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Longevity 60 amp non contact start mod for CNC

04-22-2009, 11:38 AM
This modification should only be considered for CNC cutting. Non contact start could be extremely dangerous if you were to bump the trigger at an inconvenient time. Use with extreme caution. This is the Longevity 60 amp torch and can be purchased separately. Check to insure it will fit your cutter before ordering. The attached wire goes to the cutter ground clamp (is clamped on there)


04-22-2009, 12:50 PM
Wow! That looks like a simple mod. With this arrangement, will it maintain the arc for as long as the trigger is pressed, regardless of contact with the base metal?

Art R.

04-22-2009, 01:28 PM
Quick answer, yes.
I use this setup on my CNC table. I start the pierce with a gap of .125 and after .4 seconds it drops down to .080 for the cut. This really saves the tips and will maintain the arc if you have to recut for some reason. It never needs contact with the base metal.

04-22-2009, 08:25 PM
For CNC torch it looks fine.
For a hand held torch, It looks very dangerous!

04-23-2009, 01:29 AM
Thanks Gadget for the Ideas I need this vary thing to cut expanded metal. I will have to get a 60 amp torch and give it a go. Don't worry I have been around this stuff for 50 years. I first started welding pipe with an acetylene torch in 1957.

04-23-2009, 05:19 AM
If you are going to use this for hand held operation, I suggest using a second switch in series for safety. The second switch could be at the plasma unit or even a foot switch. It wouldn't necessarily have to be a momentary switch, just something to insure when the plasma torch is started it is actually intentional. That way if you were to bump the hand trigger while working nearby it wouldn't start.
I even have one on my CNC plasma table for this very reason.

04-23-2009, 01:07 PM
Hi Gadget, You recommend the switch be on the #10 wire between the torch and the ground.

04-23-2009, 04:32 PM
No, I meant the trigger switch. If you add another switch to that line both would have to be on to start the torch. when you are not using the torch turn both switches off. Then if you bump the trigger accidentally, the unit will not fire.
You could use a switch in the ground wire but it would have to be able to handle the heavy current used when cutting.

04-23-2009, 09:02 PM
Ok Thanks I got it now. I looked at my torch and there is no way to hook it up, the torch is a lot different so I can't try it untill I can afford a 60 amp torch but I have it logged into memory Thanks.

04-25-2009, 02:13 PM
wow, I really like that idea.

05-20-2009, 02:12 PM
Gadget . . .Could the torch handle be attached to the gantry this way also, if you could find a "nut" the right size?

05-20-2009, 04:29 PM
You wouldn't have enough threads left for the cup and if you did, the cup would be too close to the metal. Too bad though, that would be a nice setup if you could. The metal I use is thin and even that cuts the useable thread pretty close.