Spray paint.

I took the opportunity to use the spray booth in the model shop at work to spray the head tube and bottom bracket. It has been a while since I had to do any proper spray painting and I didnt want to have to rub it down and start again because of drips. The lots of light layers on a solid primer is always the best way forward. The paint went on well. I then rubbed it down to prepare it for the lacquer. The lacquer needed a slightly heavier hand in order to create the smooth caot. My first tentative pass left a dinlpled finish. One of the model makers gave me some advice and I took it. More spray. Luckily it was still wet at this point and it took well. It is a fine line between having enough lacquer to get the smooth coat and too much a nd causing drips.

Luckily I got it right first time. Next stage is to get the head tube reamed and faced to fit the head set.

Metal work takes a step forward.

Even though this is a wooden bicycle frame project, certain parts do need to be made from metal.
The head tube fixing and bottom bracket are areas of huge stress so these need re enforcing within the wooden frame.
I have worked with the same design I came up with on the first PLYCYCLE. It uses metal plate brazed onto or around the main component that is the sandwiched between the wooden layers with epoxy and then bolted for good measure.

Bare bottom bracket beside scale drawing of stress plate.

Once the parts were made up I asked my pal Lew Gardiner to braze them together. Which as before he did. This time his welds were not very tidy but strong none the less. This is a major step as I could now get onto fitting the bottom bracket into the frame.

Head tube and bottom bracket with stress plates brazed on. Deep score marks added for gripping to epoxy.

The fitting was fairly straight forward. Just a case of routing out an equal cavity on either side of the frame for the plate to sit into, plus any additional excavation for bulges in the brazing.

Frame routed out to fit plate.

Plate fitting nicely.

I'm glad to say that the bottom bracket fits well, see below. Next I have to fit the head tube.

Frame fitting over bottom bracket and plate. Side view.

Frame fitting over bottom bracket and plate. Front view.

Tacking the wheel hangers.

While I wait for my old pal Lou to braze on the stress plates to the head tube and the bottom bracket I thought I should turn my attention to truing up the rear wheel.

This is the bit where I put all the rear stays onto the frame, fit the metal wheel hangers and their connection sleeves and see if all my guestimates have worked out. I am pleased to say that they were quite close. I did have to trim down and shave off some extra wood on the rear stays. But I would much prefer that than be short and have to start again.

So with the wheel fitted ( I intend using the wheels on my existing bike, an Alfine 8 speed ) I found that it all lined up. A true result and quite a relief!

The rear wheel fitting.

All lined up.

As it all fitted I thought I had better tack the pieces together with some deadly super epoxy. I did this last time and it worked well. It allows me to set the bit in the correct place and then the assembly can come apart and the metal pieces will stay in alignment ready for brazing. Then once brazed it should all go back together perfectly. The small amounts of resin will be burnt off in the brazing process.

  

Rear wheel hangers tacked together for brazing.

I had played with the idea of gluing these parts with a weld replacement resin. However without the time or experience to test this concept properly on what is a vital structural component I decided to leave it to another time.

The bottom bracket hole.

I set up my little pillar drill and cut the hole that will eventually take the bottom bracket. Making these cuts are nerve wracking as there is no going back, mess this up and essentially I have to start over. Most of the things I have to do from now on are the same but it is all part of the fun. Luckily I have learnt to think it through and test as much as I can before actually going for it.

 

Take a peek at this vid for a closer look.

Apart from the big bottom bracket hole, I started sanding away the excess resin that leaks out in the laminating process (there are some shots of it in the vid) and are generally just a pain. The dificulty is that over zealous sanding eats away at the intended shape of the frame, so again as above there is no going back from a mistake. it is good to to though because the frame starts to look better with every step now.

The next job is for me to prepare the metal parts for brazing, then the build can enter its final stage.

Gluing the frame part one.

There was a window of warmer weather last weekend which allowed me to do the first epoxy resin work on the frame this year. I glued the left hand quarters of the frame together.... making a half. A small but significant step.
I Mixed up the West System epoxy, 'wetted' up the two sides and then spread on the resin with microfibers for the main bond. All god so far. it was only when i cane to clamp it all together that i remembered that last time I had to borrow extra g-clamps. I had forgotten to do this so I had to improvise. I used what clamps I did have to hold the main sections and then to clamp the remaining areas I placed the frame on some wooden blocks and then used some heavy engineering bricks from my back garden to apply pressure. it wasn't quite enough so I put a tool box on top of the bricks.

Make shift clamping in action.

I am pleased to say that it worked. The bond is good. however I will be borrowing more clamps as it really is much easier that way.

Laying out the pieces.

I had a good stint on the build this weekend, and the main aim was to lay out the main pieces and see how it all looked. This was the first time all the main bits have come together and actually resemble a bicycle. Finally! It was a mile stone.

After I got over the fact that it looks like a bike, I started to take a more critical look at how it was actually shaping up. As it turned out there was a much larger gap between the rear wheel and the frame than i had anticipated. I think this was because when I first set the geometry I was going to use track style drop outs as I had on the Plycycle Mk1. But I changed to vertical drop outs, and although the geometry lines are the same, the place in which the wheel sits is set, and it is quite far back. I hadn't appreciated how much difference this would make. Not to worry though, it is a wooden frame and it is simple to shorten the stays, but this changes the angles of the rear triangle. I couldn't change the bottom stay fixing as it is surrounded by the main frame, however the top stay junction is fairly simple. So I set about the fix and an hour later it was done. See the before and after pics below.

 Before fix. Large wheel gap.

After fix. Wheel closer in.

I also notice now that the angle that I had placed the forks on is not great. They are just placed on, but along the pencil line I had thought would be best. I think that the problem is the opposite to the rear wheel. I think that the front wheel needs to come forward, away from the frame a tad. I will have to look at that properly when I have the head tube made and ready to fit.

Putting  a temp wheel in made me realize that it will be much more critical getting the rear drop outs in the correct place now that i am using vertical rather than track style. With track style there is a bit of wiggle room when bolting the wheel in as you can slide the wheel left and right a tiny bit to get a good alignment. However with the vertical drop outs the wheel is set, one position only. I think I will need to make a jig fot the final gluing.

Rear stay rough assembly.

Over the winter I have managed to get some time to tinkering done on various bits and pieces on the frame. Mostly it was tidying up details and making joins more accurate.

Rear drop outs rough assembly.

 The biggest step forward has been the shaping and fitting of the metal work to connect the rear stays to the drop outs.
I am doing it loosely at the moment to get the fitting. I will then spot bond the metal work in place with an epoxy ready for braising. I have to be sure of the fit as I don't really want to have to remake the metal parts, so it is has to work first time. This system worked well on the Plycycle Mk1 so I think it should be fine this time too.
Incidentally I bought the drop out ready made and raw tubing from Ceeway.

Making it hollow.

As I am not an engineer these stages of a build often cause me to procrastinate over the next stage. The solution has usually been just to get on with it and follow my instinct. So that is what I did for this bit, the hollowing. On Plycycle Mk1 i created a lattice of triangles along the top and down tube sections. I wanted to try something different, so I have used a simplified version of a technique that Renovo Bikes in Oregon USA use. Rather than hollowing out the whole frame section as one, the idea is to add some strength by creating a devider and making two cavities. I really hope this works as it is critical to the integrity of the frame. I am not reducing weight to make some sort of feather light bike, I just want it to be a reasonable weight, with out compromising the strength or becoming too flexible.

Here I removed the outer two layers of the frame and bolted the two center sections back together so that the holes lined up, obvious, but really vital that it all lines up when it is time to bond it all together.
Just on a technical note, I was possibly a bit hasty with my 27mm spade drill and I caused a couple of laminate layer chips in a couple of places, I will have to cut them clean and resin in some filler strips. unfortunately two of them are on the top tube section and will be very visible if not patched up well.

The two middle sections with cavities cut out.

I think I will drill additional holes once more of the finishing is done. Once I am happy with this it will be time to bond the two half's together to allow for more accurate shaping to continue.

Some lovely bits arrived.

A very strange looking parcel arrived in the shape of a blunderbuss.

However it was the Ceeway parts delivery.

Lots if lovely metal bits for the build.

The long tube is the shortest length I could buy the 22m diameter 0.9 chromoly in. I will make the sleeves to connect the wooden stays to the rear drop outs. 

So now I just need to get busy bringing it all together.

Resurrecting the build.

I had intended to make most of the frame by the end of the summer, however, real life (family, work, money) got in the way and I have had to endure seeing the project sitting idle in my garage  as I get on the Plycycle Mk1 and ride to work each day. However, I have got the wind in my sails again and work on the Plycycle Mk2 continues!

Where I left the frame was cut out with some very basic shaping and also some basic shaping of the rear stays. However they were all still separate bits.

So to move things forward i decided that I needed to see the frame come together. To do this I needed to cut out the receiving shape for the bottom stay. I had originally intended for this to be a simple 90 degree cut into the main frame, however when I came to cut it I realized that there was enough material to make a slot. So I carefully cut the slot and i think that with some shaping it will not only add a bit of extra strength, but will look really good too. this is another example of the organic nature of my design build process.

Plycycle Mk2 frame cobbled together for the first time.

Bottom stay junction.

 

rear stay wheel space.

I am pleased that all of the measurements worked out so far. The curved shapes of the rear stays seem to work out too, which is great as they were hit and miss with several attempts. I have ordered the metal pieces from Ceeway hopefully they will arrive soon and that will be a focus for the next stage.

A look at the cobbled together frame.

An extra problem is that with the onset of winter doing any resin work becomes tricky as it doesnt like the cold, it takes an age to go off. I am looking into some heated workshop options, but in reality the resin work may have to wait until the spring. 

Rear stay rough carve.

 

So having trimmed off some bulk material, it was time to do some carving. I attached a rough grit car paint grinder to my angle grinder and set to work. It worked a treat. Fast and suprisingly accurate. I wouldnt use it for anything fine, but as a tool for getting the shape fleshed out it is marvelous.

 

Rear stay sections rough positions.

 Rear stay sections.

 

 

Getting the symetry to work on this has been a challenge. The parts do not have to be identical in shape, but the points at which they meet the frame and the wheel drop outs do need to be very acurate. So the stay arms will be a little organic in shape, but the wheel will (all being well) sit true to the main frame.

 



 

Video clip of the rear stay work in progress.

Trimming.

Having bonded the 5 layers of each rear stay it was time to start the shaping process. However I needed to get rid of lots of material in some places, so instead of hacking at them with files and rasps, I set about them with a wood saw.

Cutting rear stays down to size.

 

Nesxt step is to actually do some broad stroke shaping. I am going to give the angle grinder a go fitted with a car body paint stripping grit disc. Should be interesting.