Practically Classics Forum

ouch!

Ouch indeed. Yet another reason that I'm sticking with carbon arc as my preferred method of gluing bits of steel together. OK, so it requires darker screens than are supplied as standard with most automatic helmets but they're cheap enough compared to shielding gas, wire, liners, tips, torches, etc. for MIG machines and besides, for thicker material the arc welder can be used without the pencils and stray 2mm sticks can roll quite harmlessly down the bonnet of a car, if one of those lands on the operator, it is extremely unlikely to cause even the slightest bruise.

If I need the best possible weld off the torch, then oxy every time. I appreciate that gases aren't as easy to organise for the hobbyist these days though.

+1 on gas, though I have changed from BOC to Hobbyweld for oxy in the last month or three. Buying the hobbyweld cylinder was about what it cost to rent a BOC bottle for a year and, as I hadn't used the welders (either oxy or MIG) for a year and found the oxy was empty when I did want to use it, savings on rental are welcome! The Hobbyweld supplier (a local welding equipment firm) also sell acy bottles, but mine is fairly full at the moment and the £160-odd to buy their small (5l) cylinder is a bit of an unnecessary expense at the moment!

Having spent hours patching the small tractor's bonnet, I can say that stick welding is a dangerous thing in the hands of an amateur! I suspect the previous owner had been given an arc welder for Christmas and used it straight away (filled with Christmas Spirit). That was why I bought the first MIG - there were large areas to patch and trying to weld paper-thin metal with oxy was a bit more like using a gas axe!

Meanwhile, the mods to the MIG have proved highly successful and I was able to make some neat runs on my digger's new stays. However, joining the spacers to the second side was most certainly a codge (reach into the 3/4" gap with the torch and weld what I could hit! I suspect a rod would have done a neater job there!!

Hi Guys,

new to this forum, but I may be able to add something useful, having been a professional car restorer for the last 30 years!

I've just been reading your comments regarding welding, there are some things you should consider;

1) Gasless MIG welding is a serious compromise for most welding jobs, but the ONLY way to MIG weld outdoors!
2) The better the MIG welder, the better your welding will become, this is because the critical thing with MIGs is the wire speed and amperage control. Modern cheap MIGs do have pretty good amperage control (by cheap I mean £200 plus) and bigger is not always better: A welder with 35-100amp range will be be a struggle on thin material, because you may find you need 20 amps or less for some delicate jobs. Far better is a 0-90 range for general use, with a stepless control if possible (and two range if you can get it). Just remember, the ability to adjust in 2 or 3 amp increments is what you need. It follows that a 2 amp increase on a 0-90 welder is 2.3%, whereas on a 0-200 amp welder it is 1% and twice as hard to achieve.
3) The wire feed is critical, as again small steps are best. 0.6 wire is the norm for thin work, a thicker wire needs to be fed slower, which is harder to control. This is where more money is usually well spent.
4) 100 amps is going to suit anyone welding up to say 5mm steel, although thicker metal can be welded by several passes.
5) You may see the maximum amps listed with a % duty cycle. This is the amount of time the welder will operate flat out before it cuts out to cool down. This is important in a professional environment, when you may end up waiting 10 or 15 minutes for the welder to cut in again, but not so troublesome for a DIYer.
6) If you remember your school physics lessons, you'll remember that Watts=Volts x amps, so a welder operating at 50 volts and 150 amps is 7500 watts. A 13 amp plug will deliver 13 x 240=3120 watts, so you can't run a 150 amp welder from a 13 amp socket! You will need a dedicated 30 amp supply, which will deliver 7200 watts. Anything more than this is 3 phase territory.
7) And here is the plug! I am a stockist of Hobbyweld rent free gas bottles, which I strongly recommend you look into. The big rental companies are ruinously expensive on rent, admin charges, delivery you name it, and a big bottle is also incredibly heavy, dangerous and hard to transport. If you lose one, or get it stolen or damaged, you can be asked for upto £350 by the rental outfit, but with Hobbyweld, the deposit is all you will ever pay. This isn't a hard sell, since I only supply in the Northwest, anyone else can check their nearest stockist on the hobbyweld website, http://www.hobbyweld.co.uk

Although I stock CO2, which I sell for £32 inc VAT, the Argon mixes are so much better. A 5% mix is perfect for upto 5mm, 15% over that, they are £38 inc VAT. Pure Argon is a must for Aluminium and TIG work but an expensive option (£52 inc VAT)for a MIG on mild steel, and the mixes include 2% oxygen which helps the bead flow, so is actually preferable . Also,
it surprises some people to know that the 5% refers to the amount of CO2, not Argon, so you are getting 93% Argon anyway. The extra cost of the pure Argon is the complexity of acheiveing 99.9% purity

Hope that helps you guys a bit - let me know if there is anything classic related I can help with,

The trick here.....still agron shield.....but get a tig

A scratch tig can be got for as little as £200....you dont get splatter, easier to control as you go along a weld, and a lot cheaper to run.

If you cant afford a tig...make one from scrap you probably have in your shed. All you need is a motor, an alternator, a piece of old plastic number plate, some stainless mig wire, and an air cooled tig torch.......but thats just a stop gap.......buy one off the shelf

Go for something like THIS which can be used with or without gas and priced keenly too.

I've got a little machine mart type 90 amp inverter welder, will just about push a 2.5 rod flat out ...pretty crap really ,(but smooth and stable) , can be handy on thin stuff . I also bought a new scratch start tig torch thinking i could make a poverty Tig welder , with a little disposable Argon bottle , but when i looked it up on the internet ,it said it would use the whole bottle in 5 minutes ! So i didn't try it £15 for 5 mins Is it correct info?

The machine mart welders which can do gas / gasless only come equipped for gasless. You have to spend some extra for the other odds and sods required to run with a gas bottle.