Ohmic sensor & breakaway torch

[whiskeymike]

I’ve been away from my table for a while and started cutting some things this past weekend. I have a starlabs table with CandCNC, dthc iv and ohmic. I noticed when the torch comes down to find the plate, it taps the plate, dislodges the torch slightly, continues going down an 1/8” (eyeballing it), senses the plate, then comes back up to pierce height, meanwhile the torch breakaway reconnects in the right location, and it starts pierce and cuts. I think this is causing my pierce height to be off. Is this likely a dirty connector, breakaway torch holder needs to adjusted, or something else?

[jimcolt]

Best bet is to contact Starlab….they can offer the best advice on their table.

[acourtjester]

The ohmic sensor should stop at contact, but from what you state it seems to be going past and the floating head switch is being activated. this would put your pierce height off. If your table is using the feather touch from CandCNC there is a led for power and another for torch contact with the metal. First check to see if the torch tip is clean, next move the Z down to touch the metal and see if the led for contact comes on.

[BTA Plasma]

The 1st thing I would do would be to change your shield or use a little Emery cloth or something to break up whatever's on the end of the shield. Ohmic uses continuity to close a contact circuit to establish the top of the material and if there is resistance to that continuity it will not do that correctly.

[whiskeymike]

Thanks guys, will try cleaning things up.

[whiskeymike]

Just following up on this for someone troubleshooting in the future. I took a wire brush and acetone to the shield, but it didn’t seem to improve. But as I watched it closer, I realized the torch hose was pulled tight at full Z down. I made some slack and made sure it wasn’t caught up and that did the trick. I found that just as it would touch, the hose would pull it back stopping the shield from making a solid connection.

Hopefully this helps someone else having trouble.

[BTA Plasma]

In addition the 3/4 thick upright that attached to the gantry is a great spot for the ohmic plate part of the sensor if your ohmic sensor is on top of the Z axis. If it is on top of the control box then the bottom of the water bed or frame is a good spot for it. In 2017-present all Ohmic sensors were put on top of the Z axis.