It took me 3 full days and cost about $100 and a donor bike. I have a bit of tidying up to do but its pretty much finished.
Step 1: Getting started.
I had a $20 donor bike and decided to copy the frame geometry. I think its a fairly good bike but its about to cease to exist.
Step 2: Supplies and my Jig
The pine I then cut into +\- 150 mm pieces as the uprights on my jig. I then screwed them to my jig with 2 big screws each and some glue. They have to be fairly strong because thats what the first layer will be clamped to.
The pic below is just a pic of the jig with a mock up bend just to see if I had enough clamps. Wel as it turns out I dont have enough clamps- YOU CAN NEVER HAVE ENOUGH CLAMPS.
Step 3: Cut and laminate
I laminated the both sides separately . As I'm using steel for the connections I can laminate in 2 halves and dont have to do them in one go.
I used 5 layers of 4mm ply and that got me to 24mm total thickness. I used PVA white glue as it's cheap and I had some. The glue was painted on thick till the complete surface was covered and then I just clamped them on one by one. After about an hour each time I just stuck some screws in from the back to hold the last piece in place, took the clamps off and glued another one on.
The right way would probably be to wait a day between layers. Its amazing but after the 3rd one I released all the clamps just to see what would happen and it kept its shape. This is the first time I bent wood and although I know it works it still blew me away.
Its all drying in the shed overnight.
Step 4: Release the clamps and sanding
I used and electric plane and a belt sander.
I also started working on the steel bracket that will connect the top and bottom curves to the steering head.
Step 5: Chop it up.
Firstly I cut the dropouts off. Thats the bits where the back wheels connect to the frame. Save them for later.
Now I started cutting out the bottom bracket with the seat tube still attached. I use a 125mm angle grinder with a 1mm cutoff disk. It slices like a hot knife through butter. Then I cut the steering neck out as well, while removing brakes and cables and things as I run into them.
In the last photo is the result of what I had left over. It took about 1 hour to grind all the welds off and smooth it all over. I then hit all the grinds with a bit of grey primer as i live at the beach and it will rust almost over night.
Step 6: Fabrication
Today was a big one, about 7 hours on the bike. I had some bits of 2mm plate so I cut some pieces out to make an attachment bracket for the steering head. After lots of cutting, grinding and halfround filing I was ready for welding.
All my angles were worked out very loosely by holding all the pieces on the ground and tracing it on the floor with a pencil, then transfer to paper. I then cut out the paper and transfered to steel plate for cutout.
So I cut the 3 pieces out and welded them all together to the steering head tube.
Step 7: Dropout brackets
Now remember when I cut off the dropouts before and told you to save them for later. Well this is later. I cut out the shape out of plate and bent, blowtorched and hammered till I had these brackets. I then welded it all together and also welded the dropouts on.
I probably should have approached this more scientifically but...
A bit of primer paint after welding is always a good idea.
Step 8: Assembly
Other than that it all went together nicely.
Step 9: Seatpost and bottom bracket
I am making a little wooden box to cover the ugly bottom bracket. I still need to do another couple of coats of varnish and back brakes and front derauler. Other than that the bike is done and very strong.
I then put all the bike bits on and it was test drive time. I had to stop a couple of times for adjustments but it felt very strong. At first I let the seatpost slide through the top beam so all my weight pressed on the bottom beam only. It was nice and springy but not in a good way. There was no shock absorbtion and it didn't improve the ride at all just very bouncy. I didnt like it so I put a couple of screws in to stop the seatpost from sliding. The bike now feels solid to ride and I gave it heaps of testing: Up and down pavements, wheelies, stoppies, top speed down the road , 150kg load test. Its all holding up.
Step 10: Photos
Some photos and one of woodbike1 as well.