. It's all cleaned up. New seals are on order from Mazak so we won't be reassembling for a few days. The face seal was about $6 and the little hydraulic V seal was about $6 too.
 
Dragging up an old thread here i know, but i am trying to re align my turret but it will not budge!

Are the taper pins (if it has them) only visible once you remove the entire turret from the machine?

I thought they might be behind the 2 big grub screws but there is nothing behind mine

Thanks
Marc
 
Hi

It turned out mine didnt have them fitted anyway and but if they were they should of been behind the 2 large grub screws and could of been removed with a threaded slide hammer tool

Thanks
Marc
 
yeah my recollection was they changed up somewhere during the t2 years
I had qt8's that were both ways
the particulars start to blur after 20 years
i left them out for years
then went back to replacing them after a big pissin' match with an application guy about "lost rigidity"
fine by me i wasn't paying for the turn around time on a wreck

everything works if you let it
 








 
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