What can you expect from a plasma cutter?

PineRidge · Jan 5, 2005

Have no experience with plasma cutters whatsoever so really need to draw off the TBN collective knowledge base. I like to ask lots of questions and do my homework before making any purchase.

Curious as to how much control one might have when freehand cutting 3/8 to 1/2 plate steel while working with a plasma cutter. What quality of cut should one expect, will cut edges still need to be dressed with an angle grinder to make them look presentable or will they look rough like an oxyacetylene torch cut?

Is a welding helmet required for plasma cutting?

Can a plywood template be followed with a plasma torch tip without setting the template or worse on fire?

What size machine would be the proper size for cutting 3/8 to 1/2 steel in a 220 volt model?

Are some machines cheaper to operate as far as consumables? What are consumables and why are they used up by the machine?

Are plasma cutters rugged? I mean I have had an old Lincoln buzz box for 20 years and if plasma lasted half as long it might be easier for me to justify the cost of one.

How long should one be able to still purchase consumables before the style of the machine is obsoleted?

Thanks for being patient with my many questions.

Tractors4u · Jan 5, 2005

I bought a small Hypertherm plasma cutter a few years back. I wish I had bought bigger. But I will give you my two cents worth.

( Curious as to how much control one might have when freehand cutting 3/8 to 1/2 plate steel while working with a plasma cutter. What quality of cut should one expect, will cut edges still need to be dressed with an angle grinder to make them look presentable or will they look rough like an oxyacetylene torch cut? )

Your free hand control will be as good as your hand is steady. When you shop for a plasma cutter you may see them spec'd out and read something like "Cuts 1/2 inch - Severes 3/4 inch" meaning that you will get a smoother cut on 1/2" material but when you go after 3/4" it will look more a torch cut it.

( Is a welding helmet required for plasma cutting? )

No, I usually use tinted safety glass.

( Can a plywood template be followed with a plasma torch tip without setting the template or worse on fire? )

You should be able to use a plywood template. I have never used one but I know of people who have. The majority of the hot stuff is blown out the bottom.

( What size machine would be the proper size for cutting 3/8 to 1/2 steel in a 220 volt model? )

Not sure about that question, depends on the manufacturer.

( Are some machines cheaper to operate as far as consumables? What are consumables and why are they used up by the machine?)

I have only used one brand, mine. The consumables are the tip shields, electrodes for the "torch". I was going through them real quick when I first got mine. As my technique got better, I went through them slower.

boustany · Jan 5, 2005

Ask these fellas

http://www.hobartwelders.com/mboard/

Lotsa of good advice. I'm waiting a bit longer to buy my plasma cutter. My understanding is, for the most part, the bigger the better because you get cleaner cuts on thicker material. The above board suggested a '625' class machine.

Also, remember that plasma cutters got consumables, so you want ready access to spare parts.

jimgerken · Jan 5, 2005

The cut kerf is so fine, it will show your every heartbeat and breath in the final cut. Seriously, it cuts so fast and so fine (in thinner materials anyway), if you blink, it shows in the final product (before grinding). Consumables: The tip goes first, and this leads to a flame shape that is irregular. If your product isnt fussy, it doesnt matter, you can run it till its really bad. It simply comes out at an angle and isnt quite as well defined. Starting is tough on the consumables. And penetration is about the worst, cause molten metal flashes back upward at the tip. The fumes from plasma may be more damaging than most other metalwork. The metal is cut so finely it is like fine dust in the air. It would be best to do this work outdoors. Or at least collect the fumes/dust at the source (under the cutting grate for instance) and duct it out. I have found that to dress the edges to remove the dross (the molten waste on the backside of the material) it is very easy to simply shear it off with a small hammer, hitting the dross with a shearing motion. It will snap off easily this way. Do not try to grind it off. That will bind it on harder. Grind later, but knock off first. All plasma cutters bevel the workpeice. Some more, some less. Thicker materials are worst, its almost unnoticable on thin stuff (under 0.125"). The bevel is about 6-8 degrees, and forms in a direction depending on your direction of travel. If you cut a circle, it will bevel one way on the right side, and the opposite way as you round the top and start cutting back toward you on the left side of the circle. If this is unacceptable, you need waterjet or laser. I would not expect the plasma machine to last as long as a good old welder. The old welders were simply copper wound transformers, not really anything to go wrong. The inside of my plasma cutter looks a lot more like a computer than a welder. /forums/images/graemlins/crazy.gif

EastTexFrank · Jan 5, 2005

I'll try to answer the part that nobody seems to have covered yet. I have a little 110 volt plasma cutter that the literature says is good to cut 3/16" and up to 1/4" with "proper technique". Obviously my techique is not proper since about an 1/8" to 3/16" is about all I can cut cleanly and I have noticed that they have since changed the specification to top out at 3/16". Any 240 volt machine should be able to handle the range of thickness you are looking at, the smaller ones maxing out at around 1/2", bigger ones going up to an 1" and thicker.

It did take a lot more practice than I thought to use it reasonably well but it really is great for cutting patterns in thinner metal and you can cut so close to your line that it cuts down on grinding time. Now, I wish I got the smaller 240 volt type that you are looking at, just to get more cutting capacity.

The cut edge is a lot smoother than a torch but still requires dressing with a grinder. As for using a plywood template ... I don't know. One of the things that I have found using my little cutter is that the stand-off and angle are very important in getting a good, clean cut, so as long as it doesn't interfere with that, it should work OK.

slowzuki · Jan 5, 2005

Link to my webpage on plasma cutters:

http://moose.ca/~slowzuki/slowzuki/tech_info/Plasmacutters/

I have used it a while now and it does wonderful things. Maybe not worth the price I paid but it has saved my arse on a few hard cuts that the torch would have set something on fire.

I have learned it is not the tool to be hacking stuff with, a regular torch is your tool for that.

tomrscott · Jan 5, 2005

Harbor Freight has a small 230VAC plasma unit for under $800 that might do a job I've got (about 2500 inches of 1/4" structural steel plate). Is it a mistake to get a Chicago Electric brand? Can I use consumables for another brand if these get scarce? Or do I have to be able to get special stuff for this model?

Is there enough difference in these machines to justify spending hundreds more for a different brand? If so it probably means I don't get a plasma cutter... /forums/images/graemlins/frown.gif

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=45949

Soundguy · Jan 5, 2005

Brent gave you good info.

The units I'm familiar with use compressed air.. It needs to be clean.. so use either a reneuable filter.. or disposable (painting) filters.

Tips get used up. You can get a drag tip setup and it lets you place the torch esentially on the workpiece, and that stedies the cut.

As others have said. Every micro-movement your hand makes shows up in the work. I've cut with a jig with great results.

Also.. different manufacturers have units with different amp requirements for certain cutting.

The slag can literally be knocked off with the flat side of a standard chipping hammer.. just drug across the cut.. In other words.. NO grinding to remove slag.

Soundguy

Dargo · Jan 5, 2005

I'm one of the silent stalkers on this thread. Over the years I've become quite proficient welding and using my DeWalt chop saw, sawsall, torch & grinder. That being said, I've had this burning desire to know more about the plasma cutters. Every time I speak with someone I know about one that knows what I weld, they always tell me that I need a model that costs about 1700 bucks. That has always stopped me in my tracks. I saw the ones at Harbor Freight, and figured that I'd waste $800 on their plasma cutter. I've yet to receive or use a single Chicago Electric item that I would describe as even of "average" quality. Everything of theirs that I've seen and used has fallen into the category of positively "throw away" junk. That has included chop saws, angle grinders, drills, drill presses, buffers, and an electric impact wrench. Each of the above items broke during the very first use. I've completely ruled out anything by Chicago Electric. Lesson learned! /forums/images/graemlins/blush.gif

That having been said, exactly how nice is it to have one of the $1700 dollar Miller or Hobart or Lincoln models? Are they worth the money for the recreational user? Do they save that much time, and do they make that and complex cuts? I'm in that category where I won't throw away $800 for a junk Chicago Electric model, but can't justify the cost so far of a good mode. /forums/images/graemlins/confused.gif

PineRidge · Jan 5, 2005

Lots of good advice from you guys so far, Thanks.

If we make a purchase on a plasma cutter we want to be sure that it will handle the thickness of steel plate in the 3/8 to 1/2 inch range. Think this range would best fit the construction or modification on most tractor implements.

Ken (slowzuki) supplied a lot of good information as well as a link to the Powermax 600 which by the way sounds like a very capable and well built machine. I would think the torch shielding that enables you to drag the torch directly on the workpiece might be a big plus and give better control than stand-off devices used on other torches.

I like the idea of being able to easily follow a plywood pattern with the torch to cut multiple pieces.

Anyone else have any other recommendations to a particular make or model without breaking the bank too bad? The Powermax 600 looks to be about $1400-$1500.