As an avid watcher of ScrapHeap Challenge (I know, I'm sad), I'm always impressed at how useful welding is. I want to start a hobby building devices such as a water pump for an allotment or a generator for small amounts of electricity, using wind or pedal power. I was hoping to use old bicycle/car parts but face the problem of joining metal to metal. I suppose I could use rivets or bolts, but is there a kind of welding that doesn't require too much outlay in money or learning. I realise that the kind of welding they do on ScrapHeap Challenge would be ideal, so I suppose I have two questions.
1) How much money/time would be involved in being able to do their kind of welding.
2) Is there a cheaper alternative? (using electricity maybe)
MIG is ideal for this. I don't know what I'd do without mine.
You can pick up a good hobby mig ~150A for around £250. I have a Clarke 150 which is about 6 years old, gets regular use, and is still performing very well.
Alternatively you can get a low end pro MIG from around ~£450 (e.g. Cebora - that's what my next welder will be).
There are two ways of MIG welding - gas and gasless. Google for the difference. Unless you intend to do much of your work outside in high winds, go for gas. The hobby machines all come with awful disposable gas cylinders which give about 15 minutes of use. Get yourself a propers cylinder and strap it to the back of the machine. It will work out much cheaper.
Having purchased your welder, you will need to learn to weld. This is best done by getting someone who can weld to spend a couple of hours with you. If not, then schools/colleges often run evening courses.
A basic MIG welder isn't incredibly expensive, prices for the smallest ones hover around the £100 mark. I recently bought a SIP 130 amp MIG welder and have found it excellent. It's one that can be used with gas or without gas (using 'gasless' wire).
The disposable CO2 bottles (or argon/CO2) that you need for gas welding are the major running cost. If you find you're using a *lot* of CO2 then there are cheaper alternatives.
I had to practice a bit before I got the hang of it (having previously used a basic electric 'stick' welder). Once I'd realised how close you need to hold the feed to what you're welding I got on a lot better.
With a 130 amp welder like mine you can weld anything from very thin sheet (I've managed down to 1mm or so) up to, maybe, 5mm or so.
One extra I would recommend is an 'automatic' helmet, I got a bargain one for £70 and it's brilliant, makes welding a whole lot easier.
All of the Scrapheap welding I've seen has been MIG. Even when they were building the pulsejet and welding stainless, I didn't see a TIG set in use (and there were plenty of people on that show who could TIG)
You can get a S/H hobbyist MIG for £50. These are expensive to run, because of the small wire reels and the disposable gas cylinders. But it's cheap to buy and you'll get to make some stuff while you learn your way around things.
£150 gets you a new hobbyist MIG. They're rubbish (I wouldn't touch an SIP at any price).
£300 gets you a better MIG, maybe a Cebora (which is the first decent machine I'd buy new, rather than S/H).
£500 gets you a Murex with a removable torch (if you keep your eyes open for offers), and then you can stop worrying about upgrading your machine.
Don't use CO2 gas, get some proper welding mixture (Argon and a little CO2). You'll get much better welds. Gas is basically free and you just pay bottle rental (which isn't cheap 8-( ). With two people doing fairly large quantities of hobbyist welding, we still can't remember when we last replaced bottle or wire reel, it's that infrequent.
Stick welders are dirt cheap, but not much use under 1/4" plate. Maybe 1/8" if you're careful, but you're not going to do thin sheet with them.
Gas welding is also pretty cheap to get the equipment, but bottle rental is another expensive cost. A "Portapak" with tall skinny cylinders will fit in a car when full-size cylinders are a "delivery only" option. Gas welding is a wonderfully restful process, but it's not a quick way to build things. OTOH, it's also a good way of getting things hot, which is a whole new world of fun techniques.
TIG is about a grand for reasonable entry kit.
If you're doing any electric welding, get an automatic hat. Wonderful things. You'll also need to budget for stuff like an angle grinder, flap disks, wire brushes, a leather welder's jacket (cheap ! worth getting), earmuffs, etc..
New steel is cheap and nicer to weld than rusty scrap. But you should still collect useful scrap when you find it - but avoid galvanised and stainless.
Gibson's "Practical Welding" is a good book.
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can also do some Googling. I've posted a few rants on "How do I begin MIG welding" to various ng's, and there's also sci.engr.joining.welding
While I've had several bad encounters with SIPs, I have to defend my Clarke - which also falls firmly in the hobby mig range.
It takes 5kg reels, and has a pretty good wire feed which hasn't given any trouble in 6 years. I get through a 5kg reel every year, so usage isn't very heavy, but not too light either.
Machine Mart supply all the consumable parts (tips/shrouds/necks/liners/complete torches/rollers), so I've never had trouble getting bits.
1) Do a course. Your local evening college will provide.
2) Basic AC arc welding (aka "stick") is dead cheap. < £75 for a welder, but don't expect to be able to weld anything much thinner than railway lines.
3) Basic MIG is quite cheap, but the bottles don't last long.
4) Did I mention doing a course?
5) Gas is dead good, but you have to give BOC your firstborn.
6) About that course ...
Definitely - both the SIPs (a 130 and a 150) I've used had wire feeds which bounced all over the place. Getting a constant feed was nigh on impossible.
Yeah I know - I also know that you have one with which you're happy (or at least were last time we discussed).
It is quite possible that they have changed the wire feed. It's also possible that both the machines I used were faulty. There were a couple of other things wrong with one of the two machines
- a crappy gas valve in the torch, and a very poor non-rigid umbilical between the machine and the torch.
Actually, on the safety day I did get one of Scrapheap's resident engineers to tidy up some of the MIG welds using a TIG torch -- so we didn't get any catastrophic and potentially dangerous failures on race-day.
Bruce Simpson Expert for The Destroyers in the Jet Racers episode.
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