Have a look at the original Plycycle here .

29 September 2014

Fiddly bits.

Along side building the main frame I have been gathering together all the components and additional bits that will need to come together to complete the bike. Wheels, gears and brakes will come from a donor bike. Seat, seat post, crank, bottom bracket head set and handlebars have been gathered together over the summer. In an ideal world I would love to fit it out with new parts but I am doing this on a budget of as little as possible. All these bits and bobs will come together once the frame is finished.

There are however some bits that are vital that need a little more thought. The cable routing and securing. In metal frame building they are called 'braze on's', the tiny parts that route the cables and the like. I cant braze these parts onto my frame so I needed another solution. I had thought about routing the cables through the frame, but decided not to for simplicites sake. So I needed to use a cable clip or bracket that would fix to the wooden frame.
I found a great selection of parts at Ceeway frame building supplies. I found two options so ordered both to test (and to fulfill their minimum order requirements) out mu options.

Here are the two options.
The two cable fixing options.

 I planned to silver solder on little stumps of metal bar that I would then epoxy into a pre drilled shallow hole in the frame. However after a couple of attempts I realized that it could potentially work but that I was over engineering the problem.

Failed silver soldering attempts.

Thinking it through I saw that I could use the hook type fixing by simply routing out a very shallow pit to match the shape of the base plate and simply epoxy the clip into the frame. This way the bracket would sit flush with the frame contour and was also thin enough to be slightly bent into and concave or convex profiles.
So I set about spraying them up. I lightly roughed up the surface with wet and dry paper, then super glued little a little leg onto each clip then pushed that into some plasticine for spraying. The little leg will snap off after spraying only leaving a tiny unpainted section that will be covered with epoxy once bonded.

Clips with primer coat.

Clips painted and lacquered.

Next step is to decide on the positions they will take on the main frame then rout / chisel out their pits.

18 September 2014

Bonding the main frame.

Like many of the steps in this project this bit was one was a one way journey, no going back. I had to join the two main halves of the frame together and bond the head tube and bottom bracket into place all in one go. There was no other way to do it.

So after an hour or so of checking and prepping all the contact surfaces, I started to mix the epoxy. There is something wonderfully focusing about mixing up the resin, the chemical reaction starts immediately and the clock is ticking. Despite having gone through the procedure a few times now, there is still a huge element of nerves and excitement.

So after wetting up the two sides of the frame and the two metal components with straight West System epoxy I added microfibers to the remaining mix and spread an even layer over one side, filling any dents or cavities along the way. It was then a case of marrying up the two halves using the registration bolts and gently clamping the whole lot making sure that even pressure was applied as far a possible and not too tight.

All clamped up.

Head tube and bottom bracket sticking out of the frame sandwich

All clamped up - video.

Having got it all clamped together I just had to wait. Twenty four hours later i took the clamps off, and it had all worked brilliantly. 

First look at frame with the clamps off -Video.

The good news is that it worked! I now have the main frame in one piece. I will have to be very careful about not knocking the head tube and bottom bracket as I cant take them out for repainting. The next step is to remove all the excess resin and get down to the final shaping of the main frame. I still have to epoxy in the rear stays and the reinforcing plat in the down tube which will all need cleaning up and refining once set.

I am considering making additional supports around the bottom bracket, i will mock some up and see what I think.

1 September 2014

Head tube fitting.

Getting the metal work to interface with the main plywood frame is critical and the latest step has been to get the head tube to fit. I had left the frame extra long at the front to allow me to change the fork angle. I offered up the forks with the wheel fitted and drew on the angle line I liked then simply cut the line with a chop saw. This gave me a good clean and true ninety degree cut.
Getting the correct curve inside the frame is tricky and I made a bit of a mess of it on the first Plycycle project where I tried to drill out the hole then cut it in half. This time I took a more measured and staged approach. First I  used a router to cut away the inside to a 'V' shape, then used a small one inch drum sander on my drill to get the curve. A rasp ironed out any lumps and bumps. It will need a bit of refining which I will do using a spare bit of head tube with sand paper wrapped around it which should create a tight fit.

Head tube first fit.

Head tube fit video.

However as I was working on the head tube I dropped it and put several large dents in the paint work which means I will have to rub it down and start again. It is not a big problem, more of a nuisance.