|
Harry Harrison
|
|
|
Group: Forum Members
Posts: 5,
Visits: 33
|
Hello Talk Composites, I am a small scale bespoke frame builder, building frames from steel in Sheffield UK. I build using traditional methods, fillet brazing, silver brazed lugs etc etc. I use these traditional methods but always look for opportunities to build in technical and functional improvements in to the frames. Have a look at my web site for more of a picture www.fieldcycles.com I am building a few frames with an integrated seat post like the images attached. I would like to replace the extended seat tube / seat post with a composite tube. My idea is to build a frame with a lug at the bottom bracket and the seat tube top tube junction and then bond in a carbon tube. Any advice would be greatly appreciated, things like clearances, bonding composites to steel would be really helpful. Ideally I would like to use a composite tube that has an o.d of 28.6 mm (1 1/8") so it will work with the seat post top I make.
|
|
|
|
|
wozza
|
|
|
Group: Forum Members
Posts: 688,
Visits: 5.4K
|
Hi Harry and welcome. Beautiful work there. Very nice to see traditional skills are still alive and well in the U.K. I am in Todmorden, so not a million miles away from you. I run a small (just me  ) Composites Business.I have had a carbon mountain bike frame on the go for a while now. (It's for me so I am doing it between customer work). The seat tube is made by wrapping carbon around a vacuum cleaner extension tube. (very high tech I know  . Because the tube is tapered I can cut the tube at the exact OD/ID I require. A similar technique may work for you.Good luck and keep up the fantastic work. Warren
Carbon Copies Ltd
|
|
|
|
|
Matthieu Libeert
|
|
|
Group: Forum Members
Posts: 955,
Visits: 3.4K
|
Hi Harry, I'm not here to help you with your problem, I think Warren can give you better advice for what your looking for. I'm here to tell you that what you do is awesome! I realy like the colors and design on your bikes. Just like Warren says, It's nice to see traditional skills are still alive! How do you make your front logo-plates above the front wheel? CNC?
|
|
|
|
|
Harry Harrison
|
|
|
Group: Forum Members
Posts: 5,
Visits: 33
|
Hi Warren, Thanks for the reply, I wasn't sure if my ye olde methods would appeal to people on here !! thanks for the tips, I think making a lug and bonding a tube in will be the way to go. I realise why the i.d of tubes are the specific measurement with the wrapping round a mandrel method to form a tube. Ideally I would like to just find the right sized o.d tube and not get too involved with the production of the tubes, just cut them and then bond in. Do you have any tips on the correct adhesive to use and what sort of glue gap I should leave ? Your mountain bike looks like a really involved job, I will be interested to see it come together.
|
|
|
|
|
Kevin-Lee
|
|
|
Group: Forum Members
Posts: 44,
Visits: 2.4K
|
Hi Harry,
Those bikes are amazing!
And I think the man who does the paintwork on those bikes knows his s*** too...
Kev.
|
|
|
|
|
Harry Harrison
|
|
|
Group: Forum Members
Posts: 5,
Visits: 33
|
Hi Matthieu,
Thanks for the reply and cheers for the compliments. The head badge is investment cast bronze. I made a plastic version using a laser etcher and then shaped it up to the correct dimensions then made a silicon mold of it so I can produce wax versions and then the lost wax casting process. Takes a while but when you have the mold you can make them reasonably quickly. |
|
|
|
|
wozza
|
|
|
Group: Forum Members
Posts: 688,
Visits: 5.4K
|
Hi Harry, I use the ET 515 from Easy Composites. It's a semi-flexible adhesive that can cope with shock/flex loads. I use it to bond Aluminium inserts into Carbon tube for Wishbone Suspension Units for race cars and it has proved to be perfect for the job. If it is possible machine some small grooves or knurl the lug/boss. This increases the surface area of the joint massively. (sorry if I am trying to tell you something you already know). The tubes I make are 40mm OD (Oval) and I use 0.5mm clearance between the two parts. I think you may struggle to find a suitable tube "off the shelf" If you need some making or want more info on how to make your own just let me know. The bike I'm doing is full suspension so a lot of "head scratching" has gone on I can tell you  Regards Warren
Carbon Copies Ltd
|
|
|
|
|
Harry Harrison
|
|
|
Group: Forum Members
Posts: 5,
Visits: 33
|
Hi Warren,
I might take you up on the offer of some help. I have been looking at the stock tubes that easy composites do and I think I could make the 28.5mm (ID) / 31.3mm (OD) roll wrapped tube work if its a suitable strength for my application.
The bigger O.D of 31.3 would require me to make a new seatpost top clamp, which would be a nice thing to do in composites, another project brewing !! there is not enough hours in the day !! |
|
|
|
|
Harry Harrison
|
|
|
Group: Forum Members
Posts: 5,
Visits: 33
|
Cheers Kev, I make the frames and my pal paints them, he has the right amount of O.C.D to do a fantastic job !! he paints the odd carbon frame so might be able to fit some carbon stuff in in the future.
|
|
|
|
|
wozza
|
|
|
Group: Forum Members
Posts: 688,
Visits: 5.4K
|
Hi, the problem with "roll wrapped" round a mandrel is that the OD can vary quite a bit +/- 0.5mm (or more) and is not perfectly round/ concentric. This is not an issue for many applications. In your case I think there would be an issue getting a nice fit between the two tubes. In the past I have used a thicker wall tube and then machined the OD to size.(only a short 40mm at the ends) Not ideal as you then start introducing "changes of section" into the tube which is not good for "high load areas". (plus extra weight of course) I now use a "split" mould with an internal bladder. This gives me an accurate OD and the ability to add extra layers of reinforcement at the ends of the tubes (where the inserts go) without affecting the OD. The link looks like very nice German Engineering. I think those would look good on your bikes, a nice mixture of traditional with a hint of modern.
Regards Warren
Carbon Copies Ltd
|
|
|
|