50 replies to this topic

[mike.]

Yeah i'll have to look into the gas thing abit more. That links pretty intresting anyway - Something to look into.

But looking at the price of a disposible bottle - about £8 for about 7 mins use doesn't seem too bad to me for the amount of welding i expect i'll be doing. Alot of the welding i'll end up doing will be the odd small patch - I can't see me needing some sort of gas contract.

So how is argon better than co2? I've read that the gas is used to sheild the weld from oxidization - So what are the effects to the bead of weld when it comes into contact with oxygen?

[GreaseMonkey]

the bead oxidises and looks abit like its rusty when it comes into contact with oxygen, not really good for penetration

linky

[Shifty]

Ok I'm no expert on this but I believe that co2 is a WET gas and argoshield is dry. i have used both and can honestly say that argoshield is best. Price wise theres no comparison, I used to get CO2 from the pub for £10 a bottle.

http://www.mig-weldi...welding-gas.htm

[mike.]

Right i see.

Thanks for that link too. Looking at that, looks like a couple of the disposible argon/co2 mix bottles will be suitable for what i'll be doing.


Now about the wire. What are the different thicknesses for? Does this differ for the thickness of the metal your welding?

[Shifty]

Yep, for car body, 0.6 is considered best

[mike.]

So then the thicker the metal the thicker the wire i take it?

What about the wire material itself? The ones i've seen are described as mild steel - Is that what i need?

i.e. If i want 0.6 then is this what i need: http://www.halfords....tegoryId_128815

Also just so i can get an idea of cost again - How long will a 700g roll of wire like that last me? I guess that'll depend on how thick im putting on the bead of weld and things doesn't it?

[Shifty]

As a rule of thumb yes, if all you are going to do is weld up rusty minis, then 0.6 is all you need.

I have no idea how long 700g will last as I use 15kg reels!!!

If you only use the weld infrequently then small reels are best as welding wire "goes off" after 12 months. it can also go rusty which is fatal!!

Yes you need mild steel wire

Screwfix also sell it cheaper!!

[mike.]

Cool.

Just had a look through the screwfix website - Can't find anything apart from welders - Pretty poor search function on the site i guess. According to the branch locator theres one a 10 minute drive from me so won't hurt for a trip down there. You don't have to be some sort of trade member to buy from there do you?

Just looked on the machine mart site - They do a 5kg real of 0.6 mild steel wire for £15 - So that seems nice and cheap and 600g co2/argon mix disposible gas bottles are a tenner.


One last thing i need to ask about - Voltage. I have no idea what to even ask about this but i know its a pretty important factor i need to know about.

[Shifty]

Not as important as amps!!

For car bodywork you will need a welder that goes down to 30amps. Some clarkes will go down to 25amps, however 30 is the norm.

[mike.]

So can you ellaborate abit on amps and voltage then?

[mike.]

Also about the sill replacement itself - Can somebody confirm the way i guessed you weld a new sill on?

'Clean up the surrounding metal, hold/clamp/secure new panel in place, tack the sill into place with small blobs of welded dotted every... say 6 inches?, then once thats done do i continue adding a full bead of weld all the way around the sill in small sections? Then clean up the welding with a grinding disk on the grinder?'

Have i missed anything there?

[R1mini]

There is no need to fully weld it as your using a genuine sill, stitch welded is fine. Tack welding the sill on to check for aligment and fitment is the way to go, I would weld the sill ends fully as the water gets blasted on these areas

Cheers
David

Edited by R1mini, 10 April 2008 - 01:17 PM.

[mike.]

So if i just do abit of weld at intervals along the sill i'll be ok? How much should i leave between each bit of weld?

But doing it this won't it leave some parts of the sill pretty open to the elements? Replacing sills isn't i job i want to do every 6 months - I'd rather them be watertight.

[panelbeaterpeter]

Seam weld the ends, spot/plug weld the along the length of the bottom edge, and spot/plug weld across the top. Make your welds about 2 inches apart, no more. This is the method used by the factory, and it is perfectly good. Don't know if anyone has mentioned, but don't use oversills, they are sucky. You don't want to get a watertight seal, if it's sealed then condensation starts inside and they will rust from the inside out. You need ventilation and lots of waxoyl to keep them in good order. Do it properly and they will probably outlast the rest of the car.

[mike.]

Is it possible to slap aload of underseal on the inside of the sill? Will that cause any problems with the welding?