Advice on buying a welder
Discussion
I quite fancy getting a small MIG welder. I don't want to spend a whole lot of money, as is so often the case, but I do want something that is going to last more than a few months before giving up the ghost. I've seen ones in machine mart for around £150 upwards. Will I need more than 130 Amps (max) for most situations? It would only really see action on thin metal upto a couple of mm. Also would it be such a bad idea to look for a second hand one on ebay or will they most likely be shot?
Another question, is welding iron much the same as welding steel? and is it possible to weld them to each other?
Sorry for all the questions! I've done a bit of welding in the past but that was just playing around with scrap steel tbh.
Rick
Another question, is welding iron much the same as welding steel? and is it possible to weld them to each other?
Sorry for all the questions! I've done a bit of welding in the past but that was just playing around with scrap steel tbh.
Rick
If it's only for occasional use and you're only going to weld thin stuff up to 3mm then a mig welder from machine mart will do the trick.
You won't be able to use it to weld cast iron though. For that you need a either tig welder and cast filler rods or for the occasional cast iron repair you can get special rods for your electric arc 'stick' welder.
You may find that your local college does hobby welding courses. That would be a good place to start for practical help and advice. I did a 10 week course of Saturday mornings before I bought my mig welder. Course was about £70 and was money well spent.
You won't be able to use it to weld cast iron though. For that you need a either tig welder and cast filler rods or for the occasional cast iron repair you can get special rods for your electric arc 'stick' welder.
You may find that your local college does hobby welding courses. That would be a good place to start for practical help and advice. I did a 10 week course of Saturday mornings before I bought my mig welder. Course was about £70 and was money well spent.
Big gas bottles are cheaper, hence get one which is bigger, also the arcs are generally better. Try something like a Lincoln 170. My mate has one and it's great. I'd get a small tig inverter if I were you, then you can weld anything, use arc rods or filler rods and gas. Tig welders are more expensive generally but are the cheapest to run. Mig wire (BIG SPOOLS are the cheapest) is expensive, avoid the gasless ones as the wire costs a fortune. If you ask me, stainless steel mig welding is a waste of time. Get a tig. £250 will get you a good one and it'll work a treat, for the advice, you can make me a nice oil catch tank in alloy!
Err... you CAN weld cast iron with MIG, I've repaired cracked exhaust manifolds that way.
Modern MIG welders tend to use aluminium-wound transformers, rather than copper-wound. For two reasons: firstly it's ligher and second it's cheaper. There's a surprise.
The drawback is that alu can't withstand heating and cooling cycles like copper can, so the transformer has a thermal cut-off in it which stops you welding when the transformer gets too hot. If you're a novice, that'll be quite often as your early welding will tend to be spluttery stuff that causes lots of current surges and heats the trans very quickly.
So, you could aim for a 'turbo' model - just means it has a cooling fan fitted, but by christ do they jack the price up for a fan....
You won't find a copper-wound transformer in anything under a few hundred quid... unless you buy an older quality model secondhand.
Most Machine Mart type stuff (Clarke, SIP etc.) is either Italian or Far Eastern built. Ebay has a huge range of used stuff and you could easily pick up something worthwhile that will outlast you or I, for less than you'd waste at Machine Mart.
Modern MIG welders tend to use aluminium-wound transformers, rather than copper-wound. For two reasons: firstly it's ligher and second it's cheaper. There's a surprise.
The drawback is that alu can't withstand heating and cooling cycles like copper can, so the transformer has a thermal cut-off in it which stops you welding when the transformer gets too hot. If you're a novice, that'll be quite often as your early welding will tend to be spluttery stuff that causes lots of current surges and heats the trans very quickly.
So, you could aim for a 'turbo' model - just means it has a cooling fan fitted, but by christ do they jack the price up for a fan....
You won't find a copper-wound transformer in anything under a few hundred quid... unless you buy an older quality model secondhand.
Most Machine Mart type stuff (Clarke, SIP etc.) is either Italian or Far Eastern built. Ebay has a huge range of used stuff and you could easily pick up something worthwhile that will outlast you or I, for less than you'd waste at Machine Mart.
I have several plants for work, i have got a clarke 150 invertor cost me 300 and it's a pile of junk, i've also got a stel invertor, absolutely superb.
I would'nt get a mig under 180 amp, as said before, use the mid or large reels, and ebay is a good place to buy a good used one or ad mag.
Clarke, Sip, sealey etc lower end of market dependent on model, Lincoln, Migtronic, Esab, Eland, Miller etc good qualitybut expensive if bought new.
For what you are doing, Sealey 180 mig will do fine, i had one for years, i bought it used for around 200, abused it for 3 or 4 years, then sold it to a friend for 100 pounds and he still uses it without any problems.
Mick
I would'nt get a mig under 180 amp, as said before, use the mid or large reels, and ebay is a good place to buy a good used one or ad mag.
Clarke, Sip, sealey etc lower end of market dependent on model, Lincoln, Migtronic, Esab, Eland, Miller etc good qualitybut expensive if bought new.
For what you are doing, Sealey 180 mig will do fine, i had one for years, i bought it used for around 200, abused it for 3 or 4 years, then sold it to a friend for 100 pounds and he still uses it without any problems.
Mick
Right. Now I'm even more confused! So we reckon my best bet is on a second hand MIG then?
I've just checked the website of my local college for courses. They do a few welding/fabrication courses but none of them seem to be weekends. I'm going to give them a ring tomorrow to see whats what.
Rick
I've just checked the website of my local college for courses. They do a few welding/fabrication courses but none of them seem to be weekends. I'm going to give them a ring tomorrow to see whats what.
Rick
rick_172 said:
Right. Now I'm even more confused! So we reckon my best bet is on a second hand MIG then?
Rick
Er... not necessarily
What do you plan on welding? MIG is good for long fast runs on medium thickness (say 1-5mm). For thicker stuff you'll be there a while doing multiple passes, or you could use a 'stick' set - but still takes a while cos of all the rods (sticks) you use up and have to change!
An AC/DC TIG set gives you the best of all worlds: it will weld really thin (a lot of cheap MIG sets struggle on thinner stuff as much as they do on thick stuff) to medium-thickness mild steel, stainless steel or alloys as a TIG set, and usually will double as a stick welder for the heavy stuff.
Allegedly you can MIG weld alloys, but from stories I've heard it'd be a brave man who'd try it with a budget MIG set.
Similarly, I've never heard good reports on the budget 'no-gas' things either. A guy at college (15 years ago!) bought one for car body repairs and ended up bringing it in to see if the welding instructors could show him how to use it: none of them could get a decent weld out of it either (and yes, the polarity WAS correct, before some expert pipes up
). I have an Oxford 120A MIG (copper-wound
) that was free off a mate (and you can't get cheaper than that) and an SMP AC/DC TIG set that will go to 170A - but not on my house mains it won't! That's where an 'inverter' set comes in useful: they can generate more current out for less in. However there are a lot of Chinese companies jumping on the inverter bandwagon and I'd be suspicious of a lot of the cheapo Whang Chung-type stuff that pops up on Ebay. Unfortunately the 'professional' brands like Lincoln, Miller, Esab etc are expensive for a reason - and some of the 'used' prices reflect this.
If you fancy going for a TIG set AND you want to do alloys, it'll have to be an AC/DC set as you can't DC TIG alloy. As mentioned earlier, you can pick up a nice lightweight DC-only inverter that will do mild and stainless no problem, but not alloys. As soon as you add AC capability, the price trebles...
As for used MIGs, see it working before you buy. It's OK thinking you could buy a scruffy one and tart it up, but if it's been hammered (worst case, the transformer's burnt out) all you'd have is a box of scrap metal.
I have a clarke 151TE which I bought new. I taught myself to weld with it and have welded up a complete locost chassis with it. On full power I've been able to weld 3mm CDS tube to 3mm plate although most of the chassis is made from 1.5mm box. I use the disposable gas bottles and unless you do absolutely shitloads of welding you'll do just fine with these. You can always convert later to a bigger bottle if you want. You'll hear tails of buying massive bottles of pub co2 and really, when you're learning, just get a reel of wire, some steel and a couple of bottles of argon mix (which will make the welding process a bit calmer than co2) you'll go a long way.
A pro will tell you these little welders are shit but that's bollox. Sure they are crap compared to proper pro rigs and they won't last long if you use them in a shop but for home use they're fine.
Watch the power supply requirements though. Mine needs a 32A supply so you need to rig up an extra supply in your garage which is pretty easy. Having said that I've used it recently on a 13Amp plug and it was fine although it wasn't on full power.
I'd buy new if you're learning. You won't get a bargain second hand in my experience and if you buy new you'll know what you're getting and if you don't like it flog it on ebay and you'll get a good amount for it.
If you can afford it and can get trained I'd go for tig over mig. I like mig as it's dead easy but would love to be able to do tig because the welds look so nice and you can do alloy so you can make your own fuel tanks, swirl pots etc that I'll have to make out of steel or buy. Once you need a couple of bits like that you've made up the difference between a half decent mig set and a tig set... wish it had occured to me at the time but the mig I have has been fine.
Good luck,
Mark
>> Edited by dern on Sunday 29th January 20:39
A pro will tell you these little welders are shit but that's bollox. Sure they are crap compared to proper pro rigs and they won't last long if you use them in a shop but for home use they're fine.
Watch the power supply requirements though. Mine needs a 32A supply so you need to rig up an extra supply in your garage which is pretty easy. Having said that I've used it recently on a 13Amp plug and it was fine although it wasn't on full power.
I'd buy new if you're learning. You won't get a bargain second hand in my experience and if you buy new you'll know what you're getting and if you don't like it flog it on ebay and you'll get a good amount for it.
If you can afford it and can get trained I'd go for tig over mig. I like mig as it's dead easy but would love to be able to do tig because the welds look so nice and you can do alloy so you can make your own fuel tanks, swirl pots etc that I'll have to make out of steel or buy. Once you need a couple of bits like that you've made up the difference between a half decent mig set and a tig set... wish it had occured to me at the time but the mig I have has been fine.
Good luck,
Mark
>> Edited by dern on Sunday 29th January 20:39
Our learned colleague Dern raises a good point: gas supply.
Personally I wouldn't touch the disposable bottles due to cost,but each to his own.
The 'pub-sized' bottles last MUCH longer but as Dern says, CO2 isn't the ideal shield by itself. Firstly you need a bottle (local free ads papers ), then the right reglator to fit the bottle, then you need an actual gas supplier to refill it for you. But where?
I didn't tell you this, right, but fire extinguishers use CO2, and where do they get refilled...?
Anyway, for chassis work CO2 isn't a limiting factor as you can't really see any spatter once there's a bodyshell on it!
Once you get into TIG you NEED Argon, and that's where the fun starts. The gas suppliers won't deal with you unless you have an account - you can't just buy a bottle over the counter. What happens with, say, Air Products is that you phone their central order line where they process the order, then they fax it to your local AP dealer for you to collect the bottle. BOC is similar.
I'm lucky in that my company has accounts with them both, so I just place a purchase order through the company and my next expenses cheque gets altered accordingly
It's about £70 a year to rent the bottle and £50 a refill, plus or minus a bit depending on what deal you negotiate according to usage. BOC is a fraction cheaper for the actual gas but then they charge a tenner 'handling charge' when you swap bottles.
Personally I wouldn't touch the disposable bottles due to cost,but each to his own.
The 'pub-sized' bottles last MUCH longer but as Dern says, CO2 isn't the ideal shield by itself. Firstly you need a bottle (local free ads papers
), then the right reglator to fit the bottle, then you need an actual gas supplier to refill it for you. But where? I didn't tell you this, right, but fire extinguishers use CO2, and where do they get refilled...?
Anyway, for chassis work CO2 isn't a limiting factor as you can't really see any spatter once there's a bodyshell on it!
Once you get into TIG you NEED Argon, and that's where the fun starts. The gas suppliers won't deal with you unless you have an account - you can't just buy a bottle over the counter. What happens with, say, Air Products is that you phone their central order line where they process the order, then they fax it to your local AP dealer for you to collect the bottle. BOC is similar.
I'm lucky in that my company has accounts with them both, so I just place a purchase order through the company and my next expenses cheque gets altered accordingly
It's about £70 a year to rent the bottle and £50 a refill, plus or minus a bit depending on what deal you negotiate according to usage. BOC is a fraction cheaper for the actual gas but then they charge a tenner 'handling charge'
when you swap bottles.wedg1e said:I heard a rumour that pub gas suppliers were putting some other gas in with the co2 to make it unsuitable for welding because so much of it was going that way - can't confirm it though.
The 'pub-sized' bottles last MUCH longer but as Dern says, CO2 isn't the ideal shield by itself. Firstly you need a bottle (local free ads papers
I didn't tell you this, right, but fire extinguishers use CO2, and where do they get refilled...?
Anyway, for chassis work CO2 isn't a limiting factor as you can't really see any spatter once there's a bodyshell on it!
dern said:
The 'pub-sized' bottles last MUCH longer but as Dern says, CO2 isn't the ideal shield by itself. Firstly you need a bottle (local free ads papers
I didn't tell you this, right, but fire extinguishers use CO2, and where do they get refilled...?
Anyway, for chassis work CO2 isn't a limiting factor as you can't really see any spatter once there's a bodyshell on it!
It certainly used to be the case that you slipped your friendly landlord a few bob to swap your empty for a full one. Not sure that I fancy anything else being pumped through with my beer! AFAIK fire extinguishers only have CO2 in them. Mind you if you ring up the extinguisher people they will tell you that they don't refill pub bottles, but nip in ten mins before closing on a Friday and see the storeman...
It's due to the pressure of the bottles. CO2 is a lot less than Argon/Oxygen etc and the bottles have to be safe. They work at 230 Bar full which is lots.
CO2 gives a hardening effect with welds due to the higher carbon content and oxidation of the metal takes place at those temperatures IIRC. I agree, the gas companies do shag you for bottle rent and the gas is bloody expensive. What I can't get my head around is the fact that you need Argon for Mild steel and Argon + for stainless. Argon and Argon are the same thing, unless they add an impurity so that they can charge you more for stainless gas. I tried welding mild steel with stainless gas and it played up something chronic, spattered like hell. I was wondering if you could use nitrogen. Sure, again, needs high pressure bottles but you can get nitrogen separators. I wouldn't use CO2 on principle.
Can't remember the boiling point of argon, but I think it is what's left behind after oxygen and nitrogen have liquified. I suppose it's why it costs a load of cash. I suppose you could advertise for light bulbs and build yourself a thing which smashes them and collects the gas under water, before hydraulic pressure drives the gas through your hose.
I have thought long and hard about how to avoid the bottle tax.
CO2 gives a hardening effect with welds due to the higher carbon content and oxidation of the metal takes place at those temperatures IIRC. I agree, the gas companies do shag you for bottle rent and the gas is bloody expensive. What I can't get my head around is the fact that you need Argon for Mild steel and Argon + for stainless. Argon and Argon are the same thing, unless they add an impurity so that they can charge you more for stainless gas. I tried welding mild steel with stainless gas and it played up something chronic, spattered like hell. I was wondering if you could use nitrogen. Sure, again, needs high pressure bottles but you can get nitrogen separators. I wouldn't use CO2 on principle.
Can't remember the boiling point of argon, but I think it is what's left behind after oxygen and nitrogen have liquified. I suppose it's why it costs a load of cash. I suppose you could advertise for light bulbs and build yourself a thing which smashes them and collects the gas under water, before hydraulic pressure drives the gas through your hose.
I have thought long and hard about how to avoid the bottle tax.
Rich 36: looks like a light industrial grade MIG set (seems to be big enough to take a full-size bottle on the back). Should be competent on the majority of car jobs and more reliable/abuse-proof than the DIY sets. Without the specs, it's not really possible to be more specific.
Does it? If your shield's working properly the only oxygen will be from dissociation of the CO2. Oxygen + carbon + iron preferentially oxidises the carbon (Bessemer converter). OTOH, welding/metallurgical chemistry does get a bit weird
I think the stainless version has oxygen in it. Apparently this helps with wetting round the edge of the weld pool, or something. I find the idea of including oxygen in the shield gas really weird, but if it works...
Yeah, you can, not sure what particular processes/metals it's most suitable for but nitrogen is an established welding shield gas.
Interesting, what principle would that be? I'm ruling out global warming on the grounds that welding CO2 is extracted from the atmosphere in the first place AFAIK, and also there's a pretty large evolution of CO2 generating the electricity to run the welder.
Apparently it's -185.7 deg C, nicely in between the two...
As have I, albeit with thought processes hampered by my extreme anger about the situation being as it is in the first place... and the gases I'm after are oxygen and acetylene, which makes the problem a bit more awkward. Everything I've come up with involves a large, awkward, messy plant that consumes shit-loads of energy...
For a shield gas you're not too badly off - burn the fuel of your choice in air then pull the exhaust gases through quicklime to scarf up the water and CO2 leaving a nice nitrogen-with-a-trace-of-argon mix. You could use cement instead of quicklime - easier to get hold of, but the product goes hard... Or just condense the water out on something cold, or use coke as the fuel, and leave the CO2 in, for a simpler but lower-quality shield.
Oxygen is a bit harder - either building a massive refrigeration plant, or a massive electrolysis tank followed by more quicklime/cold stuff. Shame that the hydrogen's not useful - hydrogen/oxygen is a pretty shit gas-welding mix - but there's always the option of filling bin liners with it and sending them aloft with lit cigarettes attached
The fuel gas is the big arse. Acetylene's the best... easily made from readily-available materials, roasting coke with quicklime to produce calcium carbide - needs a LOT of heat though. Big furnace, and big amounts of stuff that needs to be kept perfectly dry. Ethylene, from dehydrating ethanol with sulphuric acid, isn't bad - I don't think a bit of methanol screws the reaction up so meths could be used as a cheap ethanol source. Vaporised aromatics are usable but the burner is not readily available...
Then you need a pump/reservoir/regulator setup for each gas to ensure a constant supply of it at the appropriate pressure, regardless of variations in reaction rate in the producers.
However you look at it, it's complex, awkward and loses the easy sack-barrow portability of a set of bottles - a Transit van is more the size of it. I suppose it would always be possible to buy some empty bottles off ebay or something and use them portably, filled from the static plant - using a super-high-pressure compressor for the oxygen, and compressing acetylene has its own peculiar problems
love machine said:
It's due to the pressure of the bottles. CO2 is a lot less than Argon/Oxygen etc and the bottles have to be safe. They work at 230 Bar full which is lots.
CO2 gives a hardening effect with welds due to the higher carbon content and oxidation of the metal takes place at those temperatures IIRC.
Does it? If your shield's working properly the only oxygen will be from dissociation of the CO2. Oxygen + carbon + iron preferentially oxidises the carbon (Bessemer converter). OTOH, welding/metallurgical chemistry does get a bit weird
love machine said:
I agree, the gas companies do shag you for bottle rent and the gas is bloody expensive. What I can't get my head around is the fact that you need Argon for Mild steel and Argon + for stainless. Argon and Argon are the same thing, unless they add an impurity so that they can charge you more for stainless gas. I tried welding mild steel with stainless gas and it played up something chronic, spattered like hell.
I think the stainless version has oxygen in it. Apparently this helps with wetting round the edge of the weld pool, or something. I find the idea of including oxygen in the shield gas really weird, but if it works...
love machine said:
I was wondering if you could use nitrogen. Sure, again, needs high pressure bottles but you can get nitrogen separators.
Yeah, you can, not sure what particular processes/metals it's most suitable for but nitrogen is an established welding shield gas.
love machine said:
I wouldn't use CO2 on principle.
Interesting, what principle would that be? I'm ruling out global warming on the grounds that welding CO2 is extracted from the atmosphere in the first place AFAIK, and also there's a pretty large evolution of CO2 generating the electricity to run the welder.
love machine said:
Can't remember the boiling point of argon, but I think it is what's left behind after oxygen and nitrogen have liquified.
Apparently it's -185.7 deg C, nicely in between the two...
love machine said:
I suppose it's why it costs a load of cash. I suppose you could advertise for light bulbs and build yourself a thing which smashes them and collects the gas under water, before hydraulic pressure drives the gas through your hose.
love machine said:
I have thought long and hard about how to avoid the bottle tax.
As have I, albeit with thought processes hampered by my extreme anger about the situation being as it is in the first place... and the gases I'm after are oxygen and acetylene, which makes the problem a bit more awkward. Everything I've come up with involves a large, awkward, messy plant that consumes shit-loads of energy...
For a shield gas you're not too badly off - burn the fuel of your choice in air then pull the exhaust gases through quicklime to scarf up the water and CO2 leaving a nice nitrogen-with-a-trace-of-argon mix. You could use cement instead of quicklime - easier to get hold of, but the product goes hard... Or just condense the water out on something cold, or use coke as the fuel, and leave the CO2 in, for a simpler but lower-quality shield.
Oxygen is a bit harder - either building a massive refrigeration plant, or a massive electrolysis tank followed by more quicklime/cold stuff. Shame that the hydrogen's not useful - hydrogen/oxygen is a pretty shit gas-welding mix - but there's always the option of filling bin liners with it and sending them aloft with lit cigarettes attached
The fuel gas is the big arse. Acetylene's the best... easily made from readily-available materials, roasting coke with quicklime to produce calcium carbide - needs a LOT of heat though. Big furnace, and big amounts of stuff that needs to be kept perfectly dry. Ethylene, from dehydrating ethanol with sulphuric acid, isn't bad - I don't think a bit of methanol screws the reaction up so meths could be used as a cheap ethanol source. Vaporised aromatics are usable but the burner is not readily available...
Then you need a pump/reservoir/regulator setup for each gas to ensure a constant supply of it at the appropriate pressure, regardless of variations in reaction rate in the producers.
However you look at it, it's complex, awkward and loses the easy sack-barrow portability of a set of bottles - a Transit van is more the size of it. I suppose it would always be possible to buy some empty bottles off ebay or something and use them portably, filled from the static plant - using a super-high-pressure compressor for the oxygen, and compressing acetylene has its own peculiar problems
I used to swap my pub bottles at the wine wholesalers and the cost of renting a bottle is compounded by the admin charge which is about 12 quid every time you exchange, thing is, it's the same admin charge for 1 or 30.
I would steer clear of Clarke welders, in preference to something like a sealey or Cebora, pick yourself a pub co2 bottle, local wine merchants for gas and a mid size spool of wire, then if you dont use it much, it's not such a big roll to go rusty in your garage.
I also had a clarke 150 welder once, inboarded the springs on my drag car, took it down the strip, wound it up on the line, bang, both spring perches snapped off and the axle twisted. Inspected the welds, to discover they'd cold lapped, meaning all the weld was on one face but not adhered to the other, that was on full amperage, just had'nt penetrated.
I would'nt consider any less than 180 and when you look at the plant , check the amperage because a 180 on the case sometimes is less when you check the actual amps on the scale. Migtronic are the worst for this.
Mick
I would steer clear of Clarke welders, in preference to something like a sealey or Cebora, pick yourself a pub co2 bottle, local wine merchants for gas and a mid size spool of wire, then if you dont use it much, it's not such a big roll to go rusty in your garage.
I also had a clarke 150 welder once, inboarded the springs on my drag car, took it down the strip, wound it up on the line, bang, both spring perches snapped off and the axle twisted. Inspected the welds, to discover they'd cold lapped, meaning all the weld was on one face but not adhered to the other, that was on full amperage, just had'nt penetrated.
I would'nt consider any less than 180 and when you look at the plant , check the amperage because a 180 on the case sometimes is less when you check the actual amps on the scale. Migtronic are the worst for this.
Mick
You sir, are truly a man in the Dibnah mould. Maybe we should form an appreciation society...?Gassing Station | The Pie & Piston Archive | Top of Page | What's New | My Stuff