Classic cars forum & vehicle restoration.

admin · Joined: 07 Apr 2005 Posts: 925

A mate of mine was asking if I had any experience of using a plasma cutter, and whether it'd be worth splashing out for one. Are they much better for cutting out rusty bits from a bodyshell, than using angle grinders etc?

all advice welcome!

Rick

buzzy bee · Guest

May be worth looking into a decent air saw or even using a plate cutting nozzle on a oxy acetlyne or oxy propane as it is a lot cheaper. My mate has done quite a bit of plasma cutting, but I haven't done any so can't comment!

Uncle Joe · Guest

I found out years ago that the most important tool used during a restoration is a big compressor. My own is a 653 l/min., with a 200 litre tank. This I can use to power all of the "rheumatic" (hehe) tools I need continuously. Drills, angle grinders, nibblers, saws, you name it. Here at least, air tools are generally cheaper than their electric equivalents, and therefore there is a saving to be made.

Therefore, for less than the initial cost of a Plasma Cutter, which needs a compressor anyway, its possible to more jobs. Of course, a PC will cut through thicker material quicker, but the clean up time needed negates this time saving to a certain extent.

But of course, there is the "cool" factor!

admin · Joined: 07 Apr 2005 Posts: 925

so theres a fair bit of cleaning up after using a PC? whats your preferred way to cut out old rot?

cheers
Rick

Uncle Joe · Guest

I use several different methods, depending on where the rot is, but generally speaking I prefer to use a 3 inch cut off tool if possible. Straight lines, minimal clean up!

Uncle Joe · Guest

I've just seen a demonstration of a top quality Plasma Cutter, and would like to point out a few things that I found out, regarding clean up.

If the cut is made too fast, then there is a need for considerable cleaning up with a grinder on the top surface. Too slow, and the clean up is required on the bottom surface. The difference is, this can (more or less)be removed by hand. Get the cutting speed just right, and the cut is good enough to be welded without any clean up!

Would I buy one? No. Why? They are too expensive unless a lot of cutting is involved.

Comments?

48AustinPanel · Joined: 08 Feb 2009 Posts: 4

I use a 120 volt plasma cutter with a built in compressor. It is good for body work only, as it can only cut up to 1/4" metal. It is clean and easy to use. My opinion is if you plan on doing alot of projects its worth having.

Greeney in France · Posted: Sun Feb 15, 2009 8:20 am Post subject:

Practical classics magazine has an article on them this month price is coming down for the general use ones the "best buy" was about 400quid
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buzzy bee · Joined: 23 Nov 2007 Posts: 3382 Location: South Cheshire

Hi

Since my last post in this thread, I have started using one at work.

After cutting I can knock any mess off with a chisel, or a quick rub down with a sanding disc on the grinder. They do use allot of power and air though. We have a big compressor at work, and I soon emptied it the other day!

Cheers

Dave

crownpoint · Joined: 26 Feb 2009 Posts: 7

I use a plasma cutter regularly. I managed without for years simply because they were expensive to buy. I considered the Chinese inverter type that are now reasonably priced but the user reviews indicated poor quality build. I settled for old technology and bought an SIP transformer version, second hand and cared for. These are my observations/procedures.
It's very heavy so I keep it on a trolly.
It draws a heavy current.. a thirteen amp fuse struggles to survive.
It uses vast quantities of compressed air, when you have finished the cut the air continues to flow to cool the nozzle.
I don't run the compressor whilst the plasma cutter is in action; I fill the 50 litre receiver and switch it off. This limits the maximum current drawn. This obviously shortens the duration of the cut but because the cut is executed so rapidly it's a minor inconvenience. When the air pressure drops below the cutters requirements the plasma cutter shuts down and I refill the receiver.
What are the advantages? In use it is analogous to running a knife through water; you apply no mechanical force to the work piece. There is no damage, no displacement, you don't inadvertently create problems of alignment as you might when using mechanical cutting methods. The edges of the cut are virtually burr free and no distortion occurs. The cut is immediately cooled as you proceed.
The nozzle can be guided freehand but for improved performance an MDF template or a straight edge can be employed. It helps to have a band saw to produce templates. The nozzle has an external diametre of 10mm so you have to reduce the template by 5mm. This is where the band saw speeds things up.
When do I use it? On insitu panels there is generally no contest. On bench fabrications it excells at internal curves, holes in the centre of panels and the inevitable cut outs and adjustments that become apparent.
What'doesn't get used now? The hand drill mounted nibbler that leaves thousands of needle sharpe chips! The chain drilling that never quite joins up and that needs any amount of filing to finish it! The Gilbo's that often need an Orangs strength to operate.
Plasma cutter recommended? Most certainly![/img]

Rick · Site Admin Joined: 27 Apr 2005 Posts: 22458 Location: UK

very interesting crownpoint, are you working on any cars at the moment?

Rick
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crownpoint · Joined: 26 Feb 2009 Posts: 7

My current project is a'68 morris minor pickup. It's a body off 'economic refurbishment'. My philosophy is: rebuild costs must not exceed eventual retail value of the vehicle and the finished appearance has to convey 'still in active service'. I don't like the 'two pack tart' look. Chassis and cab now completed.Cab is back on chassis, with interior sprayed. Original pickup sides have been restored. I've side tracked at the moment on to building a replica pickup back... just for fun! The morris minor van that I completed last year awaits its first season. The californian MGB roadster has been converted to RHD and will get its rebuilt engine soon. The Aus import VW baywindow is booked to holiday in cornwall... 2lt injection.... they should all have been given a decent size engine. See pictures on webshots.com. Type in 'morris minor roofing'