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Thread: Difference between HF and Pilot arc

  1. #1
    Senior Member Nicholas's Avatar
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    Difference between HF and Pilot arc

    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
    Longevity Force Cut LP-50D Plasma Cutter
    Lincoln SP170T Mig Welder
    Miller 330 A/B/SP Tig Welder
    Miller Two Fifty Twin AC/DC Stick Welder
    Oxy/Acetylene Rig
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  2. #2
    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.
    Units owned Longevity PROmts 200

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  3. #3
    Senior Member Nicholas's Avatar
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    Gadget,
    Are you saying that I could by a pilot arc torch and I can use it with my machine.
    Longevity Force Cut LP-50D Plasma Cutter
    Lincoln SP170T Mig Welder
    Miller 330 A/B/SP Tig Welder
    Miller Two Fifty Twin AC/DC Stick Welder
    Oxy/Acetylene Rig
    Arcair gouging torch

  4. #4
    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.
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

  5. #5
    Senior Member Nicholas's Avatar
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    Quote Originally Posted by Gadget View Post
    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.
    Longevity Force Cut LP-50D Plasma Cutter
    Lincoln SP170T Mig Welder
    Miller 330 A/B/SP Tig Welder
    Miller Two Fifty Twin AC/DC Stick Welder
    Oxy/Acetylene Rig
    Arcair gouging torch

  6. #6
    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.
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

  7. #7
    Moderator KHK's Avatar
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    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.
    keith
    The older the Boys, the more expensive the TOYS
    Previously Owned equipment;
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  8. #8
    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.
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

  9. #9
    Moderator KHK's Avatar
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    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.
    Attached Images Attached Images  
    keith
    The older the Boys, the more expensive the TOYS
    Previously Owned equipment;
    lot's
    Current equipment;
    3HP Speedair air compressor, Wilton drill press, Craftsman 10x36 lathe, 10 ton hydrolic press, Portaband band saw, OA torch, Small home brew CNC machine, powered by my 200PI
    2 Longevity autodarking helmets
    160d MIG
    WeldAll 200PI

  10. #10
    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.
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

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