I want to gain more knowledge on CF builds leading to a build in a year or two.
I know a few out there are keen on this.
Love the work of Crumpton, BERK, etc. on VSalon.
Lets start a thread for all those links and maybe some group bulk buying on products?
https://home.comcast.net/~pinnah/dirtbag-bikes/geometry-project.html
Spent a lot of time researching this very subject…
Same as always many ways to skin a cat.
Crumpton, and Appleman use prepreg which requires time in the oven in a Vac bag
Cyfac and others use a wet layup which requires Vac bag but no oven.
Main hurdle is supplies.
Prepreg min buy is 10Lm ( depending on layup schedule you may need multiple types of prepreg) ( needs to be refigerated)
Resin min buy 10kg
back40 bicycleworks
Catastrophic Failure | Christopher Aldgate – ‘a. frame build’
tubing in NZ
C-Tech Manufacture parallel or tapered Carbon Tube
tubing in Aust
Tubes, Rods & Components | CST Composites
Tubing States is Rockwest and Enve. Enve are rolling out there new range in the coming months and are not taking new customers at the mo… min spend is 5000 us
Cyfac process
Paging Mik.
now can we bring back kanye?
I wasn’t aware that SK was in the crabon frabication bizzo.
i just thought he’d have a fair bit of good info around it
haha burn
Totally interesting. Would totally love to play with this kinda thing. Time / Money probably wouldn’t allow it.
Berks stuff is amazing though.
Well let me know if anyone needs a tubeset. I have one spare…
C-tech main tubes
Enve rear stays and Crumpton dropouts
Do lots of research into heath hazards plz, nasty nasty shit involved
yep, give Mik a PM, he has done a bit of carbon stuff for his Bamboo frames.
Hey Peeps,
Thought I would share my experiences with C.F bonding processes. After completing the internship with Ted Wojcik I felt disallusioned and bitter but decided to perservere and develop my skills in other manufacturing processes. I have been practising fillet brazing and I am about to order stuff through Keith (sorry Keith, nearly ready!)
I am using what can be defined as a wet layup although I did try and make my own ‘prepreg’ by coating the fibres in resin and storing them in the fridge. Each piece of uni or twill was infused with resin and sandwiched between greaseproof baking paper (bike building is serious business) and stored in the freezer. After a few days it solidified and was thrown into the oven to see what would happen and yes, the resin became activated and solidified. Lesson learnt.
The next batch was also ‘prepreg’ but was taken out of the freezer after a day. This worked well whilst the resin was cold but as it came up to room temperature, it became a god awful sticky mess and was difficult to apply to the tubes. Speaking of which, I sourced the tubes through Bill of VSalon (Progetto Cycles) He sent me a bunch of off cuts. We discussed the bike industry in Australia and he used to build for Teschner (aluminium) and now makes a few C.F frames for mates.
So basically, without a vacuum pump and associated ancillaries, laying up C.F can be a right pain. That said, I was able to support my entire bodyweight on a completed test sample and I was unable to break it so I cut it half.
The compound used for the fillet is a two part adhesive made by Araldite (part no. 2014) Apparently many bike companies such as Baum and Spray your bike etc use this compound for seat tube inserts and bonding cable guides etc. The only issue with this stuff is that is a rather heavy and reducing density via microballons or another secret ingredient would be the way to go.
A piece of prepreg with the backing still attached. This unidirectional C.F was sourced from Ironbark composites in Torquay. The only two issues that need to be resolved are the GSM of the C.F and those adhesive strings covering the back of the fibres. This is to prevent the fibres from disassembling themselves but it does mean they will remain in the finished part.
Also sourced from Ironbark Composites. A slow curing resin with good viscosity. Improves with temperature but I think this will cure at ambient temperatures but will take 3 days or so. Into the oven you go at 120 degrees C until “al dente” The resin turns a slight brown tinge if you over cook it. Clear resin is a good sign that it has cured properly.
Improper fibre compaction due to insufficient pressure whilst using the adhesive tape compression method. Joint did not fail but there was far too much excess resin and C.F. Broke the adjoining C.F tube and smashed my finger on the vice. Yippee.
Internal fillet and good fibre compaction. Unidirectional underneath with twill top layer.
Rough as guts due to the release plastic becoming crinkled and moving once the tape was applied to compress the joint. Ideally, there would be little finishing work as possible which would also indicate a lower quantity of resin used to produce the part.
Galvanic corrosion? We’ll see about that. Currently being weather tested in my garden. Inital twill layer to for a ‘lug’ and then stratified with unidirectional C.F (secret layup shhhhhh!)
In summation, this process of building a bike has benefits and disadvantages. Benefit: no brazing and distortion issues. Negative: Still have to sand down the fillets for ages. Ideally I will get a frame jig or surface plate and get some tubes organised. I will then acquire a decent vacuum pump and some sort of oven to cure the parts. Sourcing prepreg is a pain and I have tried but again, you can only get minimum orders and I would also prefer to specify the resin used and GSM of the fabric. Most companies do not want to deal with hobbyists, which I can understand) I have a few ideas relating to improving processes and developing layup schedules that are repeatable and use minimum C.F and yet are strong enough (strength v. weight)
I hope this helps and shoot me a message if you have any questions/comments.
Peace,
Blake.
Wow.
Keen to hear your thoughts on this, shoot me an email if you have a moment
Just to clarify, I was not bitter and disallusioned with Ted. He is honest, hardworking and down to earth. We disagreed on many things and had a different intrepretation of what to expect from the internship. It came to an abrupt end and I came back to Australia.
Am just interested to hear of your experience, learning from another builder directly is a rare thing in this age
I use wet layup with electrical tape compression followed by heating in an improvised black bag with hairdryer oven (gets to about 60-70 degrees).
I get my CF, epoxy (west systems, 105 + 206) and microfiber filler from Carbon fiber Australia You can buy very small quantities if you want.
You can avoid galvanic corrosion with metals by wet sanding the epoxy into the alu/steel just prior to bonding. The wet thing in this instance is the epoxy, not water. Doing this removes any oxidisation on the surface, which is what would cause galvanic corrosion.
I’m currently sticking together some pre-moulded CF tube sets that Huw @ Commuter gave me. I think they originated from an Australian frame builder who’s no longer in existence (GSX? or someone?). The first one’s almost finished. I’ll let you know if it falls apart!
Impressive stuff spirited away!
Hey Gman, ya gonna teach highschool kids to build CF frames in tech??
That’d be fkn rad!