Axis limit on Z axis - TRIAC PC 1993/1994

[el$syd]

Hi,

My Triac PC 1993/1994 vintage has been working fine but now has a strange fault and is not working to its usual high standard.

The Z axis was going up and triggered the emergency stop signal.
I overrode this with the limit stop switch on the front panel.
But as soon as I let that go the emergency stop signal re-appeared.

The machine has been left switched off for a few days to 'cool off' in case it was getting temperamental

Returning to the machine, all seemed well again and it re-homed once.
When I asked it to re-home again there was no movement on any of the axes.
And VR milling showed the Z axis increasing beyond 160 and not stopping.
Pressing the 'Disconnecting machine' in VR milling then produced a timeout error.

Is this a fault with the limiting switch in the Z axis?
Or is there something else wrong?
what should I look for?

Many thanks

[Martin]

Have you updated the software recently?

If so I often have to bend the dog that trips the Z axis sensor in order to overcome exactly what you are reporting. The easiest way to do this is to look down from the top. The sensor is mounted inside the colum & the dog is mounted on the head assembly. If you look down behind the motor you should be able to bend the dog slightly. Be careful to not bend it too far though.

Hope this helps.

[el$syd]

The software has not been upgraded - that's why I found it so strange.
The machine was merrily working away until I needed to change the tool and jogged the Z axis up in order to do so.
Then the error message.

Thank you for replying so quickly I will have a look at the dog - I am not certain what that looks like so hope it is obvious.

[Martin]

If you identify the Z axis datum sensor first.( a silver bolt about 12mm diameter coming through the colum pointing towards the spindle motor) then you should see the Z shaped metal bracket that activates it attached to the Z axis assembly.

[el$syd]

I took the motor cover and column covers off and had a good look.
There is a micro switch near the top which causes the emergency stop when I press it, so I cleaned it as far as I could.
That may have helped.
I could not see a silver bolt.
The Z axis ball screw and belt drive obscure viewing into the column.
The spindle motor obscures any detailed views behind it.

I am hoping that the cleaning of the micro switch did the trick as it seems to home OK for now.

Many thanks for your input, it helped me look in the right places.