[JKMotorsports]

I'm getting sick of the inconsistency on thin sheet of my floating head on my table. I'm pretty sure the Trafimet S75 torch does not have OHMIC ability so I'm wondering if my idea willwork.

I want to surround my torch with a light spring. Run the 24V- to this spring (insulated from torch housing) then continue the 24v- via a clamp on the plate. This will go to the Neg side of a relay. When the spring meets the plate it will trigger the relay sending the signal to my Break out board. I will have the torch on relay open the 24v- so that it cannot be damaged while cutting (not sure if it will)
Quick paint Diagram (note sping will be around torch and adjustable to be a hair lower then the torch):
Attachment 248434
Only thing I can think of is that on more detailed cuts the diameter of the spring may miss the plate. I do play on keeping the floating head as a backup.

Thoughts?

[davek0974]

Hmm
It might work but the spring being light could be bouncing up and down and cause inaccuracies.

The thin sheet can be an issue but I have just fitted a new THC and found that even if it touches off too low it soon corrects itself when the THC kicks in.

My floating head is very light too.

[Torchhead]

This is similar to a "poor mans" ohmic sensor that is a battery or floating wall plug that powers a small low current relay. The positive side of the relay is tied to the plate via a connection (usually to the table structure the positive side of the battery/power supply goes to a clip that makes contact with the isolated shield of the torch when the shield touches the plate the circuit is closed and the relay pulls in . The NO contacts pull back to your BoB just like the mechanical swtich does. The negative side of the power supply ties just to the negative side of the relay coil. It may not work too well on an HF start plasma and even on a regular blow-back start there are lots of volts across the connection at some points. it would be nice if you could put in another relay tied to the torch fire circuit that would disable the power supply to the ohmic side. We provide an Ohmic sensor as an option but it is all electronic and highly isolated and protected. It is designed to work with our BoB (table I/O). One really annoying problem is that the ohmic sensor tends to give false ON from water or debris in the shield cavity. Cause it to sense as soon as the homing move starts way up in the air and fires the torch too high. The solution was code in our custom post that check if the input is active BEFORE it starts the Z down move and if it is it stops and warns the operator.

TOMcaudle
www.CandCNC.com