Wednesday, 16 October 2013

Day 5: Wednesday

The frame triangle comes together!

Today has been a lot better than yesterday: I started off by tidying up the downtube and then turned my attention to bottle cage mounts on the down and seat tubes. A quick measurement on my existing bike and a bit of estimating in conjunction with more measuring on the new frame provided me with the correct locations so I marked them up and drilled them.  6 mm holes to accept the braze on bosses, 65mm apart. They'll get brazed on tomorrow with any luck or perhaps Friday as tomorrow's a bit of a rest day when I'll probably go out for a ride.

That done, I got on with marking out the top tube with a centre line and contemplating the critical mitres in it.  After yesterday, I took a little longer in the calculating and measuring which that meant that after an hour and a half I'd ensured that I'd got the mitres correctly sized and located, and also the right way up which helps!

Guess what I did next?  Yes, that's right - filing!

Once the two mitres were cut, I could offer the tube up and begin to gradually decrease the length of it until it sat nicely in place.

This bit of metal won't be joining me on any bike rides!

With that done I breathed a big sigh of relief: the initial triangle was finished and sitting nicely in place:

However, I was celebrating too soon!  Turns out that that top tube is sitting right at the beginning of the seatpost butting so that's some very thin metal.  Also, I need to consider what sort of seat clamp I'm going to have.  A purpose-made lug is the easiest solution but it's also heavy and my frame isn't going to be lugged - that's a whole load of weight I don't need on the frame!  So.... I have to make a custom sleeve to go around the seat tube where the top tube meets it and also where the seat post clamp goes.

Here's what I have come up with - might make it a little more ornate tomorrow, or actually start again to get those drilled parts in line - I hadn't noticed that the step drill bit in the pillar drill was creeping out of my centre mark until it was too late so the large hole is slightly off-centre. I think I can do better!

Anyway the point of the holes is to make it easier to braze it in place - you can heat the whole lot up and then drop the brass into the holes.  They also look quite cool.  Tomorrow, I'm going to file the top of the sleeve a little to make it look a little  nicer, by adding a couple of shallow curved cut outs on the side.

Here's the back of the bike with a few bits in place (just held there for now) note the nice wrap around seat stays:

The eagle-eyed among you will have spotted that this means I need to re-mitre my top tube to allow for the extra diameter that the sleeve gives to the seat tube.  Damn it!

Anyway, I'm pleased with the progress so far - it's been hugely enjoyable and pretty challenging at times - the actual job in hand isn't that challenging but thinking it all through and having the courage to take the hacksaw to your valuable and expensive Reynolds tubes is.

I've been keeping a notebook and a list of critical dimensions as I've been going so I may well share some of them with you so you can see the process behind it.  But anyway, tomorrow's a day of rest so it's time I nipped out into Kent on the bike to see if there are any old and famous brewers anywhere near the town of Faversham.

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