Getting slammed with hours at the FD, but had an afternoon in the shop before heading back for another 36 hour tour of duty. Moving on with Steve's retro inspired build...
The seat tube is the "backbone" of the frame, and as such, requires that it is as precise and true/striaght as possible. When we cut the miter at the bottom bracket, the tube was squared up and put in phase based on the pinch collar, ensuring that the two planes maintain alignment.
When drilling the bottle bosses, I use these same indicators to set up the tube so that the boss holes are dead center on the apex of the tube.
Now, it's time to slot the tube for the seat post clamp. I use the binder bolt again to square off of the table, check level of the tube with the table, then position the slitting saw for the two part cut; first cut flush with the bottom aspect, next flush with the top aspect.
After the two part cut, now it's time to set up the center drill for the relief hole...
Once my seat tube is all set up, all the pieces were placed back into the fixture, the locations circled with sharpee, the tubing all drilled with vent holes, then everything deburred, filed, degreased, washed, dryed, acetone applied, and put back into the fixture for welding...whew!
Some fine motor skill action, a little heat, some inert gas, and a bit of luck and time and here ya go... one front triangle all done up.
These weld beads should dissapear under a nice thin layer of Pierce fire engine red... oh yeah!