Hi All!

How have you all been? Have not logged onto the forum for awhile, got tied up with work.

Just want to share some experience... over the weekend, I had the welder supplier dropped off a Kemppi Super Migger. Tried it and it is sweet & smooth & less splatter! Also basically I was using Argoshield.

Now, I have a Miller MIGMatic 210 and the Kemppi. Gotta decide which to keep. Looking at the quality of the weld, I would go for the Kemppi, as the weld result is so much smoother and nicer, makes me look like an experience welder. And Kemppi support team is the friendliest. Unlike Miller, they are not helpful at all! But the thing that bugs me is, the gun/torch on Kemppi is not removable, anyone care to comment any disadvantage for that?

Also, anyone using/used Kemppi? Any complains?

Argoshield is the way togo! Try it if you have not, you will never look back at CO2!

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Originally posted by iceT
Argoshield is the way togo! Try it if you have not, you will never look back at CO2!

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The Kemppi torch is removable, it's just not a euro connector. All the parts are available, although the only bits you are going to need are new tips and probably a liner after several thousand hours of use.

Thanks Mark! Yeah, Kemppi's torch is removable, just that it requires tools, not so convenient. But again, I dun see why would one wanna remove it. Parts are available, as Kemppi reseller showed me their store. Friendly bunch of ppl. I think I know the winner now!

(Smug grin from all those here who've been saying this for months/years! )
I guess some will have to learn it the hard way...

A big part of getting the weld right is the feed. If the feed roller and block work well it's half of the battle won. If it feeds in fits and starts you will never get a good run. Get some good instruction on how to set it up and most welders will perform.

yours, Pete.

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Originally posted by David Jenkins

(Smug grin from all those here who've been saying this for months/years! )

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Originally posted by craig1410

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Originally posted by David Jenkins

(Smug grin from all those here who've been saying this for months/years! )

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I would love to be able to agree but I get much better welds from CO2 than I can with Argoshield. The bit which really scares me is that when I use argoshield it looks like a beautiful smooth weld on the surface but is basically hollow inside and I do mean completely hollow! With CO2 I can get better penetration and except for the spatter I get a clean weld.

To be fair I think it has a lot to do with the fact that the Argoshield that I am using is Halfords little bottles (as is the CO2) so maybe proper Argoshield would be better. Anyway I'm going to stick with CO2 for now.

Cheers,
Craig.

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Sounds to me that the gas pressures too high just gone on to argoshield myself so Im still getting used to it but did find you only need a whisper of gas or higher current.But the finished weld is beautifully smooth.
Bob

After using the CO2 that came with the welder I borrowed from a mate and not being totally happy, I set it up with pure argon, the welds seemed much better.

Argon comes out colder than CO2 due to being at a higher pressure in the bottle so depressurising more, and this can result in less penetration. A thing to try is placing a coil of copper tube in the gas line and placing this in a bucket of luke warm water. In my experience of doing this the welds looked cleaner, gave less spatter and penetrated well.

However, I still managed to burn the odd hole going too slow and thought the process a bit brutal so after speaking nicely to a guy at work and getting a few pointers Ive succesfully learned to TIG. This has proved to be time well spent and I would definately recommend it if you can be bothered trying..

You get complete control of the weld, no mess and it is a quiet relaxing welding process. If you do manage to lay a weld that doesnt look as nice as you'd like then it can be gone over with the torch and neatened up easily

Plus.. when it comes to your wishbones you can do them in stainless and polish them up... mmmm lovely

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Argoshield is the way togo!

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when I use argoshield it looks like a beautiful smooth weld on the surface but is basically hollow inside and I do mean completely hollow

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Not recommended for carbon steel, only stainless or aluminium. It isn't the temperature of the gas it's the shielding it gives. Different percentages are used for different steel thicknesses in process work. Pure argon is also more expensive.

yours, Pete.

Hi pete...

I realise that its the shielding thats important, what I meant was that as the gas is colder when exiting the bottle, apparently it is possible to be generating insufficient heat at the weld thus not getting enough penetration.

Im no expert, but at the place I work, any carbon steel pipework has a 'root' put in with the Tig using Argon as the shielding gas, with the thicker stuff usually being capped off with arc. This is the usual spec given by our clients in petro-chem industries.

As far as I'm aware Argon is fine for carbon (mild) steel, its cost being the only factor for not recommending it when cheaper alternatives can be used with no adverse affects, as in the case of Mig welding mild steel.

It also helps that they have 5ft tall bottles of the stuff around the workshop which they let me use for gratis

It has come to the point where i have to say something.......
Afro. there is a saying that a little knowledge is a dangerous thing and in this case your little knowledge is a dangerous thing.

when next your gas man delivers to your company ask him for some tech info on the gases that are used in welding and you will find there is a specific reason you don't mig with pure Argon, they mix co2 with argon to give penetration, co2 alone gives a deep penetrating weld but with the drawback of spatter and a hardness to the weld, the higher % of argon the shallower the penetration but a lot less spatter, so when welding thin guage mild steel it is easier to use a argon co2 mix, you only use pure argon (as has been said) on stainless and alloy the reason is a matter of purity in the weldpool.

So i would suggest before you go and give advice to someone you realy should do your homework a little better.

Viper,

Why should one gas affect the weld pool more than another?
Not trying to be controversial, I just like to know why!
I understand the principles ,but it has been a few years since doing the coarse and need reminding!
Old age makes me forgetful! now wot were we talking about.

Terry

God now your asking......
i don't know why different gasses affect the weld pool the way they do (its been 20 years since i did my appretiship) i just know what affect they have through day to day experiance. i do know that it has nothing to do with the prssure in the cylinder.
as a footnote you can use Helium as a shielding gas and that gives a much hotter weld pool great for heavy alli, the yanks use helium more than argon..

Fair enough Viper..if a little venomous

As I said Im no expert, most of my info comes from people in the workshop and my own albeit limited experience..

I did notice the welds sitting more on top of the metal than penetrating into it which, as you say, would be dangerous. After adjusting the settings on the MIG set and adding in the copper tube to the line (how much effect this alone had Im not exactly sure) I get good penetration in the weld. It is definately worthwhile welding offcuts and cutting them up to have a butchers before setting about welding the chassis... the large hammer test comes in handy too

If I could ask you a question before I get too far into my chassis (at the 'four uprights' stage now) do you think there is any mileage in re-doing the welds already done with the MIG and argon? I am confident that the penetration was good from looking at those done on offcuts but its no major drama to re-do them with the TIG which has become almost a pleasure to use


By the way, if you want danger, I've seen a site somewhere of a guy building one of these locosts who got very frustrated with various welding processes and has now resorted to BRAZING it.... anyone coming for a spin??

[Edited on 11/8/03 by Afro]

Just a foot note about cylinder pressure... the pressure at the torch is the same regardless of the pressure in the cylinder... the gas is effectively venting to atmosphere. The higher the pressure is to start with, the colder it will be when it has depressurised, not got the figures on me now but the Argon in the bottle is at a far higher pressure than a CO2 bottle therefore is colder after depressurising.

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and has now resorted to BRAZING it.... anyone coming for a spin??

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Welding gas cyls, co2, argon, argon/co2, heliarc (helium) are all filled to 300bar.
Duno about the mickey mouse stuff halfords sell. but all BOC, Air Products, Linde etc etc are 300 bar and have been for about7 years now.

As far as your welding goes , that is a decision you will have to take,

Brazing a Chassis..
Take a look at tubular racing car chassis a lot of them will be brazed, especialy older formula ford etc. nothing wrong with brazing if you know what you are doing, in fact a brazed joint (being more flexible) can be very beneficial, my old kart chassis was brazed and i never had any problems with that and that often exceeded 170mph...

Correction there not 300 bar but 3000psi

[Edited on 12/8/2003 by Viper]

and brazing doesnt form stress raisers like welding does.......

Two comments on brazing:

First of all, it's not copper/zinc brazing (i.e. general purpose), the stuff car chassis makers use is bronze (copper/tin). This is much stronger and less prone to corrosion. Also much more expensive!

Second, brazing requires a higher standard of metalworking. The tubes have to be cut and files to a good fit, with a constant gap of a few thou all round to provide capillary action to get the braze right into the joint.

Personally, if I was starting again (i.e. before even buying a MIG) I would now seriously consider brazing, especially as I have had some experience before.

cheers,

David

One thing I have learnt on these lists is that welding is a subject thats hard to give advice on, cos as an amateur you just dont have the experience that someone doing it every day has.

There are those on here that can shoot you down in flames with their better knowledge.

My father until he retired last year was a toolmaker / machinist / welder, and gave me advice, as did a guy I work with who is a qualified welder. I also spent an hour or two at a welding supplies company ( our cleaners son worked there) getting advice on a previous project before I started welding.

My end result is still no where near that of a time served professional, but its strong. If its not, in most cases I have used extra gusseting and tubes cos im a natural pessimist.

I have seen Vipers welding (his company makes parts for the place I work at) and the standard is high.

As far as gases are concerned, I have used pure argon, co2 mix an co2.

I have agon cos I thought i may weld alu one day, but have given that up as way above my capabilities - and the little bit I did need to do can be done with a product called technoweld. Its a bit like aluminium solder and is applied with a blow torch. Worked ok to tidy up joints on the rear of my car on folded over corners.

When I ran out of gas once I used a bit of argon on mild in non structural metalwork. There isnt much penetration, the weld sounds completly different, and it looks a bit porous.

Most of my work has been in co2 cos I have only a 100a welder and I need to maximise penetration - and the bottles of co2 at machine mart have a greater fill level! CO2 isnt nice to use - lots of spatter and not so tidy welds.

I have recently tried and taken to mix. Its much much much better and is more forgiving for an amateur, as an amatuer I would say its the best compromise.


atb

steve


[Edited on 12/8/03 by stephen_gusterson]

Thanx ste, just yesterday i was in machine mart wondering if i should be bold and get argon, i got the CO2 cos there is indeed more in the bottle. I may well try a mix next time, cos there is a lot of splatter with CO2, especially as its usually windy when i do it. Nearly all my welds need touching up when its finished.

An afterthought on brazing...

I was reading a book about the 750 Motor Club the other week. One of the authors described a crash that the other author suffered...

Driving along in a brazed space-frame single-seater open-wheel racing car, he got nudged by a beginner into the end of the pit-lane wall - 100mph to zero in 3 feet! He suffered several heart attacks due to the impact of his chest against his harness, but fortunately a nearby mashall was a doctor who kept him alive until he got to hospital. He had almost no physical damage apart from that.

The point they were trying to make was - if a brazed chassis is designed and made properly, it is very strong.

DJ

230 bar in the argon (Linde) but the CO2 full was less than 150... the bottle is of unknown origin... possibly a pub, we dont generally carry CO2 in the workshop.

Brazing seemed always to be the preferred method on the road bike frames I used to ride about 12 yrs ago but most were built using lugs too. The Italian ones being almost pretty enough to hang on your wall rather than take out in the rain.
I just had a vision of a very frustrated man in a workshop who had given up on trying mig and gas and thought 'next I'll try brazing'... I wondered how long it would be before he'd given up on that and was off down to the nearest school for a bottle of evo-stik... Excellent deposition rates, adjustable feed, minimum effort to ensure a flush finish where required etc etc...

JoelP:

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there is a lot of splatter with CO2, especially as its usually windy when i do it. Nearly all my welds need touching up when its finished.

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Cheers Rorty, i'll look into it!

Washing up liquid does the same job - I have worked for some tight employers in my time!

Wow...! Thanks all for your responses and sharing.

I have just confirmed the Kemppi w Argoshield. It really feels much better than the rest. It sounds like bacon frying in the pan with all correct adjustments. And yes, when the gas flow too high, the weld does look a little porous! Looking for RHS now and hopefully to start by Sep! Can't wait...

What wire size should I go for? Is 0.8 ok? I've read somewhere (probably from previous postings) that 0.6 would be ideal. The reason I ask is, it is rather difficult to get 0.6 wire spool. I have to specially order and that will cost. On the other hand, 0.8 is widely available. So is it really worth to go thru the hassle and pay for the difference for 0.6 or 0.8 would be just fine tho it may not be as good as 0.6?

I built my car with 0.8. It is probably slightly easier when joining tube edges to use 0.6, but certainly not impossible to use the former.

I always use 0.8 wire and find it builds better than the 0.6 and is much more forgiving. If you cock something up putting the power up a notch and running over it again to flatten it out works better with the thicker wire. I don't know if it is a trait of my welder but I also find the arc easier to control, maybe that it feeds thicker wire better.

yours, Pete.

Just a quick tip, don't be tempted to use 15Kg spools on a small welder, even if they fit and the manufacturer says you can use them. It puts a hell of a strain on the wire feed at the begining of the weld and the flywheel effect can over feed the wire at the end of the weld. With welds only 25mm long there ain't much in the middle!

On my second reel i got the 0.6 by accident, it seemed not enough was coming out, so i turned up the feed to compensate, but it wasnt the same... i cranked up the current for good measure. Next time i'm definitely gonna use the 0.8 again, even if it is a little harder to thread...

With the thicker wire you have the wire feed slightly lower, so it seems more relaxed - the wire comes out gentler.

All IMHO of course!

Cool! Thank you all for all the inputs! Glad to hear that 0.8 wire is better, as 0.6 is very scarce here and it will cost a bomb to special order it.

Yippee! One bit of good news for the weekend!

Have a great weekend everyone!