Here it is, fresh out of its clamps, the two halfs finally fixed together with the metal bits and the rear stays all in ONE PIECE!
The frame all in one piece for the first time.
And a vid of the frame.. all in one piece for the first time.
What this really means is that the project has taken a massive step into the final phase. Sanding off all the resin seapage, and final smoothing to make it ready for varnishing.
I could put it together and attempt to ride it, but really I need to put the saddle in and the final strengthening bolts in the topof the stays. Its going to be tough, but I am going to resist.
I think this bike will be called the 'Plycycle', and in order to represent this on the head tube I have knocked up a logo to go with it.
In other news the drop outs are coming on, getting to grips with the metal work.
Drop outs work in progress.
The next stage is to line up the frame accurately and tack glue the drop out components in position ready for braising. Inside they are scuffed ready for fixing to the frame. I just have to decide what adhesive I will use. I was planning to use the same epoxy as everything else, but I have been given some acrylic structural adhesive, that may just be a bit better. I will do some tests.
A bit of progress. Firstly I cut some rear stays and tacked them onto the main frame. The main reason for doing this was to ascertain whether the crank would clear the bottom stay. I am pleased to say it does. See the vid.
Crank clearance test.
The other reason for tacking on the stays was to see if they lined up and would actually fit. They did, so I made four more. Each stay will be made of three layers of the 12mm birch ply.
Rear stays all cut.
I spoke to the resident mechanical engineer at work about giving me some help with the fabrication of the bespoke metal fastenings. He had a great idea about how to connect the stays to the drop outs. I had always been worried about weakening the stay by drilling it, his suggestion was to make the end of the stay round and slot it into a metal tube that in turn would be welded to the drop out. I like it, quite simple and will maintain the strength of the stay.
After my last post, I did get the epoxy I wanted, even if I did have to cycle to the other side of town. I bought a small kit of West System Epoxy to learn how to use it. So the first thing I did today was to mix up a small amount (30ml) and have a go at laminating three strips of off-cuts. I found it easy to use thanks to the very clear instructions. I haven't gone back to see how strong it is but I am confident it will be fine.
Epoxy Resin test.
But the big job today was to split off the two outer layers of the main frame and to reduce weight by cutting out as much as I dared. The idea being that when the outer layers are laminated on top it will create a box section and maintain strength but loose weight, as the frame is really quite heavy at the mo.
Drilled out.
Shapes cut with jig saw.
I drew on the shapes I wanted then drilled out the main cavities. I then trimmed out the remaining bits with a jig saw. What I didn't do was weigh the frame before and after, but it has made a huge difference. I like the look of it. My son asked why the whole frame couldn't look like this. Its a good question, I think it would look great, but I don't think it would be strong enough. I think the box section idea is vital, as I think the frame would flex too much if opened up like this. Also I would have taken more care on the cutting had that been the plan. Next time maybe.
Just the curve around the back wheel, head set groove to drill out and the rear stay shaping to do to complete the wood work. Metal work next. Then fix it all together.
Today I started swatting up on plywood for the frame components of my wooden bike. I am lucky that in Bristol there are a couple of very good suppliers, who stock a variety of hard wood ply in most thickness's. I have based my design around 25mm ply, so that is a given, what is not so cut and dry is the wood base of the ply. The one I have my eye on is a 100% mahogany ply. The only problem with that is the cost, £168 per 8x4 sheet. Too much for a test project, maybe if the proof of concept bike works I can make another with the expensive wood. So the question is, what else is out there. Well the main wood in cheap ply is spruce, a soft wood, which although lighter, I have ruled out because I don't think it will be strong enough in the high stress parts of the frame in the longer term. So that leaves other hard wood options. The one that seems best, affordable and made to high standards is birch ply. It is the most commonly available high quality ply, both my local suppliers carry graded birch ply from rough and full of knots to architectural grade. Best of all, birch ply usually comes from sustainable forestry, something that is harder to to be sure of with the more exotic hard woods. The really good stuff is about £45 a 8x4 sheet, I think this is what I will go for.
Around the corner from where I work is a chandlers, so having walked past it many many times I decided to pop in today on the hunt for epoxy resin. It was a treasure trove of goodies, everything one could ever want for a boat, including a nice selection of epoxy resins. There are several good options for me, that are an all purpose laminating/ filling/ covering two part kits, in several sizes. I cant remember the brands but I will go back armed with pen and paper to study the options further.
I will use the epoxy resin to bond the two half's of the frame and to laminate any additional smaller parts. I may also use it as a covering coat, for durability, although that may well depend on how much I have left after the construction phase.
Those guys at Ceeway were quick. The first parts I ordered are with me already. They dont look like much but they are the main conecting components between the wood and the metal. They are, a mild steel blank bottom bracket and a long piece of mild steel head tube. There is enough head tube for several bikes.
The plan now is to buy some plywood from Avon Ply and shape up the main frame. From this I will be able to measure up the plates I need to weld to these new metal parts, for the best join. Both are high stress parts so getting the size and placement right crucial.
