South Jersey Skybolt :: A Radial Engined Biplane

Aircraft Welding 101:
Size does matter !

May 3, 2007

Back out to practice... more welding.

Pulled a few thick pieces of flat stock and round tubing out of the box of pieces Howard handed to me to say go practice. Lit the torch up. "We're gonna have some fun." Afterburners lit and I'm ready to go. Wedged a piece of tubing under the flat stock so that it laid flat against the thin-walled 4130 I was to weld it to. Playing the flame over it, warming it up. Ready for the puddle to flow. Waiting. Waiting a little bit more. STILL WAITING ! Damned if I wasn't getting frustrated with being unable to get a decent puddle going. No puddle, no welding. What's up with that ?

What happened over the past day that turned me from "expert welder guy" to a "you don't know your torch from your igniter guy ?"

Think, Jerry... think.

Lesson Number One: Confucius say... man who try to walk, before he comfortable with stand, fall on ass.

In other words... when learning to weld, stick with the new learned skills you acquired, before moving ahead. Get use to welding thinner walled tubing and thinner flat stock before pulling the larger, thicker stuff out of the bin and having a go at it. You'll stay a happy welder instead of getting frustrated with it.

After hitting my head up against a wall for a half hour I pulled a few pieces of metal that were quite a bit thinner than the first dig in the box. Turns out Confucius was right. My welds were nicer and I was a happy camper again. :) Lesson one learned.

Lesson number two wasn't far behind lesson one.
I tacked a piece of flat stock to a length of round tubing. There was a pretty good cavity to fill with the weld. I happily began to weld the two together. The more I ran that bead down the two pieces the more unhappy I got. Something just wasn't working. The throat on the weld was shallow, almost a concave look to it. It seemed like I couldn't feed enough of the stick into the puddle to keep it happy too. Not only was I unhappy, but the weld bead had a frown about it.

I went about trying to weld like this for the better part of an hour. You're at that point when you know something is wrong but just don't have a finger on it yet so you continue the task at hand hoping that it will reveal itself after asking yourself enough questions. Low and behold, the heavens opened up again, rays of lights shown down from above and I heard that choir of angels. If the rod I'm feeding into the weld joint isn't filling it, no matter how much I feed it, THEN there must not be enough material in that rod to do the job.

Lesson Number Two: Size does matter.

If what you are feeding it doesn't fill it... ya need to go to the next rod up. This secret revealed itself in the beginning of my welding 101 class. The guys on the biplane forum filled me in on that bit of knowledge. There are occasions, I was told, that the 1/16th inch rod isn't going to do the trick. You're going to need a handful of 3/32nd rod to use on some of those larger weld joints. This, my good friend... was one of those times that I needed to use a 3/32nd to get the job done.

I grabbed one of the rods out of the container I keep in my workshop. "Jeez... look at the size of this thing." How the heck am I going to be able to keep the puddle going while adding this thick, heat-robbing rod to the equation ???

Simple enough... I learned this from one of my other lessons. Turn up the heat ! Once I started feeding the 3/32nd rod to the joint, playing the flame over all three pieces of metal, it all came together. After running a few nice, proud-to-say-they-were-made-by-me welds.... It was time to hang up the goggles for the night. Leaving a happy man. Total time spent learning these two lessons, 1.9hrs.

Note: If turning the heat up makes the torch pop, go up to the next size tip.

May 7, 2007

Back out and having another shot at honing my "skills." Spent a little over two hours trying to find that groove that I was getting into just a few days ago. Forged ahead into that deep "V" weld joint. May have been quite a bit deeper than the last session. I didn't find that groove I was looking for until I backed up a few steps.

That groove was just out of reach. Small rod... not filling it enough. Large rod... filling it too much... stopping the run of the puddle. A lot of popping going on tonight when I was trying to push through those large mounds of welding material. Hmmmmmm..... something for me to ponder over the next day or two. I've got the patience and observation down tonight looking and finding that new understanding. I just need to understand how to apply that knowledge to skill. (what was that ???? practice... practice... practice...)

I continue to explore the welding "environment," the living, breathing life form that it is, building on the understanding that I've gained from pushing the limits previously. I'm begining to get that feel for when it's going to blow a hole into the wall of the metal, when to massage the puddle with the weld rod, when to turn up or turn down the flame... You get the point, it's all about practice, practice, practice

One problem I'm finding (and it's a self created one at that) is that I'm running out of the thin-walled flat stock that I can work with the thin-walled tubing. "FREE" doesn't last forever. Howard's "throw-aways" kept me busy for awhile. Time to put some coin out so I can continue progressing instead of getting fed-up with the material I have left. Flat stock which is 3x's as thick as the thin-walled tubing, with that extreme "V" joint, is a little too advanced for me today. Give me another month and I'll be welding those puppies up.

I'm learning a lot by pushing it a bit more each time. Ended the nightly session welding up a few easier weld joints. Left a happy man. Back to blaze new trails next time. Need to keep the confidence up.

May 8, 2997 Update: I had a question concerning the popping I was getting when welding. I wasn't getting any sparks which I've read about previously and mentioned here. I threw this out to the biplane forum guys. Dennis, the guy I purchased my tailfeather ribs from, answered my question on the forum.

He says quote, I think you'll find that it's a function of tip size and gas flow. You are getting an explosion back inside of the tip. I'd go with a slightly larger tip., end quote. I think I had to wait a painstaking 12 minutes for the reply. Ain't it great ! Thank you, Dennis.

"Next week... welding round tubing to round tubing. Now we're talking !"

It's next week and I haven't started welding round tubing to round tubing. hmmmmmmmmmmm ??? where oh where has that groove of mine gone, where oh where has it gone ..... ?

Side Note: By keeping this journal I can visually see my progression in the short amount of time I've actually had the torch lit. It's not that black art that a lot of folks claim that it is. They're probably the ones that haven't tried it yet.

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