Wednesday, September 8, 2010

Brazing the Front Triangle

I did a really bad job documenting the brazing of the front triangle but hopefully next time I'll take more time and take pictures of the whole process. This is a picture of the frame after I had tacked the HT and ST lugs and was checking the alignment before I tacked the bottom bracket. I don't have a real alignment table right now so I've been using this big ass piece of granite counter top. I figured it was level enough to get a decent measurement off since they shave these things pretty flat.  I use a digital height gauge and 1-2-3 blocks in conjunction with the flat surface to check how my alignment looks after each tack.


The basic process I went through to braze up the front triangle this time was:

1. Drilled and pinned all the lugs in multiple places with 4d finishing nails.
2. Fluxed up the lugs really good with white Stay-Silv
3. Made sure the alignment on the HT and DT were as good as I could get them and then I tacked them with sliver
4. Checked the alignment after the braze then moved on to the HT/TT connection and checked alignment and brazed
5. Same process was done with ST lug connections
6. Final alignment check was done and then I tacked the bottom bracket in place.
7. After everything had been tacked I checked alignment again then re-fluxed the lugs and brazed them completely.
8. I let the frame cool down then soaked all the joints in warm water.

The process to align and braze the frame was my attempt to follow Richard Sachs method which he so graciously posted online recently. It seemed to really work well for me and I was able to get the frame pretty straight this time. There is definitely a lot of room for improvement on my part and so here is a list of the things that didn't go so well for me.

1. I definitely need to work on my brazing technique. The tacks I made were really difficult for me and ended up pretty messy in some places.  The final brazes went much better but I still need to work on getting the shorelines properly worked out. After I soaked the joints there were a couple of gaps in the shorelines that I'm going to have to go back in and refill.

2. Even though multiple alignment checks were made at each phase of brazing the frame did not come out as aligned as I would like.

3. I need to be more careful when shaping the lugs to fit my set of angles. There were some gappy spots from reshaping the lug that I thought would fill in fine but when it came down to it I had trouble filling them and pulling the silver to the shore line. Next time I need to make sure everything fits perfect before I braze.

The next step will be to clean up all the lugs with files and 40 grit emery cloth, go back in and fill the little gaps with silver and think a lot more about how I can improve on building up the front triangle.

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