Plasma cutting - how much air do I really need?

[joshuabardwell]

I have never owned a Plasma cutter but I plan to get one for home use. How much air flow do I really need? My compressor is a 2.5HP 10 Gal Harbor Freight jobbie.

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.

 

[yomax4]

Look at the Thermal Dynamics Cut Master 42. It has Vent to Shield technology that requires only 3.2 cf of air. Still cuts 1/2 and it's 115v / 230v. you can use your comperssor with it. At worst on the other units you can cut a minute, wait a minute etc.

 

[joshuabardwell]

I have a small Oxy-Acetyl torch kit that I can use for crude cuts up to 3/8".

If you have an O/A torch that you already know how to use, I'm not sure why you're looking at plasma, unless you just really want a plasma, in which case more power to you. Especially since you say you can't step up to a 220v compressor right now, I think you're going to have a hard time making plasma work. I don't use O/A myself, but I have seen others produce perfectly nice cuts with it. Sure, it takes some skill, but plasma takes skill too. Maybe your time would be better spent practicing with the O/A torch, and put the thousands of dollars you would put getting set up with plasma into something else?

 

[jgayman]

If you have an O/A torch that you already know how to use, I'm not sure why you're looking at plasma, unless you just really want a plasma,

Let me reset.... I'm not an expert with the torch. I probably should have been more specific. My torch kit is one of the small 10CF/20CF portable units. Again, it meets my needs. Saying I "know how to use it" would be a stretch. I can turn one piece of metal into two. I am sure I can cut just as ugly with Plasma.

I would like to eventually get rid of my torch. I don't like messing with the gas as I really don't have a proper place to store it.

 

[joshuabardwell]

I would like to eventually get rid of my torch. I don't like messing with the gas as I really don't have a proper place to store it.

Got it. Not wanting to deal with the gas is the main reason I don't cut with a torch now. Well, that and the up-front expense of getting set up, but that's similar for O/A vs. plasma.

The Thermal Dynamics plasma looks really exciting if it can run off a small portable 110v compressor.

 

[Buckgnarly]

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' $$

 

[jgayman]

The Thermal Dynamics plasma looks really exciting if it can run off a small portable 110v compressor.

Yes, the Cutmaster 42 looks nice and at 3.2 CFM should work with a smaller compressor.

 

[jgayman]

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' $$

Yes! That is the one other thing I forgot to mention. I actually wasn't aware that Oxy/Acetyl had so many limitations when I got it. It has served me well but I'm ready to swap the bottles for an electric cord. I have to keep my unit in an unheated storage shed which is an issue when the weather is cold. I tried using it last weekend and my Acetylene pressure was ZIP.

 

[BukitCase]

When I got my plasma cutter I looked all over the net for reviews - the Hypertherm PM45 was the ONLY one in that size range that I could find ZERO negative comments about, other than price (around $1600) - it's rated for 1/2", but I've seen videos (soon to be verified personally) of cuts over 1". I have a large (21 CFM, 80 gal., 5 REAL horsepower (Baldor motor, 25 amps @ 240 volt) compressor, so it's not starved :=) - I set up a manifold just for that, with a spare outlet in case I want to run another tool. Since this compressor puts out 165 psi, my manifold consists (in order) of a regulator (so I don't blow anything), then this Amazon.com: Astro Pneumatic 2618 Air Control Unit, 120cfm Capacity: Home Improvement as a pre-filter, then this Amazon.com: Motor Guard M-100-KIT 1/2 NPT Clean Air Filter Kit: Home Improvement -

So far, I've only put maybe 10 hours on it total, with NO sign of wear on consumables. As previously mentioned, practice is everything. A cutting guide also helps make you look like you know what you're doing, and weren't "CUI" (cutting under the influence)

The PM45 is made here in the US - the Cutmaster 42 is NOT. Last I checked, the Cutmaster 52 and up were still made here.

Check out several videos of cuts made with the 45 here

Powermax45 handheld plasma cutter | Hypertherm

Bottom line - no buyer's remorse here... Steve

 

[jgayman]

Thanks Steve.

Let me ask a dump question. Is the volume of air only required for the max cut? Example, the PM45 specs say like 6CFM. But if I am only cutting 1/8" or 1/4" can I assume it would need significantly less than 6CFM?