PP256 Perplexing Plasma Problems

I have a PP256 I purchased in 2012. Have never been able to make friends with the plasma cutter, so have not used it.


Today I had to cut a 15" circle out of 1/4" hot rolled steel so I thought I'd give it another try. I connected the torch and re-checked the settings and polarity, and made some test cuts on the corner of the work piece and everything seemed to be working. First problem was the arc wouldn't fire using the circle cutter. Only if I free-handed it using the wire standoff would it cut. So I drew a circle and started cutting it free-hand.

The information I've gathered indicates that at 60A and 75 psi, cutting speed through 1/4" mild steel should be about 70 inches/minute, or a little over 1 inch/second. I couldn't get it to keep from blowing back unless I cut about 1/2"/second. When I turned the piece over I found that slag had obliterated the kerf and I had to grind it off and free the part using an abrasive cutting wheel.

I've never been able to get the plasma cutter on this machine to cut cleanly. Other plasma cutters I've used seem to cut cleanly with the same settings. Wondering what I'm doing wrong.

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Hard to tell from the picture, but in one pic it looks like the standoff is allowing the tip to be way too close to the metal to be cut. Looks lie the standoff is either melted or bent, etc

Quote:

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Originally Posted by ljdm1956

Hard to tell from the picture, but in one pic it looks like the standoff is allowing the tip to be way too close to the metal to be cut. Looks lie the standoff is either melted or bent, etc

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Yes, the standoff melted from the backsplatter and the remains of part of it was lodged in the kerf. My question is why this plasma can't cut 1/4" reliably when it should be able to cut 1/2" no problem.

Are you sure you had the swirl ring installed properly in your torch? If your circle cutter was grounding out your torch, then something is wrong in the torch head. Either not put together properly, shorted out with slag, or a combination of both. For sure your torch is toast in those pics. Have to take it apart and inspect to see what is salvageable and what needs replacing.

Once the torch is messed up the cuts will be bad. First things to check is 72PSI on that torch, clean dry air. Swirl ring in and right side up on that model. Then it is just the right standoff. Pop the torch open and take a picture and we can see if there is any damage.

Here is what it should look like (if I can attach from my phone). Crap, no dropbox on this machine. But I have USB cable.

Attachment 11861

Be sure you have 72 psi while the air is flowing through the torch. If you set it to 72 psi static, it may drop to 60 psi or lower while cutting. Dry air is a must.

Your standoff may be adjusted (bent) too high. I prefer to remove the standoffs and cut free hand. The stand offs are training wheels and must be adjusted.

Mark/Mike/Zoama,

The air was about 75 psi, from a 30 gal tank slow speed belt drive compressor that's older than I am. The line from the tank to the regulator on the back of the PP256 is 3/8" hose, 15' long. Water traps are clear and the tank has an automatic drain on it, too, and the ambient conditions are 70s and dry.

Here's a pic of the parts. It's hard to assemble one of these torches wrong. But in my case all I've done is take the tip off to inspect the insides and swirl ring. The parts are original.

The standoff was set so the tip was about 1/16" from the metal work.

I wonder why the cutting guide (training wheels type) kept the torch from firing. The tip appears to be insulated.

Anyway, here's the parts:
Attachment 11864