Clever Solutions to Stupid Mistakes

#1 Rear Wheel Misalignment
Okay, this is not so much of a clever solution. It's more a stupid solution to a stupid mistake.

The rear wheel must, of course, be mounted with the gears on the correct side of the bike, so it lines up with the gears on the crank set.

Once I did that, my problem went away.

#2 Chinese Crap
This solution is more clever. It turns out that the biggest problem with the bearing set was that the parts had been tightened too much. Once I loosened appropriate nuts, the sensation of riding on a cog railway went away.

Okay, a better solution would be to throw the Chinese crap away and buy real bike parts. This is a poor man's clever solution.

Stupid Mistakes #2

I did it! I bought the kid bikes from which I will harvest the front forks. Walmart kid bikes are much cheaper than buying the parts from even online bike shops, and who knows? I could even put the rear section together with the front wheel from the mountain bike and make a delta trike later.

I got what I paid for, which is Chinese crap. The steering and the axle turn like in place of ball bearings, they have twenty-sided dice. If you apply a little force, they go bump-bump-bump, about 3-4 bumps to go through an eighth of an arc. Swell.

Stupid Mistakes #1

Dang!

Anyone else trying this, learn from my supid mistakes. When attaching the rear fork into the bike frame, do it with the wheel in the fork. I just put the wheel into the fork, and it's all but impossible to keep it from rubbing up against either the bamboo, the brake, or both.

Now I have to cut off the rear fork and put it back on again.

A Place to Sit

The crank is secure. Secure enough that I can sit on the bike, put my feet and the weight of my legs on the pedals, and pedal. The first of many tests.

Which brings me to the place of making a more comfortable place to sit. I have a fine plan to make the seat, two pairs of poles joined at an obtuse angle, and joined by two parallel poles perpendicularly, and a back and seat made of nylon. But the big questions are where to put it, and exactly how wide an angle, and how large must the seat and back be.

I answered the last question by measuring some chairs and the placement of my butt on them. I didn't want to make the seat too large, as I didn't want my pumping legs to chafe agaisnt a seat edge. I want it under by butt, not my legs. I answered the second question by sitting against a board and reclining it to a good angle, then replicating the angle.

I thought the last question would be the easiest, because I could simply put the seat on and secure it. But I find that the placement of the seat is dictated by the placement of the pedals and length of my legs, and I fear that the place dictated is so far forward as to make the bike front-heavy. Depending on the weight of the rear-mounted engine, during a hard stop it could try to do a nice face-plant on the pavement.

I was imagining the only solution would be to cut off the nose and shorten it, but while I was typing it occurred to me it would be far easier, and involve less threat of weakening the structure, to cut off the crossbar and move it forward. Problem solved, thanks for listening.

Splicing in the crank supports

This is a close-up of the joint for the crank support poles. The one that joins to the lower pole is cut on the angle and butted together. A slot is cut in both poles, sufficient to accept a 3/16" ply, which is carefully cut to the precise angle required, making a long, skinny triangle. Epoxy is applied to the edges of the slot and the butt joint, it is assembled and bolted near the joint. A wooden pin (not shown) will be inserted near the points of the triangle. The wire wrapping is to prevent the bamboo from splitting at the cut.

If I do it again, I will cut a slot through both sides of each pole, and have the triangle pass all the way through. As it is, the ply can wiggle slightly inside the poles, and depends on the epoxy to prevent this.

The upper bracing pole is cut on a very careful angle (took me several tries to perfect), and rounded out a bit with the dremel for a firm fit. I also cut into the pole it connects to, so that it can butt up against a solid edge, but not so far as to open the cavity of the pole. I single bolt holds it very firmly, although I will probably add epoxy as an additional measure.

My God! It actually looks like something

Top View

I know it's a little hard to see, with the stray bamboo pieces, and the 2x3 support the tail. It was hard to get a good view on it in the basement. But you can see the rear wheel fork and the crank in place.

Rear Wheel Fork

You can see here the bolts into the bottom side of the rear fork, that connects it to the hardwood dowel that is bolted to the bamboo. The gray line on the steel is epoxy that seals a cut I made when I though I could get the bamboo itself into the steel. Dumb idea. There's a half-circle cut-out in the top bamboo pole that should keep the rear side of the fork from shifting fore-and-aft, and a bolt that holds the fork firmly into the cut-out.

Crank

Not finished yet, there'll be a second support pole connecting to the second top pole of the frame, but here you can see the plan. The crank is sandwiched between curved cut-outs. The support poles cross, and when the last support pole is added I will pin them together, which will prevent them from spreading and releasing the crank. That and a generous amount of epoxy.

The crank is heavy, and reminds me how much weight I am saving using bamboo. I think the crank weighs more than all the bamboo in the frame!

Crank

I cut the crank off of a mountain bike. I now have a cylinder with little metal tube remains pointing in three directions. My plan is to secure it between three short poles with a joint known as a "bird beak," where the poles cross and pinch the cylinder between them. Excellent idea, but execution is difficult, since the poles need to be positioned with some tension. I've tanken the first step:

I cut two slots in one of the poles, that precisely correspond to the edges of the widest tube. Then I epoxied the crank onto the pole. Next I'll attach this pole, then add the others. The epoxy will allow the "unpinched" crank to hang in the air from just one pole.

Metal-bamboo joints

Well, I've finally done it. I've joined bamboo to metal. Someday maybe I'll tell the story of my adventures trying to drill hardened steel, and how I wound up with three 3/16" drill bits. But I slid one end of a 5/8" dowel into a bamboo pole, and the other into the tube of the bike, where it fit snuggly. Drilled twice through both ends. Took it apart, smeared the dowel with JB Weld (epoxy), put it back together and bolted it fast. It's permanently joined, now.

What I actually connected was the rear half of the rear bike triangle with the support poles.

On the Other Hand

Maybe a hacksaw is better. I'm always checking and trying things. Had a tight space where the 1" wide dremel cutting wheel didn't really fit. So I used the metal cutting blade on a keyhole saw and quite easily finished the cut. So for the next tube, I tried the hacksaw, and went faster with less dust.

Caveat: I didn't check the blade before I started, but it was ruined when I was done. 3" of teeth were worn away. If this holds true, I'm going to prefer to go through 2-3 dremel wheels (15c each) rather than 1 hacksaw blade.

The incomparable dremel

I had assumed that I would have to use a hacksaw to cut up the bicycle, and was not relishing the thought of the time spent going ree-ree ree-ree on hardened steel. If a hacksaw could even cut hardened steel. I have a scroll saw with a metal blade, but that was a slow screaming terror when I tried to use it on aluminum.

Behold! The indefatigable dremel cuts through hardened steel using only its ordinary emery board cutter. The cutters wear out fast, but they are working!

Destruction!

Part of my plan includes using bicycle parts. I plan to use the aft section of a bicycle to hold the rear wheel, and the steering hub and fork of two kiddie bikes to hold the fore wheels. I've got the adult bike, so today I started disassembling it. What fun. Had to break the chain to get it off, but I figure I'll have to link two-three chains to deal with the longer length, so, no big deal their. But getting off all the fancy new components (bicycles have changed a lot since I was a kid) was a treat.

Progress

As you can see in the photo below I have added the supports for the third pole so I will have a strong, triple poled frame. I built these braces a little differently than the first, as you can see from the close-up below.
I cut each brace pole on a 30deg angle, and drilled their mortises at a similar angle around the main poles, so that they meet in the middle snuggly. Only one of them required any real trimming to make snug. Then I make three oval holes in the third pole, set it down over these braces, and secure with a single pin through both braces. This oval hole is on the large side. To keep it from getting too large, and weakening the pole, I notched the peak of the braces.

It all worked very nicely. I don't have pictures of the main frame assembled, yet, but it is almost done. Next will come building the support for the front wheels.

Bracing the frame

I've been adding diagonal braces to the frame poles. It took some experimenting to determine the best way to do this, but this is where I settled:

1. I use a mitre saw or coping saw to cut two 45deg cuts opposing each other on the inside of the poles, at each end of each brace. These cuts go down only a 1/16th of an inch, not even enough to go through the bamboo wall.
2. I use a 1/2" chisel to cut out the opening.
3. I use a dremel or rotary cutting tool with the drum sander to shape one side to the shape of the brace pole. The other side, which takes the end of the brace, is kept flat.
4. When I have two good openings like this at the proper places on the two poles, I measure and cut the diagonal brace from 1/2" bamboo.
5. I firmly hold the brace in place, and drill through the frame and brace at a slight angle.
6. I insert a 2" machine screw (bolt) through the hole and bolt it together.

The use of bolts unfortunately adds a noticeable amount of weight, but appears required. I suppose I could mortise this joint as well, and secure with a pin, but drilling at a 45deg anle into the bamboo would be challenging, and there would be complications, such as the difficulty of getting the brace in between the poles, or of passing it through the poles.

The frame is started!

I have constructed the first piece of the frame!

This is the two lower poles that for the main part of the frame, which will make a triangle-beam with a third pole. The 1" bamboo poles are joined by short lengths of 1/2" bamboo, mortised and pinned, as shown in this photo:

The wire is 18 gauge galvanized steel I wrapped around the bamboo to prevent/repair splitting when the snug crosspole is inserted (an issue). The pin is a 3/16" hardwood dowel that prevents the crosspole from coming out.

This entire construction has nothing to do with my plans, and indeed contradicts advice I gave elsewhere: a speedbore can be used successfully on bamboo, if the bamboo is prevented from vibrating with a firm parrallel clamp. I decided to go with this joinery option, thinking that I would use several half-inch bamboos for triangulation anyway. Other sites described this sort of motising as a strong joint, and it appeared to be the simplest and least fussy option. Here I go!

Joinery Experiment

I just tried both the methods listed below (Joinery 2 & 3). For the hanger-bolt joint (joinery 2), I omitted the epoxy, since I hoped to reuse the materials. For the mortise-and-tenon joint (joinery 3) I used a piece of 1/8" ply cut in a modified rectangle for the tenon and bamboo skewers for pins. The modification was essentially a tail, an extention of the rectangle at a width slightly less, so that it could slide inside the cavity of the crosspole, giving more pinning length while requiring the bamboo to be cut less.

Hanger-Bolt Joint
Joining caused splitting of the hardwood dowel, and subsequent stress and splitting of the crosspole. Joint was not square. No problems with compression of the bamboo from the bolt. There was minimal wiggling in the joint, but when I applied pressure the screw of the hanger-bolt pulled out of the dowel, due to its split.

The non-squareness of the joint was likely due to the difficulty I had centering the hole for the screw-side of the hanger-bolt, and making the hole perpendicular. Also, I did not perfect the curvature of the crosspole cut to fit the main pole. The splitting dowel was encouraged because of the difficulty getting a snug fit between the dowel and the bamboo cavity.

Also, screwing in the hanger-bolt is challenging.

Mortise and Tenon Joint
Fitting the mortise-and-tenon to each other was easily done with a dremel. Getting a tight fit was not difficult (the hanger bolt pulls the parts together in the other joint, in this joint this must be done manually). Pins held without glue. The resulting joint was square with minimal wiggling. However, when force was applied, the wiggling gradually increased. Eventually, pins cracked, one failed entirely, and the tenon tail split off.

Conclusions
I like the mortise-and-tenon joint, despite its failures. 1/4" ply and larger diameter pins (bamboo chopsticks? wood dowels?) will improve strength. Epoxy in the joint will not only give adhesion, put will also fill gaps and minimize the wiggling. Triangulating joints will also minimize wiggling. If wiggling can be eliminated, the progressive growth in wiggling should also disappear.

Most important, of course, was the ease with which I was able to get a good-looking joint. Precision is not a strength of mine, so any method that doesn't require me to hold my drill perfectly vertical is a better method.

Bamboo Joinery 3

Here is an alternative joinery technique I just found on the web. It has a number of advantages over the technique I planned in the previous post:

• It doesn't rely on glue anywhere
• It doesn't use expensive hardware (hanger bolts, at 50¢ each, add quickly)
• It doesn't compress the bamboo as a bolt does, something the literature says is not good for bamboo.
• It doesn't require one to make a precise fit between a dowel and the bamboo interior.

On the other hand, it does require one to make a careful joining tenon, to drill the bamboo four times rather than one (which has proven tricky for me), and to fit pins precisely. Here it is:

1. Use a dremel cutting wheel or similar tool to cut a slot in the main pole, the dimensions of the tenon you will make. Make another cut in the end of the cross-pole the length of the tenon.
2. Make a tenon out of plywood the thickness of the slots (mortises) you have just cut. I show above a triangular tenon, which would give more support for bending of the cross-pole, but requires the slot on the main pole to be slightly longer than the joint, leaving it visible. A rectangular tenon, the width of cross-pole, would not have this defect. Insert this tenon into the two mortises and close the joint.
3. Drill four holes through the bamboo and the tenon, making sure that the joint is very tightly closed as you do so. Two holes lengthwise on the crosspole, and two lengthwise on the main pole.
4. Cut four pins and insert into the holes. You may use a weatherproof glue to hold the pins in place. This glue does not hold the joint: no force applied to the joint is resisted by the glue, but it does prevent the pins, that hold the joint, from working loose. What to use for the pins? Smaller-diameter bamboo is recommended. In some applications, bamboo skewers from grocery aisles are all that is needed, and have the advantage of being a consistent size. I think they are too small for my purposes, however.

I neglected to include in this illustration that you ought to first cut the crosspole end into the shape of the bamboo mainpole (see Bamboo Joinery 2, below).

Bamboo Joinery 2

Making a T joint:

1. Cut the end of the side pole into a curve closely fitting the cross-pole, using a coping saw.
2. Take a 1" length of a hardwood dowel that fits snugly into the bamboo cavity, apply a strong, weatherproof glue such as Weldbond Outdoor wood glue, and insert into the end of the side pole.
3. Bore a hole into the dowel in the side pole (use a bit the diameter of the shank of your hanger bolt screw-side) and another through the side of the cross-pole (use a larger bit, the diameter of the threads of the hanger bolt bolt-side).
4. Drive the screw end of the hanger bolt into the dowel, and insert the bolt end into the cross-pole.
5. Secure the bolt with a washer and nut.

Bamboo Joinery

The official way I read about doing bamboo joinery is with bins and hooks and bolts. Say, to make a T-joint, you would put a pin through the stem of the T, bend one end of a threaded rod into a hook, insert the hook into the end of the stem and hook the pin, then put the other end of the threaded rod through a hole bored in the cross bar and secure with a nut.



The problem is, my bamboo is so narrow there is no hook can be inserted into the hollow.

My solution: cut 1" pieces of 1/2" dowel (or other size that fits snuggly inside the bamboo cavity. Glue one piece into each end of the bamboo with a strong, weather-proof adhesive, such as Weldbond's outdoor wood glue. Bore a hole into the butt end of the dowel, and insert a hanger bolt (one of those bolts with a screw on one end and the bolt on the other. Bore a hole through the piece you want to join to it, put the bolt through, and secure with a nut.

This method should be equal to the official in sheer or compression. If pulled apart, the joint is dependent on the strength of the glue. I think I might use an epoxy between the two part, such as JB Weld, to help. This would make two distinct glue joints which each support each other: this chain is as strong as its strongest link.

Simplify

Okay, on second thought, the hole saw doesn't work. Spent $25 on a new hole saw the right size (1"), just rip the bamboo apart.

New approach: the coping saw. I use one of my successful hole saw bamboos as a template, trace it, and cut the next one out by hand. It goes really fast, doesn't require pre-drilling or extension cords, and NEVER splits the bamboo.

Working Bamboo

This is my insightful discovery: bamboo is different than wood.

Bamboo is very strong in terms of bending and load bearing. But let something sharp strike it across the grain, and WATCH OUT!

Bamboo handles like a bundle of silk threads running the length of the pole. It is prone to splitting.

• Don't use a speed bore on bamboo. The moment that spinning blade touches the bamboo, POW! split if not shatter.
• Be careful using a large-bore (3/16"+) drill bit. A very gentle touch works, but push too hard and it splits.
• Predrilling with small bore bits helps. Ironically, the spear point on a speed bore has never caused trouble for me, and I use it to pre-drill. Just have to stop before the blade touches.
• Use small-tooth saws. I used a mitre saw.
• I wouldn't dare nail it.

Don't know if this will work, or if I'm off on the wrong direction. We'll check in again.