Plasma cutting - how much air do I really need?

[jgayman]

I think he said a 220v compressor was not an option right now due to space.

Unfortunately this is true. I won't say money is no object but if I had the room and an available circuit I'd be sporting a 12-14 CFM unit already.

I appreciate all the suggestions. I'm just trying to determine the largest cutter I can run with my facilities. A year or so down the road I may be able to add a bigger compressor and I wouldnt want to be limited by having bought a too-smalr cutter in the first place.

 

[grsthegreat]

My plasma cutter is hooked up to a 80 gallon tank, uses 12 SCFM @ 90 PSI, and its running nearly constantly while cutting.

My Hypertherm 1000 uses lots of airflow.....especially when cutting the thick stuff.

Not sure what the smaller plasma cutters need in air flow.

When i worked on a metal stud building as few years ago, contractor had a nice portable plasma cutter with enclosed compressor. it could cut metal studs great...but was hard pressed to cut thru steel structural framing.

as was stated earlier, a dryer and filter is a necessity. Moisture will destroy the cutting tips of a plasma cutter. I use the harbor freight refrigerated dryer, and have been VARY happy with it for many years now.

 

[grsthegreat]

Somebody correct me if I'm wrong, but I was under the impression it was realistically impossible to get more than about 2 HP out of a typical 120v outlet. No? HP and cfm ratings on those little compressors are optimistic.

I have basically the exact same compressor, but with an 8 gallon tank, and only a "2 HP" motor (air-quotes intentional). It is rated at 4.5 cfm at 90 PSI and I have measured it at about 4.2 cfm. If you want to estimate the actual cfm of your compressor, you can follow these steps. They're not the most accurate, but they will get you in the ballpark.

1 HP = 746 watts

a 20 amp , 120 recepticle provides 2,400 watts max (1,920 watts continuous duty). so theoretically a 2-1/2 - 3hp motor could work.

 

[grsthegreat]

Plasma allows you to cut anything conductive, not just steel like oxy. I do not cut much Al, but when I do the plasma is nice! There is a pros and cons for both, and f you can swing it both is best....but lots o' $$

yup... i cut lots of diamond plate aluminum with my plasma table. it sure cuts clean.

 

[joshuabardwell]

When i worked on a metal stud building as few years ago, contractor had a nice portable plasma cutter with enclosed compressor. it could cut metal studs great...but was hard pressed to cut thru steel structural framing.

The only ones of these I have heard of run off of 110v and are therefore limited in the thickness of metal they can cut. If you know of a 220v one, I'd be interested to hear about it.

 

[grsthegreat]

The only ones of these I have heard of run off of 110v and are therefore limited in the thickness of metal they can cut. If you know of a 220v one, I'd be interested to hear about it.

this one was 110. never seen a small one 220 either. this one sure burnt thru tips though.....was crazy costly to use.

 

[BukitCase]

"A year or so down the road I may be able to add a bigger compressor and I wouldnt want to be limited by having bought a too-smalr cutter in the first place." -

Here's a thought - current draw won't be as high when cutting thinner metals, and even though the air requirements won't change, you can stretch the amount of cutting time by adding a secondary air tank connected to a smaller compressor - they make portable ones that are 10 or 11 gallons; I have one. IF you only need 90 psi and your compressor shuts off at 125, instead of a reservoir of 4 gallons, you would have 14 gallons.

I know this won't make your compressor any bigger, but it WILL extend the time before your pressure drops enough to shut off the plaz. So, if you're cutting 1/4" material you're cutting at 1 inch per second - even if your air only stays above cutoff pressure for a minute, that's 5 FEET of cut in that minute. Even with 1/2" stock, the 45 will do 20" per minute.

Not trying to sell you something you don't want or need, only pointing out some options so you WON'T be sorry you didn't get more capacity when you DO get that larger compressor.

Personally, since I bought the plasma and a Miller 211 my stick machine's been gathering dust and my O/A bottles have only gotten used once, when a bucket curl cylinder on my 580B didn't wanna cooperate any other way (seal kit)

That's my story, YMMV :=)

 

[Boris1]

What are the thoughts on the Hobarts with the built in compressors, I had a gas supplier tell me to stay away from them but he did not elaborate? (and yes, he did not sell them)

 

[Buckgnarly]

What are the thoughts on the Hobarts with the built in compressors, I had a gas supplier tell me to stay away from them but he did not elaborate? (and yes, he did not sell them)

Usually less amps, more to go wrong. If you are getting a plasma then most already have a shop compressor, so why pay for something you have?
On a plus side though, they are great if you are looking for portability, but I really do not see any other advantage.

 

[yomax4]

If you want a 1/2" machine with a built in compressor 230V look at a Thermal Dynamics Dragon Plus.