Well If I do go ahead with the repairs I've decided it's time to be a little less brutal. Mr Grinder is going to get some hard earned R&R.
I've got my head around the basic principle of Plasma cutters. And I had a few lessons at college on oxy acetolene cutting and welding however which would you go for?
Is Oxy as acurate as Plasma?
If I go the oxy route what costs other than the hoses and mixers etc are involved?
Lee D
Plasma is neater and more accurate than oxy, especially in inexperienced hands, and puts out less heat so things distort significantly less.
Gas cylinders and their contents, regulators, the right cutting tip.
A correctly sized Plasma cutter is much faster and more accurate than an oxy-acetylene. Typical "kerf" in 4mm plate is around 1mm. There is a slight flare at the back of the cut.
There is now one in the landrover hospital :-))
Steve
I've got one here too but sadly it's a bit too technical for me... needs a Bottle of Nitrogen.. set of mixers and a BIG compressor to work as designed.. Way beyond my apptitude and nearly as big as a smart car... Infact It would be simpler to fit an engine and seats.
I'm seriously considering the option of replacing my compressor and going for a Plasma able to cut 8mm which should be way more than I ever need to cut but with the 101 Chassis and making angle iron bit's and bobs may be handy to have a little extra grunt.
Then I'll be looking for a way to make a plasma bench next. :-)
Lee D
What's its capacity in mild steel.Whats the nitrogen for ?
We reckoned 1/4 " was enough - the price hike between that and an 8mm is quite a big one, and the electrical supply doesn't need to be 3 phase....
Steve
Lee D
The shielding nitrogen is generally only used when cutting ally or stainless that is going to be welded afterwards; for mild steel it's not necessary.
Now that alone is more input than hours of surfing I've done. I may just try this one on a bigger compressor first based on that theory.
When I did try it I was getting a very small amount of plasma out but the tip was burned badly just in my 3 minute trial.. Is this indicative of no enough air? I'd assumed (as you shouldn't) that is was the lack of nitrogen.
Lee D
My small (10mm) plasma cutter needs about 5cfm of air at 70 PSI to operate correctly. To get this you will need a compressor rated for at least 12cfm free air displacement - my 16cfm keeps up quite well. Also make sure you use the supplied standoff - some plasma cutters are not made to be the contact type, and they all work better 1-2mm off the surface.
The tips burn relatively quickly especially if you're working on galvanised, dirty or painted material. It's not unusual for me to get through half a dozen tips in a morning - still much cheaper than using oxy/acteylene. For heavy cutting work (>12mm) the most economical way (if you haven't got a big plasma cutter) is with oxy/propane - cheap, clean and not affected by rust.
Right, I think I'm getting somewhere now. I got a little confused by the output of my compressor. But as you say it's the free air displacment figures I need to know and not the figures quoted off the cuff in the machine mart catalogue. I was very diappointed when I got my compressor to find it wouldn't power half the tools I wanted to run on it yet the CFM was as matching.. Is there a method to work out the free running air cfm from a compressor to know what tools will or won't work properly on them?
Don't suppose you have access to a digital camera and a new tip? I'm still trying to find a source of tips but awaiting a reply from Linde gas america having had no joy from Sweden.
Lee D
The link below has a good review of one of the Miller plasma cutters and some quite good explanations and tips if you're new to the game.
Free air displacement is what the catalogue probably states (and it's normally an optimistic figure). My 16cfm compressor at home delivers a fairly honest 6cfm at 100psi, the 55cfm at work delivers about 20cfm at
100psi. So as a rough guide you'd be fairly safe dividing the quoted output by 3 to get delivery at 100psi and by 2 for 60psi.Sorry, digital camera has been swimming (long story involving a Landrover, a flooded road and lack of thought) and I haven't replaced it yet. Page 23 of the Miller manual below has a pretty good diagram though.
On or around Wed, 08 Sep 2004 20:29:51 GMT, "Lee_D" enlightened us thusly:
depends how good you are with it. more chance of setting things on fire.
bottle rental, gas costs. You can use Oxy-propane for cutting but you'll need lots of Oxy. if you want to weld you have to have Acetylene, though no-one ever gave me a convincing reason why.
Current BOC pricing is £68 a year rental for the bottle, £14.64 per fill for the gas, and £8.95 for the transaction (ie swapping an empty for a full bottle. All these for the 'W' size bottle which is the biggest for practical purposes. I dither between think this isn't unreasonable and thinking it's a right bloody rip-off.
Supposed competitors (eg Linde, Air Products) may be cheaper but I've never been able to find out any information about them, has anyone else?
AIUI, acetylene provides the hottest oxy-fuel flame of any readily available fuel gas, but MAPP is a close second and a lot safer in many respects so I don't know why it isn't used more.
You can weld some materials using oxy-hydrogen and oxy-propane.
Nick
On or around 09 Sep 2004 17:36:56 GMT, snipped-for-privacy@aol.com (Nicknelsonleeds) enlightened us thusly:
we have the small air products cylinders, size MD30 I think, about half-height and slightly smaller diameter than the "big" oxy ones.
I'll try and find out the prices of bigguns when I next go for gas.
That would ne helpful, thanks.
Nick
Hi,
You can weld with Oxy Propane it is just a bit cooler. Not such an easy job. Acetylene is much better.
As for cutting go for a Plasma every time. A cutting torch will only cut ferrus metals. It is very crude and tends to leave a poor edge. It gets the metal red hot then burns a hole with pure oxygen. Plasma will cut any metal, steel, brass, Aluminium (nice blue colour). It has a very concentrated heat and will give a nice edge first time. Put a steel top on your chippy's saw horses and lay the metal over it. then attach the earth to the steel tops and away you go.You can cut arround shapes or along rulers to get the shapes needed. It blows away bolt heads nicely. Great for Land Rover body work.
Not cheap but definatly the professionals choice.
John Kaye
Call me semi professional , shares in Machine mart should see a rise in the very very near future.
It was the blowing heads off bolts that won me over. Especially looking at a few on the Rangie which are well past it.
Lee D
I'd like to see how you'd do that.
Steve
On or around Sat, 11 Sep 2004 18:00:42 +0100, Steve Taylor enlightened us thusly:
drill ickle holes in 'em and fill same with tiny charges of dynamite?
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