Tig Brazing

[Lee Finstad]

As I continue work on my Experimental Colt, I'm having a bear of a time working/welding with the very thin 3/8" Piper U-channel material. Is utilizing Tig Brazing with Silicon Bronze rods acceptable way of tacking these on to the airframe? I'm quickly burning through with my Tig machine, even set at low amps, my inexperience is evident. Any tips on techniques?

[mmoyle]

Use the 0.020” tungsten (thoriated commonly used). ER70S 0.035 filler wire. The trick is in grinding the tungsten. Grind to 45 degree angle then just blunt the tip. Use a magnifier to see the tip. The tiny flat spot on the end of the tungsten will make a very tiny ball of plasma. With a practice piece. Set your TIG on very low, enough to heat the metal to red but not melt it no matter how long you hold the ball of plasma there. Now sneak up on the heat until it begins to melt. Once it’s hot enough to make a puddle it’ll melt through, the small diameter filler rod is used to fill but it also acts to cool the puddle. It’s an art…. Always heat the bigger heat sink, which means, start the bead away from the edge of the “U” channel, angled towards the larger heat sink. Then work the bead to the butt joint of the“U” channels.


Sent from my iPad using Tapatalk Pro

[mmoyle]

I’m wondering about using 15% silver, silver solder. That stuff is easy to use. Makes a good filet bead.
I wouldn’t use a TIG to braze. Get a small A/O torch.

https://www.tinmantech.com/products/...h-accessories/

Kent makes a tip kit as well. Use a small orifice, set the flame quiet. As in you can’t hear it. Be patient… if you have to hurry your bead your torch is to hot.

Sent from my iPad using Tapatalk Pro

[Jim]

Hi,

In my helmet I use a shade 8 or nine to see what I can. I've never seen things as well as some internet videos show, the ripples forming on the edges of the pool etc.

[mmoyle]

I either have to get my face right up close using my bifocals or use 2.0, 3.0 or 4.0 reading glasses. All depends on where my head is and the distance to what I’m going to weld when I’m inside the structure. Sure wish they’d come up with some way of softening my old corneas. I remember my first set of corrective lenses and asking my optometrist what’s the average age wherein people need glasses…. He asked how old I was…44. His answer 44.


Sent from my iPad using Tapatalk Pro

[Steve Pierce]

Piper brazed the brick brack (3/8" channels) on the early J3s and they are a bear to repair because you have to get that brass off the tube before you can weld to it.

[Stephen]

I agree with Steve. I OA brazed U channel and stringer attachment pieces on my J3 many years ago. It was a major pain to fix. Now I use a Smith torch and small tip. I turn down the gas once it is lit. Keeping the heat mostly on the tube the welding works fine.

[MrBill]

I either have to get my face right up close using my bifocals or use 2.0, 3.0 or 4.0 reading glasses. All depends on where my head is and the distance to what I’m going to weld when I’m inside the structure. Sure wish they’d come up with some way of softening my old corneas. I remember my first set of corrective lenses and asking my optometrist what’s the average age wherein people need glasses…. He asked how old I was…44. His answer 44.


Sent from my iPad using Tapatalk Pro

Everybody I talked to about when your eye sight goes bad said 50 years. I swear I wasn't even a month into my 50's and my eye sight failed. I never associated my bad welds with my eye sight till maybe 58 years old. God, I could not have been happier after welding with a pair of reading glasses. I have always been known to have very good welding skills so that was a pretty depressing time, ha.

[Jim]

Hi,

Steve wrote; "Piper brazed"

My carb heat box is also brazed together, stock as far as I know.

[dgapilot]

A couple of comments, I’ve seen cracks develop in 4130 when brazed. Not an issue with 1025. For welding the thin stuff I use .025 ER70S2 mig wire. I set the TIG machine to about 20 amps and use a “TIG button” on the torch to control amps. I use 2% lanthinated tungstens. You can go as low as .020 but if you grind it right even a 3/32 will work. I have a variable auto darkening hood ($139 Vulcan at HF) and can set the shade based on the work I’m doing. I wear my reading glasses and have a 3X cheater insert for the welding hood. You have to get close to see! If you want to go OA, get a small lightweight torch. I have old Smith #2 torches (WWII era). The Smiths airline is similar.

o/A or TIG, controlling the heat is the key. Low amps or small tip.