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materials and welding
robertst - 10/11/05 at 04:49 PM

First and foremost: hello, im tom and i'm from Madrid. I'm on the "planning and sourcing" stage and have sourced pretty cheap steel, but the guy that sold the metal to me said 1.6mm thick steel does not exist, so i had to go along with 1.5mm (i guess a millimeter will not drastically change things).

i have decided on buying an arc welder, as here in Spain it appears that MIG welders are considered something from space (cheapest is around €300 a opposed to €100 for a 140Amp arc welder). one thing i dont really understand is how are you supposed to deal with the sparks and heat? i know it must be common sense not to hold the steel tubes with your hand whilst welding, but how do you hold the tubes in place? specially at right angles?. Furthermore, when welding, i see that many builders here and in the book use a wooden bench to weld... doesnt it burn? or are the sparks not THAT hot?.

I don't really have that much space in my house, so i was thinking of welding the initial frame in my terrace and then the rest in the garage. is it silly and dangerous to weld in my terrace? it's quite big, and im only concerned about the windows (if the sparks were too hot, maybe the windows can crack?). i know these are quite silly questions, but i dont know absolutely anything, and i'm just reading stuff, but dont know how welding behaves in real life.

are there any other big NO-NOs to have in mind apart from those in the book?
thanks
tom

[Edited on 10/11/05 by robertst]


JoelP - 10/11/05 at 05:39 PM

hi mate.

firstly, i wouldnt weld indoors, the sparks arent hot but they will still ignite some carpets or sofas etc. Wood might singe/smoulder but will not catch light usually unless you get carried away. Always have a suitable extinguisher to hand

A wooden jig is the perfect way to get the tubes held in place. You can draw vrey accurately on wood, and then screw in blocks to hold everything in place


GeoffT - 10/11/05 at 05:53 PM

....also don't be tempted to use magnetic welding clamps if you MIG weld. These do something very strange to a MIG arc, and cause it to splatter all over the place. Unfortunately I'd thrown my welding torch across the workshop and smashed it before I found this out....


BKLOCO - 10/11/05 at 06:22 PM

Welding 1.5mm steel with an arc welder is a serious challenge for an experienced welder. The chances of a novice getting a good weld are minimal. You really do need to invest in mig unit.
If you are welding on a terrace be aware that the spatter (sparks) from the process are hot enough to mark glass!!
I speak from personal experience. I wrecked a set of patio doors in my last house.


caber - 10/11/05 at 07:04 PM

I am going to gas weld my chassis , Oxy acetelyne. You may find this is cheaper than investing in Mig though it is an learned skill and you need a good bit of practice and some tuition. Wood does not work well with gas welding you are useing a flame and it all gets hot and catches fire! magnetic clamps are OK but they do cook and lose magnetism after a while.

I would not even try and arc weld the chassis I botched up a perfectly good set of table legs made out of 2mm box with my arc, I only did it in desperation as it needed doing immidiately and my gas set was elsewhere!

Caber


emsfactory - 10/11/05 at 08:05 PM

I used magnetic clamps when i was tig welding. It took me a few minutes to click. Made some very cool looking flames though.


robertst - 10/11/05 at 08:08 PM

i myself prefer a MIG welder, but it is almost impossible to find anything less than 300 euros, which is far off my budget. plus, arc welding was used way before MIG welding came up right? it will be a pain in the **** but a weld is a weld right? The two cheapest solutions here are gas or arc welding. u spend a lot on gas bottles though.
they also sell very small units called inverters. these are sold for around 700 euros. what do these do?

btw. arc welding is too powerful for 1.5mm right? thats why its a bummer? i guess i'll have to find a voltage/current combination that will not burn holes.... MIG is too expensive 4 me, and there is almost no supply.

[Edited on 10/11/05 by robertst]


Bob C - 10/11/05 at 08:29 PM

For arc welding the quality of the rods makes SUCH a difference. I bought a big pack of rods I could NOT get a good weld with, ever. 'fraid it's so long since I used a stick welder I don't know what makes to avoid any more.
The inverters use switching transistors at high frequency instead of mains at 50Hz - so the wound components are correspondingly smaller. They should be easy to strike up & produce good results but I've never used one so I can't really comment.
lots of non-information there. . . .
Bob C
PS buy a 2nd hand MIG then sell it after the chassis is done - - - - then it costs nothing???


JB - 10/11/05 at 08:33 PM

It is possible to weld 1.5mm steel with an arc welder but it would take lots of practice.

If you go the gas route I would recommend Nickel Bronze welding, this is basically a high strength brass based braze. The disadvantage of gas welding is the amount of heat you put in and the distortion that will result. With brazing the amount of distortion is minimal. Race cars in the UK used to be (some still are) nickel bronzed.

Mig however is the "best" option. It is relativly cheap, easy to learn and will produce a good weld. It nearly is a case of if you can not afford a Mig then save up until you can.

I am unsure of the real technical details but an inverter is a way of producing the current required for the arc. They are generally smaller than the normal transformer way.

John


caber - 10/11/05 at 10:07 PM

Most inverters are also useable for TIG welding much better current control than a straight transformer I believe.

Check ebay for second hand MIG kit in spain there must be some somewhere! Can't you hire equipment?

Caber


robertst - 10/11/05 at 10:35 PM

quote:
Originally posted by caber
Most inverters are also useable for TIG welding much better current control than a straight transformer I believe.

Check ebay for second hand MIG kit in spain there must be some somewhere! Can't you hire equipment?

Caber


yes, but they are arc welders. around 15 euros per day. i am really better off buying one and then selling it or returning it 20 days later for a refund.


dl_peabody - 11/11/05 at 03:26 AM

Cheap Clamps

Here is what I tried for clamps and holding peices in place.

1. Buy a 12 ft peice of 1"x2" (convert to meteric equivalent)
2. Cut into foot lenghts (convert to meteric equivalent)
3. Drill it with three holes one on each end and one in the middle
4. Match the peices up, best you can.
5. Buy bolts, nuts, and washers...you may need two or three bolts per unit depending on how you use it.
6. Tighten the bolts so that the wood sandwiches the metal and holds it in place.
(Good for holding a peice, or 6, until you can tack it into place)


robertst - 11/11/05 at 12:21 PM

great idea!, so you bolt the wood sanwiches to the bench and thus keep the metal in place right? ill do that thanks!


James - 11/11/05 at 12:37 PM

300Euros is about £200 isn't it?

That really isn't *that* much for a MIG Welder. Okay, we might pay half that here but in the scheme of the £5000 build I don't think it's a massive issue!

As said by others I wouldnt weld near glass- the effect cause by angle grinding is bad enough but welding would be worse still I'd guess.

Cheers,
James


zzrpowerd-locost - 11/11/05 at 02:36 PM

could you not find a mig in the uk? im sure the cost plus carrige to spain would be alot closer to the spainish arc price???

Based on quick calcution and look on web i reckon you could get one to spain for around 200 euros

Wouldnt recommend arc welding, even if it is cheap! i been welding for 13years and still catch the odd arc, sleepless night anyone??


[Edited on 11-11-05 by zzrpowerd-locost]


David Jenkins - 11/11/05 at 02:42 PM

quote:
Originally posted by JB
If you go the gas route I would recommend Nickel Bronze welding, this is basically a high strength brass based braze.


Pedantic correction (sorry! )

Bronze brazing is not brass! I'm sure you know that bronze is an alloy of copper and tin and is very strong. Brass is what's used in ordinary brazing, and is an alloy of copper and zinc and is brittle and prone to corrosion.

The difference becomes obvious when you try buying each type of rod - ordinary brass brazing rods are cheap, and bronze-brazing rods are bl**dy expensive!

There's also a different technique to assembly when brazing - well illustrated in the book 750 Racer, but I don't suggest you buy a copy of that 'cos it's currently going for £200+ in the 2nd-hand market!

Apologies if the expression "suck eggs" comes to mind...

regards,
David


79 civic - 11/11/05 at 03:24 PM

my dad bought himself that book but i dont think he would have paid that much for one now, he bought it at a yard sale for $30 US.:


robertst - 11/11/05 at 06:33 PM

whoah! that was a bargain

can u believe i went today to three different specialist shops and all of them told me the second i said the word MIG:
"You dont want that type of welding, only professionals can handle those, and they are too much for what you intend to do". aaargh! one of them even suggested that i weld with an electric chip welder (one of those small pen welders) "just get the most expensive one and it should cope with 1.5mm!" seriously, some people...


zzrpowerd-locost - 11/11/05 at 06:37 PM

quote:
Originally posted by robertst
whoah! that was a bargain

can u believe i went today to three different specialist shops and all of them told me the second i said the word MIG:
"You dont want that type of welding, only professionals can handle those, and they are too much for what you intend to do". aaargh! one of them even suggested that i weld with an electric chip welder (one of those small pen welders) "just get the most expensive one and it should cope with 1.5mm!" seriously, some people...


h,hmm! mig only for pros??? other way round i think! Mig is easy compared to arc!!!


JoelP - 11/11/05 at 07:05 PM

i started welding my chassis on the same day i first did a mig weld, and nothing fell apart. That shows how easy it is to pick up


Confused but excited. - 14/11/05 at 12:12 AM

Having tried to learn all three techniques of welding ie; gas stick and mig ( tig is too expensive for most of us ).
mig is by far the easiest.
However I would not advocate learning to weld by getting a set and building your chassis. Surely someone local could give you a hint, failing that at least buy a book.
As mentioned previously, the best option or even the only option for a welding novice is, buy a mig set and when you have finished ,sell it!


slopecombat - 18/11/05 at 01:25 AM

Hi from Barcelona,

I'll begin to practice with my new arc welder this weekend. As robertst I have not been able to find a cheap second hand mig welder in spain.

I'll test welding 1/16" RHS steel tube and if it results really difficult I'll make my frame with 1/12" tube as the difference of weight is few Kg.

I hope steel will be more "rust-proof" than my english !

Suerte robertst !

[Edited on 18/11/05 by slopecombat]


robertst - 18/11/05 at 07:36 PM

gracias el soldador de arco esta bien para soldar el chasis, electrodos de 2mm son suficientes. nunca he soldado, y mis pruebas de ayer fueron geniales!. voy a estar en bcn este fin de semana! un viajecito de turismo


LHFever - 6/12/05 at 01:40 PM

hi hi....
I am from spain too and i have been planinng my locost for the last four years....
is there any other from spain....
thanks...
I have many manuals about soldering if u need some ask for it....