Tig Welding question

[Rmc]

Anyone know the compatibility of welding either cast mild steel or cast 4130 to hot rolled mild steel? I'm trying er70s rod and gave it the hammer test seems solid... Found an issue with this stupid bugs front arms so I need to modify em. Just thinking out loud here but in the beginning I'm guessing people used to modify stock arms before foddrill and woods came along right? Appreciate the help guys.

[Rmc]

Have a look see.

[Rmc]

I did notice crap floating up on occasion out of the cast steel piece. I also used a lot of heat, very slow feed. Figured one of you guys have done cast steel to mild steel before.

[Tchajagos]

There was a thread about it and welding onto cast spindle for a double shear stealing mount. Can't seem to find it though. They said they had put in on the BBQ for preheating.

[Tchajagos]

Steering*

[cs_drums]

I welded double backing plates and double sheered the stock cast knuckles. When I researched it I found that the preheat and slow coooling is the key and using a high nickel content rod I dont remember the name but it was $$$.
I used the BBQ got it as hot as I could pulled each knuckle off for a few passes then put it back on. After everything was welded I slowly turned down the heat, left them in the BBQ with the lid down until hours later. So far so good. There are pics on my build thread.

[bajascott]

I have used 7018 rod with the flux taken off in a pinch,works good.
But yea I use the gas grill too. I have a chunck of stainless 3/8 thick 12 x 18 I use as a sync to set stuff on.

[ESHALLBETTER]

You want to us "super missile rod" it is basically a glorified stainless rod.

[Rmc]

I have also read high nickle rod, but was unsure due to both being steel vs iron ill see if I can get specs on super missile and stainless

[ChaseTruck754]

I forget what thread it was in too, but know it's covered. As has already been said - pre heat & post heat (slow cool down) are very important. As is the high nickel rod. Brian (BDKW1 / Partybarge) explained that stainless rod has about the same nickel content as the more expensive "super missile" rod.

I was the one that brought up the BBQ for pre/post heat as it was a trick a buddy told me. He uses a charcoal grill. Gets the coals glowing & parts go on. Check temp with a temp indicating marker or infared thermometer & weld the parts. Then leave the stuff on the grill while the coals burn out for the super slow cool down.

[robertcrav]

It was in Brian's build thread....

http://www.gofastbroncos.com/forum/view ... dle#p53566

[Rmc]

One side note, I took 2 cast steel pieces and butt welded them then took a chunk of mild and welded it a little ways down. I beat it with a hammer till the point I laid it over both directions holding it by the mild steel end, then held it by the cast end and continued beating it till it broke. It broke in the untouched cast section. I'm assuming the annealed section gave way. It did not break at the weld as I had hoped it wouldn't. I will normalize (BBQ trick) when I'm finished boxing them together. I think it will be plenty strong for a bug.

[cs_drums]

THis i show I set it up.
[img]

[Rmc]

Got another tig question for you guys, so a coworker suggested I try lanthinated rod, everytime I use it it goes along fine for 30 or so seconds has a strange flare up, and balls up big time. I've asked at a few welding supply houses but those guys rarely have answers to my questions so I figured I'd put it out there for you guys. Any idea what causes the balling? This does not happen with both pure tungsten or with thoriated. Any ideas? The coworker suggested lanthinated in place of thoriated to limit radiation exposure.

Conditions: clean material, new rod, 120amps, straight dc polarity, .5 pre flow, 10s post.
Machine: miller dynasty

[Rmc]

Shoot forgot, 3/32 tungsten in all cases and number 8 cup pure argon 1/4 inch out of cup.

[ChaseTruck754]

What color coating is the lanthanated again?

Not sure I have the real answer to your question, or if it's even the same deal, but when I had the heat up too high in welding aluminum the tungsten was balling up like you describe. It seemed like I was welding with the thing set on straight polarity vs. reverse polarity. Asked a buddy who welds a ton & he said the heat was too high. Crank the amps down a bit & it will stop & sure enough it did.

So what material and how thick is the stuff you're hitting with the 120 amps?

[Rmc]

It was just me screwing around awhile ago and couldn't figure it out. It was probably 2 pieces of 3/16 scrap just trying figure out why it wouldn't work. Like I said funny thing is the exact same settings (just swap tungsten and go) work fine with both thoriated and pure. The lanthinated is gold band btw and thoriated red. Pure is green. Pure is best for aluminum I've been told but I've had success in both steel and aluminum with either red or green. So here's my notes for you on ac balance control if your machine has it, it may help you out, it did me but the notes are ac balance control in ac only. And a blunt or sharp tip can be used if the settings are correct. If no ac balance blunt the tip before using it stops some of the balling.

[BDKW1]

Balling up on DC is hard to do, usually from over heating your tungsten. Might need to move up to 1/8". I use lanthinated for everything. Saves having to figure out what that unmarked little chunk in your supply try is. With 3/32", the only time I have it ball up is AC over 100A, then it goes quick and retreats back into the cup.

[BDKW1]

Oh, back to the cast question. Cast steel does not require special rod. Cast iron does. Big difference. Bothe require pre-heat and post cooling control manly due to the dissimilarity in mass's.

[Rmc]

Hmmm ill try that stuff agian. I since have removed the high freq arc start points or what ever there called (I can't remember now) but I lapped them and re-gapped them and have gotten the arc wander under control. When I first got the machine it came out of a storage unit, it had been collecting dust for 5 years so who knows corrosion wise. Initially the arc would start normally, flash, walk completely up the electrode far up into the cup then after you floored the petal it would snap back to the tip. I did some reading on it but I was bassically trying to establish if the machine needed to be repaired. This was after I thought everything was working correctly. It was over a month ago but it's one of the nagging questions in the back of my mind. The arc wander hasn't come back since then so I think that's what it was. The lanthinated is recommended so I don't know. Like I said ill try it agian and pay closer attention.