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Wednesday, March 17, 2010
Tuesday, March 2, 2010
Before you get started
There are a few things you should know before you get started.
1) Although likely better than metals in some ways this process uses a fair amount of toxic chemicals (epoxy). There really is no avoiding it, epoxy is nasty stuff. I look forward to hearing from folks trying to use epoxy alternatives.
2) It going to take a long time, but as long as you like longer projects it will keep you content and busy for at least a few weeks.
3) You need a lot of space and a room that can be filled with dust and filings etc.
4) I am still working on my frame, this is a bit of trial and error but I will let you know if something didn't work and how you could avoid it. Also if you want to contribute feel free.
Unfortunately the blog format doesn't lend itself to this project, but its what Ive got for now.
1) Although likely better than metals in some ways this process uses a fair amount of toxic chemicals (epoxy). There really is no avoiding it, epoxy is nasty stuff. I look forward to hearing from folks trying to use epoxy alternatives.
2) It going to take a long time, but as long as you like longer projects it will keep you content and busy for at least a few weeks.
3) You need a lot of space and a room that can be filled with dust and filings etc.
4) I am still working on my frame, this is a bit of trial and error but I will let you know if something didn't work and how you could avoid it. Also if you want to contribute feel free.
Unfortunately the blog format doesn't lend itself to this project, but its what Ive got for now.
Sunday, February 28, 2010
5) Tacking it together....
Front Triangle
As you miter your going to want to start tacking the frame together.
Here is the order that I used:
1) Seat tube to bottom bracket. Be careful that you account for the natural bends in the bamboo in this case I allowed it to natural bend slightly backwards towards the rear wheel. Make sure to sand the metal and bamboo parts. Apply a thin layer of epoxy to the metal, let it dry and then sand before attaching the tube. For the bamboo sand till dull and then rub with a small amount of acetone (or acetone alternative) 15 mins before bonding, see materials blog for more info. Also, during this whole process make sure that you are using a respirator w/ an organic vapor filter. If you start getting a headache, its probably just your brain melting.
2) Then I mounted the head tube in the jig and mitered the top tube into place. Again this is where having a frame to copy comes in handy you can hold it up to compare angles, heights etc. When tacking the joints use more epoxy than you think necessary, add microfiber filler to thicken so it doesn't just run off. It also likely helps to wet down the inside of the mitered joint to help adhesion. Add more epoxy than shown above, cover the whole mitered area if you can.
One nice thing about this jig design is the ability to microtune it. The picture above shows me dialing in the correct angle, making sure everything is straight.
3) Next step was the down tube. I started by mitering the bottom bracket joint first. When that was set I slowly mitered down (using sand paper laid on top of a wide pole, see mitering post) the head tube - bottom tube joint. This worked quiet well because it allowed me to get the angled miter to the head tube correct, since the bottom bracket miter can swivel.Rear Triangle
4) Next is was the chain stays. Things to keep in mind. Seems obvious but its worth mentioning. You need your wheel on straight. There is probably a better method but here is what I did. First I drew a straight line from the middle of the bottom bracket to the middle of where the hub will be. I hung a straight piece of metal from the carriage bolt (shown below... its a hacksaw blade). I then measured the hub spacing from my metal frame and fixed that distance on between the washers and centered the hacksaw blade in the exact measured middle point. This is important because it allows you to eyeball it much easier. Then trust your eye. Make sure everything is inline, including you seat post and head tube.
The hardest part here was mitering and setting the poles in such a confined space. Again use the techniques described in the mitering post on this blog. Be very incremental, small changes make are a big deal here. I tried to keep the joints far out on the bottom bracket to free up extra space for tire clearance. Also always look at each poles characteristics and try to use it to your advantage, use slight bends to free up tire space etc. Also keep in mind that bamboo nodes are the weakest link in you bamboo pole avoid depending on them if possible.
Before you tack your chain stays in place make sure you have enough clearance for you wheel and tire, and also make sure that you have you dropouts set in a place that will allow you to get the correct angle for your seat says. Use a lot of epoxy for this tack because its a long lever arm and its holding up your heavy ass dropouts.NOTE: My intuition is that your epoxy and hemp fiber will not be enough to hold the dropouts in place. For this reason when I tacked the frame together I only applied glue to the hub-side of the dropouts. This keep a nice open hole on the outside which you can better fill with thickened epoxy or fiber/epoxy later.
5) Seatstays
After your epoxy from the chainstays has hardened, you can start touching it again. Here I used the online miter pattern tool and alot of slow progressive sanding to get everything in place. After the upper part of tube was mitered I trimmed, mm by mm, the lower part of the tube till it was flush and striking the right place. Then I applied some epoxy and let it dry.
Next I tacked the dropout side of the seat stay. NOTE: I regret not taking more time to make sure the clearance was good for the rear wheel. Unfortunately I do not think that I will be able to run with a disk brake in the rear any more... just not enough clearance. Also the gear-side chain stay does not have as much clearance for a 9 speed cassette as I had hoped, but it looks like it will work.
The next step was to properly fill the rearmost (dropout side) openings of the seat and chain stays. Here I worked a whole crapload of thickened (mayonaise-like) epoxy into the tubes ( I was trying to fill them as much as possible. You might even consider cramming some hemp fiber down in order to prevent the epoxy from fracturing. Each pair of tubes I used one batch of epoxy as measured by the West System pumps. I believe that this will help to hold the dropouts in place and avoid getting cracks in any of the tubes. I then used my torch to harden the epoxy on the outside and hung the frame from the head tube, thus encouraging the epoxy to work its way back around the dropouts. You can see the slightly burnt epoxy that was holding in the liquid epoxy inside the tube above.
NOTE: I have found after some trial with both that the West System 404, high density filler is easier to work with. It more easily disolves (microfiber filler gets very clumpy but does seem to thicken more rapidly) and should provide better load-bearing properties.
That's it!
2) Choosing your metals...
The bits you need and where to get them...
You need:
1) Bottom Bracket Shell - I went with lugless 68mm english thread - steel
2) Headtube - 36mm x 200mm for 1 1/8" threadless headset - steel
Alternatively you can look at the miter posting on this blog and find a description of how to make a hemp fiber headtube.
3) Some kind of seat tube or seat tube shim. I went with a seat tube 28 x 9/6 x 650 mm
This however is a problem left unsolved. I haven't yet gotten to the point where I need to attach a seat. So either I will keep a long bamboo tube and fit a seat directly to that, or I will ream out my bamboo seat tube and sink the metal on into it (this is probably preferable since the seat tube takes a huge portion of you weight and the strain from peddling). I would not recommend sinking the actual seat post directly into the bamboo and then clamping it. This would likely crack you bamboo...
4) Dropouts - I would recommend something like this. Although Im not of fan of track style dropouts but what you are looking for is longer arms so that you have more room for error. Also keep in mind that each bottom bracket has its own fixed angle...
5) Any add-ons you might want, water bottle bosses, cable guides
Where to get it:
There are a number of bike building suppliers (here's a good list).
Material types
Aluminum - its light its cheap and you can get it off your old jalopy bike. Which is handy. The only problem is that aluminum apparently requires special chemical preparation for bonding with epoxy, or at least I read that somewhere. You should be able to find out more from the West Systems site. "Sand and prepare with 860 Aluminum Etch Kit."
Steel - sure its harder to come by but you can always buy it. Steel is more pliable, which could come in handy, and does require anything more than a good sanding to join with epoxy. I have been having a bit of trouble with the epoxy bonding to the surface of steel so I looked at the west systems site. Here is what they say to do: "Remove contamination, sand or grind to bright metal, coat with epoxy then sand fresh epoxy into surface. Re-coat or bond after first coat gels." So I guess I wasn't doing it right.
Some Notes On bonding:
Surface prep can't be overlooked. It is critical that all the surfaces bond properly together.
Since bamboo is an waxy wood you need to make sure that you both attempt to sand down the poles where you will be bonding them until the dull brown fibers are exposed. Believe me the epoxy does not bond well with a waxy surface. You then need to strip the surface further with a strong solvent. West systems suggests using acetone, this stuff is toxic as hell so use it outside and with your respirator if you have to. Apply and attempt to remove any extra wax 15 mins before applying epoxy. One alternative is biosolve by mas epoxy. This stuff is much better over environmentally.
Bonding:
Applying fabric:
You need:
1) Bottom Bracket Shell - I went with lugless 68mm english thread - steel
2) Headtube - 36mm x 200mm for 1 1/8" threadless headset - steel
Alternatively you can look at the miter posting on this blog and find a description of how to make a hemp fiber headtube.
3) Some kind of seat tube or seat tube shim. I went with a seat tube 28 x 9/6 x 650 mm
This however is a problem left unsolved. I haven't yet gotten to the point where I need to attach a seat. So either I will keep a long bamboo tube and fit a seat directly to that, or I will ream out my bamboo seat tube and sink the metal on into it (this is probably preferable since the seat tube takes a huge portion of you weight and the strain from peddling). I would not recommend sinking the actual seat post directly into the bamboo and then clamping it. This would likely crack you bamboo...
4) Dropouts - I would recommend something like this. Although Im not of fan of track style dropouts but what you are looking for is longer arms so that you have more room for error. Also keep in mind that each bottom bracket has its own fixed angle...
5) Any add-ons you might want, water bottle bosses, cable guides
Where to get it:
There are a number of bike building suppliers (here's a good list).
Material types
Aluminum - its light its cheap and you can get it off your old jalopy bike. Which is handy. The only problem is that aluminum apparently requires special chemical preparation for bonding with epoxy, or at least I read that somewhere. You should be able to find out more from the West Systems site. "Sand and prepare with 860 Aluminum Etch Kit."
Steel - sure its harder to come by but you can always buy it. Steel is more pliable, which could come in handy, and does require anything more than a good sanding to join with epoxy. I have been having a bit of trouble with the epoxy bonding to the surface of steel so I looked at the west systems site. Here is what they say to do: "Remove contamination, sand or grind to bright metal, coat with epoxy then sand fresh epoxy into surface. Re-coat or bond after first coat gels." So I guess I wasn't doing it right.
Some Notes On bonding:
Surface prep can't be overlooked. It is critical that all the surfaces bond properly together.
Since bamboo is an waxy wood you need to make sure that you both attempt to sand down the poles where you will be bonding them until the dull brown fibers are exposed. Believe me the epoxy does not bond well with a waxy surface. You then need to strip the surface further with a strong solvent. West systems suggests using acetone, this stuff is toxic as hell so use it outside and with your respirator if you have to. Apply and attempt to remove any extra wax 15 mins before applying epoxy. One alternative is biosolve by mas epoxy. This stuff is much better over environmentally.
Bonding:
Applying fabric:
Saturday, February 27, 2010
4) Mitering and such
Method
Give yourself a lot of room for error. Cut poles so you have at least an 1" to an 2" on each side, just in case. Mitering should be incremental, not an all-in wager. You can use this really handy online tool to help you get the pattern right. Make sure you read the instructions below the tool though. Diameter 1 refers to the piece you are mitering, and diameter 2 refers to the tube you want to fit it too. Make sure you check the angles too. Keep in mind since bamboo isn't perfectly round, this tool just helps as a general guide.
Pattern from mitering online tool.
Use your tungsten cutter, I find that trimming at a hard angle from the inside allows you to make smooth cuts (in first picture). Then I suggest slowly shortening the poles using sanding paper and a similar sized pole (below). This will create a nice fit with a lot of surface area for the glue.
Tip! If you over do it and cut something too short your in luck. Sure its not the best solution but it works well enough. Mix some epoxy and then add West System's 403 microfibers or 404 High density filler to the mix. This allows you to rebuild a bit of the tubing and re-miter it.
Tip two! Remember the nodes on the bamboo are the weakest link (although they look the strongest). Read about bamboo issues here.
Long-armed protractor-like thing
for checking your angles
they sell a cheap flexible plastic one
at Home Depot
6) Making a joint... for a bike you dope
Making a strong joint isn't too hard, but making a good looking one is surprisingly easy. With a little extra work you can have a good looking, calfee-esk bike.
Above a shaped joint waiting to get a top-coat.
My first experiment....
Materials:
1) Hemp fiber - loose and hemp fabric (optional) or use cord/belt (like at Evolve bikes)
2) West system epoxy - w. fast hardener
3) West systems products like cups and application sticks are useful b/c they are reusable
4) Sander
5) Dremel - with tungsten cutter, tubular sanding disk
6) Respirator w. organic vapor filter (just use it, if you start getting a headache... its brain damage)
7) Spring loaded rubber tipped metal clamps (shown below)
8) Heavy duty rubber gloves (disposables get stuck and rip easily)
9) Perforated roll of electrical tape (take a small drill bit and drill a bunch of holes into it while its on the cardboard roll)
Method:
Take some hemp fiber carefully make a 1 and 1/2" wide strip of it. Keep in mind that you want a consistent layer of this stuff, so make it even. Lightly roll it in your hands to make a very loose rope like product. Although making a tight rope seems appealing it is not. For two reasons, first you want as much overlap between fibers to make a strong bond, and second, with a tighter rope it is difficult to get proper coverage. Wrap one layer of this where you want it and pin it with a clamp. You can also use a glue gun to pin down the end of the rope. Then mix your epoxy and apply until you think you have just saturated the hemp.
The metal clamp... very handy.
You can use a hitch to finish up the end of a rope or you can use it to switch the direction of your wrap.
Above I used a piece of pipe insulation to try to keep epoxy out of the treads of the bottom bracket. Not sure if it worked yet. If I don't come back to complain, assume it worked.
NOTE: the pipe insulation worked Ok, not great. Tips for next time. Try rubbing some of your bike grease on the threads first. Then shove some pencils or something into the pipe insulation (try to overstuff it, it will expand a bit into the threads, thus keeping the epoxy out).
It is important to not put too much epoxy (reduced tensile strength) but not too little either. I add epoxy up to the point where compression with my applicator stick pushes up a small amount of epoxy from the surface. Make sure that work it into all the nooks etc. As with many other composite materials (such as reinforced concrete), the two materials act together, each overcoming the deficits of the other. Whereas the plastic resins are strong in compressive loading and relatively weak in tensile strength, the hemp fibers are strong in tension but have no strength against compression. Try a practice one to get a feel for it.
Now to reduce the amount of epoxy and to compress the fiber, wrap the area with the perforated electrical tape (sticky side out). I try to pull as tight as I can without breaking the tape. Wipe off the excess resin as you go. After the tape is applied, I massage the area, in an attempt to work the epoxy deeper into the fibers and to remove any excess. Here's an example. Let it set. Oddly enough the epoxy doesn't stick to the tape too much. Take it off well after the epoxy is no longer sticky to the touch, after 1-1 1/2 hours depending on how hot and dry the area you are working in is (epoxy sets much quicker in high temps). It doesn't matter if you let it set over night either. You will be able to remove it relatively easily. Just make sure to sand it before applying more epoxy.
Here is the first application. The next 2 layers I will concentrate more on the aesthetics. Add more layers progressively until you think you have added too much.
Now take your dremel and sander/sandpaper and have at it! The mini tubular sanding disks for the dremel work extraordinarily well, to get a very even surface a normal sander comes in handy too. Try them out you will be surprised. It will save about three years of your life. Get one you wont regret it. You can shape the joint down to a nice looking calfee-esk thing in a few minutes. Depending on your likes you might want to add a polish coat of epoxy to clean it up nice. NOTE: If you build the joint out to the waxy part of your poles (the unsanded part) you can easily cut away excess resin with a razor. This allows you to make a nice clean edge between your joint and the bamboo. This sharp edge can then be shaped using your dremel sander.
Note: If you want to go with the black joint look on some of the calfee bikes I believe he uses an outer layer of thickened epoxy (404 high-density filler) with graphite additive. See below for more info.
An example of a good sanding job and an ok mitering...
Interpreting Calfee Techniques
Surely the best builder in the field is Calfee. Here are my thoughts. First it looks like he is using a graphite additive here from west systems to get that nice dark look. Second I interpret his use of epoxy here as a plug. You build up the bottom bracket arm so that it is level with your tubes using thickened epoxy (additives from west systems) or using your fiber/epoxy mix. This plug will take most of the force off of the bamboo and put it directly onto the metal arms. Then its just a matter of building it up some more and then sanding the hell out of it until you have a pretty looking thing. From the picture below we can see that you need to think about the shortcomings of bamboo also. Since he is using a disk brake here he knows that additional force will be placed on the chain stay on that side. So he builds out some extra support for it.
Fun projects
It is also possible to make tubes out of this stuff. Here is an experimental head tube. I used pipe insulation as a mold (with wood pole through it to keep it straight). They I applied wetted hemp fabric to make the inside of the tube and then used the loose fiber for the rest. You can set a headset in this thing and Im pretty sure it legit. Although I should say that calfee seems to use alot of metal components.
Attempting to make a seat out of hemp fabric. Planning to treat the canvas cloth like carbon fiber. Multiple layers of canvas layered on at different angles to increase strength.
Above a shaped joint waiting to get a top-coat.
My first experiment....
Materials:
1) Hemp fiber - loose and hemp fabric (optional) or use cord/belt (like at Evolve bikes)
2) West system epoxy - w. fast hardener
3) West systems products like cups and application sticks are useful b/c they are reusable
4) Sander
5) Dremel - with tungsten cutter, tubular sanding disk
6) Respirator w. organic vapor filter (just use it, if you start getting a headache... its brain damage)
7) Spring loaded rubber tipped metal clamps (shown below)
8) Heavy duty rubber gloves (disposables get stuck and rip easily)
9) Perforated roll of electrical tape (take a small drill bit and drill a bunch of holes into it while its on the cardboard roll)
Method:
Take some hemp fiber carefully make a 1 and 1/2" wide strip of it. Keep in mind that you want a consistent layer of this stuff, so make it even. Lightly roll it in your hands to make a very loose rope like product. Although making a tight rope seems appealing it is not. For two reasons, first you want as much overlap between fibers to make a strong bond, and second, with a tighter rope it is difficult to get proper coverage. Wrap one layer of this where you want it and pin it with a clamp. You can also use a glue gun to pin down the end of the rope. Then mix your epoxy and apply until you think you have just saturated the hemp.
The metal clamp... very handy.
You can use a hitch to finish up the end of a rope or you can use it to switch the direction of your wrap.
Above I used a piece of pipe insulation to try to keep epoxy out of the treads of the bottom bracket. Not sure if it worked yet. If I don't come back to complain, assume it worked.NOTE: the pipe insulation worked Ok, not great. Tips for next time. Try rubbing some of your bike grease on the threads first. Then shove some pencils or something into the pipe insulation (try to overstuff it, it will expand a bit into the threads, thus keeping the epoxy out).
It is important to not put too much epoxy (reduced tensile strength) but not too little either. I add epoxy up to the point where compression with my applicator stick pushes up a small amount of epoxy from the surface. Make sure that work it into all the nooks etc. As with many other composite materials (such as reinforced concrete), the two materials act together, each overcoming the deficits of the other. Whereas the plastic resins are strong in compressive loading and relatively weak in tensile strength, the hemp fibers are strong in tension but have no strength against compression. Try a practice one to get a feel for it.
Now to reduce the amount of epoxy and to compress the fiber, wrap the area with the perforated electrical tape (sticky side out). I try to pull as tight as I can without breaking the tape. Wipe off the excess resin as you go. After the tape is applied, I massage the area, in an attempt to work the epoxy deeper into the fibers and to remove any excess. Here's an example. Let it set. Oddly enough the epoxy doesn't stick to the tape too much. Take it off well after the epoxy is no longer sticky to the touch, after 1-1 1/2 hours depending on how hot and dry the area you are working in is (epoxy sets much quicker in high temps). It doesn't matter if you let it set over night either. You will be able to remove it relatively easily. Just make sure to sand it before applying more epoxy.
Here is the first application. The next 2 layers I will concentrate more on the aesthetics. Add more layers progressively until you think you have added too much. 
Now take your dremel and sander/sandpaper and have at it! The mini tubular sanding disks for the dremel work extraordinarily well, to get a very even surface a normal sander comes in handy too. Try them out you will be surprised. It will save about three years of your life. Get one you wont regret it. You can shape the joint down to a nice looking calfee-esk thing in a few minutes. Depending on your likes you might want to add a polish coat of epoxy to clean it up nice. NOTE: If you build the joint out to the waxy part of your poles (the unsanded part) you can easily cut away excess resin with a razor. This allows you to make a nice clean edge between your joint and the bamboo. This sharp edge can then be shaped using your dremel sander.Note: If you want to go with the black joint look on some of the calfee bikes I believe he uses an outer layer of thickened epoxy (404 high-density filler) with graphite additive. See below for more info.
An example of a good sanding job and an ok mitering...
Interpreting Calfee Techniques
Surely the best builder in the field is Calfee. Here are my thoughts. First it looks like he is using a graphite additive here from west systems to get that nice dark look. Second I interpret his use of epoxy here as a plug. You build up the bottom bracket arm so that it is level with your tubes using thickened epoxy (additives from west systems) or using your fiber/epoxy mix. This plug will take most of the force off of the bamboo and put it directly onto the metal arms. Then its just a matter of building it up some more and then sanding the hell out of it until you have a pretty looking thing. From the picture below we can see that you need to think about the shortcomings of bamboo also. Since he is using a disk brake here he knows that additional force will be placed on the chain stay on that side. So he builds out some extra support for it.
Fun projects
It is also possible to make tubes out of this stuff. Here is an experimental head tube. I used pipe insulation as a mold (with wood pole through it to keep it straight). They I applied wetted hemp fabric to make the inside of the tube and then used the loose fiber for the rest. You can set a headset in this thing and Im pretty sure it legit. Although I should say that calfee seems to use alot of metal components.
Attempting to make a seat out of hemp fabric. Planning to treat the canvas cloth like carbon fiber. Multiple layers of canvas layered on at different angles to increase strength.
3) Building a Jig
Getting Jiggy with it...
Unfortunately, although my jig has many nice qualities, ended up being a bit of a bear. But here is what I did and I will try to make comments on what I would change for next time.
Oddly enough I would say my biggest problem was not starting with a straight line. I would suggest starting with a long straight line on the floor board and orient everything around that. I would also suggest using a frame as a template. It can be surprisingly complicated to design your own bike. Although tools are available like bikecad online. Don't ask me how to use it though.
The hardware I use are long carriage bolts (4" or so), nuts, large washers, and pipe clamps. I retrofitted the carriage bolts onto the pipe clamps by cutting out some of the rungs with my dremel and tungsten cutter #9903 1/8". (This thing rocks you NEED one not optional unless you want to build your bike out of sweat.
Things I learned:
1) Keep things straight
2) Orient the bike in the jig using the carriage bolts, not the jig around the bike. (this is particularly important for the rear triangle, which is a pain)
3) Glue and PVC dont work well together. Instead fix the joints using some screws.
4) You might do better tacking together the front triangle using a flat surface and a large piece of paper and an outline of your bike.
5) Mitering properly is hard when things are in your jig
6) It would have been nice if I could have integrated my actual rear wheel into the jig setup, this would allow me to get all the clearance I needed around the rear triangle.
Unfortunately, although my jig has many nice qualities, ended up being a bit of a bear. But here is what I did and I will try to make comments on what I would change for next time.
Oddly enough I would say my biggest problem was not starting with a straight line. I would suggest starting with a long straight line on the floor board and orient everything around that. I would also suggest using a frame as a template. It can be surprisingly complicated to design your own bike. Although tools are available like bikecad online. Don't ask me how to use it though.
The hardware I use are long carriage bolts (4" or so), nuts, large washers, and pipe clamps. I retrofitted the carriage bolts onto the pipe clamps by cutting out some of the rungs with my dremel and tungsten cutter #9903 1/8". (This thing rocks you NEED one not optional unless you want to build your bike out of sweat.
Things I learned:
1) Keep things straight
2) Orient the bike in the jig using the carriage bolts, not the jig around the bike. (this is particularly important for the rear triangle, which is a pain)
3) Glue and PVC dont work well together. Instead fix the joints using some screws.
4) You might do better tacking together the front triangle using a flat surface and a large piece of paper and an outline of your bike.
5) Mitering properly is hard when things are in your jig
6) It would have been nice if I could have integrated my actual rear wheel into the jig setup, this would allow me to get all the clearance I needed around the rear triangle.
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