Need Help!- 4020 Won't raise Z to allow tool change!!

[john-john]

Hi
I was running our old faithfull, 1989 VMC4020 with cnc88 control today, everything was fine, but I hit E-stop instead of feed hold during a program and now the machine REFUSES to raise the Z axis during a tool change. If the program calls for z-moves, it moves no problem, and jogs no problem, but I can't make it change tools anymore! What should I check??
Thanks
John

[donnelson]

shut down machine restart than cold start machine see if that helps you willl probably have to line upthe marks on all axes

[john-john]

Hi
I've done that, as well as reset the setcs, seth, and setz. Everything works perfectly, except that the machine is forgetting to raise the spindle enough to clear a tool. It slams directly into it, no upward z motion past the CS mark at all!!
I'm thinking maybe a relay or fuse?? It happened immediately after an E-stop.

Thanks
John

[Mike Stevenson]

john-john,

I know what the problem is. There is a proximity sensor the knows when the head is in position for a tool change. Go look at your machine and see if it's lined up correctly. When you move head inline with the sensor turn the machine off then back on again and do the normal start-up procedure. All should be well. I had the same thing happen to me.

[donnelson]

i dont think there is any limit switches on the fadal it is looking and the encoder which has lost its spot go to the page that says home send it to home tnan look at the right side of the z and see if the cold start marks are lined up exactly

don nelson

[Mike Stevenson]

Don,

Of course there are limit switches however there is a big difference between limit switches and magnetic proximity switches. I know about the start mark and I didn't see it at first either. Look at the head when it's up on the right side, you will see it.

[donnelson]

i have 2 fadals i have had them somewhat apart checking belvile washers and such i have never seen and type of limit switches in the z i have a 40x 20 millport with dynapath 40 and you can see the limits on all axes i have a new hardinge vmc1000 11 and you can see them but not on the fadal they might be there but i have never seen and i think it has lost it place just like if you have a brown out it has to be re cold started i think thats all it needs

[ssurfview]

I got it, Our 1989 4020 has been doing the same thing for years. I comes and goes. After reading you post I noted the failure after an E-stop. Get out your ohm meter. Disconnect main power. Disconnect one wire from each side before you check. Put the meter in ohms and check the e stop contact blocks. The green side, the Normally open did not read fully closed when the e stop is in. We changed it and the problem dissapeared. For now. when the button is out, the red side should be closed and the green should be open. With the button in, the red should read open and the green should be closed. Closed meaning no more than 1 or 2 ohms. Also watch the meter is the reading constant or does it wander?
Steve

[Elmss12]

Hi,
I have a 2001 4020 that i had a similiar problem with. I had to hit the resets on the tool change board in the electrical cabinet. after it was reset had to reset and re cold start machine. then had to raise head in jog to 3.25 tool change hieght and check the board to make sure head pos led was lit green. If it's not you may have to adjust proximty switch. mine was very particular had to move it closer and up about .01 it's been fine since about 5 months now. hope this helps