Z-Axis Problems on Trotec Speedy 500

[Stephanie Koenig]

My shop has been having some trouble with the Z axis on our Trotec 500. This has stumped me, my boss who has a phD in engineering and the techs up in Ypsilanti. A few weeks ago the bed would just rise up at start up instead of dropping down and going through the initialization routine. We updated the firmware, swapped the Z driver boards. Easy, breezy, done and fixed. Not so fast.

After a few weeks happily running jobs we had the exact same problem with the bed rising. We did the usual firmware updates and trouble shooting, then we got really aggressive. We switched the Z and Y plugs in the I/O board. Next we checked the cord from the I/O board to the Z driver boards with a multimeter- nothing wrong there. We used an external power supply to raise and lower the bed. We monitored the encoder to the Z motor. I checked back with the techs, and we disconnected the auto focus from the I/O board. We also checked the keypad that lets the user move the bed up and down and move the head around. Nothing.

All signs point back to Z driver boards, so they're sending us more. It just seems like there might be something that is causing this that we're all missing here. The techs told me that the power supply is on the Z driver boards so it's not getting fried from that. Any thoughts?

[Mike Null]

On my Speedy 300 there are sensors which can become dirty and won't function. They are small openings at either side of the machine and I clean them with a q tip. You must clean both.

This is probably not your problem as it would normally cause the table not to raise but it doesn't take a minute to check.

[Jon Colley]

If it is rising slowly on initialization, it is a problem with the home switch on the Z-axis. The switch is stuck in the closed position so the system thinks that the table is on the switch. It will keep moving the table up to get off of the switch until the switch is open.

You can unplug the switch from the Z-axis CPU board and check for continuity. If it doesn't change when you press the switch, then the switch needs to be changed.

[Stephanie Koenig]

Thanks for the tips. John, we checked the lower switch by manually pressing it and got the expected error code. If the machine thinks the lower switch hasn't been tripped, shouldn't the upper switch still get triggered? The weird thing is that the bed will continue to rise after it has fully engaged the switch at the top, so it's ignoring the upper switch. We lowered ours a bit to prevent collisions between the head and bed. The problem with the rising bed happens instead of initialization- instead of lowering the bed and moving the head to the 0,0 position, it just starts rising the bed as soon as it has power.

[Jon Colley]

Which error code did you get when you pressed the switch?
During the initialization, the system likely isn't "watching" that top switch so I can see how it would ignore it.
Assuming you are running recent firmware, the Z-axis references first so it has to hit the home switch and then back off of it before the X and Y will home.
If it is moving up slowly, I believe it is trying to back off the switch and it will continue to do this until the switch opens.

Let me know what the error code is, but I'm still pretty sure it is the switch from the way it has been described.

[Stephanie Koenig]

I can't remember now what the code was for the error. We did get the machine fixed just a bit ago. I misunderstood the techs on Wednesday (it was a hectic day on both ends, we were communicated through voice messages), they thought it was the CPU and I/O board for the whole machine, not the Z driver boards. I did go ahead and clean the auto focus sensors as recommended by Mike. I don't think the 500 uses those in initialization, but I thought I would give it a shot. I checked both the upper and lower switch for the Z axis- both showed continuity until the switch was pressed then the connection was lost as expected. After that I replaced the CPU board, updated the firmware and everything worked just fine. Trotec support was great and got the parts as fast as we needed them.