Welding - MIG choice

[Osprey]

While I have been using my Arc welder for some years, I have another project coming up and am thinking that I may treat myself to a MIG welder.

I did a fair bit of MIG welding some years ago using Argomix rather than CO2, and know how useful MIG's are on thin material.

As use will very infrequent ... be interested to know any views on Gas or No-Gas MIG machines.

Looking at 150A models the standard GAS MIG machines come out at the same price as the Flux-cored NO-GAS machines. The difference of course is consumables ...

5kg of standard MIG wire is around =A39 with the same for a CO2 gas bottle (390gm) 4=2E5kg of No-Gas mig wire is =A339

Anybody know what the life is on the flux cored MIG wire, does it oxidise ? ... if it does not go off then a single coil may last a couple of years.

Be interested in views as to which type to aim for.

Also how many bottles og gas do you use per 5Kg of wire ?

Also I have never welded with a No-Gas mig ... is this just as easy, especially on thin metal and finish just as good ?

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[EricP]

You cannot beat a gasless unit for infrequent use with long storage periods between uses, on price and storage space taken up.

Buy a gas machine because it is of course dual use.

I have a reel that is 6 years old. Keep it nice and dry and dump the end 6 inches of wire before use.

The finish can be equal but you get a lot more splatter with gasless, but wind does not figure as highly as with gas.

Trying to summaries the information you want is difficult because you fall into the nomansland that many of us are in.

For regular use gassed is the only way to go. Talk to the local welding suppliers and you can get a nice deal. Pay a fee of say £30 and then get a gas bottle and refills for a few pounds whenever you want. But you have a lot of plant hanging around that takes up space and may get little use.

A gasless unit is compact and does not cost much, although do get one that can take the large reels of wire and not just the stupid little ones. I have to wind off the big reel and onto little ones, it is Fuckwit City!

With luck Palindrome will come along and give you some real info shortly.

[Osprey]

This was my asumption, so good to have it confirmed.

on my qusetion of: "Also how many bottles of gas do you use per 5Kg of wire ?"

any idea on that, it may help sway decision either way.

[EricP]

I avoided that because you didn't state the size of bottle and they come in all sizes. The silly little disposable bottle that goes on the back of the units we are talking about last half an hour or so and cost £10 the last time I bought one years ago. I have a big cylinder that I can get filled on the quiet for about £15 and lasts about 14 hours. You must go for a big bottle or gasless wins hands down on cost.

[adder1969]

On Mar 30, 3:18 am, EricP wrote: The silly little disposable bottle that goes on the

How many gas bottles per 5kg of wire? Well it's lots per 1kg of wire. I always use argon/CO2 mix as for me it gives a better appearance but the bottles only seem to last a short amount of time and don't seem to store well once they've been used for the first time. If say I'm putting a new sill on a car I guess I'd get through two bottles at least. Maybe my regulator isn't working properly! My

1kg reels of wire though have lasted years.

I've never used gasless but have been put off by reports of messier welds and more spatter.

[Osprey]

sorry ... the size seems to be 690gm

reel may not be such a bad deal after all. Unless you can get midsized CO2 bottles ? .... don't want the hassle of the industrial size CO2 bottles at home.

[Tom Woods]

For occasional use just use the 690gm gas bottles but they dont last long atall! I've been using these for years but just upgraded to a proper bottle for some big jobs (gates and a trailer). One little 5kg reel of wire will outlast many little gas bottles if you are welding thick metal with a slow wire speed.

I'm now using a pub gas bottle - which i wouldnt say is industrial sized. Will just stand up under the kitchen worktop and is about 6 inch diameter. £50 to buy bottle and regs and £12.50 or so to fill it up. Holds 4.5kgish of gas i believe.

I've had the regulator set at about 12Litres/minute to mig weld on a calm day. Bit higher in the wind. Can you do some maths from that? the capacity of a pub bottle must be published somewhere?

My welder is gas or gasless. I ran out of gas the other day and tried a bit of gasless. It didnt penetrate as well as the gas stuff did (I was welding thick angle on the highest setting on my welder and the gasless didnt do it very well wheras the gas has no probs). It was also a lot messier as it spits everywhere. Gas is much nicer.

[Osprey]

This afternoon I had a brainwave ... and thought why not use a bottle of beer gas ... seems it's not a unique idea then :-)

Assume that the beer gas is plain old C02 ... possibly food grade even, did you have any problems with getting reg to fit or was that easy enough ?

I can get the bottle & refills for free.

[Tom Woods]

I've been to 2 proper welding supply shops so far and both have sold regulators and all the stuff you need to use a pub gas bottle on a normal MIG. Find your nearest and pay them a visit. Regulator goes onto the bottle then a length of flexy pipe with a push fit connector to join into the pipe on the welder.

Get a proper spanner for the connector too while you are there if you dont already have one!

[Duncan]

A mole of gas (any gas -- its just the number of molecules that matters) occupies 24 litres at room temperature and pressure. CO2 has a molecular weight of 44g per mole, so your 4.5kg bottle contain about a thousand moles or 24000 litres. at 12 litres per min it'll last 2000 minutes.

Duncan

[Dave Baker]

I think you might want another crack at the long division there. 4500g / 44g = approx 100 not approx 1000 so about 2400 litres of gas.

Alternatively the density of co2 gas at STP is given as 1.87 kg/m3 which again converts to 2400 litres for 4.5kg. That would indicate more like 200 than 2000 minutes of welding.