If you have not already, read Part 1 of this project here.
Then read Part 2 here.
It took 9 whole seconds after installing version 1 of my stub stack exhaust to realize I had made a mistake. In my haste to see results I skipped over building a welding fixture jig. Once all four stub stack exhausts were installed it was immediately and painfully obvious.
Many people would not have not noticed the ever-so-slight misalignment between the exhaust stacks on cylinders 1 & 3 and 2 & 4. Even fewer people would actually care if they happened to notice. Even so, I would notice. Every pre-flight, every time I hand-prop, and every time the light caught the airplane just right after shutting down and pushing the craft into the hangar. Even after 9 whole seconds, I was down right annoyed.
Imperfections in hand-crafted work is normal and should be expected. Some might argue those imperfect details are what give a work its charm, its character, its je ne sais quoi. That is true when the artist has poured his or her all into a piece, but it is not true when the artist simply skipped over a step to save time.
So, I spent the time & money to do the idea justice. I started back with the 3D model:
...then built up some negative space around the desired tube form to create a 3D printable welding jig:
As is my normal design process, I printed out both the exhaust tube template (grey) as well as the welding jig (green):
With the jig ready, we can line up the actual tubing and tack weld in place:
Once I spent a few hours perfecting my settings, when correctly back purged 304 stainless has turned out to be an absolute joy to TIG weld. I may have not said that before spending hundreds of hours TIG welding dirty aluminum, so possibly it is all in the perspective.
I have a little more color in the weld in some spots than desired, but like everything in life my TIG skills are a work in progress. Another 9,992 hours welding stainless and I may master the artform. Until then I will keep practicing inch by inch, weld by weld.
Four new visually identical stub stack exhausts installed on the mighty Titan O340:
Was the re-do worth re-doing?
As a rule I don't keep track of how many hours a project takes me. A project takes me what it takes me.
Often I have re-do something three times until it is right. While I might initially throw a small fit, I am continually learning my way through every 3D model, every CNC toolpath, every TIG weld, and every composite cure. Why should anyone (much less me) expect to be able to build something from scratch perfectly the first time? In this case I only had to re-do the exhaust twice, so from that perspective I am way ahead in the game.
Of course, this stance is only allowed because I am paying for all the materials, all of the argon, and can spend weeks tweaking small details I alone see. My failures now make it easier to help you build your ideas later, which in the end is the whole point of COLORADO CUB.
So, was re-doing this little stub stack exhaust really worth the time and expense even though no one will notice nor care?
Absolutely.