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.

billbill1 · Jan 5, 2005

The welders where I work have a red (Lincoln??) unit and it cuts almost clean enough that no grinding is required. I've seen misused units that the cut looked terrible. If the plasma cutter is used by a select few and a jig is used I think you would be amazed at the job of cutting they do.

Tevi · Jan 5, 2005

I've got a Thermal Dynamics Cutmaster 50.I've upgraded to a 50 ft lead and a 1Torch.I highly recomend the !Toech it saves on tips and cuts alot cleaner.It's defenitely worth getting a good brand and a 230v.I also reccomend the 70 degree tip

MMM · Jan 5, 2005

I use a 480v Unitor torch at work and it has wire guide that attaches to tip and is handy for keeping correct distance from work. I doubt plywood will last very long except on thin stock. We use flat bar as a guide for straight cuts. Speed and air press are a major factor in producing a clean cut.

BGL990 · Jan 5, 2005

I've got the Lincoln Pro-Cut 25 and really like it. A plasma cutter is WAY more convenient than an oxy-acet. torch and generally makes nicer cuts (although a torch can make incredibly clean cuts with little slag as well if used properly).

The output current capability of the plasma cutter is what determines the thickness of material it can cut. Mine is 25 amps and is rated for 1/4" clean cut and 3/8" "severence", meaning it will go through but not as nicely. I have managed to hack apart slightly thicker stuff than that, but it isn't pretty and is slower than a torch would be. The next step up in the Lincoln Pro-Cut series is 50 or 60 amps I think and is rated for 7/8". I often do wish I had gotten that model but it was double the price (~ $3000 CAD at the time). I was stretching it to spend the $1700 that I did on this model, so couldn't go for the bigger unit.

As long as you don't often need more than 1/4" capacity, a 25 or 30 amp unit should be OK. If you need more than that then you will need to step up to something bigger. I don't know if anyone makes a 40ish amp unit, which would be a nice size. The Lincolns seem to have a big gap between the smallest unit and the next size up.

You do need to filter your air supply very well. Water in the air will destroy the consumable tips quickly. I put two water separators/filters in series directly on the back of the plasma cutter.

I don't regret my purchase (other than wanting a bigger unit), but it was expensive, especially considering that I just use it for hobby purposes. If I had to justify the purchase to someone, I wouldn't be able to but I just figure that anything fun is expensive, so what the heck ....
/forums/images/graemlins/tongue.gif

Taylortractornut · Jan 5, 2005

my friend William has a welding shop and has a HyperTherm 2000 It cuts 3/4 pretty good and severs 1 Inch. He doesnt use his torches much at all now. I get Luan panels from work and make wooden patterns for him to trace with the cutter to make sheet steel patterns for my magnettic tracer torch.

TOMLESCOEQUIP · Jan 5, 2005

Pineridge.......I got my plasma cutter from these guys Plasma cutter a couple years ago...........They beat my local welding shop by about $700 on the model I bought. Good people to deal with & shipping on my hypertherm 600 was only about $30 and came in less than 3 business days................Tom

theonlybull · Jan 6, 2005

ok. i run a mahine shop with my father, and we don't have a plasma. for thin material, and stainless they are nice. but for anything over 3/16" a good hand on the o/a will do just as nice of a job.

i do have access to a hypertherm 50 if i need it ( local plant we work for has one), and i've used it a fair bit for stainless. it works nice on the SS, and i'm sure, if i spent asmuch time behind it as the o/a, i could probably do a better job.

IMHO, for general work, ( repairing tractors as you said), a good, o/a setup, with 4 hole tips, and the correct tip for the job will work just fine.

good luck with your purchase, and if you take good care of it, it will last you a long time.

Soundguy · Jan 6, 2005

At work we have a thermodynamics cutmaster 50... 50 amp.. cuts 1/2" and severs 3/4 like a torch cut.. though does 5/8" almost as good as 1/2". Unit was a tad over 2000. We end up doing alot of metal fabbing for our heavy equipment. It has saved us money over the gas axe and grinder method.. not to mention time. I'm not sure the casual tractor owner needs one for garage use though.

Same reason I only have a small 70 amp stick welder at my house.. because we have a powermig 250 at work, as well as a lincoln ac/dc 225 amp buzzbox, and a hobart 10kw genny/welder combo. if I need anyhting big welded.. I just tote it to work with me.

Soundguy

leaddog · Jan 6, 2005

I bought a T/D cutmaster81 this spring on ebay. $1867 del. It will cut clean 1in. and sever 1 1/4. It has been the handiest tool I have bought next to my welder. You do NEED CLEAN DRY air so by a good filter for your compressor. I cut out my shanks for my toothbar from 1in scrap for my first job and it took a learning curve but once I made my template right it goes good now. I do not have a steady hand so my cuts are not smooth freehand but with a template they are very smooth. I also got a circle cutting attachment and I have cut holes in 1in stock that are as good as cutting with a holesaw in a drill press.
The other thing that works very well is the gouging tips. You can remove weld beads and metal just where you want . I had to remove a bearing off a 1 1/4 shaft and I just cut it off and didn't put a mark on the shaft. Really saves time.
Yes a o/a setup will work but plasma is FAST. On thin stuff you have trouble moving fast enough. ON 1/4in it will cut 80in per min. Try that with o/a.
Consumables are not bad once you learn to operate properly and will be less than the cost of o/a. Just make sure you have a good ground on the part so you get a good ark, Other wise you are trying to cut and its not working and you are burning up tips and electrodes or so a dumb guy I know told me /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
I am really glad I bought mine and with I had done it sooner, and I recomend you check out the t/d cuttmaster. The bigger the better
Leaddog

PineRidge · Jan 6, 2005

Leaddog when you say template what materials are you using, wood or steel templates? I would assume that your template is slightly smaller than your finished cut piece, since the torch tip itself would add some width.

Does your torch allow you to make direct contact with the material that you are cutting or does it use some type of stand off? I keep hearing the term "pilot arc" is that how one starts the cutting process?

That machine that you are describing sounds to me like a major player.

Questions, questions, questions sorry but curiosity is a driving force with me.

TC-40D SS web pictures click here