Operation: Arbalest - pt1

So, for no other reason than simply because I can, I decided to make a medieval crossbow. Also called an arbalest in medieval times.
 It's one of the more complicated projects I've attempted, simply because I've done bugger-all working with wood before. I have this unshakeable preconception of it as a nasty piece of recycled nature that lurks, waiting until you are attempting the most vital part of any shaping procedure, & then gleefully splits along the grain with wild abandon, scuttling all your plans out of simple human-hating spite. Metal was created by man, so it's much easier to work, but wood, wood is vengeful...

 Anyway, seeing as I'd have to base the dimensions of the wooden stock on the draw length of the bow, or "prod", as it was called back in the day, I decided to make the bow first. First stop, Trademe, where I scored a set of leaf springs from an old Jaguar. Naturally, leaf springs are made from spring steel, which is perfect for making a strong, long-lasting bow. So I set out to disassemble the leaf sets & choose a suitable blank for the bow.

I choose you... spring.

 The first step was to clean the leaf up, which I did by hitting it repeatedly with a mallet, & then got rid of the rest of the rust with a sanding flap disk & my trusty angle grinder #2. Angle grinder #1 is bigger, & always has a cut-off disk mounted on it, so I used that to cut it to length, & rough-shape the ends into nocks, for holding the string on.

Not traditional, but effective...

 Now, the trick to working with spring steel is keeping the temperature low. If the metal gets too hot, it ruins the temper of the steel, softening it, sometimes to the point where it will simply bend & stay bent. Quite embarrassing if you then pull the trigger & the arrow just falls off the front of the bow. So, after every 20 seconds or so of working the metal, I had to wrap it in soaking rags to keep the temperature down. I kept it down to hot enough to touch, which is probably a bit retentive, as steel doesn't change it's structure until it reaches several hundred degrees, but better safe than sorry, I figured.

After cutting the nocks, I started on the long tapering cuts, in order to make the bow bend properly. It needs to be tapered for several reasons. The first reason is to spread the stress evenly along the bow. If the bow was the same width along it's length, the increased leverage from the tips would force most of the bend to the centre of the bow. By making it easier to bend as the leverage decreases towards the tips, the bow can be made to bend evenly along the entire length .The second reason is to remove weight from the ends. Seeing as the bow has to accelerate the tips in order to straighten & fire the arrow, the lighter the tips, the faster they accelerate, & the faster the arrow is shot. In order to go slowly to keep the heat down while making the long cuts, I had to take almost 2 hours for each cut, stopping & cooling it for 5 minutes every 20 seconds of cutting or so. I have now learnt patience.

Halfway through the long cuts.

The downside of using leaf springs, apart from the difficulty of working them, is the fact that they usually have holes through the centre, creating a weak point right at the place of maximum leverage. I decided to go OTT, ADD, & possibly even NATO in reinforcing the centre, creating a steel sandwich with a high-tensile steel bolt holding it all together. The front slice of the sandwich also gave me a place to attach the foot stirrup, which makes the bow a lot easier to cock. The stirrup is made of mild steel bent & hammered into shape, & then welded onto the front plate.

The "slices of bread" for a steel sandwich.
Not as tasty as you might think.

After completing & assembling the bow, I took it to an archery pro shop to get a string made up. I figure a properly made high strength string is going to keep me whole longer than anything I could come up with myself.

 When fully strung, with a 6" brace height, I can draw it back another 12" unassisted, for a full foot of power stroke. Draw weight at 12" is 180 pounds, which should produce a pretty respectable speed with a heavy bolt.

 Stay tuned for the next post in the series, in which I impose my will upon the wooden stock.

Project: Drift Trike

Continuing with the process of getting the blog up to date, I thought I'd post the drift trike I constructed, with the help of my mate Dale, who's a whiz with a welder. This was probably the project that cemented my desire to learn to weld for myself, although I'll admit Dale makes it look easier than it really is... :)

 I started off with a BMX I got from Trademe, & spent some time disassembling it. Turns out the mechanism for holding the steering column into the neck of the frame is actually a pretty nifty bit of engineering, simple yet elegant. Sadly, I don't have any pictures of the process, seeing as I built it before I had the idea for this blog. I then cut off the upright seat column, & the horizontal bar that joins the steering neck to the top of the seat column. The main reason for this is to lower the height for the new seat, so I could keep the center of gravity as close to the ground as I could. In the interest of a low center of gravity, I also made sure to have a large meal before testing it.

 The next step was to head round to Dale's place, with the frame, steering head, wheels, & a hand truck/sack barrow to cut up for the rear wheels. I had planned to use the tubing from the hand truck for the rear frame, but Dale had some superior steel tubing with a thicker sidewall lying around, so we went with that. We decided to go with a bare metal finish, as opposed to painting it, so we proceeded to strip the paint from the frame with wire wheel, angle grinder, & blowtorch. This resulted in shiny metal & also 2nd degree burns on my forearm from said shiny, very hot metal. Once clean, we (Dale) welded up the rear frame to my design, using 2 parallel tubes in order to provide a nest for the stub axles, so as to keep them lined up perfectly. This was reinforced with an angle bar running along the front & bottom of the tubes, so we had more surface area to weld the rear of the bike frame to the axle.

 Then it was just a case of welding the bike frame to the rear axle arrangement, a bit of paint for the wheels & sealer for the bare metal frame, & reassembling everything. I obtained a couple of PE sleeves for the rear wheels from Azzman of the D-Trikes.com forums. The PE plastic is quieter, slipperier, & more resilient than PVC, in addition to being much thicker. It's also black, & black is cool. True Story. The way to get them on is to deflate the rear tires, slip on the sleeves, centre them & make sure they're angle just right, & then reinflate the tires. Air pressure holds them on quite tightly. Obviously, the sleeves are needed to make the rear wheels slippery, which is the whole point of a drift trike, ie going around corners sideways at the kind of speeds that make one's instinct for self-preservation throw it's hands in the air & stalk off in disgust.

Note the rear reflector.
Safer Communities Together.

 Of course, testing was mandatory, & as Andy Prentice happened to be coming over to pick some stuff up, it seemed the perfect time. The inevitable result was much yelling, grinning, & a whole lot of sliding - forwards, sideways, & usually ending in a panicked application of the brakes while skidding backwards & looking over the shoulder at rapidly approaching parked cars.

Success all round. :)

Project: Bobber

Pretty much the first thing I did upon arriving back from Africa was to get myself a motorbike. I was looking for something cheap, commonly available, & easily modifiable. And seeing as I'm too lazy to get off my learner's bike license, it had to have a 250cc engine. The Suzuki GN250 is pretty much ubiquitous as the learner's bike in NZ, & used ones are available cheaply on Trademe, so I managed to find an '84 GN250 for $1000. It had an old-school drum front brake & spoked wheels, which perfectly suited the look I was after. I was tossing up between a cafe racer & a bobber, & decided the lines of the bike were much more suited to a rat bobber look.

Simple, classic, & downright butt-ugly.

Now obviously, being me, the stock standard look was not going to suffice. So the first thing I did was pull off  all the panels & strip them back to plain metal with a wire wheel, remove all the rust, & prepare to repaint. During this, I was to come across the first of many incidents, eventually culminating in a basic theory of workshop equipment quality: Don't Buy Chinese-Made Tools.

Shiny.

Seriously, just don't.

The next step was to give everything a couple of coats of self-etching primer, followed by 3 coats of matte black paint, applied liberally by rattlecan. The daft mini apehanger handlebars had to go too, as I don't much fancy riding around feeling like I'm in a skinny recliner chair.

Better, but she still has a big-ass ass.

After that, I bobbed, primed & painted the front fender, & wrapped the exhaust in thermal tape. I primed & painted the headlight, & also primed & painted the front forks, wheel, & spokes, to remove some more shiny.

Shorter. Better.

New house, bigger workshop. :)

Lastly, I entirely remodelled the back end. After consulting an LVV certifier & my local VTNZ shop, we agreed that chopping the frame off behind the rear suspension gussets wouldn't need re-certifying, so that went off.  I fabricated a new set of mounts for the rear mudguard, lights & license plate, including a reflector for illuminating the license plate at night. I bought a new LED tail light, & new indicators, & wired them in. I created an entire new seat out of the metal side panel of an old PC, some foam matting, & some black leather. It ain't a touring seat by any measure, but it's comfy enough for riding around town. The rear mudguard & mounts got hit by some more matte black, & I replaced the missing right-side battery cover with some plastic sheeting from the old PC.

Seat minimalism.

Intel Inside. Hopefully it doesn't crash.

New rear end mounts.

Much trimmer.

She's still rough & she ain't the quickest thing on the road, but she's plenty fun to ride, & I can't help but grin whenever I'm out on a sunny day. Given that I wear an open-faced helmet, this results in a higher than average number of swallowed insects. Bumblebees in particular hurt at anything over 40km/h.

G'day all.

Well, this being the first post, I guess I'll kick off by welcoming you all to this, the record of whatever I happen to feel like constructing at any given moment. Projects may include but are not limited to art projects, steampunk artifacts, weapons of mass, middling & very localised destruction, useful household items, & stencilling.
 I'll be updating as often as I have anything new to add, but I guess I'll start off by getting the blog up to date on my back-catalog, as it were.

So, check back here regularly, & feel free to let me know what you think of whatever I'm doing, or make suggestions for improvements, future projects, or where to stick whatever it is I've just finished.