welding Q

[radardog]

i am building a set of arms like this

http://img116.imageshack.us/img116/6787/buggy0050yo.jpg
next week and i wanted to be sure that i can weld 2"x.250 wall dom to it using a standard MIG wire.

or do i need to use nickel rod for this job??

[caglezxj]

yeah a standard Good Mig will due. Tig would be better, but Mig is fine. Thats what most of your long arms are made from. Just turn the heat up get good penetration and take your time.

[radardog]

most excelent, thank you.

[MogifiedXJ]

You don't need to use nickel unless it's cast fyi

[Mr.OverKill]

You don't need to use nickel unless it's cast fyicast iron that is. cast steel, HI-NI is not required and is a waste of money.

[MogifiedXJ]

cast iron that is. cast steel, HI-NI is not required and is a waste of money.
Yeah cast iron is what I meant...sorry for the confusion

[Bob Myers]

A low hydrogen rod(7018) would be the easiest/best method, mig second with common wire and 50/50gas, Tig could be done, but what a waste of several hours and nowhere near the strength of either aforementioned method.

[rokjeep]

I have arms almost identical to those and I just cranked up my 220 and burned them on nice and slow.

[Weasel]

A low hydrogen rod(7018) would be the easiest/best method, mig second with common wire and 50/50gas, Tig could be done, but what a waste of several hours and nowhere near the strength of either aforementioned method.

Whys that? I understand the time part but strength should really be close to the same.

[Bob Myers]

The tig is super at small welds where the parent materials are both exactly the same composition. In this case they are not.
Both the mig and the 7018 are 70,000psi tensile strength but the low hydrogen rod is meant more for dissimilar metals than the mig.
The ultimate for dissimilar metals would be the "Super Missile Rod" distributed by Airco/Linde. But at 34.00 per pound and the fact that it'll crack from being so hard without preheat and postheat I would not consider it for this, for you.

[ashmanjeepxj]

Mig it... youll need at lease 135Amp for 1/4in, a 110A machine dosent cut it.

I have a 210 miller matic Id run it at 4(heat)-60(speed) that means nuthing to different brands. Id do a pre heat with a propane torch to get the cast steel warm, this will help prevent cracking on cooling.

When you done laying your beads tap the welds with a pointed hammer to release tension in the welds (to prevent cracking).

let it cool naturally or in the sun, or keep it warm with propane so it cools slowly.

Your Mig technique and settings (skill) is more important then all the other fancy stuff.