Designing and Building my own Carbon Fibre frame

Who are you (no off-topic talk please)

Moderator: Moderator Team

euph
Posts: 151
Joined: Wed May 13, 2015 10:35 pm

by euph

Thanks Clannagh

I was inspired by your Y Foil and used your write up on making the mould for the derailleur hanger as a basis for my process. So, thankyou!

by Weenie


User avatar
Clannagh
Posts: 248
Joined: Tue Jul 15, 2014 7:37 pm

by Clannagh

Cool, Im loving your 3D printer work looks amazing, I need a 3D printer!
Third and final year no pressure then! if you think I can help in any way just ask.
Good luck :thumbup:

User avatar
Clannagh
Posts: 248
Joined: Tue Jul 15, 2014 7:37 pm

by Clannagh

Just having a look at you wing mould, have you heard of Low melt thermoplastic moulding granules? you should be able to pick them up on eBay. Ideal for making fast prototype moulds. You add the granules to hot water they then form a malleable blob of plastic, form this around one half of your piece to be moulded, let it cool then form the other half. both sides can be cracked open once cooled, epoxy doesn't stick to it either so does away with all the mess of release agent etc. Speeds up the prototype/testing process no end and its reusable, drop you moulds back in hot water and they become malleable again ready to make a new mould. I guess you will have to try a bit on your 3D moulds first as it is probably made up of the same plastic but with a higher melt point so could stick to each other!

euph
Posts: 151
Joined: Wed May 13, 2015 10:35 pm

by euph

That's not a bad idea. I looked at a few different options including some epoxy compatible moulding putty that you add hardener to then work it by hand and form around your part. I have heard of that type of thermoplastic but it never occurred to me that I could use it for moulds. I will continue with the fibreglass mould for the moment as I have all the supplies for it. However I will pick up some thermoplastic stuff and see if I have any success.

Thanks

alistaird
Posts: 120
Joined: Thu Jul 21, 2016 8:21 pm

by alistaird

Interesting thread and good luck. Definitely subscribing to this one.

A

euph
Posts: 151
Joined: Wed May 13, 2015 10:35 pm

by euph

Updates!

I had success with the fibreglass mould for the helicopter propeller so I have made a mould of the headtube.

I made an aluminium mandrel which can be disassembled and removed from the final part. The mandrel is the exact diameter of the final holes but a tad undersized. So this should provide a good inner diameter for the tubes and bearings.

I layed the carbon fibre up today and can already see some issues in the tighter corners but I will have to wait until it is out of the mould to see how it turns out. Experimentation and failure is the only way to learn!

I have spoken to clannagh and he has shown me a way to make inflatable bags for the inside of the mould which I will try after this attempt with the mandrels as I feel this will give guaranteed compression to all sections of the mould. This method will sacrifice the guaranteed hole sizes however if built oversize these can be machined out to spec.

Sorry for the picture dump. I still haven't figured out how to put pictures in the middle of text in Tapatalk.

ImageImageImageImageImage

euph
Posts: 151
Joined: Wed May 13, 2015 10:35 pm

by euph

I made a headtube lug. It is definitely not good enough to be a final part but it has been reasonably successful for a first try.

I used slow hardener which means I have a longer pot life but the cure time is at least 30 hours which may have caused a few problems. The main problem is that the aluminium mandrel is quite heavy and has no indexing points which caused it to sink to one side. This has caused one side of the part to have a thinner wall than the other. Some of the tighter corners have got some voids as well. The part is strong though.

I will put some pictures up but please don't judge too hard! I will make a internal bladder for my next attempt which should work a lot better.

ImageImageImageImageImageImageImage

euph
Posts: 151
Joined: Wed May 13, 2015 10:35 pm

by euph

Hey guys. Sorry for the lack of updates. I have been working on making samples for testing with the Instron Machine at uni. I am going to compare the compressive and tensile strength of multiple layups, the difference between post curing a part and not and also compare my results to the values stated on the datasheets given with the resin and fibre that I am using.

While I have been setting up for this I have refined my current process with the mandrels and experimented with some new processes involving air bladders. Thanks to Clannagh for giving me some pointers on how to make the air bladders.

I have made a few headtube lugs now as my main test part. Each one has been better than the last. My primary issue now is getting the inner diameter perfect as the tubes have to bond into them and bearings have to pressed in. We all know what a bottom bracket shell with poor tolerances causes so I am paying particular attention to getting these areas perfect.

I have also made a few chainstays. This is the only tube I am making on the whole bike and for my final report I will include some testing data on the deflection of the tube under different loads. The chainstays have come out very successfully and are very strong.

All of this is completely new to me so each attempt is a chance to learn and improve. Thanks for reading.

rekhyt
Posts: 57
Joined: Sat Jan 02, 2016 7:04 pm

by rekhyt

Would be cool to see some more pics. Sure, things might not look as refined as those from builders with more experience, but at least i think it's more interesting to see the outcome of a DIY approach.

euph
Posts: 151
Joined: Wed May 13, 2015 10:35 pm

by euph

I finished up my final headtube today. Finish is still a tad rough but I gave it a quick wetsand just to polish it up. Headset cups are ready to be pressed in but will wait until final assembly. Now to get the other two lugs to this level! ImageImageImageImage

chris47
Posts: 97
Joined: Thu Apr 10, 2014 11:06 pm

by chris47

Cool! so very cool! and thanks for sharing :)

beanbiken
Posts: 514
Joined: Tue Mar 18, 2014 10:13 pm
Location: Great Southern Land

by beanbiken

chris47 wrote:
Fri Jan 26, 2018 7:27 am
Cool! so very cool! and thanks for sharing :)
Ditto, very interested to see how this pans out. Please keep the updates coming

BB
Ahhh, coffee & carbon

User avatar
michel2
Posts: 1172
Joined: Mon Jan 10, 2005 10:47 am
Location: somewere floating between here and the other side

by michel2

impressive work your doing !I build out of steel but would like to have ago with carbon (-:
why do you go with lugs over tube to tube ?
thanks, mick

euph
Posts: 151
Joined: Wed May 13, 2015 10:35 pm

by euph

michel2

I have berated myself constantly for not going tube to tube the deeper I have got into this project as it probably would have been easier. I don't know this, however lugged has definitely proven difficult.

I went lugged because I was inspired by the early carbon fibre frames in the 90s which where just a step away from lugged steel and the beginning of exploring carbon fibre as a new material to make frames from. So I figured it would be a good a reasonable place to start, as that's where big manufacturers begun!

Hope that answers your question. Although I am struggling to justify it to myself. Weight, complexity and design limitations are many of the flaws with this method. Not to get ahead of myself but in time I will try a tube to tube frame with more focus on weight.

Thanks

by Weenie


User avatar
prendrefeu
Posts: 8609
Joined: Wed Oct 31, 2007 10:32 pm
Location: Los Feliz, Los Angeles, California
Contact:

by prendrefeu

This is so exciting!
Exp001 || Other projects in the works.

Post Reply
  • Similar Topics
    Replies
    Views
    Last post