Jar_head's WCB-M-062

[Jar_head]

I thought it would be better to start my own thread about my bike..

As I said, I ordered some screws for both brakes.. Another 18 grams lighter now 






In the next days I await some Carbon fiber rovings to build clamps for the brake levers. My father will help me out a little bit on this, cause I don't have much experience with that.

[activ3]

Can you list the current build specifics and weight?

[carbonazza]

In the next days I await some Carbon fiber rovings to build clamps for the brake levers.

Please send details about your build, this is the first time we see this here
Why do you want to do this? Just for the weight?

[Jar_head]

Here we go 



And this is the bike:



Built for long distance marathon and CC races.

For the weight and to see if I can build (small) carbon parts by myself. 

[cklein]

Your bike looks very great. Nice build.

[Carbon_Dude]

Very stealthy looking Chiner!

[Jar_head]

So, the first pair of clamps is almost done. Now they have to harden 24 h. Can't wait how they work out 





The very first pair I made this weekend, I used for testing. Bent, smashed and broke them. Gives me a little confidence to really mount them 
Also tried to build a seatpostclamp.. Don't really know, if this is able to clamp the post tight enough.. but we will see.



Has someone from this forum tried something like this before?

[RS VR6]

Wow man...nice work!

[SportingGoods]

I played it easy and ordered parts from Smud-Carbon 

Probably better quality and more reliable then your parts but definitely a lot less fun and much more expensive!

[Jar_head]

For me it's more about the building process..



Does anyone have an idea how the f*** I can get the screws out without damaging the parts? 

[carbonazza]

Does anyone have an idea how the f*** I can get the screws out without damaging the parts? 

I'm afraid the only option is to do some new ones, knowing now that anything in contact with the epoxy will stick
Maybe using some wax coating, release agent or plastic wrap around the mobile parts.

And to have a nice finish, you need to put pressure against the mold, either with some air balloon or thermic shrink tape.

Another option could to draw and 3D print a mold of the pieces( some rubber plastic is possible) and then the carbon+epoxy.

[Jerryno]

Hi Jar_Head,

here are my 2 cents for the design and process:

The stress is only distributed in couple of the strands (highlighted), whole lot of them are not load-bearing. This is because the bolts and carbon piece are at an angle. This makes the design weaker. I don't also feel good about those open holes (marked circle). In that area the strands rub against the edge of the bolt which is imho not good.



Look at this clamp how it is designed, I like this design much much more:



Also I suggest to run some software simulations or tests, or to make many many test iterations. Put too little carbon and the part will fail. Put too much carbon and resin and it will end up heavier than a piece from thin spring-steel.

It is also very good to press the part (vacuum or other means) to squish the excess resin out the part. The less resin inside the better and stronger part. Also if you cure the resin with some heat applied to it, it will cure into better resin.

[cklein]

Your bike looks great and respect for building parts by yourself.

[Jar_head]

First of all, thanks for your advice! I will consider this in the next parts I build. You were right Jerryno, the seatpost clamp failed in the first test with 4 Newtonmeters on the screw due to lateral force on the strands.
The next design will be like the clamp you showed.



But the weight was okay ^^ the bolt is steel and the round thing too. With a titanium bolt it should be around 7 grams.

I tested the brake lever clamp (only the rear brake, for the case it fails) today and it worked out so far.. the next ride I will test it in rough conditions to see if it works.



And just as a marginal note: I know that what I am doing here is not highly scientific. Just want to know how carbon fiber handles and is built since my studies (aeronautical engineering) deal with all that stuff. We unfortunatly don't really get the chance to test those things.. everything's very theoretical.

By the way, tomorrow I will receive a new seatpost (New Ultimate) with just 125 grams  I'm very curious about it!
The paint (of course) will come off, so maybe another 5 to 10 grams will fall..

[seahog32]

Does anyone have an idea how the f*** I can get the screws out without damaging the parts? 

Heating the screws without heating the carbon parts directly. How to do that is another question. Soldering iron??