Dawoo Puma 6HS Z AXIS PROBLEM

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tobydbaker74

Aluminum

Joined

Sep 8, 2018

Location

Columbus

• Feb 4, 2020

• #1

While running on the 8th out of 8 parts I needed the lathe decided to stop and says z soft limit. The tool is about 2 inches from the chuck and in no way near a limit switch. It will home out in the X but the Z will only move towards the chuck with the hand wheel. If you try moving away it will change the numbers on the screen but it's not moving at all. I have never seen this before and a little stumped. Bad Z encoder?? Any ideas?

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Other Brother

Hot Rolled

Joined

Dec 6, 2014

• Feb 4, 2020

• #2

It sounds like a mechanical issue with the coupling between the motor and ballscrew. Does this machine have a torque limit between the shaft on the motor and the ball screw?

I have seen the proximity switch for the torque limit damaged and then it doesn't alarm out when the torque limiter trips. The slide doesn't move but the motor still turns. If you don't have a torque limiter it sounds like the coupler is slipping.

 

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tobydbaker74

Aluminum

Joined

Sep 8, 2018

Location

Columbus

• Feb 5, 2020

• #3

I am going to pull the Z axis off this morning and look to see if I can see what's going on with it . Above the motor there is a plate that says z axis shear pin. Maybe that pin is sheared??

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tobydbaker74

Aluminum

Joined

Sep 8, 2018

Location

Columbus

• Feb 5, 2020

• #4

Well think I found the problem!

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tobydbaker74

Aluminum

Joined

Sep 8, 2018

Location

Columbus

• Feb 5, 2020

• #5

After I found the pins we had to manually move it back so we could home it out. Otherwise it would just keep saying it had a soft limit on the Z. Anyone know of a way to override the limit switch for the next time this happens?? Also would like to find a source for the pins and have a few extra on hand. We were lucky to find a spare inside the enclosure.

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Other Brother

Hot Rolled

Joined

Dec 6, 2014

• Feb 5, 2020

• #6

That limit switch was not the cause of the soft over-travel alarm. That alarm was because the z-axis "Machine" position reached the limit in parameter 1321. The motor was turning but the slide didn't move, so the position was at the limit. You should be able to order the pins from any Doosan rep, like Phoenix.

The limit switch in the photo is usually a torque limiter or break-away switch. It would not cause a z-axis soft OT, but another message. I have never seen that set-up before, so thanks for posting the photos. Daryl

 

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tobydbaker74

Aluminum

Joined

Sep 8, 2018

Location

Columbus

• Feb 5, 2020

• #7

Thanks for the help. You gave me a idea of where to start otherwise I would still be scratching my head.

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LockNut

Stainless

Joined

Jan 6, 2007

Location

Bergen County

• Feb 5, 2020

• #8

tobydbaker74 said:

Thanks for the help. You gave me a idea of where to start otherwise I would still be scratching my head.

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Click to expand...

I work for Doosan. Call our service department first to see if that part is available. 973-618-2500. That's a pretty old machine. Have the serial number handy.

 

LockNut

Stainless

Joined

Jan 6, 2007

Location

Bergen County

• Feb 5, 2020

• #9

These part should be in stock or so I was told. Email me at [email protected] and I will send you a print of the Z axis drive and the parts list.

I tried to attach the jpegs but they are not very good, better to email them.

Paul