Allen

For me it was price. I bought five pounds of hemp fiber for twenty bucks ($35 with shipping). It is enough to make quite a few frames.
2nd reason was esthetics.

Canaboo

FWIW there are plant based epoxy resins that claim to be much more natural than the other varieties.
At some point when making a frame you have to let go any "go green, save the world mentality".
All the bamboo frames in the world probably hardly register in the grand scheme of things when it comes to environmental impact, no matter how they are made.
The idea should be more along the lines of making something like a fine guitar or violin that is never going to be intentionally tossed in a landfill.

jroots

Grew up building my own boards and glassing my own fins here on the coast. When you've been around epoxy for a good part of your life you can recognized the difference in resin that are bio-derived. The guys at Entropy are pretty progressive in the natural resin area - they've got it down to 66% pine based resin for and you can definite feel the difference when you're glassing with those. As far as natural fibers go - I'd put hemp up there with bamboo in bio sequestration... plus that stuff just looks amazing when you finish it. Check out the joint finish jobs from Calfee and Stalk, those things are beautiful.

cbchess

Bump- I think I will build a second Bamboo frame as the weather warms up here on the East coast. I've got a set of IRON bamboo poles that have been stabilizing for over a year now. Still using Aero Marine epoxy and this time I've got some Fiberglass cloth tape , carbon tape and Kevlar tape. I've also got some scrap pieces of woven Carbon fiber cloth that I might try to use. Just need to set up my jig again. I've got a nice donor frame a voodoo steel frame with some sliding dropouts.

cameronbrown

Here is a write-up I did about how to build one: https://www.cameronbrown.ca/blog/2013...final-touches/

Dancingbear

I agree with most of the other comments regarding adequate saturation of the fibers, but the other observation that stood out to me is fiber orientation. Strength of most reinforcing fibers is best utilized in tension. It appears that the bulk of your lay-up had fiber orientation that ran more parallel to the miters than spanning the miters. Your joint relied on the strength of just the epoxy, not the composite.

MassiveD

+1, the fibers have to cross the joint or there aren't doing much of anything to tie the joint together. 45 degree angle reduces strength to 70%. So alignment is key. The problem is that given the angles it can be hard to get the flibers to lie down well at the tight angles. The hoop wraps are mainly just there to consolodate the underlying linear fibers. If you were making glass tubes, the hoop fibers would have substantial effect in creating toughness in crush resistance in the tubes, but since the bamboo tubes are already tough and well metered, there isn't as much call for that. If I wanted the hemp look, I would use glass or carbon tow under a neat hoop of hemp twine.

Aeromarine epoxy is not all that high end. WEST is the gold standard here, and there are others of similar quality, but WEST is well distributed. You want a hard epoxy to match the qualities of something like carbon tow, or even glass tow. There is a lot of nonsense spouted about flexibility, If flexibility was such a good idea you could use rubber bands in place of the carbon. The higher you go up in fiber grade, the more you need to match it with hardness in epoxy. Post curing the joints with heat will help a lot, but it might be difficult to pull off without cracking the boo.

That hemp noodle looks really unruly to work with, it will have a terrible resin to fiber ratio, and it looks like it doesn't even want to saturate with the epoxy. And as has been said the fiber orientation is a mess.

Bamboo is strong for what it is, but it takes a relatively small amount of composite to replace it's strength, so the emphasis should be on making clean working joints with good load paths (smooth, tight, etc...) Rather than just shooting a pile of stuff at it. In order to get good runs of material, the joints should have clean radiuses built with epoxy fillets. Ideally, one can get these radiuses in with wet epoxy, and build all the layers above it with fiber in the same wet. But sometimes that is not possible.

unterhausen

I suspect the OP has figured out his technique over the last 2 years, or at least moved on to other projects

fietsbob

Panda Attacks?

cameronbrown

If you ride one of these you always need to be on the lookout for a roving panda attack

aprhockey

Sorry, I had no idea this thread got bumped. I've been absent for a long time.

You're right. I didn't really know what I was doing at this stage. As you guys have pointed out, I did not orient the fibers in any particular direction.

This is the frame I'm currently riding and have been riding for about a year exactly to this date.


This frame was built with fiberglass tape and roving died with some pigment to give it a smokey gray color. So far this frame has been much better than my previous 2, however, it still has some flaws. I did not protect it well enough. Using regular exterior varnish from Home Depot didn't last through the winter in Montreal. Gravel and salt wore down the varnish real quick under the downtube and otherwise just didn't put enough layers of varnish. Besides that, the frame is a little too flexible for my liking. I have it set up as a fixed gear with front brake. The torsional rigidity about the headtube is too low. However, that may be amplified by the relatively cheap carbon fork that I have on it. I'm used to riding with steel forks.

I have since abandoned the fiberglass route to an extent. It is very labor intensive and sanding fiberglass is not a fun experience. I am now experimenting with a mix of fiberglass tape, carbon tape, and carbon 2x2 twill fabric. I am also using a vacuum bagging system to compress the joints and squeeze out excess epoxy. This was the most recent completed frame.


The time it took to complete the most recent bike was roughly 35 hours compared to roughly 50 for the bike I am currently riding.

unterhausen

thanks for showing us your progress, that looks great

Canaboo

Those look great. It's best to use the modern wooden boat treatment on bamboo for ultimate protection through Canadian winters. 2-3 coats of Epoxy with a thinned first coat and then knock the shine off and coat with a catalyzed polyurethane finish. I have a first frame that has survived four Toronto winters with just the Epoxy coating.
It's a big difference maker to limit moisture cycling through the bamboo which is very hygroscopic.
Here's a frame that is Epoxy coated:

squirtdad

pandas eat bamboo

fietsbob

Watch out if a Panda takes the drive-through window,. they Eat , Shoots, and Leaves..