plasma cutter help needed

mroldstyle · Jan 20, 2011

Let me start by saying that I just got a plasma cutter, with no previous expierence. So I got it all hooked up, dissecant air dryer, filter, regulator, 50 amp breaker and started cutting. Well the results were anything but spectacular. I'm sure all due to technique. I realize theres a learning curve but thought maybe I could get some direction on here to shorten it up alittle. I statred out with 3/8" steel, had no problem geting through it, the problem was the slag building back up and "welding" the cut right back together. I tried going faster, going slower, more amps- less amps (40-50) more air - less air (50-70 psi) all with similar results. I started off using a standoff but had better results free hand, but still ended up having to go back several times to get a cut through. What am I doing wrong?
Thanks for any help.

jimcolt · Jan 21, 2011

Plasma cutters are not all the same. They perform differently, must be used differently, and have different capacities. If you provide us details about the make and model system you are using, I'm sure we can chime in and help!

Jim Colt

gwdixon · Jan 21, 2011

You might check the air pressure while the cutter is running. A long air feed line or a small in-line desiccant air dryer can cause a significant drop when the line is opened for cutting.

Removing the restriction or shortening the line will give you a fix if that is it. Plasma cutters have a high air demand.

When at rest, the air pressure will build back up to the correct setting and fool you.

mbrule · Jan 21, 2011

I would have to look at mine, but that air pressure sounds high to me.

You might want to try working with some thinner material to practice. I only have a small unit, forget the model but it is Thermodynamics smallest and maxes out at 3/8", I use mine mostly for sheet metal, in my experience, heavy slag is a result of too much current or a worn electrode.

Take it for what it is worth, I am no expert. But, when you get used to it, you WILL love it!

Mark @ Everlast · Jan 21, 2011

What unit do you have? It would help to be able to know. What type start?

mroldstyle · Jan 23, 2011

I have an Everlast powerplasma 50. After a little more use over the last two days its working better, so its probably a technique problem.
Thanks

Mark @ Everlast · Jan 23, 2011

It can be experience, and technique, for sure. However, give me a call and we can go over some basics. Also some pics might give a clue. Any slag formation should not "weld" over, and shouldn't reach significant levels until you get to about 3/4" or more.

One thing worth mentioning, is that the "standoff" has to be adjusted for best distance. Usually you have to adjust it to be closer to the metal, around 1/16 of an inch, no more than about 3/32. 35 amps and under should be able to be cut by drag cutting, without any issues, allowing clean bottom cuts. Too far of a standoff will result in a lot of slag on the back side.

mroldstyle · Jan 23, 2011

how do you adjust the stand-off? Also there was as much slag on top of the cut as the bottom.

J_J · Jan 23, 2011

The cutting air pressure for the Lincoln Pro-Cut 55 is 70 psi for 25 ft torches, and 75 psi for 50 ft torches. The air flow is adjusted with the purge button which gives full air flow. To much slag is caused by too much stand off.

Stand off is usually 1/8 to 3/16 in.

Mark @ Everlast · Jan 23, 2011

60-65 psi is ideal, for our torches, especially with the torches 15 ft or less. If you are getting slag on top, then you must be trying to cut like an O/A torch. You must be right on top of the metal to cut it with a plasma. The wire standoff is easily bent to the distance. Care to post pictures of the problem/unit?

Barring any issues with you missing the swirl ring, loose consumable or a issue with pilot arc transfer (which it shouldn't be if you are hacking through 3/8"), that is really about all that could happen.

Again, keep the torch about a 1/16" off the metal.

mroldstyle · Jan 23, 2011

That sounds like the problem ( to much distance) I'll practice keeping the tip closer. I cut thru 3/4" without much problem so I don't think its equipment failure. I'll post a pic but it wont be until Wed. when I'm back to a computer.
Thanks for the help.

patrick_g · Jan 24, 2011

I have the Hypertherm 600. It does 20-40 amps. The amp control knob when rotated CCW beyond the lowest amp setting turns on the air through the nozzle. This allows setting the pressure regulator dynamically instead of statically therefore compensating for all losses due to hose length, dryers, or whatever.

The supplied torch has a non-adjustable spacing for standoff and is intended to be lightly dragged across the work (I like a two hand grip as it gives me a much steadier result.)

I am not a welding guru and got the plasma mostly due to poor ability with O-A cutting torch and much more convenience. I get much better results with the plasma. One difficulty I sometimes have is like the OP, I cut through the material but it fuses back together after the torch passes by. Another is that the "arc" goes out and I have to release and reapply the trigger to try again, sometimes several times before getting a stable "arc." When it works OK for me it is a wonderful tool.

I like making wooden templates for cutting out circles and other shapes with such pro looking results. I clamp a guide board (like a rip fence for a saw) onto the workpiece and SHAZAM I get an almost sheared look. Terrific for cutting light gauge sheet metal, ending up with a "fire polished" edge with no "meat hooks." Beats snips 7 ways from Sunday.

My recommendation is get a coach and practice.

Pat

mroldstyle · Jan 26, 2011

Heres a pic of two pcs. of 3/8 I cut after adjusting the standoff.

jimcolt · Jan 26, 2011

Here are a couple of pieces stacked and cut with a hand torch on the Hypertherm Powermax45 (45 Amps). The top piece is 1/2" and the bottom is 3/4" for a total stacked thickness of 1-1/4".

The second picture is of two pieces of 3/4" stacked, for 1-1/2" cut.

I must say that both of these cuts were extremely slow, and are asking way too much of a 45 Amp unit that is sold with a max cut of 3/4" and a production cut rating of 1/2"....but it can be done. This was with the front of the torch resting right on the plate, edge starting, and dragging the torch along the edge of a piece of 1/8" steel as a straightedge.

Jim

Mark @ Everlast · Jan 26, 2011

two pieces of 3/8= 3/4". That's within the quality cut specs of the unit. It looks like some technique issues still, as there is a lot of gouging and stray marks on the cut. You'll see more improvement with more practice. What's your standoff distance now?

If you'd like to see some videos of one cutting well, then you can go here and see the videos, maybe it will help to visualize his technique: YouTube - EVERLAST PLASMA CUTTER POWERPLASMA 50 CUT 1-1/8"
YouTube - EVERLAST POWER PLASMA 50 PLASMA CUTTER PART 2

mroldstyle · Jan 26, 2011

Mark @ Everlast said:
two pieces of 3/8= 3/4". That's within the quality cut specs of the unit. It looks like some technique issues still, as there is a lot of gouging and stray marks on the cut. You'll see more improvement with more practice. What's your standoff distance now?

If you'd like to see some videos of one cutting well, then you can go here and see the videos, maybe it will help to visualize his technique: YouTube - EVERLAST PLASMA CUTTER POWERPLASMA 50 CUT 1-1/8"
YouTube - EVERLAST POWER PLASMA 50 PLASMA CUTTER PART 2

About 1/16 standoff

tractorboy5500 · Feb 14, 2011

Hey guys, I am in the process of buying a plasma cutter, any tips on a certain brand or make?? I have a Miller mig 180, its a good machine, but the Miller plasma cutters are very exspensive. Thanks.

jimcolt · Feb 14, 2011

There are many plasma cutters available from 12 to 1000 amps....hand held and mechanized. If you let us know what materials and thicknesses you would like to cut...then we could steer you towards the right type of plasma system! Major brands are Hypertherm, Thermal Dynamics, Miller, Esab There also are lower cost imported units avaialable as well.

Jim

patrick_g · Feb 14, 2011

There are no cheap good plasma cutters. I'd avoid brand X even though it will cost more for a name brand but you will never regret good function and longer trouble free service life.

This is one of those times when even I would avoid Harbor Freight and the like unless I had a knowledgeable friend who could test the unit in actual operation and I had an iron clad "Return it for full refund if it doesn't work to your full satisfaction" guarantee. Still, I think it would probably be a waste of time to go brand X.

One piece of advice I do feel confident in giving is, "Don't under buy... Get all the cutting power you will need. Nothing is so frustrating as trying to work with an underpowered (for the task at hand) tool. I bought a good brand (one of many), a Hypertherm... but too small... I was splitting a 12 inch pipe lengthwise to make feed troughs and was growing older way faster than I was cutting the material. Took the unit back to the welder supply shop and traded up. Much much happier now with 20-40 Amp unit. Enough power for my needs.

Pat

tractorboy5500 · Feb 14, 2011

jimcolt said:
There are many plasma cutters available from 12 to 1000 amps....hand held and mechanized. If you let us know what materials and thicknesses you would like to cut...then we could steer you towards the right type of plasma system! Major brands are Hypertherm, Thermal Dynamics, Miller, Esab There also are lower cost imported units avaialable as well.

Jim[/QUO

5/8" and smaller