Halloween Costumes

I like making Halloween costumes.  When I was little my mother did a lot of sewing, quilting, embroidery, knitting, crochet, tatting, etc.  She showed me how to do the basics.  How to sew on a button, and encouraged me as I worked on various projects.  A square of cathedral window quilt, a lion embroidered a lion on my lucky sock, a counted cross stitch bear.  I can remember arriving at a friends house, only to realize that the embroidery hoop was unexpected affixed to my knee.  I’d stitched through my pant leg during the drive.

So I knew the basics, but had never gone very far with it. Then for many years I didn’t do much more then hem a few pairs of pants.   Then my son Pioneer was born, and when Halloween rolled around I realized that I was interested in making him a costume.

I had seen a cute baby dressed as a pumpkin, and though “I can do that.”

I discover I have a super power

Well, I wasn’t exactly bitten by a radio active spider, but I did spend many hours sifting through the mixed buttons bin at “Finche’s Fabric Farm” while my mother shopped.  I’d spent untold hours in the sewing room listening to the whir of the sewing machine, playing with the snap pliers, pinking sheers, tracing wheels. I remember the smell of the sewing machine oil in its little can.

mommy_and_pumpkin_boy_smallAs I started in on Pioneer’s pumpkin costume I discovered that all those hours in my childhood had instilled in me a mysterious power.  I was totally at ease at the fabric store buying materials for the costume.  I knew exactly what to do, just by going with what felt “right”.   I made paper templates.  I folded them in half before cutting to make the symmetrical.  I cut test pieces, left seam allowances, added piping.  I knew how to lay things out, pin them up, sew them, turn them inside out and stuff them with fiber fill.   It all felt totally comfortable.  Like I’d done it a thousand times, even though I’d never actually done it at all.  It felt like coming home.

standing_pumpkin_smallBest of all, the results were actually pretty good.  Now it may seem like silliness to spend 7 hours making a costume that Pioneer only ever wore for 5 minuets (seven month olds aren’t big on wearing hot heavy outfits with hats for very long) but once you’ve discovered a mysterious power, who wouldn’t want to try it out?   To give it free reign and see where it takes you.

Why Costumes?

Halloween costumes have a lot to recommend them.  They’re 85% aesthetic.  If they look good, they are good.  They only need to be sturdy enough to survive a few hours of trick-or-treating.    They have a fixed deadline, and a short schedule, and a very short lifespan. These are ideal conditions for getting in touch with ones inner seamstress.  If I’m not sketching, cutting, pinning or sewing every minute. I’m not going to finish, so I don’t have time to second guess.  It turns out to be ridiculously fun.

I try making an owl costume.

costume_on_floor_smallFor his second Halloween I had Pioneer choose what he wanted to be.  He chose an owl.  He likes owls.  He points to them in our bird book, makes hoot  hoot sounds with me when we see them in his “Animals Showing Off” pop-up book. We’ve stood together on the deck, under the stars, listening to their deep calls. Yup.  He wanted to be an owl.  It wasn’t until I did some web searching that I discovered how difficult a task k this was.  These human owl hybrids are tricky, and every owl costume I saw on the web looked either sad or ridiculous.  I had my work cut out for me.

Rule 1.  No mortar boards

One thing my research into owl iconography made clear was that if you’ve failed to get people to recognize your owl you slap an mortar board on top.  Owls are very striking birds. I was hoping I could get the owl idea across without resorting to whacking people with a board.

The pumpkin had been all about fleece, but in my book owls are corduroy.  Something about the the texture and softness.  So I went off to the fabric store and bought three kinds of corduroy.  I also started making some sketches and paper mock ups of what the owl might look like.  I got in the zone,  and cranked out the owl costume in one weekend (plus two weekday evenings.)   I knew I was going crazy when I considered making a lining for the costume.  I had to remind myself that I’d be lucky if he’d wear it for more then 5 mins.

Lessons learned from the corduroy owl:

pinned_in_messy_workshop_smallNever mark white corduroy with a sharpie unless you’re ok with both sides being black.  Doing lots of sewing in a shop littered with sawdust and metal shavings involves the fine art of never dropping anything, and perhaps most importantly when you’re son pulls out some polyester fiber fill and puts it under his chin and says “beard…  beard!”   it’s so cute that it is very nearly fatal.

I had done a nice mock up in paper of what I wanted to do.  However when it came time to make that vision a reality it turned out that toddler heads are pretty darn big, and in order to make the owls eyes/face the way I’d originally intended I’d have had to make the head HUGE.  I think this a problem many of the web owl costumes were suffering from.  A too small head perched on top of the kids face.  Weird and distracting. I don’t think Pioneer would have dealt with a full owl mask because that’s just too much face coverage.  Besides his face is super cute, so putting something over it, or right above it seemed like a tragic waste of cuteness.  So I opted for a more stylized treatment of the head.  Just a kind of owl horns hood stiffened with sheet plastic and welding wire on the inside.  As it turns out he actually likes wearing that part of the costume.  He didn’t want to take it off.

hands_on_head_smallSo on Halloween he wore the main part of the costume pretty much all day.  It looked great.  He came to work during lunch time, and then we went out trick-or-treating with his baby group pals at night.  We couldn’t quite get him to say “track-or-treat” but he kept saying “candies” and motoring on to the next house.  He did freak out a little at one house when a motorized disembodied hand started crawling across the porch towards him, but we distracted him with a kitty that was right there, and he seems to have not been to scared by the experience.  He loved all the lights and decorations.  We went to quite a few houses, and then our friends/neighbors Carl and Rita invited us in and gave us dinner, and he got to see some old school stop motion dinosaurs in “The Lost World.”

All in all it was a very successful Halloween.  I’m hoping next year he’ll be willing to try some things on before the big day.  After I’d seen him wear the thing, I realized there are some alterations I’d like to do.  The lower back section is pretty square, and could really use a couple of seams to take out some of the extra material and make it more form fitting.  Also the Velcro flap that holds the front closed isn’t sewn all the way to the top, and that made it so it was free to flop out a bit at the top.  I was going to hand sew that section, but didn’t manage to get around to it.
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Hey, I even have a picture of Pioneer clearly contemplating how many licks it takes to get to the center of a tootsie pop:

how_many_licks

The original web page in the internet archive.
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Building a Bar Themed Lamp 

drinksonme_thumbnailI like making lamps.  You get to have fun playing around with light and shadow, they’re useful, and as long as you do it right you don’t burn down anyones house.

My friends got married, and I wanted to make a wedding gift for them.  They are into bar paraphernalia.  They even provided the wet bar at my wedding, so it seemed like a natural to make them something with a bar theme.  I’ve made a number of lamps so I built them this lamp made from 4 jiggers, 4 martini glasses, and a martini shaker.  Pushing the cap on the shaker acts as the off/on pushbutton for the light, and the glasses are not fixed in place, so the lamp can be used to serve drinks!

The basic idea is sketched out

At first I didn’t have a plan, so I poked around the web looking at various shakers, jiggers, tongs, juicers, strainers, etc.  I noticed that the bell shaped jigger looked like it would make a nice bulb enclosure.  I wanted to do a low voltage halogen lamp for it’s nice warm light, so I needed something big enough to hide the power supply.  A shaker fit the bill nicely, and it seemed like glasses could act as the light diffusers.  I also realized that maybe the glasses didn’t have to be fixed in place so people could actually drink out of them!  I originally thought of making a base out of a serving tray, but had trouble finding one that looked nice, and was thick enough to hide the wires.  So I eventually opted to fabricate a solid wood base.

Building Details

base_construction_thumbnailI used a push button toggle under the shaker’s cap to provide the on/off switch.   I routed the circular recesses in the base so that the whole base could act like a big coaster.  The recesses are stepped to form 2 concentric rings the inner matches the base on the glasses, the outer adds a nice additional detail.  The recesses help keep the glasses in a nicely aligned position.  I needed a way to put the shaker up above the base (so it would be at the right hight above the glasses) so I opted make a faux rubber bellows by cutting disks from particle board, gluing them up, turning them, and then painting the whole thing mat black.

The bulbs are 10W halogens that plug into ceramic sockets that are riveted into the jiggers using rivets I formed from lengths of brass tubing.  There was a lot of fiddly small hole drilling through the jiggers since I had to drill 2 holes for the wires, and 2 for the rivets.  I also had to avoid drilling out the spot welds that held the jiggers together.  The wiring is co-axial 16 gage power cord wire from the surplus store (from a laptop power supply.)  I just wanted nice black circular cross section 2 conductor wire that was thick enough.  That fit the bill.

Building The Arms

before_assembly_thumbnailI had to build a special jig so that I could center drill a passage into each of the jigger handles.  I also machined some tubes that could be bolted together to form a + shape with each of the jigger handles sliding over an arm of the plus, and wires going through channels inside the + to meet at the center.  That’s what keeps the arms from drooping, and keeps then at a nice even 90 deg spacing.

arm_closeup_thumbnailThe wires emerge inside the jigger and meet up with the fuse, switch, and power supply.  The wire passes through 2 small grommets, and the whole jigger handle feeds through a big grommet into the main body of the shaker.  That gives all the connections a nice professional feel.  I hope the rubber doesn’t degrade to quickly because the final assembly of that sucker was a lot of octopus wrestling.

The base was made from some nice figured wood that I found by picking through the boards at Home Depot.  Hey, only $2.80 a board foot for wood with a lovely figure.  I biscuit joined two consecutive sections of the board to make a sort of pseudo book match.  The recesses were cut using the router, a circular template, and a collar.  I made the template by cutting a hole in some particle board using one of those single point circle cutters.  Actually I think I cut 5 holes before I got the diameters just right.

A few rounds of sanding and polyurethaning the lamp was basically done.  I bead blasted the interiors of the glasses to make them a nice diffuse white.  It wasn’t that complicated a project, but the stainless, and the grommets really give it nice professional feel.  About the only thing I’d change is that the push button I used was one I got at Radio Shack, and frankly the action on it is clunk-clunky.  Not that slick a feel.  I could have gone around to the various surplus places and found one that had a nicer action, but hey it works.

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base_view_small

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The original page in the Internet Archive.

 

A Steam Engine Built With Hand Tools 

A torch lights the way

Well I finally broke down and bought one of those butane pencil sized blow torch/soldering irons. Its all metal construction, and under $20 dollar price tag made it irresistible. Hey I could always have a soldering iron with me in case I encountered any electronic emergencies. So I filled out the order form and waited for the package to arrive. When it arrived it was lovely. It’s tiny and accurate blow torch flame… Ah but what to do with it. The situation demanded some sort of little blow torch intensive project. Hum. I decided upon making a hero’s engine. I had made one in grade school constructed from a soup can and some pieces of rubber hose. The whole thing hung from a tread and was powered by a candle. Even under full steam it’s thrust was almost imperceptible. Now I had a chance to make one that might actually work.

I got some pieces of brass tubing from an art store, and started soldering together a 4 jet hero’s engine. Whilst working on this I happened to mention it to an acquaintance of mine. He said that he’d built a small double acting piston steam engine and he drew a little diagram of the basic principal on a nearby envelope. I was enthralled. I imagined making something that would go chuff-chuff-chuff as it ran. Wow. So I put the hero’s engine on a back burner, and (envelope in hand) I set out to build my own steam engine.

So I set out with nothing but a hand drill, hacksaw, and some files.

I made the sliding valves, connecting rods, and main cylinder from more art store brass tubing. A big problem was finding a suitable piston head. It had to fit into the cylinder exactly.  The art store carried brass tubing large enough to form the cylinder, but they didn’t carry every size increment, so I couldn’t build up a piston by just nesting successive tubing sizes, and soldering that into a single mass.  So I spent a lot of time combing the hardware stores looking for a brass fitting that was of the right side. I happened on a flange that was very close, so I cut it off, and soldered on the main drive rod. Then I chucked that into the hand drill that I had, and (while holding the drill with my feet) managed to turn the flange and pinch it with some steal wool until it was just the right diameter. (And people wonder why I eventually went out and bought a small lathe. 🙂

I found a fly wheel at a ham fest in the form of a big brass gear that had been part of an old radio. I made (what I later discovered was called) a vertical fire tube boiler by silver soldering together brass sheet and tubing. Originally I took the steam from the top of the boiler, but it’s long transit through some rather thin tubing caused a lot of it to condense in the boiler, so I ran the tube down through the boiling water, out the bottom of the boiler, and back through the flame to give it an extra boost of heat before going off to the steam engine. Apparently real steam boilers sometimes have a similar element called a super heater. I also insulated the boiler itself for better efficiently, and now my steam engine runs on two little alcohol flames. (Or I can run it by blowing into it.) Amazing what you can cobble together with a few hand tools. I have a very early  movie of the steam engine in action, as well as these more recent images.  Live steam is a fun hobby, and there are a few pages dedicated to that very topic.

The original page in the Internet Archive

Sorry for the horrible quality of the video, it was shot on a Apple Quick Take, and I just converted it to GIF now.  I built the thing in the early 1990’2 so be amazed there’s any documentation of it at all.   Looks like maybe I originally made a the web page for this in 2006.

 

Making Our Wedding Rings

So I always planned on making my own wedding rings, so when I asked Cheryl to marry me it was time to make it happen.  I did some sketched on paper of things that I thought wouldn’t be too hard to make.  After we decided on a basic design I decided to machine the rings our of acrylic.

First Cut on Acrylic Rod

Then I turned it to the correct outer diameter.

Turning the Outer Diameter

Then I used a hand ground profiling tool to form the outer shape.

Forming the Outer Radius

For my ring I then turned a simple groove on the outside.

turning_the_outer_groove

I bored it out, shaped it a bit, added a wax sprue and it was ready to be invested.

Plastic ring with wax sprue in flask

Cheryl’s ring was a bit more complicated.  I did a CAD drawing of the ring, and wrote up the deg increments I’d have to rotate it to put in each of the dimples.

CAD Drawing of Cheryl's Ring

I set it up on my Sherline Mill with the rotary table to do the precise rotation.

Sherline Mill setup

And after doing a few practice runs I was off and drilling the ring blank.

Drilling Holes in Cheryl's Ring
I then bored out the inner diameter of the ring.

Boring Inside of Ring
Then just like the other ring I added a wax sprue, and it was ready to invest.

Cheryl's Ring with Wax Sprue
I mixed up some investment, and used the vacuumed pump to draw out the bubbles.

The Vacuum Setup
Here you can see the investment bubbling.

Investment  Bubbling

Once it had hardened around the rings the flasks looked like this.  The dimple is formed by that black rubber cap that you saw in the other pics, and now only the red wax sprue is visible.

Flask Before Burnout
Then I burnt them out in this kiln.
My Kiln before Burnout

I was originally going to use my home brew electric spin caster to cast this, but I didn’t have 24v worth of heavy duty batteries, and my beefy 24v supply wasn’t up to the task, so suddenly I had to improvise.  Thankfully I knew I had an old mechanical spin caster in a box (that I’d picked up at a garage sale).   I dug it out, screwed it to the floor of the shop, and cast the rings without any sort of nice safety barrier making sure I wasn’t about to spin a lot of molten silver all around the shop.

spin_casting_machine

At this point the inside of the rings is mostly cylindrical, with a bit of a rounded edge.  I wanted more of a “comfort curve” kind of shape, so I did that by hand with a sanding drum. I made a number of acrylic jigs so I could polish/clean up the rings on the lathe.

Shaping the inside of the ring

After a bit of chemical darkening, and clean up the rings were done.  (They’re silver, but the red sheet makes them look a bit like gold.  Oops.)
both_rings_on_red

Making Wedding Wine Charms

I made personalized  win charms for everyone at our wedding.  I used Press-n-peel Blue as an etch resist and etched them out on copper sheet.

dewling_irons

I masked the border with contact paper and used Ferric Chloride to etch in the details.

charms_resist_mask

I drilled all the little holes using an etched starter dot,  and then I used an arbor press and this circle punching die to cut each charm out.

arbor_punching_small

arbor_press

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Electric Scooters Before They Were The Rage

When I first started restoring my Isetta, I swore off any non-Isetta related projects.  I knew that project was so huge, and had so many different parts to it that it could act as its own heap of projects, and if I was ever going to get the whole thing done, I was going to have to focus.

Somewhere just before the end of the second year of working on the car, my project composure cracked. I wanted to do a big project.  I wanted specifically to do something unrelated to the Isetta.  I wanted to bust out. I did NOT want to be derusting or restoring something.  I wanted to make something new.  Preferably something a bit electronics heavy, something fun. Thus was born the Electric Scooter project.

Now let me just state that I knew I was biting off a fairly large project when I started this.  The electric bike project was going to pale by comparison.  First, with an electric bike you’re starting with a complete vehicle.  You have wheels, a frame, steering, brakes, a place for cargo, in short, a whole host of things that are already there, and all you have to do is not screw them up as you add motors, batteries, etc.

Secondly when starting off on the electric bike, I had specifically decided: no drive electronics. Just a two-speed  relay system that could be wired up in a few hours.  Doing a high current motor driver is a big deal.  There are a lot of tricky issues that come up that complicate the design.  In short, I have studiously avoided projects that require chopping more then a few amps through a motor.  The whole point of the electric scooter project was to face some of these tricky electronics issues (and have some fun doing it of course).

I drew some sketches and decided on an approximate size.  Then it was off to the surplus stores to find a suitable motor.  The motor would dictate most of the rest of the design.  I spent a day digging through various piles of grubby motors looking for a DC motor with enough torque.  I finally settled on a 50v motor which had started life as the spindle motor for one of those ancient reel-to-reel tape drives for computers in the 60’s.  I also picked up two wheels, some sprockets, and some matching bits of chain.  I decided I could run the motor at 48v from 4 12v lead acid batteries.

trombone_slideIt seemed like the first order of business was to determine what kind of reduction ratio to run on the motor to give me some decent torque, but also have a reasonable top speed.   I bent a piece of black pipe into a ‘U’ shape much like the slide of a trombone.  (Well a rusty thick-walled trombone slide.) I machined an axle, welded on some fitting so the axle could bolt across the two legs of the ‘U,’ and welded on a piece of angle iron so I could bolt on the motor.  Now my trombone slide had a motorized wheel at one end.  Still this was a long way from being a scooter, but I was itching to see what kind of power this thing was putting out.  What to do?

Motorized Hand-truck Terrorizes Neighborhood

hand_truck2Then it struck me.  I didn’t need steering or brakes or much of anything to give this puppy a road test.  All I really needed was a few more wheels.  So I bolted the trombone piece to the back of my hand truck, put a board on top to sit on and to hold the batteries.  I stuck the whole contraption into the street and climbed on.  I touched two alligator clips together, and zoom! I was shooting up the street.  Now let me tell you,  I have done a lot of wacky projects on this street.  The electric bike never even got a second glance.  The completed electric scooter didn’t cause a stir, but by gum a motorized hand truck really brings people out.  Within moments I was surrounded by neighbors asking what the heck that was.  I guess my other projects just end up looking like something I might have bought, but throw together a vehicle with clamps, a hand truck, and loads of loose wires, batteries, etc, and everyone’s impressed.  Go figure.

scooterRearDriveCrop2It was clear that the motor had zip, and I guess I lucked out on my guess about the gearing because it seemed to be just about right.  So it was back to the shop to build the host of things needed to turn a trombone slide into an actual electric scooter.  I welded the rest of the structure using 1/4 iron rod to form box sections.  It was strong, but wasn’t about to win any awards for being light weight.  Still it looked nice and was easy enough to do.  The next big issue was the front wheel.  It needed to be articulated so I could steer, and my design also called for another pivot so the whole scooter could be folded up.  What to do?

The Great Bicycle Caper

Now let me tell you I hate bicycle thieves.  When I was in high school someone stole my red Schwinn World Sport right off our porch.   It had been my first full-sized bike, had had many component upgrades, and had been my faithful touring bike on numerous bike tours.  I had gone thousands of miles on that bike, and I knew every scratch and ding.  When it was stolen, I wandered around town in a fog hoping against hope that I might find it parked somewhere. I knew that the thief didn’t appreciate that bike.  Not the way I did.  So you can understand why it took me some time to warm to the idea of The Great Bicycle Caper!

Now one thing I haven’t mentioned yet in the project is that I was not taking this on alone.  My friend and former co-worker Pioneer was also on the case.  He was there from the very first sketches on napkins over lunch.  Now maybe Pioneer wasn’t doing the welding, or surplussing, or electronics design, but it was his enthusiasm for the project that really saw it through to the end.  He was an excellent sounding board and made sure we maintained the appropriate goofy perspective on the project.  He was also the person who talked me into The Great Bicycle Caper.

We had been looking for a cheap donor bike at various Salvation Armies, Goodwills, etc. with no real luck.  For some reason those stores were either out of bikes, or wanted so much for them that it didn’t make sense since all I was really interested in was the front fork.  Now I knew that one would show up at a garage sale at some point, but we were looking for a bike, and the sooner we found one the better. Pioneer had noticed a bicycle frame locked to a tree near his apartment.  He pointed out that the wheels and components had been stripped, and that the frame itself was bent, but the front fork was still OK.  I balked at the idea of stealing even this abandoned wreck, but Pioneer kept after me, working the angle that we would actually be doing a public service by removing this abandoned hulk.   After a while he managed to bring me around, and I began to plot how best to steal this bike.

coneThe facts: The bike was U-locked to the tree.  The tree was at a very busy corner right next to the entrance to a Cost Plus.  The plan:  I knew my angle grinder would make short work of the U-lock, but with an obvious shower of sparks, and we’d need electrical power.  I also knew there was no way we were going to be able to do that unobserved, so going with the “public service” theme I outfitted us with face shields and orange safety vests.  We put out some safety cones, and Pioneer ran an extension cord into the Cost Plus.  We acted very businesslike. My grinder cut through the U lock in a mater of seconds.  We rolled up our extension cord and ambled off with the bike frame.

This would have all been much easier if we’d had some sort of vehicle, but since I only had a motorcycle, we weren’t going to look too official showing up on that.  Also riding a motorcycle while holding a bike frame would have been unsafe.  So we had walked over from Pioneer’s place, and we walked back with frame in tow.  I still feel a bit funny about the whole thing, but I do really think we were performing a public service, and that no one was victimized, so I guess I should just stop worrying about it.

The scooter takes shape

front_fork_cropI used a large lever arm to adjust the set of the bike fork, cut the fork much shorter, collapsed the ends, and cut slots in the flat areas to create a place for the front wheel’s axle to bolt.  I mounted the fork, extended the handlebar’s stem to be much longer, and suddenly the project started to look like a scooter.  As a quick initial test I cut a piece of plywood to act as a deck,
stuck some batteries in, and wired a switch to the handlebars.  No brakes, no speed control, but it was time for a test run.  I climbed aboard and I was off. After a little bit of use the power switch welded itself shut, and I found myself abord a runaway scooter with no brakes!

I leapt off and hauled the scooter into the air to keep it from running away. It was heavy, and the rear wheel kept brushing the ground. Now the question was how to disarm this howling squirming scooter.  I clawed as some wires and eventually managed to disable it.  Now we were having fun!  After that all tests were carried out with an exposed loop of wire which could easily be yanked free. A kind of “nearly dead man’s switch.”  The next order of business was to try a relay controller.  I wired up a big relay and hooked that to a control switch.  Pioneer and I tried this configuration out with a bit more trepidation, but things seemed to be going well.

Eerie Lights shine under the scooter

However, we did notice two things.  One was that when you released the switch, the motor did not cut out immediately, and two as darkness fell, we noticed the occasional eerie glow coming from under the scooter.  Was the scooter possessed?  Was it space aliens?  Nope.  It was the glow of an electrical arc shining out from the relay.  Because the motor was running on high current DC power when the relay opened, it was striking an arc, and electricity was still flowing through the relay even after it was fully open.  Needless to say the relay did not last super long under these conditions.  Scratch one relay.  I’ve often wondered if there is a simple passive capacitor circuit that would keep the arc from starting until the air gap was wide enough.  Who knows?  It was back to the motor control drawing boards.

Boring Technical Stuff About the Motor Controller

protoboard_cropNow I had sworn off high current chopper-based electronics projects for the same reason I don’t do high frequency digital electronics.  To many spooky issues involving high speed transients taking advantage of parasitic inductances and capacitances.   The circuit designs can get pretty finicky, and you end up putting a lot of ground planes around and just hoping for the best.  Also when you are doing high-current stuff, you end up having to deal with more expensive components, heat sinking, thermal runaway, great big gate capacitances, larger explosions, etc.  In short it’s a much bigger pain.  There are some very nice websites about these issues.  The Q4D folks have a very helpful site that talks about some of this, and SGS Thompson has a number of very interesting (well for motor control geeks) technical papers relating to this.

scooterSideView_cropI spent two months making various prototypes of my motor controller before building one that wouldn’t blow up when I actually tried it under full load on the scooter in the street.  (That’s two months when I didn’t have a day job, so that was a LOT of time.)  However the design I have in there now is pretty much exactly the design I started out with before I had decided I’d try and make all but the power MOSFETs be components that you could get at Radio Shack.  What a mistake.  I was building push pull stages to play tug of war with the MOSFET gates, and those stages always ended up having crazy noise issues, or suffering from thermal runaway, and just popping right off the board.  So I finally caved in and bought a SGS Thompson gate driver chip.  It pretty much worked right out of the gate.  I didn’t even blow one of them up, and I think they cost less than $2, so it was dumb not to be using them from the outset.  Still I learned a lot.

controller_box_cropI etched a number of different designs, but somehow even though they worked on the bench on protoboards under pretty heavy load (sticking a 2×4 against the rear wheel), they’d still blow up once I had them etched and was testing them under full load.  Finally I managed to build one that didn’t blow up.  It has some issues where when it goes to 100% on it has a lot more power then at less then 100% so it feels as if you have variable slow speed control, and then a kick of extra power when you go full throttle.  Which is fine although I’d like to know what is really causing this. I boxed the whole thing up in an aluminum box with a big heat sink sticking out one end.  The nice thing is that it’s all in one module, so I could pull the controller out and stick it into another project if need be.

Making The Throttle Handle

hand_grip2_smallAfter the motor controller was working, I needed to make a nice interface for controlling the variable resistor that was the throttle.  I decided a “motorcycle” style twisting hand grip would be swank.  So I cut off part of one of the handle bars just inside the hand grip. This part was to be the twistable throttle. I measured the amount of twist needed to go from idle to full on my motorcycle, and I made that be the amount of twist available on the hand grip.  Now Mark has been dabbling in clock restoration, and he was a great source for some spring steel that I used to act as the return spring for the handle.  Finally I used a toothed belt to hook the twisting grip to the potentiometer.  All in all it makes a nice motorcycle hand grip, but it was a fair amount of work to make.  If I were to do it again I might opt for a snowmobile style thumb lever or some such at least as a first pass.

So It Goes.  What About Stopping

break_super_closeup_cropThe next thing to consider was a brake.  You would think I’d have made one of these earlier, but where’s the fun in that?   I got a surplus stainless steel disk, and mounted that on the rear wheel.  I had been planning to use the spent brake-shoes from my motorcycle in a custom caliper made from some chunks of AL plate, but there were space issues, and it seemed like a complicated build.  So I eventually opted for an off-the-shelf caliper that I got at a go-cart shop.  It was fairly small, and was already fitted for cable drive.  So that made things a lot simpler.   I brazed various cable connections on the scooter just like a real bike, and ran the cable up to a brake lever on the handle bars.  Suddenly trying out the scooter was much less scary and entered the realm of something casual guests could try.

Dressing It Up

right_side2_cropSo then there were the countless cosmetic improvements.  I made a center stand for the scooter.  I made a clear plastic deck for the scooter with a nicely patterned grip tape surface (thanks to the local skate shop).  That and a nice paint job, and it was looking pretty good.   The scooter still sports a fairly silly plywood “kick tail” that I added for ergonomic reasons.  It turned out that otherwise the foot you had at the back would be at a somewhat uncomfortable angle. Also I still have never made a build-in locking mechanism for the folding action of the scooter.  I’ve always just used a C clamp.

Speed, Range, and Showing It Off

drew_riding_cropWell at this point, it was pretty much ready for folks to ride.  On several occasions my friends came over to check it out and ride it around.  Top Speed?  Well I’m not entirely sure; my best guess is something like 12mph.  Weight?  The bathroom scale claims it’s a chunky 56 lbs.  When I built it
weight was not the highest priority.  I’m sure it could shed quite a few pounds with a cast AL frame and lighter handlebar stem and tires.  As it stands, it’s quite rugged, but no featherweight.  Most of the weight comes from the 4 lead acid batteries and the motor.  Not much I could do about those without a full redesign.  So now comes the question of range.  How much range did it have?  Everyone wants to know about the range.  Honestly I just don’t have a clue.  In all the times it’s been ridden we either didn’t ride it enough to run down the charge, or it wasn’t fully charged to begin with.  So I guess the answer is that it had enough range to out last our attention span for riding it up and down the street or around the block.  It just isn’t really comfortable enough to want to take it for range trials around and around and around the block.

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