Plasma Cutters

**101RRS** · 14th January 2014, 01:04 PM

My oxy acetelyne bottles are getting low and will no be keeping them once they are empty.

I am thinking about getting a plasma cutter - lightweight domestic grade for use in the garage. I can do a search and learn how they are basically used but the gas has me a bit confused.

Searching I see that basically there are four gases that can be used depending on size of job and quality of cut:

Compressed Air is the most commonly used gas for lower current plasma cutting and works well for most metals from gauge thickness to 1 inch. It leaves an oxidized cut surface. Compressed air can also be used for plasma gouging on carbon steel.

Nitrogen is often used for higher current plasma systems and for cutting materials up to 3 inches thick. It produces excellent quality cuts on most materials.

Oxygen is used when the highest quality mechanized cuts are desired on carbon steel up to 1 -1/4 inch thick. The cut face is smooth, and dross is easy to remove. Oxygen can also be used on stainless steel and aluminum, but it produces a rougher cut face.

Argon-Hydrogen Mixtures are generally used for cutting stainless steel and aluminum. They produce a clean, high quality cut face. Argon-Hydrogen is required for mechanized cutting of any material more than 3 inches thick. This mixture also provides an excellent gas for plasma gouging on all materials.

Given my requirements - based on the above compressed air would be suitable but I am open to suggestions noting I am only after basic cutting, nothing really think and I want to get rid of bottes.

With compressed air does it need to be in bottles or can air from an air compressor work - I have a 17cfm compressor in my garage.

Thanks

Garry

**Slunnie** · 14th January 2014, 01:53 PM

Unless its for a specific purpose then compressed air is good. From the air compressor is perfect.

**heichen** · 14th January 2014, 02:12 PM

compressor air is fine for anything you might need to do, even stainless.aluminium, bronze. Most plasmacutters come with an air-filter.If not, use a good filter that removes moisture (as used for spray painting), moisture shortens tip life.

**101RRS** · 14th January 2014, 02:39 PM

Thanks for that - basic plasma cutters are pretty cheap these days and if I don't need bottled gas that is even better.

Cheers

Garry

**wrinklearthur** · 14th January 2014, 05:22 PM

A DIY ( or a Do In yourself ) Plasma cutter.

http://www.metalwebnews.com/howto/plasma/plasnator.pdf

This DIY or a cheap Chinese knockoff?
.

**Hymie** · 14th January 2014, 11:03 PM

A decent compressor, not one of those 2.5HP jobbies from S.... Che..
Make sure you have a decent water trap and keep it drained.
Be prepared to blow out a few consumables as you learn.

**spudboy** · 15th January 2014, 09:10 AM

Not sure how thick material you want to cut, but if it is thick stuff, like say 25mm steel, you'll need to get a good brand with spare parts backup.

If it's only thin stuff, like 1mm or 2mm, it's not so important and maybe a chinese version will do the job just fine.

If you've got the coin, Hypertherm are the one to get (in my opinion).

Once you've used a plasma, you can't imagine cutting metal stuff with a grinder or a hacksaw (or even tin snips) ever again! We even use ours to cut corrugated galv sheet. 1mm kerf - and very accurate.

Cheers
David

BTW - we just use compressed air but we have 2 filters, one at the compressor (part of the regulator) and another just before the cutter.

**101RRS** · 15th January 2014, 10:01 AM

Originally Posted by spudboy

Not sure how thick material you want to cut, but if it is thick stuff, like say 25mm steel, you'll need to get a good brand with spare parts backup.

Just light stuff - probably no larger than 5mm.

**steveG** · 15th January 2014, 10:25 AM

Slight hijack, but probably useful info for the OP.

I've got a Mitech 3in1 TIG/MMA/Plasma machine. From memory the plasma function is 40A.

Have only played with the plasma a couple of times and not very successfully. Blown out tips and got the feeling that I simply haven't got enough air supply from my compressor to make it work properly.

How would I know if its just insufficient air, and any other good tips for newbies from you experienced plasma users?
How sensitive are they to quality of consumables?

Steve

**spudboy** · 15th January 2014, 10:47 AM

Have you got a regulator on the compressor? You need to set the PSI to be what the cutter expects.

For example, my smaller 37A cutter wants 60PSI.

If you are supplying unregulated air to the cutter, it might be at 150PSI or whatever the full output pressure from your compressor is.

So even though my compressor tank is 150PSI (or whatever - high anyway) it needs to be reduced to the correct PSI via a regulator.

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