Problem- interact tnc145

[bigbaz]

my interact has got a problem that when i press start button instead of machining program the x and z axis creep slowly and the y axis moves at about 300mm minute until it trips out this happens on line 3 of program (stop M25) if i start the program on line 4 x y and z all creep very slowly until one trips out on a limit. I have taken the tnc145 control to a repair centre and was fitted to a machine same as mine and worked fine for days also a repair man fitted his tnc145 to my machine and it worked fine for weeks but when the two are put together the fault comes back, both repair men are baffled can anyone please help as i need to get back in production as this is my only mill.

[machintek]

If the axis drift, it typically means you have a open position loop.
Does it home?
The TNC 145 has a power supply board in it. Maybe there is an encoder cable fault pulling the 5VDC down.

George

[bigbaz]

Yes the machine will home in x y and z without a problem and also works fine in manual with joystick or wheel, thankyou for the info on encoder cable fault, would it be possible for my control not to work but another control to work if its using the same cable.

[gus]

What error do you get? Exactly

Have you tried a different program?

[machintek]

I must have misunderstood. I thought your control worked in another machine.
Check that your power supply in the TNC is putting out 5 VDC to the encoders. It does not sound like it is. Especially since the position loop is compromized. The top of the TNC has 5 chromed phillips head screws. Remove these and you will see plug in boards. One is the power supply board. One is the counting board. If the 5 VDC is OK, Heidenhain has a procedure to use the handwheel to check that each axis is counting. Call them. It is done by changing a few parameters.

George

[bigbaz]

Yes my control works fine on another machine, today the repair man came again and the machine worked about 8 full cycles of the program then started to drift in x y z until it trip out, restarted the machine again then it ran all afternoon without a problem.

On a different problem the machine has also started to make a noise like gears not meshing if i put it into the low ratio but seems ok in high ratio.

[machintek]

I still believe the 5VDC is dropping out to the encoders. Since they plug in individually to the back of the control, the common factor here is the control. It must have an intermittent connection in it.

Since this is a 20 year old machine, I cannot say what is good or worn out in the head. It has a back gear to it. The bull gear drops down with the side lever, and engages the pinion gear. It may not be moving enough to clear the high speed gear teeth (clutches) or a very common problem is that the bearing in the bottom vari drive starts going bad and eats its way through the vari drive causing it to move down and start hitting some screws.

George