Framebuilders - Bamboo question..

I've got some very nice large diameter bamboo, was already fairly well aged, I am however heat treating it to get some final shrinkage/darker coloring, rather then going with the torch I'm using the oven method, from everything I've read/seen I would have thought they'd only need one cooking, I have a brown but it's nowhere near as dark as anyone elses I've seen, I'm suspecting it's because I didn't scorch the outside and let it all caramalize at once instead of heating the outside to get the inside, opinions please on if it needs a second round in the oven?

I don't know, structurally - but it sounds very tasty!

KeS

Photos plz. If you have baked your tubes once and still want the tubes to get darker... try using a wood stain/finish on the tubes. I'm not a builder but i want to say that burning and baking is prob not a good thing. Stick with the oven method.

pics tomorrow, and I already plan to sand then stain/then coat with epoxy or something similar, going for a black but natural grain bamboo look.

the propane hand torch darkend my bamboo much more than the oven heat treatment did.

the propane hand torch darkend my bamboo much more than the oven heat treatment did.

I'm sure it did, I think I'm happy with the baking results though. I'm curious how you weight tested your bamboo after baking or if you did?, I'm using sawhorses and bodyweight/force myself...

I heat treated most of my smaller tubes in the oven. I had mostly pre-cut these to be Chainstays and Seatstays. The bigger tubes for the main triangle I cured with the hand torch. After the heat curing I put all the bamboo in my bamboo drying house for 4 months or so (my sons tree house). So as for a strength test comparison of torch to oven, it would be an apples to oranges test. They all seem WAY stronger than the green fresh cut stuff. I just built my table jig this weekend and glued my seat post steel insert into the top of my seat tube.

Ahh okay, very cool but I think I got lucky I found a bamboo wholesale supplier here, who was kind enough to let me into his dried bamboo shed, I'm basically heating for final shrinkage and that's about it! 4 months huh? I see everywhere people only say 3, but I'm thinking your probably on the right track. Oh and I'm doing approximate cuts ahead of time 1-2 inches larger then what I'll final need, I know it's a bit overkill but the dremmel can handle it.

much better to have them too long then you can decide which end to trim to have the best tube.

cbchess
you should really post pics of your progress! You would be the first one here to do so with a bamboo bicycle!
I'm sure im not the only one that is interested!!!

cbchess
you should really post pics of your progress! You would be the first one here to do so with a bamboo bicycle!
I'm sure im not the only one that is interested!!!

You would be incorrect sir http://www.bikeforums.net/showthread.php/596392-Bambooo!?highlight=bamboo+bicycle+build enjoy.

I need to take some pictures so I can post them.

yes you do, and I guess I do too.

SweetNess!!! Thanks

Raleighsport,

IMO--Useing a torch is only good on green bamboo. If it's too dry to start or if you singe a spot you will hear a light crackle sound and the tube will have a weak spot. By combing the bamboo with the torch longitudenally, you break the cell walls with pressurized steam which allows the whole piece to dry faster than if you just put it away. The oven does not do this, but it will carmelize the sugars making a more flexabile, harder to split culm. If it's pretty dry to begin with I would be afraid of splitting it by heating it, especially if it's never been heated. The darker color of torched bamboo is partially the carbon on the surface and the depth/darkness is related to how long heat is applied. Mine start green and I torch to a dark chocolate chocolate/coffee brown, when I'm ready to bond (after mitering) I sand the whole thing down with a DA at 220 grit until the "outer brown layer" is gone. I wipe with a tack rag, then I bond; that way there is less hand sanding later and the surface is more absorbent of epoxy. If left in the dark brown state the epoxy will peel right off (which is due to the natural surface wax the plant produces). Here's a few finished shots. 1. my second cruiser 2. composite Direct Mount spacing 3. Mtb frame 4. Road frame seatstay yoke/bridge.

211537211538211539211540

Andy

Andy that bike is gorgeous man gorgeous and so are the other shots! And thank you, you pretty much confirmed everything I was pretty sure of from experimenting. I have some gorgeous baked bamboo now, but I don't plan to use that on my bike (the baking increased the rigidity but, because of the dryness also made it more brittle BIG FLAW) I'm going to go back to the same place though, and select some more predried bamboo and this time just cut/sand/miter. Well not that simple, but stainingoutside then sealing then epoxy and inner foam is kinda my plan.

Make sure you rough up the ends with a coarse file or hand saw to give the bamboo some extra tooth for bonding. I forgot to mention you need to pierce the culm inside the tubes before hand torch curing, or baking or the gas will expand and pop your bamboo.

I tacked together my rear triangle this weekend. you can see you full sized layout and the jig I built right on top of it.

http://farm7.static.flickr.com/6143/5973708107_89d89ab101.jpg (http://www.flickr.com/photos/23773616@N08/5973708107/)
rear frame in jig w flash (http://www.flickr.com/photos/23773616@N08/5973708107/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

Here is a close up of the seat tube and seat stay joint
http://farm7.static.flickr.com/6146/5974268346_b894b24b89.jpg (http://www.flickr.com/photos/23773616@N08/5974268346/)
seatstay seat tube joint (http://www.flickr.com/photos/23773616@N08/5974268346/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr


here you can see the steel seat tube insert. I cut the slot myself.
http://farm7.static.flickr.com/6017/5973708877_7a0e2d2b72.jpg (http://www.flickr.com/photos/23773616@N08/5973708877/)
seat tube (http://www.flickr.com/photos/23773616@N08/5973708877/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

here are a few more:
close up of the dropouts - just tacked in place. These will get full carbon wraps out to the blue tape.
http://farm7.static.flickr.com/6148/5974268102_16929c51cf.jpg (http://www.flickr.com/photos/23773616@N08/5974268102/)
rear dropout close up (http://www.flickr.com/photos/23773616@N08/5974268102/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

Chainstays tacked in place - I mixed sawdust into my epoxy to create a super sturdy filler and joint. This need a bit of shaping before the carbon fiber wrap.

http://farm7.static.flickr.com/6127/5974267978_fe8c8cc71f.jpg (http://www.flickr.com/photos/23773616@N08/5974267978/)
chainstays close up (http://www.flickr.com/photos/23773616@N08/5974267978/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

BB joint close up. My donor frames were a Surly cross check and a bianchi. Both steel.
http://farm7.static.flickr.com/6021/5973708325_04c3129b13.jpg (http://www.flickr.com/photos/23773616@N08/5973708325/)
bb close up (http://www.flickr.com/photos/23773616@N08/5973708325/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr



Here is a frame builders question.
My chainstays are centered but my seat stays are not, due to a deeper miter cut on the overlap joint on the drive side. will this mess any thing up? it is about 1/4 to 1/2" closer on the driveside.

full jig view:
http://farm7.static.flickr.com/6133/5974267146_0861567f1a.jpg (http://www.flickr.com/photos/23773616@N08/5974267146/)
full jig view 2 (http://www.flickr.com/photos/23773616@N08/5974267146/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

head tube waiting for top tube and down tube.
http://farm7.static.flickr.com/6023/5973707531_4b7978a849.jpg (http://www.flickr.com/photos/23773616@N08/5973707531/)
full jig view (http://www.flickr.com/photos/23773616@N08/5973707531/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

good ;)

My wife named my new bike the Ginsu Glider.

Love it! and I really don't know about your question...

http://www.powerfibers.com/PowerFibers_Issue_44.pdf
^^^
One of my other loves are bamboo fly rods. Found a good article in a bamboo fly rod makers trade rag on building a bamboo bike frame.
I go with a different approach with the bottom bracket but it's a good example of a construction process.

great link! the 18 piece bamboo fly rod was impressive.

great link! the 18 piece bamboo fly rod was impressive.

I aspire to build an 18 rod one year.

Powerfibers is one of my favorite sites at the moment.

I must confess one of the reasons I got back into biking was so I could have something to beat on the trails on my way to the river to fish ;) very cool site.

first draft. I need to pull it apart and add more carbon to the head tube joints.219613

SWEET! nice joint wrap with that CF. I was just rereviewing my plans a couple of hours ago, going with hemp instead of CF and just started the new jig! Your bamboo doesn't look like it has any real taper to it, I'm thinking of looking for some that does so I can imitate a more modern bike, but I love yours!

I highly recommend putting something structural in your laminate besides hemp. The Bamboo Bike Studio did destruction testing on hemp lugs and found that they stretch from repeated stresses in the small to medium catagory until the bike gets floppy and the joints fail. I found their info in their blog although I don't know if the info is still available. At the very least it would be beneficial to put some fiberglass in the joints.

It is up to you, but straight hemp lugs will die faster than an aluminum frame. My first one was a hemp lug too. It lasted 6 months and went down the stairs coming back from the hardware store about 1.5 times a week. It broke at the ht/dt joint and is the only bike I've ever owned that had a name. We called it the "spaghetti bike" because it got so floppy. It's really a testament to the resin system I was using that it lasted that long. I've built the other 6 with carbon and I'm pretty sure you could jump them off the house, no problem.

Good Luck.

Andy

I highly recommend putting something structural in your laminate besides hemp. The Bamboo Bike Studio did destruction testing on hemp lugs and found that they stretch from repeated stresses in the small to medium catagory until the bike gets floppy and the joints fail. I found their info in their blog although I don't know if the info is still available. At the very least it would be beneficial to put some fiberglass in the joints.

It is up to you, but straight hemp lugs will die faster than an aluminum frame. My first one was a hemp lug too. It lasted 6 months and went down the stairs coming back from the hardware store about 1.5 times a week. It broke at the ht/dt joint and is the only bike I've ever owned that had a name. We called it the "spaghetti bike" because it got so floppy. It's really a testament to the resin system I was using that it lasted that long. I've built the other 6 with carbon and I'm pretty sure you could jump them off the house, no problem.

Good Luck.

Andy

Thanks for the info Andy, but I was already planning on layering fiberglass as well! I didn't know all that and now I'm very glad I chose what I'm trying...

:thumb:Time to add some more photos!


http://farm7.static.flickr.com/6140/6188509727_f0df7c2957.jpg (http://www.flickr.com/photos/23773616@N08/6188509727/)
rear quarter view (http://www.flickr.com/photos/23773616@N08/6188509727/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

http://farm7.static.flickr.com/6175/6188509615_a97519dcf9.jpg (http://www.flickr.com/photos/23773616@N08/6188509615/)
Frame in stand (http://www.flickr.com/photos/23773616@N08/6188509615/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

http://farm7.static.flickr.com/6177/6189028164_7bdd3956f8.jpg (http://www.flickr.com/photos/23773616@N08/6189028164/)
Front view (http://www.flickr.com/photos/23773616@N08/6189028164/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

http://farm7.static.flickr.com/6143/6189028318_a858ee4598.jpg (http://www.flickr.com/photos/23773616@N08/6189028318/)
Rear disc brake (http://www.flickr.com/photos/23773616@N08/6189028318/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

http://farm7.static.flickr.com/6015/6188509757_7c14045064.jpg (http://www.flickr.com/photos/23773616@N08/6188509757/)
Bottom Bracket detail (http://www.flickr.com/photos/23773616@N08/6188509757/) by cbchess (http://www.flickr.com/people/23773616@N08/), on Flickr

do you plan to sand down your lugs? And again, tell me how it rides after your sure it's safe for a real ride!

Yes I wanted to make sure it rode well before I did my finaly coat. I made the mistake of doing the final coat and then realizing I needed to add more carbon fiber layers. So I've added about 6 more layers and now I need to do a final sanding and gloss coat. I plan on doing somekind of valspar or poly coat on the raw bamboo as well.
Its been raining like crazy since I've built it up, so still waiting to ride it!

...dead head sticker on a cadillac....lol

don't look back... bah and now that songs in my head I almost commented on the deadhead sticker at first too though... and actually it's not bad looking at all, makes me think my jolly roger decal set might not be a terrible idea...

A lot more can be done with hemp or flax without just putting a gob of random fibers around the lug like the BBS used to do.
Their lugs were more likely failing because of lack of sufficient orientation of the fibers.
No matter what fiber choice you use an underlay of cloth in the chosen fiber makes more sense than just straight wrapping.
Unidirectional carbon cloth layed along the lines of the tubing and spanning the miter joints before wrapping goes a long way towards lasting lug integrity.
You can buy high grade Linen artist's canvas as an underlay for a natural fiber lug.
The source of your natural fiber is very important also. The way the fibers are grown and processed are crucial to the strength.
Keep in mind that modern phenolics used in very high stress areas are often based on Cotton or linen canvas or even paper in a resin binder.

A lot more can be done with hemp or flax without just putting a gob of random fibers around the lug like the BBS used to do.
Their lugs were more likely failing because of lack of sufficient orientation of the fibers.
No matter what fiber choice you use an underlay of cloth in the chosen fiber makes more sense than just straight wrapping.
Unidirectional carbon cloth layed along the lines of the tubing and spanning the miter joints before wrapping goes a long way towards lasting lug integrity.
You can buy high grade Linen artist's canvas as an underlay for a natural fiber lug.
The source of your natural fiber is very important also. The way the fibers are grown and processed are crucial to the strength.
Keep in mind that modern phenolics used in very high stress areas are often based on Cotton or linen canvas or even paper in a resin binder.

I agree that fiber orientation is all important in a composite layup schedule. The "chop" method is borderline stupid. I've tried laying the hemp in using the orientation you describe for carbon and then over wrapping that as one would with tow, and it worked for a while. That said, I've been using hemp cord, string, cloth and raw fiber for various things for about 10 years now and the problem with the hemp is that it stretches under heavy impact and then doesn't recover. Over time the bike (or whatever) turns floppy, or fits loosely, etc. It is simply not the best option for structural applications. I use hemp as an overlay (money layer) over a carbon structural layup.

I guess I should add that the BBS tests tested 5 different layups (if memory serves) and experienced failure due to repetition in all cases. As a result of the testing they developed the carbon tow method that they use today.

I'm skeptical. Hemp doesn't stretch to that degree and it should be locked in the resin matrix. If the whole system is done properly it shouldn't be possible to apply enough tensile or compressive strength to the lugs to get that type of failure.
Nothing wrong with giving up and taking the easier route if it seems safer though.
A fibre resin matrix has the potential to reach into the 30000 psi range depending on resin choice.
That foam block technique with the matrix over the top looks downright scary.

Hey guys, some of you may remember the thread I created a year or two back about bamboo. Well I'm back and still without a frame, however I will be building one soon. Now the part that may matter to you is that I will be dumping some of my test results and data for the benefit of the community and potentially for the benefit of me (which will hopefully come in the forms of suggestion or ideas).

This morning I heat treated a piece of Moso Bamboo with a propane torch until it became nice and browned. Which I then sectioned and took to my university's microscopy lab where I took some pictures at 40x of some heat treated and non heat treated samples.

Moso Bamboo:
https://lh6.googleusercontent.com/-i8ZzByQsSl4/To-SybfVRhI/AAAAAAAAACQ/PY0rwCm59Mw/s912/1007011203a.jpg

Heat treated cross section at 40x:
https://lh3.googleusercontent.com/-gC-13CjU3n8/To-RbCQDwbI/AAAAAAAAABU/B_FK3EdhoEk/s1024/DSC_0001.JPG
https://lh5.googleusercontent.com/-XAoHVs2Xrvk/To-RciN3ynI/AAAAAAAAABs/DIF1p8elBJY/s1024/DSC_0007.JPG

Note, the little silver bits are actually pieces of metal which got lodged into the bamboo while sanding it to get a better finish for the microscope.

Non Heat treated Moso at 40x:
https://lh6.googleusercontent.com/-6ock0EPNGVo/To-Rfnl83OI/AAAAAAAAAB4/QtL6Aytsauo/s1024/DSC_0010.JPG
https://lh4.googleusercontent.com/-iHTXvACC4so/To-RhBOwBrI/AAAAAAAAACI/2heX5jhM9S8/s1024/DSC_0014.JPG


If anyone has any questions or concerns please let me know and I'll do my best to address them as quickly and accurately as possible.

Canaboo

An epoxy matrix is about 95% mechanical bond, hemp is full of natural oils especially the raw hemp fiber (that I used). I shouldn't need to state this but, you know that smell when you open the bag, that's the oils making that smell.

As a result of these 2 facts you can safely assume that hemp will never be fully adhered to the epoxy matrix. It can move within the matrix. I'll offer you an easy tensile test as well. Take one strand of hemp and pull it apart with your hands. It's not easy but you can do it, or at least I can. Now take 1 strand of carbon fiber and try the same thing. The carbon strand should cut your fingers off before it breaks. It also has nothing on it to inhibit the bond.

Trust me, I wanted hemp to work, I used to own/operate a head/hemp shop in the Keys and I really wanted hemp to work, which is why I use it as a money layer. No one wants it to be functional in this regard more than me.

It simply is not suitable for advanced composites as stand alone structure.

That said...do whatever you want. If you have some magic touch and it works for you sweet. If I were doing that though, I would expect to be doing a lot of warranty work.

Andy

Before using any natural fiber I wash it several times with a degreasing solution and rinse it with acetone after a final drying. That greatly enhances the bond.
Just poppiing open a bag of natural fibres that you have no idea of how it's been handled and processed is likely a poor recipe for a lasting bond.
Having said that I don't actually use hemp in particular for the reasons you state. Linen is much cleaner and just as strong. There are several other choices that glue much better with less effort at cleaning them first. Abaca, Coir, Ramie etc.
Linen in particular is used in some pretty advanced high pressure situation composites.
So is cotton canvas.
It can be done.

Touche'

Right on. I'm just explaining why from my point of view it has a high chance of failure. The resin system I use (Mas) directs against using acetone for prep (with any surface). There are obviously other resin systems for which it is fine (goujon, sp, etc). It's funny because I feel like there are many different ways of making the same part, and none of them are necessarily wrong. Take your earlier statement about not trusting foam, As a professional laminator nearly every part I've ever made has had a core material involved (I like Divinycell H80). The foam they use is bad news in less than the 10# density, although I don't know the weight of their foam. We just work differently and it sounds to me like you've done your homework and research and simply came to a different conclusion than I did. Respect.

Andy

I'm not saying foam composites aren't a good idea I would just want to "make" the foam around the lugs rather than inserting the bamboo into the foam blocks.
By "make" I mean glue the bamboo with miter joints and then make a fillet joint with micro-baloons or mlled fibre of some sort so there is a considerable amount of structural integrity and then lay the reinforcement on top of that.
The acetone warning that many Epoxy manufacturers cauition against using may be referring to the typical re-claimed acetone that is readily available. That can be contaminated with several other substances, oils in particular that will interfere with a bond.
It is possible to get "virgin acetone" from Aircraft Spruce that doesn't have this problem. You could check with MAS and see if that is a possibility.

bump
I wanted this thread back on the first page. I got a new batch of bamboo for my next frame. This new stuff is MUCH thicker in the walls of the tubes and should make a much better frame. The first stuff I used, I cut myself from a neighbors yard. I have noticed tha it is some of the smallest bambo growing around here. I think I mistakenly picked some of the most flexible bambo possible.

The new stuff is super thick and should be nice and stiff.

I also got a bunch of 2" carbon fiber tape - woven carbon fiber cloth. This will help strengthen my joints a lot more than just plain carbon tow of my first frame. I also got some 2" Kevlar tape a bit cheaper than the carbon tape.
The carbo and Kevlar tape is not sticky, it is just is called tape. The stuff I got is 2" wide and woven in a 90* pattern.

bump
I wanted this thread back on the first page. I got a new batch of bamboo for my next frame. This new stuff is MUCH thicker in the walls of the tubes and should make a much better frame. The first stuff I used, I cut myself from a neighbors yard. I have noticed tha it is some of the smallest bambo growing around here. I think I mistakenly picked some of the most flexible bambo possible.

The new stuff is super thick and should be nice and stiff.

I also got a bunch of 2" carbon fiber tape - woven carbon fiber cloth. This will help strengthen my joints a lot more than just plain carbon tow of my first frame. I also got some 2" Kevlar tape a bit cheaper than the carbon tape.
The carbo and Kevlar tape is not sticky, it is just is called tape. The stuff I got is 2" wide and woven in a 90* pattern.
On that note another *bump* and an update, I'm going to do some experimenting with the oven method and cutting up a frame this weekend then tacking it up and seeing if I can get it anywhere near correct alignment. If that works out well enough, I'll have to order my first batch of epoxy.

How are you guys bonding the metal components to the bamboo? I work with glass/epoxy for high performance sail boats and am bamboo Bike frame curious. Was hoping to one day attend the B.BikeStudio build sessions and see first hand how it goes. Wanted a hybrid frame with disc brakes, IGH & CarbonBelt drive. They did not have their frame & component design ready for all that yet.

How are you guys bonding the metal components to the bamboo? I work with glass/epoxy for high performance sail boats and am bamboo Bike frame curious. Was hoping to one day attend the B.BikeStudio build sessions and see first hand how it goes. Wanted a hybrid frame with disc brakes, IGH & CarbonBelt drive. They did not have their frame & component design ready for all that yet.
A miter joint and good metal prep are necesary for the sturdiest lugs. A thickened all purpose Epoxy is best for tacking and forming slight fillets before wrapping.
The BBS is ready for the build you want now.
They don't use miter joints which likely explains the hemp lug failure.

getting closer to build #2

For structural bonding and coving (filleting) toughened epoxy is the best choice. It has more flexibility which helps in failure avoidance. It is also more expensive than a laminating resin and you probably won't use enough in 1 or 2 bikes to justify the purchase.

The second best route (read as cheapest and functional) is adding filler to your laminating resin and using that for bonding and coving. It has it's own pitfalls though. If you use microballoons or q-fill, for example, as your thickening agent you will get a brittle, easily breakable bond and fillet. Most manufacturers will have recommendations for their resins.

I have to back up Canaboo on the prep. Prep is everything when working with epoxy. Different materials require different prep. Once again it is usefull to check with your epoxy manufacturer as they will have tested various methods with various materials and will know the best approach for their epoxy.