Chrome Moly Tubing

[swiftprop]

What is the best method to use to weld this (thin) tubing?
Co2 Mig ot TIG?

[Duck Rogers]

TIG

[swiftprop]

Thanks Duck, but why not CO2?

[Duck Rogers]

I'm presuming you're referring to co2 as MIG welding.
The process involves a wire fed filler material (I'm sure you know that) that is used for filling in gaps and welding the 2 pieces together.
It is a dirtier process than TIG and spatters quite a lot. If you don't mind the spatter, less than stable arc and sometimes erratic wire feed then use MIG.

TIG is cleaner, a very stable arc and has a higher quality weld with less contaminants in the weld. Uses Argon gas a shielding agent. Doesn't transfer as much heat to the surrounding areas and looks neater when finished. You may even be able to melt the 2 metals together without any filler material making it even better and neater.

I've only just scratched the surface with this answer. There are a host of other comparisons to be made but this is the simple answer.

[swiftprop]

Hi Duck thanks. i am a layman at this stage but wanting to learn. Would like to build a Legal Eagle XL at some stage. I was referring to Oxy Acetalene welding sorry not CO2

[Duck Rogers]

Ag no man...........now I've got to do it all over again
Oxy-Acetylene is the old-school traditional way of welding 4130 (chromoly) metal.
4130 is prone to cracking if you use 4130 filler rods but with Oxy the weld doesn't cool off so quickly because the flame heats a larger area of the metal and that's why it (oxy) is used.
With TIG the area of metal that is heated is much smaller and cools quicker. That's why the piece has to be post-heated to a nice pink colour and then left to cool. The preceding statement is only valid if you use 4130 filler rod on 4130 steel. Try using ER80S or ER80S-B2 filler rods instead when you TIG because its a little softer than 4130 and not prone to cracking and you won't have to post-heat treat the piece.

There's very little other differences between the two. Take your pick. I can do both but I prefer the precision of TIG to concentrate the weld pool in a small spot.

Dammit........my brain's tired now from all this explaining...

[KFA]

For under 3mm the TIG is perfect because of all the reasons that Duck mentioned but also added that you do not have to normalize the weld.

[HENNING JOHAN]

Ag no man...........now I've got to do it all over again
Oxy-Acetylene is the old-school traditional way of welding 4130 (chromoly) metal.
4130 is prone to cracking if you use 4130 filler rods but with Oxy the weld doesn't cool off so quickly because the flame heats a larger area of the metal and that's why it (oxy) is used.
With TIG the area of metal that is heated is much smaller and cools quicker. That's why the piece has to be post-heated to a nice pink colour and then left to cool. The preceding statement is only valid if you use 4130 filler rod on 4130 steel. Try using ER80S or ER80S-B2 filler rods instead when you TIG because its a little softer than 4130 and not prone to cracking and you won't have to post-heat treat the piece.

There's very little other differences between the two. Take your pick. I can do both but I prefer the precision of TIG to concentrate the weld pool in a small spot.

Dammit........my brain's tired now from all this explaining...

Ghee Whizz Oom Duck!You sound like a coded tig welder or double coded welder.What's the ER80 d2 used for?

[Duck Rogers]

It's a filler rod. Or "welding rod" in layman's terms

[swiftprop]

Hi Duck your answer is much appreciated. sounds like TIG is the way to go with the filler rod you mentioned!

[bobthebuilder]

There is nothing wrong with an Oxy Acetylene setup. The equipment is cheaper.
Imho, TIG, or GTAW as it is now called, is the way to go. The smaller DC machines are available new for around R2000.
Expect to pay from around R10 000 and up for an AC/DC machine. Take a look in the Junkmail. You may find a good second hand machine for around half of that.

Ps. Great post Duck.

[swiftprop]

Hi Bobthebuilder.
Thanks for that. What does GTAW stand for?

[KFA]

Gas tungsten arc welding

[swiftprop]

thanks!

[Gaz]

You can use a normal invertor welder, just add a tig torch and a flow meter on an argon bottle, put the earth clamp on +pos and the torch on -neg and scratch the tungston electrode to arc. Very affordable if you own the invertor welder in the first place!