Take a look at the finished bicycle here..

Tuesday, 31 May 2011

Fitting the metal work.

I really felt like I have made a step forward with the coming together of the metal parts and the main wooden bike frame. So what did I do? Well.... I split the frame into its two halfs and inserted the metal pieces to daw around them.

Bottom bracket lined up for marking.

I then routed out inside the markings to allow the plate sections to neatly sit between the two halfs of the frame. I also cut some slightly deepersections in the center of each plate to allow some extra epoxy to create a plug. The plate will have some holes drilled in it eventually to allow the epoxy to bond though.

Botton bracket fitted.

Head tube fitted.

At the mement the pieces are fairly loose fitting because of my relative inexperience in this type of building. I think that the epoxy resin will help me out here.

The next few steps are fiddly and there will be no aparent progress, as in new parts. Its just bonding, and tweaking to get the rear stays to fit. Rear drop out parts are in the post, and will heavily influence how the back end of the bike turns out.

Saturday, 28 May 2011

Metal work, works!

   I have in my grubby hands two pieces of metal work greatness. Lew ( the engineering man) made the parts up for me from my card board templates. I had stock head tube section and a standard blank bottom bracket shell from Ceeway, which I bought back at the start of the wooden bike build in order to measure up to. As the wooden frame came together and I understood more clearly where and how the metal parts would need to fit, I was able to discuss the detail with Lew. He then made a jig to hold the plate at 90 deg' to the tube as he braised them together.

Head tube and fin fixing.

    Hopefully this shows how I intend to sandwich the fin between the yet to be laminated wooden layers that make up the wooden bike frame. The Head tube has a wedge shape to it in an effort to increase its holding strength in the frame, it may well be bolted through as a precaution too.

Bottom bracket with fitting fin.

      With the bottom bracket, we decided to take the fin all the way around the shell. Originally I had intended to have the bottom section of the bracket shell exposed with the fin similar to the head tube. But then I decided to surround the shell with wood, and after discussion with a couple of engineering types it seemed a good idea to get as much strength into the bottom bracket area as possible. It seems obvious, but the stresses going through this section are huge, especially if I go fixed gear or single speed with the bike. Gearing it will drasticly reduce the loading, but I don't really want that.

   Next I need to paint the bits that will be exposed to the outside, while leaving the bits bare that will have direct epoxy resin contact.

   I have also just ordered  from Ceeway, two blank stainless track style drop outs and some 22mm tube to make the rear stay/drop our connections. I had hoped to use the left over head tube but it was just too big at 31mm diameter. Ceeway is just a treasure trove of frame building bits.

   On the wood working front, I hope to have the stays shaped soon and if the weather is warm enough I will have a go at the first stage of bonding the four frame layers into two halfs.

Monday, 23 May 2011

Stays MK-2

I re-measured and re-cut the rear stays this weekend following the new design for the drop outs. I also epoxied the three layers together.

One set of stays clamped with fresh epoxy resin and one behind cured and ready for shaping.

After the initial cure to solid, it takes a further two days for the epoxy to properly cure to full strength, and I resisted the temptation to start early, just. Worth the wait I'm sure. I started basic shaping, the parts were cut over size to allow for fitting and fine tuning. This is the part where I have to try and not take too much away, and get it working properly. Little by little. 

Top stays with some basic shaping.

The good news is that the stays feel very strong and I am really happy with the way that this element has come together. But as one part is solved the next challenge arises. Once shaping is complete, I have to create a rig for aligning the stays to the frame and wheel. Essential if I want to go in a straight line. it will mainly consist of carefully cut right angle pieces mounted on a big flat piece of ply. My left over 25mm piece I abandoned earlier on in the project should be great for this. I will have to work with the main frame on is side and elevated on blocks. This will then allow me to line up the stays. I think i will tack them in place, then fit a couple of wooden pegs to hold position. These will also work when i take it apart for the epoxy fixing.

Thursday, 19 May 2011

One step forward another back.

I just popped in to see Lou the engineer, and he has the bottom bracket plate cut, ready to braze onto the bottom bracket shell this weekend along with the head tube fitting. This is amazing as he is very good at what he does as well as being an ex cycle racer back in the day and is really keen to help me out. Can't wait to see the finished items.

The set back is not that great, but i am going to have to re-cut the six rear stay sections. After a brief chat with Lou last week, we decided upon a slight redesign in the rear stay set up. Mimicking a traditional rear stay with a tube butted onto a plate, but over sized. My original design was based on what i could achieve, with with Lou happy to help out the design can be improved and made more complex.
so I will be laying out and cutting this weekend.

Also just to mention that the epoxy resin test (pictured below) went very well indeed. When cured the strength gain is immense, I tried to snap it but I couldn't. It was only when I tried to prise it apart with a chisel that it started to go, and it resisted that well too. That is good news.

Saturday, 14 May 2011

Got lots done.

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.

Friday, 6 May 2011

Poxy epoxy.

I went to get some epoxy resin today, but the shop didnt have what I wanted. So I will have to go to the place I know has it but is the other side of town.
If I can get some resin then I can start testing with some off cuts for the laminating process. Seeing as I have never done any epoxy based bonding, I think it best not to experiment on the actual frame.
I also held up a wheel to the frame today to work out the rear stay lengths. I think I will have to cut into the rear curve that follows the wheel contour as I am going to have to bring the wheel about an inch closer to the frame than I had originally thought. Its not a problem at all, I had just got used to how it was looking and the cut will change that shape.

Thursday, 5 May 2011

The frame shaping continues.

I have ben bevering away at making the shapes on the ply wood frame look good. I relly like the way it is turning out now.

I am going to get the resin soon and then take out the center two layers so that I can drill them out to reduce the weight. Next fabrication job is to cut and shape the rear stays.