Thursday, 27 August 2009

The bike is ready

We have been moving houses, so the limited time had to be divided between the house, the family, the bike and the Blog, and the Blog lost.

Now a short update with some photo's.

I managed to get the bike ready. I turned and milled the last parts for the steering and for the stoker freewheel.
For that last part I use a BMX freewheel screwed onto an old threaded hub. I completely modified the hub with a new single ball bearing and bolted a 22 tooth chainwheel onto the flange. Not perfect, but it works. I wanted to make the entire setup myself, but I ran into the problem that my lathe does not have proper gearing to make the 24tpi thread required for the BMX freewheel. I use an excenter to tighten the middle chain. To tighten the front chain I move the boom.

The handlebars have been another problem. I bought triathlon handlebars, and after mounting them I discovered that they had a diameter slightly larger than the standard 22.4 mm. So mounting the Magura HS33 brakes and the Rohloff gripshifter proved impossible. I the end I found a solution in the purchase of the handlebars for a so called "motherbike" (moederfiets). These are deep and wide. I bend them more narrow, and mounted them reversed. Together with Cane Creek ergocontrol bar ends (not yet on the photographs) it is a quite nice handlebar setup . It even allows my wife Edith, who is quite a lot smaller than I am, to ride the bike.

The bike is now christened "Santiago". The city of Santiago is paramount for travel and pelgrimmage by human power and it contains part of the name Santos, the bike builder who supplied the rear of the bike.

Ok, now some images:

Santiago in the workshop, still without saddle. The upper part of the front seat has been removed by now. The front seat is a modified old wooden M5 recumbent seat. You can see the stoker freewheel below the seat.

Just out of the workshop for the first time.

Santiago with me and Yentl (my eldest daughter).

Levia, the youngest, insists on a test drive as well. She is still to small, and I have to shorten the boom and use shorter cranks to enable her to really use the bike. Here I just hope she won't fall off.....

And a short video, regretfully on its side until I have time to change this.....

Wednesday, 8 July 2009

Sanding and coating

Only one picture now, more will follow. Look for the sneak preview below.

Sanding is the job that I hate most on carbon fibre constructions. The carbon dust is irritating to your skin and itches. So sanding is done in long sleeves, long trousers and with gloves. Not really fun when it is 30 degrees centrigrade.

First I do the rough work using file, sanding paper and a Stanly shaper. I remove most of the ridges and other small defects.

Next step is sanding the entire surface. Tjalling is a good friend of mine with a wood workshop. And in this workshop he has a professional Festo sanding machine connected to a Festo vacuum cleaner. I have asked him to use his workshop in the hope that the carbon dust will be less of a problem. It works like a charm. The sanding dust simply disappears. In stead of a black workshop and an itching skin I just end up with a nice smooth frame and nothing else.

In the weekend I go for a ride with Levia in the cargobike and buy a pot of dubbel D UV coating. This is a polyester based coating that is very tough, UV resistant and it is an UV filter. The epoxy of the frame can not tolerate UV very well, so this coating is like sunscreen for my bike.

After 2 layers of the coating the frame looks like this:

I probably will add one extra layer off coating, lightly thinned got get a smoother finish.

After that I will paint the rear triangle in glossy black.

And off with the peelply

No pictures this time.
The resin has cured, and the frame must be freed of its second skin of peelply. We put the peelply all around the frame (on both sides). This makes it extremely difficult to get off the stuff. An hour of really hard work yields sore fingers and a nice clean frame. A really nice clean frame.

To be honest, this frame exeeds my expectations and it is by far the most beautifull that I build up to now. Again some ridges, but only near the edge of the new layer. This means that I can sand those off without losing strength or stiffness.

Next step: sanding.

And now the other side

After the nice results of the first work I look forward to the other side.
The procedure is largely identical. This time we need to get the cloth really tight around the edges of the frame, because it is the last layer. After this there is no way to cover up ridges and other mistakes.

At 8 pm we start work. The first session took 5 hours, so we hope to use a bit less time and to be ready at midnight.

This time we make the first 5 layers in all directions 1 cm smaller. The last layer has the normal size. In this way we hope that we get e nice edge on the new laminate.

So first we start out with reducing the size of the template.

After this we cut all layers and stack them on a bourd in the correct order.

And now it is time for the real work. Again Andries works on the front of the frame and I on the rear. The exercise of the first session helps, and we need less effort and less small cuts to get the laminate around the edges of the frame. A trick to avoid fibre pull out on locg strainght edges is to make a few tiny cuts in the edge. This helps to get a cleaner edge on the laminate.

We take a lot of care to avoid lose fibres on top of the existing carbon. For the last layer we also try to avoid this, so we take new brushes and gloves for this layer.

The team

And again

Adding an extra layer
Next job is peelply. This time we put peelply all around the frame, and try to avoid any areas without peelply. Last time the peelply fell off when we tried this, so now we decide to use some extra resin to stick the peelply onto the laminate. This helps a lot. The bleeder will take care of the extra resin anyway, so for the weight it should have no serious impact.

What to do....

Bleeder on the frame

The last job again is the vacuum bag. And here the problems begin.
Error number 1: I forgot to buy new silicone. I think we have enough, but not plenty.
Error number 2: we start out with kitting the bag before we have measured the lenght properly. The result is that the top side of the bag is to short. Usually I would discard the bag and make a new one, but the lack of silicone forces us to go on with this bag. We patch up the short topside with an extra piece, but this results in a silicone seal that has to go over the frame in stead of along the edge of the bag.
Sealing the bag

Lots of silicone

The difficults parts: joints in the bag

Result: it takes us two hours to get the bag resonably well sealed. The pump maintains around -0.7 bar pressure at a dutycycle of 50 % (10 seconds on, 10 seconds off). This should be good enough. At 1.45 AM we call it a day.

Monday, 15 June 2009

Time to unwrap

Removing presents from their wrappings always is a nice pasttime, but taking a new frame out of the vacuumbag is something special alltogether.

The first part is quickly done: the bag itself does not stick to the frame. The result is a frame still nicely wrapped in peelply and breather. This is the laminated right hand side:
And this is the still bare left hand side:

On the left side you can see the peelply in white and red covering the foam.

A detail of the front seatpost shows that the breather has taken up a fair amount of the excess resin, just as I wanted it. The second layer of breather lower on the frame did not really fill with epoxy, so it probably was overkill.

The area around the bottom bracket shows the (here invisible) peelply with cured epoxy and little ridges of resin on the outside. Without the peelpy the entire frame would come out of the bag like this, only with bigger ridges because the excess resin does not have a place to go. I build my first carbon tandem without peelply, and it was a really huge amount of work to get the frame reasonably smooth and even.
Now the real work starts. The peelply comes loose from the frame, but only when you pull really hard on it. My sore fingers do not like it yet, but I want to do it now.
Underneath the peelply I find a nicely textured black surface. This is the frame after half the work has been done:
And these are the leftovers:

The frame has a few imperfections, but overal I am really happy about it.
Here an overview of the entire frame (the darkness difference between front and back is a problem of the flash, not of the frame):
In curves around the edges, the peelply has come apart, so you see little V's of bare resin, sometimes with breather bonded to it. This will require some sanding, but not a lot.
High up on the the rear seat post the carbon has not been pressed completely flat, and a little ridge has formed. I might sand it down as this area will later on be covered by another layer of carbon when laminating the other side.

The area around the bottom bracket is reasonably smooth. I had expected this area to be a potential problem, but it did come about quite well:

The top of the sat tube also has a little ridge, but this will be easily sanded away before I apply the next carbon. The ridge is in a direction than has no real impact on the strength of the frame when I sand it away.
One small other imperfection is a somewhat dry edge on the forward seatpost. The amount of epoxy has been to little here.

The position of the intermeadiate head tube is clearly visible below the laminate. I new this on beforehand and do not mind it. In the matte finish now it is better visible than later on when the frame will have a shiny transparent coating.
Another learning point is that the vacuum tubes leave markings on the frame, as you can see on the lower front of the intermediate head tube. For the other side will will think of a better solution. It is a reminder of the huge forces that are applied by the vacuum (to visualise the force: o.8 bar vacuum is comparable to the weight of 6 VW Golf cars on an average dining table).
Conclusion: this has been a succes. A large part of the learning curve is behind us now. With a little bit more attention to the details near the seat post we might be able to laminate the other side witout any ridges and the final result will be really good.

First some sanding (in the garden, I do not want the house covered in itchy carbon powder) and then the frame is ready for its next trip into the vacuum. Keep you posted.

Sunday, 14 June 2009

No unpacking yet

Today I wanted to get the frame out of the vacuum bag, and to rip of the breather and peelply. But when cooking dinner I managed to pick up a scorchingly hot pan barehanded, so for today four of my fingers a a bit out of order.
Tomorrow more news, I hope.

Saturday, 13 June 2009

Laminating the frame: the real stuff

All preparations are ready now, and it is time to apply epoxy and carbon.

The epoxy I use is multipoxy, bought from Polyservice in Nieuwekerk a.d. IJsel. It is well priced, has a nice viscosity and usually enough pot life. For the uninitiated: pot life is the time that you can work with the mixed epoxy before the fluid starts to get thick and to sticky to handle.

When laminating the front beam one of my batches epoxy cured far to quickly, probably because of the rather high temperatures in the attic that is my workspace. To prevent this I now use the biggest paint holders that I can find, mix a maximum of 300 grams epoxy, and I use a second paint holder for cooling. The second paint holder is filled with an icepack and some water, and the paint holder with epoxy is placed on top of this. It keeps the temperature low and slows the curing of the epoxy. Here the paint holder with icepack:

The plug is placed on the table with the right hand side up. Some foam blocks are used to support the frame.
First step after mixing the resin is covering the plug with a layer of epoxy. This makes is easier to fixate the first ply of carbon on the plug. After this the first ply is placed carefully upon the plug.

The large side surface is impregnated with epoxy, and afterwards the material is word around the upper and lower edges of the frame. When the plies are slightly to large the material is cut using normal scissors. Difficult areas may require small cuts into the ply to conform it around bends.
Nitril glooves are used to prevent skin contact with the epoxy. I take several new ones during one session as they tend to get sticky on the outside, this makes the work more difficult.

All epoxy work is done using cheap disposable brushes. large brushes work well for the larger areas, and the 30 mm size is ideal for working the details around the edges.
Andries is working on the head tube area:

Carefully ply after ply is added to the plug. Between the first and second ply we add a number of local plies in the high stress areas around the bottom bracket and the forward head tube.
A nice view of the frame with me and my lathe on the background:
Before the last ply the area around the bottom bracket is strengthened using carbon fibre roving wrapped around the bottom bracket tube.
The last ply is a diagonally oriented one. The advantage is that this ply does not fray at the long edges. This makes it easier to achieve a nice edge. I intend to leave the carbon visible, so a beautiful laminate is important. In ths laminating session we use about 500 grams of epoxy. Not all will be in the bike, as the bruckes do take quiet some epoxy, and excess epoxy will get into the peelply and breather material.
After the last ply we cover the frame with a piece of peelply. The peelply is larger than the pieces of laminate. The peelply is cut at the edges to make in form around the edges of the frame as is is much less deformable than the carbon. After this two layers of breather material are added. The breather is smaller to ensure that is only does touch peelply, and never bare epoxy as it is very diffucult to remove breather that is bonded to the cured surface . Any sharp points on the rearframe get a layer of breather as well to prevent a puncture of the vacuum bag.

Making the vacuum bag is a difficult and hasty job, so we have few photographs. We use foil that normaly is used for covering the floor when you paint the house. We start with a piece of foil with a width of 1 m and a length of 5 m. The foil is placed on the floor, and the laminated frame is placed on top of it. With a silicone gun we go along the edges of the foil, making sure we leave no gaps. The uncured silicone will seal the vacuum bag. Then the foil is folded over the frame, and in the rear triangle the foil is tucked in between the frame stays.

Vacuum connections are worked into the silicone between the upper and lower foil, or on the flat foil using a suction cup. Regretfully we put the vacuum hoses into the lower seam. This is not a good idea when you intend to place the frame on a table as we discovered to late.

We put on the vacuum and carefully work around the edges of the foil to check for leakages. We work the silicone into any creases in the foil. Slowly the vacuum builds up and we align the frame on the table.
It is a lot of work to find the last leaks, and as I had to pick up the kids Andries did most of this alone. We end up with a fairly good vacuum bag. A pressure of 0.8 bar below atmospheric, and a pump that runs for about 5 seconds out of every 13. Not perfect, but good enough.

And now the long wait for the frame to cure........