The progressing Panda

I’ve been hard at work on the 3rd frame and it’s almost ready for tack gluing in the jig. The 4th frame is very similar to the Panda so I’m going to make them in parallel, which should hopefully cut down some of the labour time. Here’s some pics.

I’ve also had Daisy back in the shop and am in the process of sanding back the finish and redoing her with a UV protective varnish instead of epoxy resin. This should protect the frame for a lot longer and prevent fading and cracking.

 

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8 Responses to The progressing Panda

  1. Jacques says:

    Been lurking around and checking out your past builds… I must say its very inspirational! So figured its about time to jump in 😉

    How’s the new Jig been working out for you thus far?

    Also noticing you appear to still be using a Dremil tool to miter out your joints. Have you been thinking about use of a drill press and using variously sized ‘core bits’ for the different tube diameters? I’ve seen quite a few other builders using this method and they’ve mentioned that it really helps shave the time needed to complete that portion of the build.

    I’ve also seen the use of pre-cut foam blocks at each of the joints where the bamboo is tacked to the block (without miters) then the block is sanded down to form the lug, at that point they then overlay with either a fiberglass/carbon tack epoxy setup or hemp fiber epoxy combo.
    https://picasaweb.google.com/108184206456596971006/BikeWorkshop#5498010697274123970

    Are you giving consideration to using disk brakes or possibly an internally geared rear hub in a future build?

    Last question, promise 🙂
    I’ve seen some of the newer bikes that are using the Gates Belt Drive system, which of course requires the rear triangle to separate. Any thoughts on utilizing that in your builds down the road?

    Just some food for thought. Keep up the remarkable work!!!

  2. Mik Efford says:

    Hi Jacques,
    The jig is great, thou it still needs some fine tuning to get it a bit more accurate.
    I bought a drill press a while ago and have been using it for the mitres – it certainly does make things a bit quicker and easier! The Dremel’s still handy for the finer work thou.
    I think the Bamboo Bike Studio guys in NY use foam blocks as you suggest – I’ve done similar things with expanding foam to fillet out the joints. I’d be wary about not mitring the tubes thou as the foam isn’t structurally strong enough to prevent flex in the joint and means you have to have longer wrapping areas (along the tube) to get the same level of stiffness.
    Disk brakes I haven’t tackled yet – I’d have to design a new drop-out for that. Internal hubs are usable thou and I’ve been in contact with the Gates Belt Drive system and can get it supplied, but again to do it properly I’d have to modify or redesign my drop outs to accomodate the break in the stays to allow the belt to be installed. I’m contemplating doing it for the current frames I’m working on, but just have to figure out the nitty gritty of the problem.

    I hope that answers your questions, thanks for your interest!

  3. Jacques says:

    Thanks Mik,

    Thanks so much for answering my questions and I appreciate you doing so so quickly 😉

    Of course like anyone starved for information, I’d like to follow up with just a few more (no rush) 🙂

    Was the components for your jig quite expensive? I’m looking into something similar from another company, but wished to compare costs with the system you got for yourself.

    The Bamboo Bike guys in NY are utilizing their foam setup as part of the ‘kit’ they sell on their website as well as the classes they offer. So the argument could be made that after they’ve been sanded and used the epoxy bonded with the foam and carbon tack, it would appear to make a pretty sound joint lest they have some very unhappy people following a failure of such a joint setup. They’ve also been at it for over 3 years, so the proofs in the results that no bikes have yet to fail from such a technique (at least none I’ve been able to find).

    Speaking of carbon tack, was reading up on Calfee Designs (hail to the king baby!) technique of using only hemp in their hub making.. and I quote, “we discovered that bamboo and carbon fiber have different rates or thermal dynamic expansion. Our early bamboo frames used carbon fiber, instead of hemp, to join the tubes and many of the joints failed over time.” So thought that I’d pass it along lest you were unawares.

    OK, last question..
    Have you had any luck in locating a soy based epoxy? I’ve been searching and know they exist, but have had little luck in discovering a good supplier.

    Thanks again for listening! Can’t wait to see your latest progress! 🙂

  4. Mik Efford says:

    Hi Jacques,
    Most of the jig is made from Maytec aluminium components and extrusion. It cost about $450 all up for the materials. I did have to do a bit of modification to the parts to make them fit (like filing off protruding tabs where I needed it flat etc) For the seat tube cone I’ve used a rubber door stops and the headset cones come from a Cyclus headset press (http://www.wiggle.co.uk/au/cyclus-headset-press/) which doubles as a headset press when I need it!

    I agree that the technique used by the BBS guys is good and strong, but it seems like it’s a time saving technique so they don’t have to teach people how to mitre joints (it’s pretty tricky!). I bet if they had time to make the most beautiful and well engineered bike they could, using as little carbon fibre as possible, then they’d mitre those poles together properly.

    The discussion between hemp and carbon is certainly an interesting one – the BBS guys argue that hemp gets soft after a while (read here: http://blog.bamboobikestudio.com/why-dont-we-use-natural-fibers-in-our-lugs/) and that’s why they use carbon, but Calfee’s argument contradicts their philosophy with his reasoning about thermal expansion. Who should we believe? All I can add to the conversation is that the 2 bikes I’ve built haven’t failed yet, and they’re both using CF and some small amounts of fibre-glass. Only time will tell for me!

    Cheers,
    Mik

  5. Mik Efford says:

    Oh and forgot your last question – I haven’t had any luck finding soy based epoxy yet. Kind of given up on it until it becomes more mainstream and tested and available!

  6. Jacques says:

    I think I might have stumbled on a supplier…
    http://www.ecopoxysystems.com/products.html

    It looks promising! They provide datasheets on all of their materials.
    Been used primarily for the marine industry from what I can see.
    Even provide sample kits so that you can try before going whole hog on their products.

  7. Brett says:

    Could you show a better picture of your bottom bracket clamp? How you keep the shell axially aligned with the threaded rod?

    Do you have something that sits inside the shell to keep is centered on the rod? I see you have it clamped on threaded rod between washers w/ wingnuts, could you provide any more detailed photos or information?

    Thanks,

    Brett

  8. Mik Efford says:

    hi brett, there’s a flat plate on the backside of the BB that’s properly aligned to the jig and the threaded rod and large washer just hold it against that. There’s no self-centering mechanism, but it’s pretty easy to get it in the middle and clamp it down with the wing nut tight.

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