himespau 

To me it looks like you got a fair bit better with your heat control. At least it doesn't look like there's as much filing to do.

Catnap 

thanks! @himespau when I'm at the shop for longer sessions, my brazing quality goes up since I'm already "in the groove". hoping I can escape my office soon enough today to finish that fork...

brockd15 

Did you finish the fork?

Inquiring minds want to know!

IthaDan 

Nice work.

What's that shop space? Looks too bike-y to be a hackerspace, but it looks too well equipped [and organized] to belong solely to someone who also has an office.

tricky 

I believe he mentioned earlier in the thread that there is a frame builder in NYC that rents out his shop in the off-hours.

dddd

Who would have thought that building a frame was so much work?

Thanks for this, it has given me an extra dose of appreciation of what has gone into the creation of my own bike's frames.

I find myself wondering how long it took to build the Japanese production frame that I am about to go riding on, and about how the hard lessons of efficient, time-saving fabrication and brazing techniques are developed.

And I really liked how the brass coil in the mono-stay brazed up without external globs of brass.

Catnap 

the full frame and fork is done! today i will be posting the photos and the rest of the diary

It is Nomad Cycle in Long Island City Queens - Nomad Cycle | Bikeshop, Café and Taproom. It's a full service bike shop. Myself and another frame builder rent space from the owner.

Catnap 

So the frame is now done and I've been riding it. But when I last left you all, the fork still wasn't finished. Now, I had originally thought that I could leave the fork blades straight, with zero rake. After all, most of the forks I've seen on track bicycles had straight blades. But an astute member of another forum where I am mirroring this diary pointed out that I was missing a crucial detail: the fork crown had no offset. What I didn't understand is that on forks with straight blades, the rake comes from a slight offset that is cast into the fork crown. Most crowns do not have this integral offset; only ones meant for straight blades. And the Rensho crown I was working with does not have any offset.

So that meant I had to rake the fork blades, something I had not planned on doing or had any experience with. After all, this is my first fork build! Luckily, my shopmate Jim, a much more experience and equipped builder, was able to loan me a fork blade bender:




Normally one rakes their fork blades BEFORE brazing in the fork dropouts and cutting them to length. Lucky for me, it didn't have much impact. I did move the fork blades in the bender a couple times to get a smoother curve on the rake though. And I tried a few different methods to get the appropriate leverage to bend the blades without damaging them. I finally settled on a steel rod inserted into the blade, which gave me leverage without marring or denting the blade.

As I slowly added rake to each blade, I checked them on a home-made template, marking off two measurements: both the rake AND the overall length of the blade. That is because as I added rake to the blade, the length changes a bit. Normally this is not an issue as the blades are raked before being cut to length. But here they were already mostly cut down so I needed to make sure that the blade length did not get so short that it compromised the tire clearance. I decided on raking the blades to 38mm, which would give good road handling while preserving the fairly tight geometry of the frame.




After completing the rake, I carefully trimmed each blade with a file until they were the same length, to a tolerance of less than 1mm. Then I checked them using a front wheel to make sure it would site correctly in the frame:




Finally, I brazed the blade in place and was done! All that was left was to clean up the welds on the fork, as well as the seat cluster / wishbone and bottom bracket on the frame.

smontanaro 

Wow! I thought these sorts of things needed to age, like fine wine or cheese. Looks neat. Do you have access to an indoor velodrome or something?

Catnap 

After another epic session of filing and cleaning, I built up the bike and rode it home. It handled fine, and tracks straight when riding no-handed. But as I sat at home, admiring my handiwork over a beer, I could not ignore a major flaw in the bike...

...the rear wheel did not sit in the center of the wishbone:



Since the wheel itself is in alignment with the seat tube and head tube, I realized that the wishbone itself had been brazed in slightly off-center. After staring at it for another two days, I knew this was unacceptable and had to be fixed. So I brought the frame back to the shop...

Looking back, I wish I had photographed what happened next, as it was quite a learning experience. But between my attitude of "the frame's already done" and my frustration with having to fix it, I didn't even think to take pics. So bear with me as I explain.

I decided that the easiest method to fix the wishbone would be to melt the brass out of the fillet. So I did that, doing my best to regulate the heat to protect the seat tube from damage. I got all the brass out and then spent two hours filing and grinding it away to prep the frame for a re-braze. But just as I was about done, I saw a tiny hairline crack in the seat tube, horizontal and about 5mm long, had appeared directly beneath where the wishbone meets the seat tube.

After overcoming the strong desire to go sit in a corner and cry for a while, I decided that the best way to fix this was to sleeve the seat tube using a laminate. I took a piece of head tube, which is just slightly bigger in diameter than the seat tube, and cut out a laminate piece that fit over the cracked area. I didn't feel like it flowed into the curves of the seat lug right, so I then cut two "wings" that fit into either side and rounded out the look. I also drilled two holes in the laminate to give it a more ornate look.

I brazed all of this in using brass, and then cleaned it up. I must say, I actually think it looks better than before! And it definitely adds a lot of extra strength to the seat tube. I also learned a good lesson using heat to melt out fillets - from now on if this ever happens again, I will cut apart the joint and grind it down instead of trying to melt the brass. It's just too hard on the tubes otherwise. Here's what it looks like all done:

Catnap 

Here it is, all built up and photographed on my commute in to work this morning:






From here, I'm going to ride it a bit more, and then send it out for paint. I'm not sure what color(s) yet - any suggestions?

In summary, I think this frame and fork took me around 50 hours of work to build. Way longer than it should, but it was more exotic and challenging than the previous three frames I've built, both in terms of the lugs and wishbone. I made four major errors during the build that extended the work time: dented the frame twice, which necessitated filling the dents with silver and then filing them smooth, the original tacking fail, and then finally all the work on the wishbone. I'd say that correcting those mistakes alone added 12-14 additional hours of work.

On the up side, I'm very happy with the final product and for the first time I have been inspired to start designing and sketching my own original ideas for wishbone stays and laminates. I'm definitely going to start using laminates to alter and extend lugs into new designs. It's like a whole new world has opened up for me. I'm also fired up about making more forks. I'm looking forward to raking more blades and starting to try to customize fork crowns.

As my fourth frame, I'd say that this has been the hardest one yet, but the most rewarding as well. I learned a lot and it's ignited a new level of creativity and confidence in me that I can't wait to express in my next project!

Salamandrine 

Nice save on that seat tube cluster. It appears completely intentional, and I agree it oddly enough really does look better than it did before.

Fantastic project and thanks for posting. Can't wait to see it painted.

Kactus 

I like what you did to reinforce the seat tube. It looks like you meant to add that detail all along.

As for paint, I would probably chrome the lugs and then paint the frame a deep, rich red.

brokensf

I've really enjoyed reading through this thread, thanks for sharing, and great work! Nice job saving the seat tube too, kind of a happy accident that resulted in a unique detail. well done

non-fixie 

Thanks for sharing this adventure, @Catnap! I thoroughly enjoyed reading it.

lostarchitect 

That looks great, nice work!

Maybe a dumb question... But did you build it with the fork crown reversed?

tricky 

So nice! Good job, sir! And, I also like that new seatube detail. It looks totally intentional add adds a lot to the cluster. It sortve offsets the loss in complexity that you get when you go with a wishbone seat stay.

Catnap 

thank you for the positive feedback everyone! I'm glad everyone has enjoyed this thread and found it useful. Good suggestion on the paint @Kactus
@lostarchitect i can see how you'd think the crown was backwards but no, it's correct. The fork blades are aero teardrop-shaped and the fork crown is the same way. The crown was pre-drilled for brakes and the counter-sinking for the brake nut was on the back side, allowing for easy orientation.

Stevensb 

Great looking bike Catnap and an enjoyable read. The red will make the bike very fast.

Brad

Homebrew01

That's key

"..Normally one rakes their fork blades BEFORE brazing in the fork dropouts and cutting them to length. .."

I brazed the fork tips in first, and built a fork bender with a cutout that the fork tip hooks into to secure the fork blade.

jimmuller 

That's a sharp looking bike. Nice work.

If I tried something like that I'd end up with puddles of brass on the floor. An burnt fingers. And warped tubes.

orangeology 

so good. i am sure it rides awesome too. what an experience of building and riding an own frame. so good.

congrats!

bikeyboy

M Mmm

JohnDThompson 

I used a huge rosebud tip to braze lugged frames at Trek. I could do dozens of frames every day, cleanly, no burning. The big tip heated the work quickly and pulled the brass through the joint with minimal heat affected zone. In and out quickly, that's the ticket.

JohnDThompson 

Functionally, it doesn't any difference. The advantage to trimming the blades after raking is that you can trim the blades at the dropout end rather than the crown end. This results in an aesthetically pleasing curve that extends all the way to the dropout rather than a straight section between the dropout and the curve.