Tuesday, August 28, 2007

Paint delays and Part 2 of How I build a bike

Folks, due to the extreme humidity and heat this past week, we have had some paint delays. The decals tend to bubble and the clear has issues of its own in this kind of weather. The weather is going to be more mild this week and painting will be complete on Jim's and Francis's framesets.

Last time, we left off with a completely machined tubeset, except for the seat stays. Next, we set up the jig and mock up the tubes to check all of the fits. Here is the frame in the jig with lugs installed.

What's goinig on under the lugs? Well, have a look...

Nice, tight mitres. Again, quality machining leads to a straight bicycle frame.
Here are some pictures of the joints with the lugs and the dropouts.

Here you can see what I mean by the "hollowed out" BB shell. No extra material hanging around.

I still do the seat stay miter by hand with a file. It's roughed in on a grinding wheel and finished with the file.

And here is the fit up in the lug.

Next time, I'll show the braze ons and tacking.


Yash Katsumi said...

I was wondering if Lugs, due to their larger contact surface area, resist tortional stress better than a typical tig welded joint?

zank said...

theoretically, maybe yes. In the real world? Probably not to an extent that a rider would notice it.