QT-15 Turret Skipping Tools

J&H · Apr 30, 2014

We've recently bought a 1990 QT-15N T32-2, turning center and it's been running pretty good for its age. One of the issues that we've been having is that the turret skips stations when it's cold. Say its at tool 1 and you push the manual index button to go to 2, it might skip right past 2 and land at 3. It does it equally in either direction and it will also do it in auto mode while cutting a part. I've adjusted the encoder in the turret so that it is in the middle of the range where the light is on when tool 1 is up and it makes no difference. Also cleaned things up in there while I had the cover off. It is really bad when the machine is first turned on and you're setting up a job. It might skip on the first couple of parts in auto, then all of a sudden it quits doing it and runs parts just fine. Won't do it again until the machine is turned off and it sits overnight.

I'm not sure if the encoder is bad, or if it's something else. It always displays the correct tool for where the turret is. If it tries to bring up tool 8 and lands at 9, it displays tool 9 and it knows it messed up. In auto mode, it will just sit there. Sometimes it throws an error, but most of the time it just sits there and you have to shut the control off and restart it. This machine has the 12 tool turret.

I hate to throw an $800 encoder at it if it's more simply a sticky solenoid valve or relay or something.

Anyone have any thoughts? Thanks in advance.

wippin' boy · Apr 30, 2014

More likely a dirty/worn hydraulic index motor
There is a shot pin in that thing that will miss which let's it get by a station.
Do an MDI tool change first thing asking for a one station move. If it hicks and then goes all the way around and hits the second try your encoder is fine

J&H · Apr 30, 2014

I like what you're telling me. I just can't see it being the encoder. But, I don't have a clue about how to run the thing in MDI mode. I'm going to need a little direction on that...

wippin' boy · Apr 30, 2014

Just right a little manual program
Some of the older mazaks have a test mode not sure about yours
As far as how to write a manual program I'm afraid that's for the button pushers and over my head

Bobw · Apr 30, 2014

I know nothing about that vintage of machine, but for clarity sake.....

When its at Tool 1 and you press the tool change button and it skips from T1 to T3, does the machine acknowledge that its at tool 3, and not Tool 2?

Philabuster · Apr 30, 2014

J&H said:
It always displays the correct tool for where the turret is. If it tries to bring up tool 8 and lands at 9, it displays tool 9 and it knows it messed up.

Encoder is fine.

wippin' boy said:
There is a shot pin in that thing that will miss which let's it get by a station.

There's your answer ^^^.

Machine needs shot pin assembly in turret cleaned up. No $800 required, just some time and elbow grease.

mbpp · May 1, 2014

I've a similar machine and it does the same thing on initial startup in very cold weather.
I always thought it was the hydraulic oil temp being too low and that if I got a heater for the oil tank it wouldn't be an issue.
Might look into the pin next winter.

....or get a building that holds the heat !

J&H · May 1, 2014

So, where is this shot pin? Do I start by removing the face of the turret or is it something that I can get to from the backside? Are there any wearable parts that I should have on hand before digging into it?

Thanks for the replies so far.

J&H · May 1, 2014

Bobw said:
I know nothing about that vintage of machine, but for clarity sake.....

When its at Tool 1 and you press the tool change button and it skips from T1 to T3, does the machine acknowledge that its at tool 3, and not Tool 2?

Yes, if it skips tool 2, it shows that its at tool 3 like it really is. So far, this has kept it from doing anything destructive.

wippin' boy · May 1, 2014

the shot pin I'm talking about is inside the "Nippon hydraulic index motor"
I have not been inside the motor, I am parroting what I have been told by the guy at

Hydraulic components
262-549-1760
in Wisconsin
the name was joe 20 years ago but not sure now

I pulled the unit and sent it to them
it may or may not be "guy whats handy with tools" kinda repair, I'm not sure

an oil change and an inline filter might be a start
the guy told me one little piece of crud will do it

the index motor is about the size of a toaster, you get at it from the back but the turret itself has to come out also I think

csteen · May 1, 2014

In my limited experience with a qt15n with t32b control from 1993 we battled this problem off and on for years with everything from turret out of balance to proximity switches out of adjustment to encoder out of adjustment to index motor. Our machine would work for 6 months then for a week or so skip stations and hang up then work fine for another six months. New proximity switches new hydraulic pump new index motor solenoids and all because that encoder must be working cause it keeps track of where the turret really is... Just change the encoder!! problem solved.

wippin' boy · May 1, 2014

In my limited experience with a qt15n with t32b control from 1993 we battled this problem off and on for years with everything from turret out of balance to proximity switches out of adjustment to encoder out of adjustment to index motor. Our machine would work for 6 months then for a week or so skip stations and hang up then work fine for another six months. New proximity switches new hydraulic pump new index motor solenoids and all because that encoder must be working cause it keeps track of where the turret really is... Just change the encoder!! problem solved.

ok then
problem solved
i'll go back to angry birds to pass the time

J&H · May 1, 2014

wippin' boy said:
ok then
problem solved
i'll go back to angry birds to pass the time

No, no.... Problem NOT solved! Lol

J&H · May 2, 2014

wippin' boy said:
the shot pin I'm talking about is inside the "Nippon hydraulic index motor"
I have not been inside the motor, I am parroting what I have been told by the guy at

Hydraulic components
262-549-1760
in Wisconsin
the name was joe 20 years ago but not sure now

I pulled the unit and sent it to them
it may or may not be "guy whats handy with tools" kinda repair, I'm not sure

an oil change and an inline filter might be a start
the guy told me one little piece of crud will do it

the index motor is about the size of a toaster, you get at it from the back but the turret itself has to come out also I think

I think maybe changing the oil and in inline filter might be the right place to start. It certainly won't hurt anything. Any recommendation on where to come up with an inle.filter like that?

wippin' boy · May 2, 2014

> McMaster-Carr <

I just hung mine off the cable festoon/hose hangy deal right inside the big back cover
I'm no hydraulic expert but if there is some sort of flushing goo breaking product for a hydraulic system that would be good too
a five minute warm up program on an old turd like ours never hurt either
somethin' slow and steady to shake out the cobwebs in the morning

J&H · May 2, 2014

Like maybe this.

Flushing a hydraulic system with Trans Tune - Sea Foam Sales Company

wippin' boy · May 2, 2014

looks like some magic shit to me
couldn't hurt

J&H · May 12, 2014

Update

So, I dumped 2 quarts of Marvel Mystery Oil into the hydraulic oil tank. I have not changed oil or filter yet. Just added the MMO. After a few days of running, the turret all of a sudden just quit skipping tools all together. It's magically just working fine. I'm going to run it for just a bit longer, then change the hydraulic oil and filter and see if it lasts.

Thanks for all the help and please keep your fingers crossed for me!

wippin' boy · May 13, 2014

ya jinxed yourself now boy

looks like I need to dump some of that seafoam stuff in my little qt20

J&H · May 13, 2014

I ended up going with the marvel mystery oil over the seafoam. It was cheaper and more available. Looks to be about the same thing. I think the largest portion of it is just mineral spirits anyway. At this point, I think I'd suggest it for any older machine that might be having some hydraulic issues.

In fact, ever since we got the machine, we get a low hydraulic pressure error when we first start it up and that is happening less and less frequently. Like maybe that sensor was sticky and it's starting to free up a little.

QT-15 Turret Skipping Tools

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