Welding Tips and Tricks

What's the difference between a blowback start and a high frequency start plasma cutter?

I believe that’s the same difference as contact and pilot arc. Contact / blowback requires that the outer copper cup be in contact with the metal to start the arc and keep it going. Hf / pilot arc are able to start an arc and maintain it while the cup is off the surface of the metal. If those descriptions are correct then I’d add your consumables last longer with hf / pilot arc, and they tend to help keeping a cut/ arc going when cutting by hand without guides / free hand.

WW, Josh is right in his thought about the contact type and pilot arc type plasma cutters. The contact type is much like scratch start tig and the pilot arc has its own "fire" internally that is blown out by the compressed air or whatever means you are using to cut with.
whatever type, the air has to as free from moisture as possible, as the moisture has this tendency to destroy the internal parts of the cutting tip of the torch....so I'm told ..

My cutmaster 52 uses a blow back start type system. It has a start cartridge in the torch. The unit fires a pilot arc when you squeeze the torch trigger. As you move the pilot arc to your work piece and the system senses the electrical circuit, the pilot arc ignites or fires the main cutting arc. This starting system works very well and doesn’t emit high electrical frequencies that can damage nearby electrical components.
High frequency start is just as it sounds. I don’t think many companies make high frequency start plasma cutters anymore. In the 100 amp and under class anyway.


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My Cutmaster 75 is a blowback start. Yes you need to touch off to start the arc, or be within 1/32 or so. But once the arc is initiated I can back of 1/2-3/4" if not 1" without the arc going out on me. Say for gouging

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snoeproe wrote:i don’t think many companies make high frequency start plasma cutters anymore. In the 100 amp and under class anyway.

i say its the oposite. all the cheaper ones are all HF start.

tweake wrote:

snoeproe wrote:i don’t think many companies make high frequency start plasma cutters anymore. In the 100 amp and under class anyway.

i say its the oposite. all the cheaper ones are all HF start.

Perhaps I should have said "good quality plasma cutters"
Those cheap cutters are absolute junk. Mediocre cut quality, performance and poor consumable life. No reputable name brand cutters made today use high frequency start in the machines made for personal (not hd industrial) use. You don't see HF start cutters from Hypertherm, Thermal Dynamics (tweco or Victor), Esab, Miller or Lincoln. There are still al lot of the older Esab cutters around that used HF start. These cutters have been around for quite a while. None of these cheap cutters today will last this long. My cut master is 10 years old and has been worked real hard on and off a cnc. Never had any issues with it.