By James Morikawa
This is the next step after I have the rear-triangle, and that's to weld-up the front triangle joints.
To begin, the rear-triangle and the mitered front tubes are remounted back onto the frame-jig. The joints are then tack-welded..
A thought on my tack-welds. I weld them at the 12 o'clock, and 6 o'clock positions. Two tacks per joint. I find I can better control against weld-distortions with my tacks there. I don't know if that's the best place for them, but that's where I've come to position them. I don't know how other builders do them, wish I knew.
With the tack-welds holding the tubes together, and I remove the frame from the frame-jig. Notice those "Heat Sink Sleeves" installed in the seat-tube, and head-tube. They help prevent the tube's diameter from going "egg-shaped" due to weld heat. In the past, without use of heat-sinks, I've ended up with a seat-tube that was egg-shaped to a point, where upon rimming it out for seat-post diameter, I rimmed away and through a small section of the tubing wall. As a cure, I came up with the "heat sink" idea, and have always used the idea since.
I fiinish up the welds on a welding fixture. The fixture enables me to better position the frame during welding. I don't show it, but the frame can be rotated 360 degrees in various directions. There's clear floor space below the welding-fixture for positioning myself, the frame, and all the weld stuff. The welding-fixture just makes welding an easier task, that's all it does.
I internal-Argon-purge the top-tube, and down-tube during welding. I purge the seat-tube, only when welding the bottom-bracket area — I don't purge the seat-tube when doing it's top-tube joint. I don't purge the head-tube. Those heat-sinks, I mentioned earlier, will act as my "internal-purge" in those areas. So, those heat-sinks serve a dual purpose — They prevent weld-distortions, and help prevent internal weld-oxidation.
Below are the completed weld-joints of the headtube, and bottom-bracket.
I did use Weld Mold 880T filler rods to weld these joints. The weld-bead at the seattube-bottombracket joint is a bit wide. I'm always in need for more practice, but it's a vast improvement when compared to my first bicycle tig-welding attempts. I hope someday to be as good as Carl Strong of Strong Bicycle Frame, Don Ferris of Anvil Bicycle, the Welders of Independant Frabrication . . . to name a few. I've also seen a lot of consistant "text-book-correct" steel tig-welds, done on inexpensive mass produced asian frames. Amazes me, and starts me thinking, "wish I could do that". There is so much more I can learn. So, these are examples of my welding — not of "perfect" welds. I've had days of consistant good welding, but on this frame, it's not.
It's true to me, that to become a welder who can consistantly produce good looking, yet sound welds, it takes "practice, practice, and more practice". That's regarding tig-welding thin wall bicycle tubes. It's something easier said, than done. Anyway, I'll still wish I could "do it better", but that will come with practice, practice, and more practice.
Oops, sorry, went a bit "off topic".
Below is the frame with fully welded main joints. I have it pictured mounted on my Henry James Alignment System. I needed to do some cold-set aligning, as the frame did end up with minor mis-alignments caused by welding. It's a confession I can improve on my welding skills, but considering weld-strength, the joints are plenty strong. There's the skill of being able to weld a frame, in a weld-sequence, that keeps the frame aligned or pulling it into needed alignment by welding. Completing welds with a frame still in it's origninal alignment, not only involves good welding skills, but also tight fitting mitered joints. The tighter, more precise the joints are mitered, the easier the welding task. But, that's just my personal opinion.
That's it for this webpage. I'll be writing about checking and correcting the welded-up frame next, and that should be the subject of my next writing.
Goodnight, and have a good tomorrow.
Bye.