Difference between blowback vs HF starting

[Scooter]

What is the operating difference between the Blowback and HF starting on plasma cutters? The PowerPlasma 50 would do everything I need but I don't know which start is better, and which of the torches that come with the PP50 or PP60 are better or easier on consumables.
Thanks Scooter

[performance]

Well, that is kind of a question that is difficult to answer. A lot will depend upon use...But if we get the torch changes done that we are thinking about, then they will all be about equal. But currently, the 50 gets as much mileage as any of them.

[everlastsupport]

Like Mark said, really depends on your use for it. CNC? Duty ctcke and power are very close so either is a good choice.

I've used both units for quite some time and about the same time with each. I currently use the PP60.

I like the PP50 because you can get Trafimet S45 consumables local in some places (Most Harbor Freight's even carry them, but they are not cheap). It's slightly more portable (lighter and smaller). I like taking it off the cart and getting a little more torch length that way.

I like the PP60 since it cuts a little stronger and the consumables "for me" tend to last a little longer. The consumables are not hard to get, but will most likely need to be ordered online. So there is a delay.

Getting consumables the same day is a good thing (Saturday or Sunday at Harbor Freight no less), but you should never get that low. Put a couple in a ziplock bag behind the machine. You will remember when you get low.

If you go the CNC route and do not have the proper shielding (lower end electronics), you will find the PP50 (blowback unit) is a better choice. No noise from the High Frequency to "maybe" have to deal with.

We do have the new CNC PP60 with Trafimet coming. I can let you know how I like it but we are looking end of this month at least and I am not sure if these are available to customers at this time, but I think they will be. Mark will know better on that. If we are not to announce this yet, Mark will edit my post

Hope this helps. Based on your post, the PP50 will make you very happy and save a couple bucks.

[Scooter]

Thanks for the replies. I will not be doing any CNC work with the plasma. I was unsure about the blowback start since the PP50 seems to be your only machine with it all others being HF start. From reading about these units they both seem good, how about some of you guys with the PP50 do you wish you would have bought a PP60. I have been retired for 10 years now and only do this as a hobby ( read as; I make no money doing it) and I am just getting tired of cutting & grinding odd shapes with the 4-1/2" grinders. I did purchase a Milwaukee 14" dry cut saw so I should be ok with cutting angle and stuff. Bottom line is I only want to buy a plasma cutter once and be happy with what I get. If I would be better off with the PP60 I am ok with the difference in price. Thanks Scooter

[Haywire]

I was also wondering what the difference between blowback and HF was. Saw the title and thought I might have my answer without posting, but found that it was more about consumables than anything else. LOL.

Ian

[performance]

Its not about consumables, its about how the arc is initiated. Air pressure forces a the electrode back off its resting point ( from a dead short to ground to an air gap) to start the arc. Some HF torches use a swirl ring and typically looking at the consumables will tell you nothing about the arc start type.

[geezer]

What is the operating difference between the Blowback and HF starting on plasma cutters? The PowerPlasma 50 would do everything I need but I don't know which start is better, and which of the torches that come with the PP50 or PP60 are better or easier on consumables.
Thanks Scooter

Scooter, as I understand it, there are two types of plasma start up, internal and external ignition. External ignition is when you touch the torch head to the metal and a HV of HF current sparks to ignite (not a good choice for CNC). The internal method know as pilot arc has all the ignition in the torch head, there are two ways of making the spark internal, blowback which is a short to begin with and a spark jumps the gap as the piston opens to create a spark gap, and HF or HV , where the current jumps across a known measured gap internally to ignite the process. This internal or pilot arc start method woud be suitable for CNC.

The life of a consumable is mostly dependant on the operator.

Here is a wikapedia thing which may help also:
The HF Contact type uses a high-frequency, high-voltage spark to ionise the air through the torch head and initiate an arc. These require the torch to be in contact with the job material when starting, and so are not suitable for applications involving computer numerical controled (CNC) cutting.

The Pilot Arc type uses a two cycle approach to producing plasma, avoiding the need for initial contact. First, a high-voltage, low current circuit is used to initialize a very small high-intensity spark within the torch body, thereby generating a small pocket of plasma gas. This is referred to as the pilot arc. The pilot arc has a return electrical path built into the torch head. The pilot arc will maintain itself until it is brought into proximity of the workpiece where it ignites the main plasma cutting arc. Plasma arcs are extremely hot and are in the range of 25,000 °C (45,000 °F).[1]

Plasma is an effective means of cutting thin and thick materials alike. Hand-held torches can usually cut up to 2 inches (51 mm) thick steel plate, and stronger computer-controlled torches can cut steel up to 6 inches (150 mm) thick. Since plasma cutters produce a very hot and very localized "cone" to cut with, they are extremely useful for cutting sheet metal in curved or angled shapes.

[performance]

Geezer,
This is always confusing information. Pilot arc is a separate thing from the start type. The HF IGBT units we sell are all Pilot arc. Pilot arc creates a torch current path to ground through the torch head true. But a blow back start is inherently a pilot arc though. HF can be internal or externally started and if the pilot arc wire is disconnectd, a drap or touch start can be initiated with the HF units. And with the new HV start it uses the same torch as the HF with no moving parts.

[geezer]

Geezer,
This is always confusing information. Pilot arc is a separate thing from the start type. The HF IGBT units we sell are all Pilot arc. Pilot arc creates a torch current path to ground through the torch head true. But a blow back start is inherently a pilot arc though. HF can be internal or externally started and if the pilot arc wire is disconnectd, a drap or touch start can be initiated with the HF units. And with the new HV start it uses the same torch as the HF with no moving parts.

My point is; regardless of the method used to start the pilot arc,(blowback which is a mechanical spark gap or HV or HF which jumps a known gap distance) having pilot arc makes the cutter suitable for CNC compared to using a drag or external start type which uses HV or HF. All of the Everlast cutters that have pilot arc can be used in CNC operations in my opinion.

[everlastsupport]

Geezer, You are right, high freq/volts will cause more problems on most CNC controller designs.

The life of a consumable is mostly dependant on the operator.

And dry air helps too. Guess that is an operator thing

[acourtjester]

It would seem to me that the pilot arc is less detrimental on the consumables as you don’t need to touch the metal surface to start cutting. And cutting that starts away from the edge would be also better with a pilot arc start.

Have fun
Tom

[everlastsupport]

Tom,

HF start units do not require touching the metal either. The pilot arc does use a little of the consumable to fire up, but very little. And the pilot arc can burn through paint, grease, etc. as well.

I did not like them at first, but I am a believer now.

[Haywire]

Its not about consumables.

Sorry, I mean that the thread was mostly about consumables. You fellas got it back on track though. Thanks for the explanation.

Ian