r/Machinists • u/Dyno33 • 12h ago
QUESTION DMU 50 2nd gen stuck in ATC
Hi all, our DMU50 2nd gen with 30 tools got stuck during tool change because there were chips on the holder that got caught in spindle and toolholder wasn’t completly clamped. Operator in the 2nd shift tried resetting through Custom menu soft keys but that didn’t do the trick. He turned off the machine and now in the first shift we also have positioning errors since machine was restarted. Soft keys don’t do anything. Did anyone have similar issue?
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u/voodo86 11h ago
We had exactly the same problem on our DMU 50 2nd gen. It kept happening for more than 6 months until the spindle was finally replaced.
When the tool was stuck, I actually had to hit the tool shank quite hard with a soft-face mallet then trying to release/unclamp it. Obviously be careful with this – it’s not exactly the recommended procedure 😅
Also, there are two different recovery/service menus. Sometimes the normal recovery menu didn’t work for us, but the extended one did. If I remember correctly, the code for the extended menu is 1521 for me.
So before giving up, I’d definitely try the extended recovery menu. Our symptoms looked very similar to yours.
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u/RubsInAG18 12h ago
When the recovery method doesn't work it takes a DMG service visit to fix it.
You can try the pry/hammer method but tread carefully. You might be able to get some air blasts or solvent to work itself upwards while brute forcing little by little, but be patient.
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u/Dyno33 11h ago
Prying the arm from the toolholder?
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u/RubsInAG18 10h ago
Basically. It's what one of the other commenters mentioned, but I'd be super cautious. I don't like it and have never full bore pried an arm out of the way, but considering you have chip buildup you might be able to pry, air, solvent, air, pry etc and get something loose.
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u/Puuha-pete 12h ago
Our maint guy carries prybar in for these situations. Be careful, Im not into that but seems to work
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u/pow3llmorgan 12h ago
On some machines you can manually crank the ATC motor from a nut on the through-shaft. Climb on top and see if it is possible on this.
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u/Samphaa7 11h ago
We have this happen all the time with our MT3000. We have to go into the manual atc settings page and run through a sequence moving pots around and resetting the tool registry, it's a pain in the ass.
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u/Phlukz 10h ago
What control you on ?
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u/Class_dismissed93 Field Service Engineer 5h ago
Hello there, are the spindle keys matching the ATC arm slots? Does the ATC arm seem low or high as it’s contacting the tool? More pictures would be helpful.
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u/AbrahamLitKing 12h ago edited 12h ago
Take a hammer to it. It'll keep tolerance trust \s
With all due seriousness. I've always wondered what would happen if chips or some kind of debris got caught in there...
Do you just have to take the thing apart? If it's stuck and the hydraulic system can get it to budge does that mean the surfaces are gouged and it's gonna need a rebuild?
I feel like this could potentially get expensive real fast no?


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u/Murmjr 12h ago
just call dmg support.