Tuesday, November 24, 2009

Bicycle Project 2, day 6

Another full day on the job. The frame is to be built in segments to allow easier handling of the individual components. So a plan of attack is drawn up and away we go.

Jobs to complete today are: slotting the seat stays to fit the dropouts in preparation for brazing, cut and miter the main tubes and braze the bottom bracket & seat tube, and finishing the details on the fork crown.

Seat stays cut and filed.

Clean slots if I say so myself.

Dave adds his trademark curved end to the stay.

Dropouts slot into place and alignment checked.

Nice bend to the dropouts as they meet the stays.

I said it before and it's worth saying again, but stainless steel slotted dropouts are a lot of hard work. The slots are measured, cut and finished by hand. Then there's the alignment to be set and the dropouts to be adjusted (and these dropouts take some convincing to make them bend). Then there's still the final alignment and the brazing to do... but we'll tackle that tomorrow ;-)

Dave then shows how mitering can be done quickly and with mechanical precision. Got to make up time somewhere...

Set the angles on this big machine.


Bottom bracket with the mitered seat tube is then set-up in the frame setting jig (after the BB has been faced to sit flat against the jig) then the construct is tacked into place with silver.

Frame setting jig prior to brazing.

The alignment is then usually checked using blocks and a surface plate (a machined flat surface). But Dave likes to mess around with a frame alignment jig as it has more knobby bits to play with...

The alignment jig has to be calibrated...

...which can take some time...


Turn that black handle and you can tune that construct into perfect alignment.

Then the brazing is done. And yep, brazing a non-stainless lug is much easier (the BB lug is not stainless in this case - I had to be able to braze something without David Bohm cleaning up after me). The silver flows effortlessly across the join.

Into the workshop and it's back to the stainless steel fork crown. Cleaning up the edges of the lug to get that sharp, clean shoreline requires special tools and a bit of plain ol' grit and determination. The lugs are then gently filed and feathered to give them a nice shape but great care is taken not to lose the sharp edge (a mark of a meticulous craftsman).

And then there's the polishing.

Once you complete the framebuilding course you get to take home one of these cool (I'm not a politically-correct metrosexual, I'm a framebuilder...) T shirts.

It's getting dark so off I go with 20 sheets of fancy abrasive paper to do a bit of homework. Each sheet has a diminishing grit with the finest as smooth as velvet.

Excuse me as I have some work to do...

No comments: