By James Morikawa
Afer completing welds for the front-triangle, I have fully welded-up bicycle frame. I proceed to check the frame for it's post-weld alignment.
It happens to have the front-triangle out of alignment, with the head-tube pulled about 6mm to the right of the frame's centerline. I know this was caused by a minor gap on the right-side of the bottom-bracket miter joint, which caused me to slow my welding speed down, and use more filler material — thus there was more weld-heat involved in this area. I even had to do a "second pass wash weld" to smooth the weld finish out. You can see the result of this — Picture of bottom-bracket weld. Darn, I'm not proud of that. Anyway, I needed to pull the frame back into alignment — a neccesary "evil" in my framebuilding, but one too many times, the only choice for this "sinner"!
A framebuilder like Carl Strong of Strong Bicycle Frames, can consistantly weld a frame that requires no post weld aligning — I think that's only because he's had a lots and lots of practice, practice, and more practice. The route to "perfection", it goes through "hell".
Anyways!
I did pull the frame back into alignment. Below are a couple of picture of the frame in my modifiied Henry James Alignment system.
You can see that straight-edge tool that I use to check alignment. The left side of the frame is checked, the tool is flipped to other the side and the right side is checked. I pulled the front triangle back into alignment, using the rear-axle and rear-triangle as alignment references. I rarely had a rear-triangle go out of alignment, once I have an aligned built one.
Notice the discoloration near the lower part of the down-tube. Sadly, I felt need to stress-relief that area with a propane torch; there was a high risk of the tube "kinking like a straw" if I didn't — the tube is never heated to a dull red color, or overheated. A lot of the lighter, thinner, and stiffer steel tubes don't like to be bend, and if torqued too much will "kink like a straw", and some tubes like Columbus Ultra-Foco Areotubes are "impossible" to cold-set align. I wish I had some pictures some frames I had to trash because of that.
At this point I have an aligned frame with all the main weld joints done. I do a number of re-checks again, to make sure all is well. I'll picture some of them below:
Using the Park alignment checking tool. The left side is being checked; the tool is flipped to right-side and that's checked.
Above, just one of the rechecks, part of the process of rechecking alignment of the rear-triangle after welding on the front-triangle.
I won't picture them, but I recheck the angles, wheel centering, seat-tube/bottom-bracket squareness to name some. You can find them in my previous "Notes On FrameBuilding" webpages.
That's it for this webpage. Goodnight.