Thursday, December 27, 2007

Catch up again

Over the last two weeks, the day job has been very busy - meaning no time in the shop. Then of course there was Christmas - which was great, but didn't allow for any building. So, today, I got back into the shop and working. I'll try to get some pix tomorrow to illustrate. Anyhow, here's what's up.

I'm back to working on Paul's track bike. The path-racer is so close to being done, but I decided that it's inspiration (the white tires) didn't look right on it. I've ordered some new Grand Bois to replace them, but I can't finish it until they arrive. That said, the Honjo hammered fenders look great against the Burgundy paint. The seat is a B17 special in dark green with copper rails. The handlebar tape will be green cotton shellacked, so as to accent the saddle. Final pictures should be ready in about 2 weeks.

Therefore, back to Paul's bike. He likes all things Italian and has been steadily collecting old Campy components. The hardest so far has been the hubs. He needed 32 hole (to match some NOS rims he has) and wanted high flange. These are a bit hard to find - but we did it.

Anyhow, the lugs are old Cinelli pressed steel. The bottom bracket is is a cast Cinelli road bracket - the one with 'spoiler' on the bottom. Of course, that isn't quite right for a track bike. Out came the hack saw and the cable eye is gone. That and a bit of work with the file and a rotary stone had things cleaned up. There are also cast in tunnels (canals?) for the cables. So I filled these using some Allstate Nickel-Silver filler. This filler has the characteristic of being Eutectic. What this means is that once it melts and rehardens, it takes significantly more heat to re-melt. So, it starts to be workable around 1200 degrees Fahrenheit, but it requires a bit over 1700 degrees to remelt. So what? Well, we'll be reheating this BB to install the Seat Tube, Down Tube, and Seat Stays. It sure would be nice to make sure that these processes don't damage the filler in the tunnels, eh? And my brass (bronze, alloy, whatever) filler works below the remelt temp of this Nickel-Silver so I can use it or silver based fillers to finish off the BB. At this point, the shell has been soaked and is ready for a little wire brush to clean off any remaining flux.

I also finished cutting miters on the main triangle today, and did a basic test fit. The lugs are close to ready for brazing and the fit up looks good. I had to adjust the lower head tube lug a bit, and may yet be doing the same for the upper and the seat cluster. The latter two haven't been checked yet for angles (the seat and head tubes are parallel - so this is basically to ensure that the top tube is level).

Adjusting the lower head lug was challenging. Basically I'm adjusting from about a 73 degree angle to a 75 degree angle. This means that the top of the lug at the back of the head tube needs to move forward. However, on this lug, this area is rather short. There isn't a lot of material to bend. I think that I have it looking good and fitting ok. But it took a lot of work with a ball-pein hammer. This lead to some additional file work to make sure that it had a smooth surface.

The pressed seat cluster had the standard hollow ears - which I always consider a possible weak point. My solution is to braze tube inside them (for the binder bolt to pass through) and then fill the lug up around the tube. Here is another good use for Eutectic filler. It's too easy for everything to get up to temperature at once, and therefore have the filler melt out of one part while trying to fill another part. Particularly on the inside (against the seatpost) there isn't much support. In fact its like a big square window into the backside of the ears. Moreover, I've already widened the slot (in part to get a nice square looking edge on the ears), leaving even less support. Working a spot, and letting is solidify
and then moving on, its possible to fill and get the filler to stay in place very easily with the Eutectic filler.

Anyhow, this is done and been soaked. Again, it may need a quick shot with the wire brush, but basically its time to clean up the filler with a file. First will be the inside of the tube so the seat tube will fit inside. Then I'll do around the inner edges of the ears, giving them some definition. Apart from this, the seat cluster appears ready to clean up and install.

Summing up, the angles of the seat cluster and upper head lug need to be checked and adjusted as necessary. The upper head lug needs a little filing and sanding. The bottom bracket needs a bit of filing and sanding - mostly in the hard to reach spots. And then we can fit everything in the jig, check numbers one more time, clean, flux and braze the front triangle. Yea!

Again, with luck there will be some build photo's tomorrow. That's all for tonight. Cheers!

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