Exothermic Cutters

Hi, I didn't know where else to put this question, so hope it's in the right place!

Does anyone have experience of using exothermic cutters, compared to Plasma cutters, and could provide some opinions on their effectiveness please?

I came acoss examples of these machines quite by accident on eBay recently when trawling for plasma cutters, and if they work as well as appear to, could be a lifesaver for my classic car which is on the verge of being sold for parts due to (noise) issues restoring the bodywork!

I need to change an entire floor pan, sill and wheelarch, which at present would have to be done with an angle grinder and cutting discs for the grunt of metal removal! BUT ...........We now live in the middle of a new housing estate where neighbours are in close proximity, so the noise factor is critical! Cleaning up cut spot welds in short blats is one thing, but carving out a lot of tin on top is quite another!

I did manage to change all one side before we moved, but now the job has stalled for want of quieter means of getting the tinworm off the body.

I was going down the plasma cutter route plus a well silenced 15 cfm compressor until I saw this device, which would appear to do away with a chunk of noisy machinery and hissing air!

Cost wise, the basic exothermic machine seems to be similar to a reasonable DIY level plasma machine, but is it a serious contender and what would any pitfalls be using one on car bodywork!

Any helpful comments appreciated!

John.

Hi John, sonds like an interisting concept, I have a classicn MGB GT to restore at some point and any 'low noise' cutting would be advantageous. I had looked at plasma cutters but I'm a glutten for new technology

I've done a quick search omn fleabay but not turned up anythig useful, if you have links to products, can you include them in this thread.

cheers

CB

Hi

From the description I found it looks like another name for the thermic lance, of safe breaking fame, which is a steel tube stuffed with some fancy wire that when lit has oxygen forced through it producing a very hot cutting flame. Showers of burning material all over the place with the hazard of having to use oxygen, presumably from a large cylinder, may not be for a residential area either.

Just a thought

Martin

PS there is a quick description http://www.oxylance.com/product_catalog/exothermic_cutting_systems

Edited By Martin W on 19/03/2012 18:59:55

Thermic lances are fine for cutting concrete, masonry and the odd bit of reinforcing steel, would not put them anywhere near a car body, much too agressive (and noisy)!

Edited By KWIL on 19/03/2012 20:17:48

Hi Martin, you're probably right about the thermic lance principle, but as I've no experience of the things, can't really comment.

I can't say I'm too fazed about showers of burning material (AKA molten metal and sparks) from such a gun if that's the main issue, because little comes close to the output of an angle grinder and cutting discs at full chat, which is largely uncontrollable, plus the sparks and grit gets everywhere and will etch glass if within a goodly spit of the fallout!
With plasma cutting and quite possibly exothermic, at least some control should be possible, but until we hear words of wisdom from someone who's been at the sharp end of the gun, we won't really know .

How much of a shower of sparks would you get cutting 16G & 22G metal? I'm just cutting through the top layer of spot welded seams to separate two car body panels.
Logically, the output of hot metal spraying around ought to be relative to the thickness of the metal being cut, which in this case is metallic tissue paper! If the kit can't do that and is likely to slice through both panels, then it's not going to be much use.

I came across the exothermic sale on eBay which went under the hammer for under £150, I did a quick google search at the time and turned up kits for around £300, which equates to a half decent DIY plasma rig minus compressor, but i bottled out of bidding with not knowing enough, didn't want to dump a wad of cash on a possible pup.

Some info on this link: http://www.westcoweld.co.uk/gas-welding-cutting-equipment/portable-exothermic-cutting-unit.htm

I can't really see oxy cylinders being a big deal in a domestic environment if used sensibly, thousands of homes use them on a daily basis for medical purposes, but any pressurised cylinder can be deadly in a fire situation. The big risk as far as I'm aware, is with acetylene cylinders, which can go bang big time if you take too big a liberty with them without any flashback arrestors (or even with them)!

CB. Good luck with the MGB, I did a rubber bumper model about 15 years ago that was a rusting hulk, much of which was invisible until the wings and stainless sill covers were off!
It got new inner and outer sills, front inner wings rebuilt, both lower half rear wings plus inner arches, lower half front wing panels plus the box work behind them, and that was before the mechanical rebuild and respray etc.
It made a very enjoyable classic workhorse though, and used for daily commutes from Sheffield to Humberside airport and back!

The car I'm agonizing over is a V12 E-Type, it's almost making me weep watching it rusting away gently in the local sea air waiting for the shell to be finished, hopefully it'll be done before I'm shuffled into my wooden overcoat!

John.

The problem with a lance is that you get a shower of sparks before you even start cutting unlike a grinder that only poroduces sparks as it cits and with the modern thin discs you don't get that much. Also with a plasma the sparks are on teh exit side, with the lance you will get them bouncing back at you making any pricision cuts difficult.

Look at this littel portable lance in action its like weilding a firework around, you also get a very ragged edge which will likely need cleaning up with a grinder anyway

http://www.securityprousa.com/mecusy.html

If its spot welded can't you drill the spots out? or just cut the panel with an oxy/acetalene torch

Edited By JasonB on 19/03/2012 20:47:04

Edited By JasonB on 19/03/2012 20:50:05

Just another thought, have you got an MMA stick welder? you could try the cutting rods with that which will burn through thin plate quite easily it sjust like using too thick a rod and too high ampage when welding - you just melt a hole into the metal.

J

For car work in close quarters I recommend a power nibbler of some kind. There are ones that you attach to a 1/2" portable drill and they use a reciprocating round punch about 1/8" dia to nibble a crescent shaped slug of metal on every stroke. No noiser than the drill itself and very little chance of damaging metal behind it or setting anything alight. They offer excellent control over the steering of the cut, they cut cleanly needing very little cleanup of the cut edge. They do need a minimum of about 1/2" headroom behind, and will not cut right up flush to an adjacent wall. They stop about 3/8" short. The remaining short cut to open a panel right up to a wall could be done with thin grinding disks in a Dremel.

I'd think twice about thermic lances or even plasma cutters on a Jag XKE, unless panels are a whole lot cheaper there than here!

Plasma and electric welding leave such a ragged edge you often spend just as much time grinding it out to a decent finish as you would making the cut itself with a thin grinding disk.

I have had my fill of cars, no more bodywork for me on stuff that rusts faster than I can weld new metal back on!

JD

Just go to a decent restoration shop that will bring it up to scrartch. What you are talking about could cut the poor car in half without trying. Also just what is this car!!

Hi John .

Your main issues with anything that puts out heat (with the exception of a plasma cutter as the heat is intense and very localised ) is distortion of the panel you are cutting and fire.

The nibbler will do most things , will keep the noise down and what ever it can't do will still minimize the usage of a grinder then thier are reciprocating saws , jigsaws , shears etc that may get into places the nibbler cant .

Ian

Thanks for the comments so far, but the main point being overlooked with alternative options mentioned, (all of which I've used at some point in my murky past), is Noise, I'd get away with short hits to grind off scruffy remains of spot welds etc, but not slitting whole panels off.
I need to remove complete panels because that's what is going back on, not patches, and ideally I want to cut around the spots to remove the panels making it easier to grind just the remaining zit of the spot welds off, plus cleaning up prior to rewelding.

The problem with car bodies too, especially when totally stripped out, is that they transmit noise like a bloody big drum!

Nibblers are ok, but they make a hell of a racket if air powered and if electric, far too bulky for the limited spaces I need to work, i also need to get up close to edges, some of which are inside a double recessed lip on the sill, and compound curves inside and on the back wheel arch.

Scruffy ragged edges from a plasma type cut are not a problem, the main panels being cut (floor and sill) are on top, and those being removed, I want to leave a relatively undamaged lower lip to spot weld back onto,
I have one sided spot welding facilities, as well as MIG, TIG and oxy acetylene, the latter I prefer not to use anywhere because of the distortion it causes.

Drilling spot welds out isn't an option i want to use but may have to consider, it's a quick bodge method which doesn't remove all spots cleanly, and would also require the holes left in the remaining panel to be welded back in again, which means more work and grinding to finish, I'd rather leave the panel whole, which would appear as close to factory fit as f*ck is to swearing,
A cut and shut job on these cars just doesn't cut it with serious buyers stumping up proper money to buy, and I will need to sell it at some point, I'd rather not have the price chipped down because someone is picking holes (no pun) in the method of repanelling.

I take the points about the 'thermic lances' spraying sparks everywhere, but all of the vid's I've seen have shown an operator lopping down stonking 2" thick steel bars, which is going to take a lot of heat, I need nothing like as big a cutter as that.

Using an electrode to cut is a possibility, but it's messy and I'm very likely to stitch the panels together in places which means more grinding, or worse, big holes blasted through the lip of the panel that's to remain!
This has given food for thought though Jason, and might experiment with the TIG. to see if it will cut locally around the spots.

JD, panels aren't cheap here either, but I'm lopping off replica colanders to fit entire new panels,so no worries there.
I'm also an avid fan of waxoyle, and 3 litres of the stuff was blasted into the O/S sill & wheelarch area with a high pressure gun, plus visible areas were etch primed, painted and then sprayed with flexible stone chip resistant coating ...........hopefully that part of the bugger won't rust away so fast, even on our (sometimes) gritted roads!

John

Hi Ian, distortion isn't such a big problem as the panels being cut are surplus and will be scrapped, fire risk is minimal as the shell is stripped, even of sealer and underseal.

I did use a jigsaw in various places on the other side, but the noise was horriffic and abandoned eventually as a method, I just kept going with disc cutters, which now isn't an option.

Going back to my Original enquiry, and to narrow things down a tad, has anyone Actually used the Smaller exothermic cutters on THIN gauge steel please? and Is it possible to cut decently with them?.

Pah, I might even just go buy a plasma cutter and be done with it, at least I know they work!

John

Just my own experiences for what it's worth, I would agree about the nibbler to remove waste or damaged panels, such as the remains of floors etc - very effective and no distortion due to heat. As for spot welds, when accessible why not use a spot weld drill. I removed most rusted and damaged panels on my Triumph Stags (plural, not a typo) etc, using those tools.

The nibbler was a pneumatic one and as the compressor was in my garage made minimal noise and the nibbler made less noise than the neighbours stereo. The spot weld drill used in a corded drill enabled me to remove a wing which was to be re used in less than an hour with no distortion or damage to paintwork, the drill leaving small convenient holes to use to spot weld it back using my mig welder. The only grinding I had to do was a couple of short blasts through a couple of mig welds on the A post joint. You can equip yourself for about for about £40.00 with these tools, not as macho as a plasma cutter etc but very effective, cheap and reusable many time.

best regards

Terry

When I suggested using a spot weld drill I was thinking of only drilling the top panel, if you stop the drill half way that just leaves you with a small pip on the panel below not a hole.

You say you have oxyacetylene why not get a cutting torch for that, in fact as the panel is so thing you could probably do it with a standard torch and just turn up the oxy as it starts cutting.

J

Nibblers are very noisy and the swarf they produce is very sharp/painful, If youre really concerned about the noise the only way you are going to make no noise is to use hand tools, I have got an old Monodex which will cut flat car panels and leave a reasonable edge with minimal distortion but I find it very tiring on my hands.

Paul

Hi John,

I agree with Paul that a Monodex is much quieter than a nibbler. Last Thursday (15 Th) Aldi had air shears on offer for £16.99 These are like a Monodex but the cutter head is larger. I have had one of these since last time they were on offer and the work well without too much noise.

Les.

Hi John .

From your original posting it sounded like you were doing a cut and shut job and not replacing whole panels .

The spot weld drill Terry mentioned will do the job and if used correctly you will have very little grinding work to do .

There are 2 types of drill though , one is the type as Terry mentioned (the best )other is like a small holesaw .

The latter leaves a circular piece attached to the parent panel and a hole in the one you removed thus needing a hit with a grinder .

The proper drill leaves a small dimple in the parent panel from the nib in the centre of the drill and a hole in the waste panel , if used correctly it will need almost no grinding of the parent panel .

I have also used a #4 centre drill to remove panels but in no way is it as good as the proper tool and you will be surprised how fast it is to use .

If you keep the speed of the drill down to 500rpm it is not that noisy and the bit will last a lot longer .

Regards ..

Ian

Hi There,

I have used a 40A plasma cutter for cutting panels and chassis repairs in a landrover - thicknesses range from 1.2mm to about 3mm. Handheld use can be tricky as it will cut the shape including every shake of your hand - especially if you are in an awkward position under the vehicle and reaching!! This is even worse when sparks land in your ear or down your back, and thats even with a welding mask and flame retardant overalls!! With a guide/straight edge the results can be good. The electrodes/tips can be eaten up quite quickly especially with dirtier materials I find however. With the 40A machine I have cut up to 12mm plate also, but the cutting is a lot slower at that thickness.

In previous employment we had a contractor use thermal lances to cut through an aluminium melting furnace outer casing and then through the refractory and oxide layers that built up during extended use. Diggers with heavy breaker hammers couldnt even break through the oxide layers but the thermal lance could. The results were not pretty however.

Thanks,

Neil

Thanks again everyone for the comments, Well, I've taken a look at available spot weld drills, and must say they're a bit different now to the things I used years ago! They had a drill bit that went right through the weld and which acted as a pilot for the hole cutter which drilled through the top panel! .............things've clearly moved on!

The holesaw type cutters now appear to have a spring loaded pin to centre, and the other looks a bit like an end mill with a centre pip, either would do the job on the accessible welds, which is about 60%, the rest of the panels needing removal are going to have to be slit somehow, and although the monodex or shear will get some of it, I'm still left with grinding or cutting by some other means, but I'll sort it somehow, I've been restoring cars professionally for most of my working life, so not short on ideas. Will be taking a shuftie in Aldi next time we're in there!

I was particularly drawn to the exothermic cutter idea because it's self contained, and some of the kit looks quite small and manageable, but in the absence of any hands on opinion for smaller jobs, I'll probably bin the idea, worth a thought though all the same, even plasma cutting scared the sh*t out of a lot of people when that came onto the market!

Well, weather's warming nicely and been mucking the garage out today to get to the beast, so will look at the affected areas again and decide how best to attack it!

John.

Hi John,

Not sure if this is what your orginal post looking for information on was for,, but have a search for Multiplaz, guessing that they are available in your part of the world. If you believe the info it looks like a neat tool for the workshop.....although your pocket may need to be a little deep! Given that it works as a plasma cutter & you don't need a compressor or gas bottle, or a welder it covers all bases!

From the NZ website

MULTIPLAZ-3500 is a unique portable multi-functional plasma device for welding, cutting, soldering and heat treatment of metals and other materials. MULTIPLAZ-3500 consists of a plasma torch and an electronic power module that weights only 9kg.

Learning to use MULTIPLAZ-3500 is very easy and the results are spectacular. No specialized training is required, with a little practice, anyone can become proficient in the multiple uses of this invaluable workshop tool.

Cheers Kerrin