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Difference between HF and Pilot arc



Nicholas
11-18-2011, 06:23 PM
My plasma cutter does not have either.
Could someone explain the difference between pilot arc and HF. I'm thinking the hf is the same as on my tig welder. Jumps the gap and allows the arc to start without making contact with the work. Is the hf on a plasma cutter continuous. What the heck is a pilot arc. Also can either be retrofitted to a machine.
Thanks
Nicholas

Gadget
11-18-2011, 07:29 PM
Pilot arc uses a pilot wire that's connected to the tip allowing current to flow from electrode to tip without any contact with the metal to be cut. If you get a pilot arc torch and connect the pilot wire to ground it will work. Pilot arc has a circuitry that cuts out once the current begins flowing from electrode to the metal, this prolongs consumable life. If you use the pilot arc torch on a HF machine that pilot voltage won't kick out. If your distance between the torch and metal gets too far apart you will burn through the consumables because it will revert to the arc between electrode and tip. The trick to fitting a pilot arc torch to an HF cutter will be the fittings on the hoses.
HF start does work like the TIG HF start. I think it remains on when cutting but am not sure.

Nicholas
11-18-2011, 11:41 PM
Gadget,
Are you saying that I could by a pilot arc torch and I can use it with my machine.

Gadget
11-19-2011, 07:00 AM
Yes, I use an S-45 torch on my HF LP80 plasma cutter. I connect the pilot wire to ground and keep my cutter at .080 cut height on my CNC table. I also have the P-80 straight torch which has a pilot wire as well. I've even modified an older torch by connecting a ground wire to the tip.

Nicholas
11-19-2011, 08:12 AM
Yes, I use an S-45 torch on my HF LP80 plasma cutter. I connect the pilot wire to ground and keep my cutter at .080 cut height on my CNC table. I also have the P-80 straight torch which has a pilot wire as well. I've even modified an older torch by connecting a ground wire to the tip.

Modifying my existing torch, I would like to try that. Is there a write up on on how to do that on the forum.

Gadget
11-19-2011, 08:28 AM
I had something on it once but pulled it due to safety concerns. If you can, post a photo of your torch. If it's similar to mine maybe I can help.

KHK
11-19-2011, 09:42 AM
There are two types of pilot arc torches used by Longevity.
One type is the S45 which does not use high frequency to stare the arc. The arc is started inside the torch head, and an air cylinder moves the torch tip to the correct distance to maintain the arc.
The other type is the PT-31, SG-55, etc. which uses high frequency to start the arc.
The torches are not interchangeable.

You need to determine if your cutter uses High frequency arc starting before you decide which type of plasma torch to try.

Gadget
11-19-2011, 02:44 PM
Keith,
My cutter is HF and I use the S45 torch on it all the time. I had to modify the hose connections to make it fit though. I also use a P-80 pilot arc torch using the pilot wire to ground method.

KHK
11-19-2011, 10:57 PM
Gadget, I plugged a S45 torch into a machine that normally uses a pt-31 and this was the result. I think that you have been lucky or I had a defective S45 torch.

Gadget
11-20-2011, 09:13 AM
Actually Keith you are correct. I modified my S-45 to a straight unit for CNC cutting and had to use epoxy around the area you show as burned out. I had some burn out there as well. At the time I figured it was a faulty torch but the HF arcing is a better explanation. I forgot when I responded above that I had to do that to make the torch work correctly.
The P-80 torch with pilot arc wire works without modifications though.

ozyjimbo
08-12-2015, 11:22 PM
Just wondering where you guy's are placing the earth from the torch i have a hf start cut40 and just bought a p-80 but when i connect the earth from torch my wire starts to fry i have tried connecting it to the material and i have tried the earth from the machine without connecting it to the work piece what gauge wire should i use from torch to earth and were would be better to connect wire to earth as to not to fry it?

thanx in advance

Gadget
08-13-2015, 07:14 AM
Hi Ozyjimbo and welcome to the forum. We like pictures here so please include some showing your work. Be sure to post a bit about yourself in the introduce yourself section so we can get to know you.
By earth from the torch I assume you are talking about the pilot arc wire. On my LP80 I connect that to the ground clamp on the plasma cutter. If you are frying the wire I suspect you either forgot to connect the ground to the work from the plasma cutter to piece or the clamp isn't grounded well. Occasionally I will forget to connect the work ground and the pilot arc is doing all the grounding, it doesn't cut very well and the wire will melt the insulation. Just be sure the plasma cutter ground clamp is well connected to the work piece and the pilot arc wire from the torch is well connected to the plasma cutter ground.
Dan

ozyjimbo
08-14-2015, 07:02 AM
Hey gadget thanx for replying yeah i was in a rush to do an intro as i wanted to figure out how to stop my pilot start wire from frying lol

i don't have any pics at the moment but i can give a better description i have a cut 40 china brand it is a hf start i bought a Panasonic p-80 pilot start machine torch i connected the pilot start wire to the earth clamp the earth clamp was also connected to the work piece i started the torch away from the work piece and got a nice full cut flame from it like as if i was cutting metal but then my troubles began i looked down only to see my pilot earth cooking that is why i asked what gauge pilot wire was being used as i think i might have been using a to smaller wire

ozyjimbo
08-14-2015, 07:13 AM
btw even with the torch away from the work piece or if i was actually cutting the wire still fries

ozyjimbo
08-14-2015, 07:21 AM
here are a couple of pics of the cutter and torch they are from other sites and not of my own equipment but they are exact to what i have10730

ozyjimbo
08-14-2015, 07:22 AM
10731 this is the torch i'm trying to connect

Sling
08-14-2015, 08:13 AM
btw even with the torch away from the work piece or if i was actually cutting the wire still fries

I'm out of my depth here, but this sure sounds like an electrical short, or some kind of electrical fault.

ozyjimbo
08-14-2015, 08:44 AM
no it's done it on both torches it's something i'm doing wrong

Gadget
08-14-2015, 02:11 PM
If your torch height gap it too large it will run off the pilot wire instead of the arc path to ground. Maybe that's what's happening.

ozyjimbo
08-14-2015, 07:14 PM
ahhh ok i'll try that and lower the torch closer to the work piece i was only using a thin gauge wire so i'll try a thicker wire aswell i'll let you know how it goes just one more question to that should the torch light up to full cut flame or should it spark then go to full flame? with the hf torch head i didn't have to touch the work piece if i got it low enough to initiate a spark then once it goes into full flame i bring it up a little

Gadget
08-15-2015, 09:07 AM
If you're using the pilot wire to ground you're basically bypassing the HF so it should just start full flame. I would use at least a 12 gauge stranded wire for the pilot wire.

brijubat
11-01-2016, 08:59 PM
First of all, thanks for the contribution,
I bought a HF plasma cutter, i would like to know if it is possible to implement a pilot arc on it, how can i do it?