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Slow chuck on qt-15

ktd

Plastic
Joined
Jun 17, 2011
Location
canada
We have QT-15 lathe that the chuck has started opening and closing slowly. It seems to be clamping with the proper strength it is just moving very slow. We have replaced the valve we a new one from MAZAK. I have also replaced all the seals in the actuator. Any ideas would be appreciated.
 
From what you say you have done. It pretty much has to be in that valve block but im not really sure what.
Is there a speed adjuster below that pressure adjuster?
What did you replace, the directional valve or the pressure regulating block?
 
Does the new directional valve have a reducing orifice on the pressure port?

Is the pressure relief valve getting excessively hot?
 
No the directional valve doesn't have a reducing oriface on the pressure port. And no extra heat. I am going to investigate the pressure reducing block today.
 
Don't want to steal this thread from you but I'm having the same issues with a qt15 from 94. But the chuck also can't bite with hard jaws while the other can with the same chuck and it is quite fast.. Any ideas to what I should check first?

Let me add to this, it holds parts fine but just doesn't have anywhere near the strength of the other, and I can kick the chuck up to 4k rpm and it sounds and runs great. The old 2 axis machines are the last thing my plant manager is worried about so I have to pretty much do it all myself and just tell them what parts to order if need be. Any help would be appreciated thanks, John.
 
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clarification

This may be a simple stupid answer, but I had a similar problem.
The lock nut for the pressure gauge was loose.

Nothing was "wrong" aside from the chuck pressure had "slipped" from 300psi to 50psi.
(the manual locknut was loose)
From experience afterwards I can tell you that it takes at least twice as long for a
50psi and 300psi chuck to fully engage.

I'm a newby w/ terminology, so "lock nut" is probably incorrect.
I'm just sayin' make sure the adjustable pressure gauges are tight.
 
Last edited:
This may be a simple stupid answer, but I had a similar problem.
The lock nut for the pressure gauge was loose.

Nothing was "wrong" aside from the chuck pressure had "slipped" from 300psi to 50psi.
(the manual locknut was loose)
From experience afterwards I can tell you that it takes at least twice as long for a
50psi and 300psi chuck to fully engage.

The gauge still moves of its loose?
 








 
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