There are three basic types of electric welding in common use. In all methods, an electric circuit if formed between the work and an electrod which is handheld. The current that flows essentially determines the thickness that can be welded.
MIG - Metal-Inert gas. A weld wire is fed into the joint automatically, while an arc is struck on one end. The wire "burns up" at the same rate it is being fed in. A blanket or shield gas is wafted over the weld site to exclude oxygen. There are "gasless" Migs, where the wled wire contains a flux core which de-oxidises the weld area. Mig is very easy to use, but is not terribly controllable in amateur equipment. Amateur Migs sets would probably top out at 4mm of mild steel, and only weld things like aluminium with difficulty. Good method for RHS. Not good for thick sections.
TIG - Tungsten-inert gas. The choice method for craft welding, TIG uses a handheld torch with a sharpenened tungsten rod down the middle. Like MIG, a shield of inert gas wafts from the torch to blanket the arc and prevent oxidation. An arc is struck from the tungsten to the job which then melts. A filler rod is then melted into the pool and welding procedes along the joint. One of the best methods to weld thin section, or aluminium. TIG sets can be very very sophisticated, and there are AC, DC and combined sets. Small tig inverters can be used with MMA too. Beautiful results, but needs great skill for good work.
MMA Metal-Metal arc. "Arc" welding. A metal rod encased in flux is used in a handheld torch. The arc is struck from the rod to the job, the arc melts a pool in the job, and drops of liquid metal fly off the tip.
2nd easiest method, works for thicker sections >4mm, needs no shield gas or fancy torches. Can't be used on aluminium, VERY hard to use on thin metal.
Get yourself a MIG for around 100 quid these days. I have an SIP MIG which is pretty good. If you go this route you do need a gas bottle, which is a (lowish) annual rental. If you weld steel, get a gas called Coogar rather than the cheaper (crap weld) carbon dioxide.
On or around Sun, 03 Oct 2004 10:47:24 +0100, Steve Taylor enlightened us thusly:
and great funds to buy a decent one. mig useable for car body and LR chassis style work is about a 130A "hobby" one, as a minimum, and a bit of practice at getting the settings right.
In fact, something around 150-180A industrial secondhand is very good, but only if you know enough about it to ensure that the cheap bargain is not terminally feckt in some way that'll cost big money to fix.
I was trying to loose my 'rarely used but soon adds up' BOC Argoshield' rental bottle (for use with my Lincoln SP-135) and was thinking of getting one of the re-fillable Co2 bottles available from car spares type places?
BOC say I can return the bottle and re-rent one when needed (min 1 month) but it would cost a fortune loosing all the unused gas each time .. ;-(
FWIW I thought I might try one of the disposable Argon / Co2 (80/20) canisters (I have one here with a mini reg) as it will probably cost less in the long run (and I don't wan't to be without it even though BOC are at the top of the road ..)?
On or around Sun, 03 Oct 2004 16:15:20 GMT, T i m enlightened us thusly:
the disposable ones are OK if you almost-never use the thing. I rent a little diddy bottle (size PT10, IIRC) from air products. I used to use the disposable ones, but they're a pain in the proverbial, run out in no time if you do any amount of welding.
Which is actually the case (if you looked over say a 1 year period) .. then I would do something big like build some steel doors for my garage or the next job, a sliding double gate for the side access ..
I rent a
Any idea of the cost please ?
I used to use the
Noted .. but cost nothing to keep (no rental) 'just-in-case' and are very portable (and they do Argon / Co2 mix)?
Plain CO2 gives less weld penetration and a larger bead of weld sitting proud. If you're using a "toy" MIG with only 130A of current you'll have trouble getting a decent weld even in 3mm plate.
I'm going to stick my neck out as usual and say that you'll want at least a 150A MIG to make a decent job of welding a Landrover chassis - I weld 3mm at 140A and get full penetration on a butt join and use about
180A on a lap join for decent penetration.
As someone else has mentioned a used industrial MIG is probably a better buy if someone who knows what they are doing can check it over for you. Among other things they are much easier to get parts for (torch liners, swan necks when you break them, etc)
When you finish using it, take it out of the welder, seal it in a plastic bag and hide it in the hot water cupboard. Also buy decent quality MIG wire - it tends to have a thicker coating that resists corrosion better than the really cheap stuff.
On or around Mon, 04 Oct 2004 08:21:56 +1300, EMB enlightened us thusly:
but, as I pointed out recently, even when new the chassis ain't that thick... There was summat about CO2 being better on dirty/rusty stuff than the mix, but I've found the COOGAR to be OK.
ah, now I made a discovery about liners. Being into bicycle engineering, we have a big roll of fancy gear cable outer. This is like a normal cable outer but has a multi-wire slow-helix outer casing inside the plastic, and a plastic liner inside that. It's made and sold for indexing gear systems, as it doesn't stretch/compress like a normal cable outer. But, and this was the interesting bit, it makes an absolutely ace liner for the mig. much tougher than the crappy plastic one, and pretty much kink-proof as well. made a world of difference.
Now, has anyone ever tried the wire for welding cast iron, and a) is it any good and b) does it need special gas, and if so, what?
I've a broken bit on the lathe and ordinary mig weld didn't fix it (was worth a try though).
On or around Mon, 04 Oct 2004 08:40:05 +1300, EMB enlightened us thusly:
and, although it costs much more per Kg, buy little reels not gert bigguns. the big reel is no economy if you end up binning 90% of it 'cos the sod's gone rusty.
I use wire-wound liners all the time anyway - they sound just like what you're talking about, but I'll bet your bicycle cable ones are cheaper.
I've seen the results and I wasn't that impressed (either with the price of the wire or the results). It was done with normal gas. The resulting weld was fairly porous looking and messy, I wouldn't go there again.
Heat it up with the gas and arc weld it with some nickel rods (ie specialist cast iron ones). Then pack it in dry sand (or better still some proper insulating stuff) and leave it to cool slowly. I've welded all sorts of cast this way (brackets, heads, my big workshop vice) and the results have generally been excellent.
Yes you need to heat the iron so any distortion takes place within the plastic limit, the slow cooling is so the heat effected zone stays annealed as it cools, I think there are still issues with the size of crystals formed.
If you want to try just a bit I can sen you a couple of nickel rods, they're marked truealloy 80 and I have used them cold on some broken lower link arms, reinforced with mild steel as well as a cracked gearbox casing. I am afraid the label has worn off so I no longer have the analysis or recommended uses.
Bear in mind that a welder is a little heavy. Only bid on ebay if you're close enough to collect it yourself. I speak from bitter experience after paying 30 quid postage on a guitar amp, which only weighed about 10th of what a welder will!!
That's the ultimate question .. Some years I haven't used it at all (a couple of mates have intustrial MIG's setup all the time so it's easier to use them ) and other years I have used it constantly on a project (like removing an 8' square up-and-over garage door and fabricating a steel frame, windows and a bi-fold and single (personal) doors). I used the MIG on all the light stuff (1-2mm) and the stick welder on the 100 x 100 x 10mm angle frame.
If I was going to do another 'project' involving a lot of welding I would probably bite the bullet and rent an Argoshield bottle, it's just that I wanted to reduce the bottle rental costs (I also have a gas set) and just have something small / non rental to go with the MIG (that works well). I just needed something for that 'emergency' job in the evening, Sunday or when I want to take it somewhere (the advantage of having a 'toy' MIG (If Lincoln stuff is toy?) set is that I can
*easily* sling it in the boot and that's another time a smaller bottle comes in handy...?
Mate and I have been looking at buying (ex-Ebay) a gas welding set. In conversations with BOC it seems (according to my mate) that if you rent the bottles for a month or less there is either no charge or a really tiny one by comparison with annual rental plus gas cost. I haven't interrogated him about this fully but does it sound plausible?
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