Expanded Metal

[millermatic]

I watching a video of expanded metal being cut with a plasma, and the pilot arc never went out in between each hole. My question is my pp50 starts and stops after each cut, I mean the arc completely cuts off then restarts when I get to metal again, instead of just staying ignited. Sometimes it won't restart and I'll have to let off the trigger and press again. This also happens when I'm cutting just regular steel plate. Is there anything I'm doing incorrectly like air pressure or consumables. Psi is 65 and consumables are relatively unused.

[geezer]

Change your tips,,,sounds like one is pitted,, also check the swirl ring is in right,,,the pilot arc should maintain as long as the trigger is depressed..watch the height of the tip,,too low will also snuff the pilot arc..

[EmptyNester]

Change your tips,,,sounds like one is pitted,, also check the swirl ring is in right,,,the pilot arc should maintain as long as the trigger is depressed..watch the height of the tip,,too low will also snuff the pilot arc..

I've seen this same behavior on my CNC and assumed that the pilot arc cut out when the arc transferred to the ground through the metal and then restarted when the arc was lost. I thought I had seen that some people cut expanded metal w/o a ground clamp for that reason.

Is that incorrect?

[Gerry]

Change your tips,,,sounds like one is pitted,, also check the swirl ring is in right,,,the pilot arc should maintain as long as the trigger is depressed..watch the height of the tip,,too low will also snuff the pilot arc..

.
Not sure there is a top and bottom difference on the swirl ring in the S45 torch, some of the other model torches there is.

[geezer]

I've seen this same behavior on my CNC and assumed that the pilot arc cut out when the arc transferred to the ground through the metal and then restarted when the arc was lost. I thought I had seen that some people cut expanded metal w/o a ground clamp for that reason.

Is that incorrect?

Cutting with out a gound clamp is possible using the pilot arc,,,but only on thin stuff... for short periods..just one of those strange things that happen,,,having a ground clamp makes the full power possible..the pilot arc maintains the ability to restart cutting without touching the material to complete the circuitry..and...fire up full power....That's why it's called pilot arc...the power or heat coming out of the pilot arc can cut flimsy materials..

[geezer]

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Not sure there is a top and bottom difference on the swirl ring in the S45 torch, some of the other model torches there is.

probably not a difference on the hole orientation,,,however on some rings there maybe an up side to point the holes in the right direction...depends if you are above or below the equator...toliets in N. America rotate one direction when flushed and ones in Austrailia rotate the other direction,,,that's how you know when your ship has crossed the equator,,,check on the toilet bowl when you flush..

[everlastsupport]

On the S45 it is unidirectional. On the 81, it is directional and if you look at it, it will come obvious.

[Gerry]

On the S45 it is unidirectional. On the 81, it is directional and if you look at it, it will come obvious.

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Mike you answered the question about the swirl ring, any suggestions or answers for Millermatic's original question.

[redbeard]

Cutting with out a gound clamp is possible using the pilot arc,,,but only on thin stuff... for short periods..just one of those strange things that happen,,,having a ground clamp makes the full power possible..the pilot arc maintains the ability to restart cutting without touching the material to complete the circuitry..and...fire up full power....That's why it's called pilot arc...the power or heat coming out of the pilot arc can cut flimsy materials..

IIRC, Mark is pretty adamant that we don't deliberately use the pilot arc for cutting. Besides, even .020 aluminum comes out REALLY ragged when you do, DAMHIK.

[everlastsupport]

IIRC, Mark is pretty adamant that we don't deliberately use the pilot arc for cutting. Besides, even .020 aluminum comes out REALLY ragged when you do, DAMHIK.

We provide extra fuses for the pilot arc, but it is not intended to cut with. One the other hand, I must admit I do it from time to time for very short little things. I have never blown the fuse doing that.

[zoama]

I don't cut with the pilot arc, but just out of curiosity, why would it blow a fuse ?

[Gerry]

We provide extra fuses for the pilot arc, but it is not intended to cut with. One the other hand, I must admit I do it from time to time for very short little things. I have never blown the fuse doing that.

.
Mike my unit didn't have any extra fuses with it and the fuse that's in the machine is not marked.
What amp fuse do they use ?

[everlastsupport]

Some have units have a fuse and some do not. Not all have them. Some are inside and some external.

As to why have a fuses? I guess I could ask why have a breaker in the panel, protection of the circuits. Like duty cycle.

The pilot arc is not meant for full time cutting. If you forget to hook up the ground it will run, but it is not designed to cut full time.

[travis]

ok I have a question now I was thinking you pull trigger and pilot would start the torch then go away does pilot stay on as long as trigger is pulled or how does it work do you HAVE to have trigger pulled to cut ?

[geezer]

The trigger on any plasma cutter whether it is pilot arc or a contact type or HF is your only way of controlling the cutter,,,keeping the trigger depressed maintains the cutting,,you don't just press it once to fire up the pilot arc,,,like you would a barbeque etc..

[travis]

Ok so how would you cut useing the pilot arc only? Is it just the standoff that keeps the torch going?

[zoama]

Ok so how would you cut useing the pilot arc only? Is it just the standoff that keeps the torch going?

When you press the trigger the pilot arc runs, as long as the work clamp is on the metal to be cut, the main arc will take over when the tip is close enough.
In other words the pilot arc runs continuously when the trigger is pressed but the main arc replaces it when you start the cut. If you forget to put the work clamp on, the pilot arc will continue to run without the main arc. Since the pilot arc is about 20 amps, it will cut 1/8" steel, just not very clean and isn't intended for that purpose. The pilot arc burns off paint and rust to allow the main arc to start... as I understand it.

[performance]

Are you touching the metal to get it to refire? Try backing your air pressure down to 40-45 to see if it will restart...or turn your post flow to 0.

[Mr120]

I believe the pilot arc is basically to ionize the air in the torch head. The ionized air then becomes a conductor for the main arc to flow through as the main plasma stream. Although much weaker, the pilot arc itself creates some plasma which is still hot enough to melt metal but because it is arcing within the internals of the torch itself as opposed to arcing between the torch tip and the metal surface, your consumables are going to get eaten up quicker.

I really like the tip saver feature in the new PowerPlasma models. You have the option of having the cutter turn off the pilot arc after the main arc has started.

[sticks]

As much as I like digging up old threads, I have the same issue when cutting expanded metal with my PP50. I can pretty much count on replacing the tip and electrode after cutting a 4' strip due to the repeated starting. Once I lose proximity to the metal the arc goes out and I have to wait for restart (trigger is kept depressed). Air pressure, CNC mode, nothing makes a difference.

At least I have found a way to somewhat clean up the inside of the tip (remove the arc pits) and the electrode for reuse for gouging or other cuts where I am not concerned with precision.

I remember reading somewhere that someone had hooked up a ground wire to the torch to "fool" the machine that it is still in proximity for cutting. I may try that.