[sdwscott]

the collet closer on my CHNC1 does not hold the part tight enough. Part will push out from the bar feed on in from heavy drilling. I have replaced orings and quadrings but parts still slip. Any suggestions?

[txcncman]

What pressures have you tried on the collet closer and on the bar feed? What type of bar feed? Have you tried different collets? Are the collets damaged or worn? Is the spindle nose damaged or worn? How are you adjusting collet for material size? What type of material are you having problems with?

[sdwscott]

Thanks for responding.
I have varied the pressure up to the max. Using brand new hex collet
cutting 7/8 hex ss but tried other collets and materials. I can still
tap the part back through the collets with any material. Got through
the job by cutting off material and using a collet stop. This job
didn't slip because of hex but other parts would slip or rotate in the
collet.

[txcncman]

Then it is probably time to disassemble, clean, and repair the draw tube and the hydraulic actuator assembly.

[Machineit]

You have a problem in one of two areas. Either the drawbar assembly itself or the solenoid that supplies it air.

Start by taking the lines off of the draw unit and make sure air only goes to one side at a time. If the solenoid is bad it could be sending air to both lines at once, but reduced on the wrong side.

If that checks good, then it is in the closer itself. When I got mine it did not work correctly and I took it apart to fix it. I replaced all of the seals, but the issue was a brass valve inside the unit. It had had a seal failure of the seal and the air had actually worn a slot in the brass. I made a new part out of stainless and all was good.

I had a gentleman who worked for Hardinge for 30 years over to help me with a software issue and he said that Hardinge made the systems so that they were always venting, IE not just open or closed. It irritated a lot of small shops with the higher air usage, but they kept it that way. That is why the turret is always venting air. So, inside the closer will be other valves.

Have fun,and good luck!

Mike

[Machineit]

Don't you all love it when we try to help and they don't get back to let you know how it is going!!

Mike

[sdwscott]

Thanks for the help all. Mike was exactly correct thank you. They all leak air. I replaced all of o rings and quad rings cleaned everything in the draw bar assembly and still part slips in the collet. Finally got back to the solenoid sending air to both lines at once. I swapped the left and right actuators on the solenoid and swapped wires 16 and 17 to err on the open side of the collet and seal the closed side. Bingo Collet closes and secures to the pressure switch settings. Ran a 1.5 dia aluminum bar feed job day all day Friday. Beautiful machines when they run well with great tolerance control.
Thanks
Scott Williams