Started the day with spot-welding all the tubes together.
Then I've straightened the thing and welded around the top tube/head and the frame bottom. For the seat tube/bottom and top tube/seat tube connection i've decided to use TIG welding process and that was a mistake. Soon i show you why. You see the photography light, it is not usually there. A friend of mine who practices photography as a hobby have dropped by today to take a few shots of me welding.
Quickly checking the geometry again.
Here are the TIG welds. Not prettiest but solid
This is the weld that became problematic. Multiple times when planning and thinking over the build I thought to MAG weld it and not to TIG. But probably got too excited and forgot about it. Well, at least it looks good here.
This is how the MAG weld on the top tube looks. The reason i went for MAG not TIG here is that the German frame was brazed before, and since TIG produces more heat it often happens that brass begins to melt, boil and zinc evaporates out of it, splatters around and makes a huge mess. Welding with MAG helps to avoid it. But the weld is not as beautiful. I actually ended up to clean it a little from the bottom.
And that extra heat from TIG also often distorts the thin metal, and that could be crucial for fine geometry, like the seat tube, where the seat post must fit...
Some of you have guessed it. Well, at least it is steel not alu, so it can be removed without creating even bigger mess. First I've tried to file it, but even though the tube has 1" ID and I've found a 1" rounded file, after almost an hour of hard filing it was still far from perfect. And it has to be literally perfect to accommodate the seatpost without causing the fitment problems. So while at it I've decided to make some small tool that is super useful in situations like that. If you haven't seen this hack before you may quite like it.
I grabbed some 12mm rod and i need to make a 6mm hole in it, around 50mm deep. I could have just tried to drill it as precise as i can, but instead i have put the drill in the vice and my rod in the chuck, kind of to emulate a lathe. This way physics works for me, and instead of the hole tending to get away from the center it would actually tend to center itself. This is the ultimate way to drill deep and precised holes, of course if you can afford to spin the work piece.
Starting with 4mm drill, continuing with 6mm. Then i am filing a flat side and drilling a 4mm hole perpendicular to the first one and tapping an m5 thread in it. Here we go, an extension for the grinding stones is done. This way i can go deep into the tube as i need. Of course it is best to grind a small flat spot on the stone axle too. Took me a few minutes to make this tool, and then another 20'ish minutes (i am so glad hours and minutes are universal everywhere and not metric/imperial by the way) to perfectly grind the inside of the tube. Would've taken me at least a few hours and tons of effort to do it by the hand file. But still that was quite an expensive mistake, considering how easy it was to avoid it.
I've spent some time cleaning the paint further off, while i still have easy access to the tubes. When the frame is done it would be more difficult to do. Done some hand filing and sanding here and there, and the time to test fit the rear wheel has come! So far so good!
Then I've eyeballed the notch on the seat stays connection bridge. Pretty neat and close again. Guess it is not just only luck in the end
Here is what i am finishing the day with. Need to get more discs for paint cleaning for my grinder tomorrow, clean the seat stays and the rests on a few other spots of the frame. Then i can weld the seat stays and make a mid tube. This would be it for the frame then! I'm thinking to make a hole in the frame bottom for the kickstand. Even though it is not "true" to run a kickstand on a sport bike, if i end up liking the bike enough to ride it a lot, it would be a pity for me to drop it in the city and scratch it. So same as with fenders, though i am not planning for it as in a framework of a build off, it is a good design to leave the opportunity to have it later.
One more thing i would need to think of is the cable routing. Both former frames had welded on cable guides, so i have some on the bottom tube and the right chain stay. But for the roller brake i would need a second cable on the left side, so maybe it wold be easier to just remove the existing ones and run the thread-rivets? Once the frame is done i still need to build a fork before i can continue assembly and painting.