OT: Oxy Propane cutting

Cutting tip size controls the pressures needed and the thickness that can be cut. If you give me some idea of what you intend cutting I'll see if I can give you an accurate answer.

no more than 50psi oxygen and about 4-7psi propane.

make sure you have a single stage 2 gauge oxy regulator that goes to at least 80psi [ie cutting reg] .

no real need for dual stage reg plus they are more expensive

note that propane or acetylene regulator will not show a great amount of bottle pressure if using propane , so in other words you might think bottle is empty when it actually isnt, its just that none of the gauges available show much bottle pressure with either fuel gas even on a new bottle .

if you want to heat materials there are heater nozzles available for propane use but not for acetylene .

get decent quality nozzles for best performance ie OERLIKON , or use PARWELD slightly cheaper .

if you are just cutting flat plate and want decent quality edge of straight lines etc then you may like to look at an EVOLUTION CIRCULAR SAW at 140 quid , this is like a normal wood type circular saw but can cut mild steel up to 10mm thick and also can cut aluminium and stainless steel with different TCT blades. each blade is 18 quid and will cut 80m length of material before resharp or new blade is reqd .

it will cut plate at almost same speed as you cut wood with similar machine .

hope this helps

Probably only steel sheet, tube/box some RSJ's so a max of about 10mm thick, I will find out what the gun is and tip size as well.

Rich

I've just dug out the specs sheet that arrived with a couple of new tips. The recommendations are below (pressures in bar)

Tip Size Cut thickness Oxy Press Propane Press

The only thing to watch out for is that you can get a high enough oxygen flow through your regulator - many that are designed for welding won't cope with the flow needed for cutting, although as you're only looking to cut 10mm it shouldn't be a problem.

It's ages since I've done any gas cutting - my little plasma cutter at home will cut to 12mm cleanly and for heavier stuff I use the one at work that's reasonable to about 40mm thick.

Bloody hell, you use a different definition of "little" to me ! Mine tops out on 7mm, and its single phase. Your "little" one is three phase ?

Steve

Single phase, 20A circuit. If I had 3 phase at home I'd be ecstatic but it'll cost me about 2 months wages to get the cables run so I'll pass on that.

That's what my tiddler runs on too. 12mm ? What's the difference I wonder.

Not that I have much call for 12mm plate cutting, but you never know.

Steve

During stardate Thu, 13 Oct 2005 22:29:21 +0100, Steve uttered the imortal words:

My 35 Amp feed Plasma tops at 10mm if my memory served me right. Single phase.

Clarke one.

Lee D

-- Success is going from failure to failure without a loss of enthusiam. Winston Churchill

Ah, someone else with a plasma cutter, I have a little one 25A 240v will cut about 5 to 6mm but eats tips is this a common thing ? like the plasma cutter quick and clean, never used gas cutting so I am giving it a go like the fact it is just the torch that you need to use and very self contained just the bottles and no mains or compressors etc:

Thanks for the replies keep it coming and I will see how it goes

Rich

I don't know. It's an inverter rather than transformer supplied one. And it's a no name Chinese made machine that claimed a 12mm clean cut when I bought it - and I was really surprised to find that it lives up to that claim.

Got mine from Machine Mart the Clarke plasma king 25, no pilot arc you have a sprung tip which starts the arc and its a heavy transformer type ( might be more robust, less electronics to go wrong ) and I think it is good for about 5 mm as they say in the instructions not a very good duty cycle though it soon cuts out on over heat so I try to give it a good rest to stop that hapening

Rich

Just where do you put the tip ? It should be against the stock being cut ? A little gap lets plasma at the tip bottom surface and I think that stuffs 'em.

Do you run the tip on a piece of sandpaper too ? I keep it very clean and I am some 35 feet of cutting 6mm through a single tip.

Steve

Yes, my SIP has the same problems. The lack of a pilot arc is a bugger.

Steve

enthusiam.

Pah - just toys ! My Hypertherm 900 will cut 22mm cleanly and sever

AWEM

Yes thanks for the advise, I do try and keep the tip on the work, have not thought of keeping the tip clean with sandpaper though will give it a try, thanks

What sort of air pressure do you use?

Rich To reply remove " spam "

About 70psi (which is much the same as every plasma cutter I've used).

Have seen one of these saws at work, have not played with it though, are they noisy. I have got a Clarke plasma cutter at home which is great for sheet and land rover type stuff, just wanted to give the gas thing a try.

Problem which seems to occur with me cutting thin sheet ( 2mm ) is the cut gap fills up after the cutting torch has passed and then I have to go back over it and this makes the cut much wider !!!

Rich

To reply remove " spam "

Smaller cutting tip needed for starters. And secondly don't hold the torch perpendicular to the sheet - you want it pointing at a 45 degree angle with the flame aiming in the direction you are cutting. And moving fast helps keep the cut clear.

Ah ok I have found that angling the torch helps will look for size of tip and let you know

Rich