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Plasma Cutter

cobbadog

Registered
Not sure if it is the right place for this topic but here goes.
I am considering buying a plasma cutter for doing my cutting. Mostly is body steel but sometimes a bit heavier and up to 10mm (3/8") thick. So far from my research anything from 40 - 50 amp unt will do the job for me. Then I have a good air supply and the units I have looked at come with their own regulator/driers and apparently it is important to have dry air supply.
My research so far has not answered my curiousity about settings especially for the air pressure. I watched one video where the user was working on 50 amps but just travelled at different speeds with the cutter on differnt thickness steels. Sounds ok in theory but still no clue as to air pressure.

Any thoughts on this is greatfully appreciated in helping me make a decision on what I should buy and how to use it.
Cheers Cobba
 

gustavus

Banned
I had a Chinese Cut 70, machine won't trigger unless it has 60 psi. The Panasonic torch was a bit of a joke, but the inexpensive consumables make up for any aggravation.

Shortly after getting the plasma it quit working, the seller wasn't any help and probably knew less about the machine than I did.

Since I figured the purchase was at a loss decided to remove the cover and what I discovered was a set of contact points with one contact arcing to one of the wire inside when it should have been arcing between the contacts.

It's those contacts that make the high frequency start possible, anyhow by moving the offending wire further away solved the problem.

I used that machine for a couple of years and cut many tons of scrap metal into manageable pieces.

Replaced the torch once because I had dropped a heavy piece of iron onto the hose severing it and the copper cable inside.

After the wife got a bad case of cabin fever I liquidated a few things then went on a holiday.

Most of the metal I was cutting was in the 1/4, 3/8, 1/2 and 3/4" range, I went with the 70 amp simply because the duty cycle aka stupid cycle would be higher.

Often we forget about duty cycle exceeding the machines rating only to see it go up in smoke.

Your new plasma will amaze you, if you've ever cut metal covered in grease or oil with an oxygen rig you would be familiar with flare up once the oxygen trigger has been pulled,

Cutting metal with half an inch of rust scale or a large truck with a double clad frame with a layer of scale in-between the metal channels - plasma zips right through like a hot knife slicing through butter.

The oxygen cutting torch when the trigger on the torch handle is activated streams a lot more oxygen than is needed for the cut, while plasma does not add any oxygen to make the cut.

I've cut things with plasma that I would never attempt with an oxygen rig.
 
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cobbadog

Registered
Thank you for your invaluable input gustavus.
Some of the machines I have looked at online do not come with a power plug to plug into the power supply. When asked why they just say we import to many different countries and my reply is that you are responsible to order the machines with the correct plug for each country and the manufacturer will supply and do this for a very small extra charge which of course you would pass on,
As soon as I fit a plug and if something fails I can only imagine that they will say it is my fault as I fitted the plug so these ones are off the list strtaight away.
 

G.M.Johnson

Subscriber
Last Subscription Date
11/05/8018
I had a Miller Xtreme 375 portable at work and we pretty much cut through anything, within reason of course. It's rated for up to 3/8" but if you go slow it will do 1/2". One time I used it to cut up a large Carrier chiller unit and it only timed out a few times. Was a great unit and did pretty well on 120v but when we ran it on 240 it really would cut then. Of course it's a little pricey. Depends on your budget though. I have used a few other portable cutters and they worked pretty good as well but I can't remember the make. None where Chinese crap though.:)
 

dkamp

eMail NOT Working
Some of the machines I have looked at online do not come with a power plug to plug into the power supply...
This is ALWAYS the case with imported units... but equally common in domestically-sourced 'non-homeowner' grade units.

Imported, simply because they don't know what type of receptacle you're connecting it to, they just ship it without a plug and make you figure it out.

Non-homeowner grade... commercial and industrial-grade units feature multiple choice voltage input. Here in the US, a homeowner-grade unit would run on either 120v/20A circuit, or a 240/20A, and each have their own type of receptacle. If i was running higher power of a commercial or industrial, it could be running on 208, 230, 240, 277, or 480v... and depending on the unit, that might require reconfiguring the wiring on the inside, but it would most certainly require the power connection to either be hard-wired into a junction box to mains via dedicated fused shutoff switch (in an industrial environment) or use a special receptacle and plug in a commercial shop.

The general rule is that you'll need a certain amount of current for a certain amount of thickness of a given material. My 100A plasma will easily cut through 1" steel on a continuous-duty operation (no stopping to rest). If I slow down, it will SEVER 1.5" or so... but the difference between 'cut' and 'sever' is that a cut will be clean, with good geometry. Sever will make two pieces from one, but it won't be particularly pretty.

I've heard guys say that X power will cut Y thickness, and while that's a fair predictor for some, it is not a perfect assumption- some metals require more, some require less... but just as much importance is getting adequate duty cycle for the kind of work you want to do.

Air pressure and flow is dependant upon the nozzle, power level, and the thickness you're applying it to. Too much pressure makes a thick cut nasty... Not enough pressure means you don't get all the way through. Fortunately, once you get using a particular unit on regular stuff, you don't have to change it much, or often.

It sure is nice to not have to worry about running out of oxygen and acetylene on a Sunday.
 

uglyblue66

Subscriber
Last Subscription Date
11/07/2018
I am not real sharp on the plasma cutters but I have 1 and I use it alot when working with metal.Best money you will spend if you build stuff or repair things that require alot of cutting.It has replaced my cutting torch for the most part unless it is BIG or some other issue.
I have a Hypertherm 380.A older unit that i bougth new but was a display model,got it a bit cheaper.I think 1100 bucks at the time. Alot of money,BUT I have done nothing to the machine but use it for close to 10 years now.It requires I think 90 psi.
I bought 1 that needed a air source as I had been told that the 1's with built in air tend to give trouble.
But the main thing to keep in mind is making sure consumeables are avaliable for what ever kind you get.
There is a Cut rating and a sever rating on most. Cut means a decent clean cut,all but ready to work with.Sever is it will make 2 peices out of 1 but there will be some grinding and clean up before the metal can be used.
 

ibdennyak

Registered
I am using a Cut60 (generic Chinese from Ebay). It has been working well for two years. Before that I had another Chinese version that worked OK, but didn't have the High Frequency start, so it ate tips quickly.

I hate to admit it, but they have both been more dependable than in the 90's I bought an esab. (name brand). That thing was in the shop more than I used it. They even gave me another brand new machine and it was about the same. I think that may be because the technology was in it's infancy, and it was more of a lab gadget than an in the field machine.
 

gustavus

Banned
Just watched a couple of demonstration vids of people showing off their Cut60 plasma machines.

In a few of the demo's the machines were connected to 1/4" coiled air supply lines and it was obvious cutting performance sufered.

On my plasma I had a short 3/8" pigtail connected to the rear of the plasma which in turn connected to a 50 ft air line with a 1/2" ID.
 

cobbadog

Registered
Work got in the way of doing any further research but I do appreciate all the replies here, I find it helpful, so thank you.
Most of what I have been looking at is genuine chinese made and all of the work is jsut for my restorations I do for our selves. Mostly sheet metal and up to around 1/4" (6.5mm) with the ocassional stuff up to 3/8" (10mm) but if that is too much I simply go back to the cut off disc on the grinder and I have a 9" one of them.
60psi seems to be the most common figure thrown about but as mentioned this will depend on the type and thickness of the steel so it is trial and error.
Some time back I bought my first MIG welder and started on gasless and now on gas and I prefer the gas over gasless. I am still learning to drive it properly but with each use I do get a bit better and by following advise offered on this site I will be very confident with it in no time.
So if all goes well tomorrow I hope to find time to carry on with my research and keep an eye out here for more hints and tips. Oops, I nearly forgot to mention about the consumables. Yes, very important that they are readily available and not over priced. IT appears that most of the guns on these genuine chines ones are similar if not the same.
 

oldgoat

Email NOT Working
Check out Magnum welders in Victoria. I bought a 40 amp one off them 4 years ago and have flogged it ever since. Run at about 60 psi and it will cut 1/2 inch if you are not in a hurry.
 

cobbadog

Registered
I still have not acted on my future plasma cutter but getting close. I nearly bought a unit a couple of hours south of me that was complete with inbuilt compressor. Price was right but then I saw what it looked like and it had been abused beyond belief so I politely decline his P.O.S.
 

Peter Holmander

Subscriber
Age
71
Last Subscription Date
12/23/2019
Cobba: I wanted to buy one for a long time, but when the small units came out, they still were more expensive than I could justify. I finally pulled the plug on one last year. I ended up going with the Longevity Forcecut 42i It comes with everything you need. Built in air compressor with filter. When I was researching a machine to buy, most common praise of the 42i was being able to run on 110 or 220 volts automatically. It comes with the 220 cord and plug, but then they also supply you with a nice adapter so you can plug it into any 110 plug and run it. That makes it truly a portable machine. Of course, it does not cut quite as thick a material on 110, but it sure is handy if you want to take it somewhere and use it. On 220 volts, I have cut 1/2 inch thick steel all day long. It will cut 3/4 if you slow down the cut. There are vids of guys severing 1 inch thick stuff with it. I use it strictly for hobby cutting for my projects and I am happy with it so far. I run it off my garage compressor and the only thing I did do with it is I found some plans on the net about building and air dryer out of a whole house water filter. I made one of those and when I use the cutter I always run the air supply through that. Moisture free air is a must. Very easy unit to learn and use. One dumb mistake I made when I first got it was I forgot to attach the ground cable. It will cut without the ground, but it will screw up the tip really bad. When I bought it,,,the sales guy talked me into buying a consumables kit. I was not going to, but the guy told me that I would definitely need it. He was right. Hope this is of some help to you. It can be very difficult deciding on what machine to buy. Good luck. After posting this, I decided to edit it and make what I feel is a big plus on this machine. The machine comes wired with a rubber cord and 220 volt plug. But to be clear, it will run on either voltage without having to change any wiring or throw any switches. Pretty foolproof and easy. If you want to run it on 110, you just plug the short adapter into the wired plug that comes with the machine, and the plug the other end into a 110 receptacle. The machine automatically senses the voltage, and powers right up. The adapter cord is about 12 inches long and easy to store with them machine. Nice feature in my opinion
 
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cobbadog

Registered
Thanks for your input Peter. Australia runs on 240v and so far most but not all domestic rated units do not come with a plug wired on the input lead for our 240v and is the main reason I have not clicked on one to buy that would more than do the light work I intend to do with it. I'm looking at a 50a unit and so far only one is supplied as a plug it in the power supply and hook up your air supply and this is probably the unit I will buy. I have a couple of compressors that if needed for the small sand blasting cabinet I have, can be both plugged into my air lines that I fitted from one end of the sheds to the other. It is high pressure water pipe that you use blue glue to join the pieces and are air tight. Also has the sockets and T sections to screw in your own air line connections. At all outlet points I have air driers/traps with regulators on top. I also made it a point that when laying the pipes I made low points or risers that drop down with a drain tap on them. So far I only have had a very small amount of water drip out over the years. The new style regulator/ driers are also automatic in emptying any moisture once the air pressure drops.
 

Tracy T

Subscriber
Last Subscription Date
07/16/2019
Been following along, dont know much about these machines but have run one! The one i ran would cut like mad for a little bit then fizzle out. I think it had its own onboard air, suppose i was running out of air? give it a minute and it would go right back to cutting. I only got to use it the one time, heard latter it was trashed. That bunch could break a anvil with a rubber mallet though!
 
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