Making a Egyptian Retro Technology Labyrinth Game

January 8, 2011 by Kurt

When I was young we used to spend time at my Grandparent’s house. It was a farm house with a porch swing and there were lots of fun things to do. My Grandfather would tell the story of my first trip around the yard on the go-cart. I was very young and when I came back around I told him I’d “never operated a motor vehicle before!” and he thought that was hilarious coming from such a little kid. There was a mini bike (until we broke the front fork doing jumps) we played Jarts, yes all sorts of “dangerous” distractions.

One of the fun things we’d do is play an old wooden Labyrinth Game that they had. We played it so much that we could run the ball all the way though and all the way back. We played it so much that we tried playing it with our feet. One day one of the control strings broke and although Grandpa “fixed” it he wrapped the string around the wrong way. Reversing that control, and permanently invalidating all our muscle memory for that game.

The Idea

Though TechShop I have access to a laser cutter. Each year I build some sort of crazy Christmas Project, and this year I decided that a Labyrinth Game would be an awesome thing to make with the laser. I decided on a Egyptian with a retro-technology flavor. (To fit in with the Secret Society theme I’d been following for a few years.) I went with the kiddo’s to the local Rosicrucian Museum to do some first hand research. I went to Toys R Us to see if they had one of those games. I talked to 4 people there and non of them had any idea what I was talking about. I then went to a smaller local toy store and the guy knew at once what I was talking about, and he had them in stock. This more modern instance of the labyrinth had the same design (same hole pattern/course) but had been cheapened in a number of ways. The metal balls were smaller, but the course had not been fully adjusted for that size change, which made some shortcuts/cheats possible. I was able to finish the maze on the third try though, so my muscle memory from 25 years ago seemed good. It was only $21, so you can’t expect much at that price point.

The Design

I started in on the design, I wanted to make a lid for the maze so it would come as a decorative wooden box. I was originally going to put brass clasps on the lid, but eventually had to abandon that plan because of time constraints. It would both cost a lot and I’d have to strip/age the brass fittings, and I was planning to build 6 of these things so it was better to keep it simple. I did some sketches, and looked at Egyptian Art. I noticed that the Scarab was a nice fit thematically since he’s such a famous ball roller. (Although this project didn’t involve any dung.)

I had bought a lot of very thin wood from Minton’s in Mountain View when they went out of business, so I decided to do an inlaid wood Winged Scarab on the box lid.

Normally with these projects I do 4 of them by Christmas Day, but then have 2 others I finish up before New Years. (For out of town folks where the timing isn’t as critical.) However when I started working on this one I realized that the physical size of the project was going to require more laser time then I was used to using. It takes a full hour to etch the scarab on the lid. So I quickly realized I wasn’t going to be able to schedule enough laser time before Christmas to cut/etch all the parts needed for all 6, so for the first time I limited much of my part cutting to the basics I’d need for the first 3 and then I’d cut the rest after Christmas when laser time is a lot easier to schedule.

The 60watt laser deep etching the scarab into the lid.

The laser etched ball glued into the lid

This is how I organized the parts. They are laser cut, but I tape them down to the surrounding wood before I take them out of the laser. That way the uncut material acts as the parts organizer, then I can just slip them into these three ring binder page protectors. Using this system one three ring binder can keep track of all 8 zillion parts. As long as you never EVER pick up the binder upside down and dump everything out! I put a big orange arrow on the front of my binder to help keep that from happening.

The main body being glued.

There are 88 pieces for the wing segments alone, so it takes a while to glue up. After the parts go in I clamp them down to dry. The pieces aren’t a super tight fit, so hopefully that’ll leave enough room for expansion/contraction of the wood.

It is ready to clamp, but I didn’t clamp this first one. It’s always a learning experience, so this one was never fully flat/level. Later ones were better in that regard. I had 3 mistakes in the wing segments. (two parts were swapped, and two were actually the wrong shape) So I had to figure that out, and cut extras. Once all that was ironed out things went more smoothly.

A shot of the very first prototype in normal plywood, and two of the final ones in the 1/4″ Mahogany Ply that I got for the project.

The lid after being glued to the sides and with it’s first coat of Linseed Oil.

The inside of the lid before finishing. I wasn’t too happy with these two corners. They align the lid to the base, but don’t look that great. Later I tried a bit fancier shape/look. the little right angle brackets with the holes are nice and fancy looking, and quite simple to do. Of course that’s 8 more things you have to glue in (two on each side of the lid.)

The lid sitting on one of the sides just to show how the wings will work. this is before I started the Linseed Oil finish work.

This is one of the sides laid out with one of the knobs. Above you can see the zip lock bags I used to organize thick knob segments. I made the knobs from three segments of 1/4″ wood plus a very thin wood layer for the eye.

The knob is made up of 4 parts. You can kind of see the funky strait knurl.

I glued the knobs up on a brass rod held in the lathe’s chuck, so you can make sure the rod would be plumb. Otherwise the stack of laser cut parts is bound to wobble as it turns. However you could just as easily do this with a piece of brass rod stuck into a hold that was drilled plumb. There’s no real need for a lath with this project. It was there, and that made it easy.

You can see a little to much glue sticking out of one of the glue joints. It’s nice to wipe it down with a damp sponge to reduce the amount of glue visible.

Here’s an early test cut of the corner joint. The laser cuts in a slight V shape, but you can compensate for that a bit by shaping the fingers into actual dove tails. (Thanks Heath for the idea!) However you can only do that in one direction if you try to compensate in two directions you get a tight joint that needs a teleporter to be able to assemble it (since there are then wide fingers on the outside of each joint) I guess you could do it the other way around, and have 2 axis fixes for both joints with reverse dove tails, but then I would have had to flip the wood over after etching but before cutting, which would have been an alignment hassle. The joints where plenty tight as it was. This test is using Cedar, but I ended up using Alder which has a less pronounced V shape to the laser cut. (And which I could get locally at Home Depot)

Here’s a final corner with a detailed look at the ball exit. The bottom part of the box extends to create the ball return area. That makes it much stronger since there’s 1/4″ plywood supporting the return area instead of something just glued onto the side.

After the design was done I had to crank up for mass production. Here are the sides/lid sides for three boxes (well minus the lid sides for one.) A set of 2 sides takes about 15 mins to etch/cut out on the 60Watt laser.

Here’s the design of the box floor. It has 3 wedges which will hold the tilted floor that makes the ball go to the exit. You can also see the 4 screw holes since the floor needs to be removable for possible maintenance.

I sanded the bottom corner of the tile floor so that it can smoothly go down to almost nothing at the exit port.

I do however have to provide a special corner piece to keep balls from getting stuck behind the post that the screws screw into. In theory the ball could still fall onto the upper corner of this piece and get stuck, so if you really cared you could sand the top to be slightly curved, but the chance of that happening are small enough that I just don’t care to do the extra hand work to handle that case.

Here you can see three of those corner pieces getting glued down. The middle tilted floor was the very first floor, using different wood. On some of them I also sanded a slight dip in the top of the plywood at the exit, but that turned out not to be necessary and it doesn’t look that great.

Here you can see the tilted floor in place. You’ll notice that the blocks glued into each corner (so the base can screw into those blocks) have tops that are cut at an angle to make it so the ball can’t get stuck on top of one of the corner blocks. You’ll notice that in this fit up I don’t have the special corner piece glued in yet.

I decided to wind my own springs for this project. Mostly because I couldn’t find the right quantity of the right size/tension of spring locally. This wasn’t that hard to do, but was a bit of a time sink. Here you can see me using a Jorgenson clamp to tension the wire as I hand crank the lathe to wind the wire into this brass rod. That is the easy part. The annoying part is then cutting/forming the ends on the wires.

Here you can see two of the better resultant springs. I used a dull Exacto blade to spread the coils enough to get in and bend the loops the rest of the way out with pliers. After the first three were built I had some time after Christmas and found some suitable springs at Tool Land, so I only had to build the first 6 springs, not all 12.

I used brass tubing pressed into the wood to form bushing for all the brass rod joints, this makes for super smooth action and long life.

Here you can see me cutting a bunch of the bushings. I used this super cheep Harbor Freight micro chop saw, and hot glued a stop to the saw at the right distance. That makes it super easy to cut 20 zillion of these things. Note how the stop is angled and only touches the edge of the tube, so it doesn’t cause binding when the tubing cuts through. After you’re done with the stop you can just pry it off of the saw. Some day I’ll make a fancy tubing holding/adjustable stop system, but this works well as long as you don’t have to do too many different sizes, and it could just be used in the saw as-is. I didn’t have to dive into an extra project rat hole.

Here you can see one of the bushings in place around the rod.

I also made a number of pivot pins using a round wooden washer and a bit of tubing. You can see one here (blurry) ready to go into the hole.

Here you can see a frame getting glued to the maze floor. I laser etch the locations of all the wall segments, and put numbers in them so I know which pieces go where. There’s also an arrow, and hazard numbers for the game itself. Notice how I used scraps of wood that were cut from the jaggy edge areas as clamping sections so the clamps wouldn’t damage the pointy parts of the wood. The first one of these I did I didn’t do that, but used padded spring clamps, but there was some slight damage done, so I switched to this system. There are about 45 pieces that get glued down to make the maze.

Here is the maze partially populated. I didn’t bother to number unique segments since there aren’t a lot of them and it’s easy to keep them strait. In the upper right you can see the piece of wood that the parts are coming from. The parts are numbered in columns from top to bottom 13 to a column.

Here’s a closer view including the now fully empty parts sheet.

The walls of the maze have this herring bone texture on them, including miters at the various intersections. The circular arc wall segments have a slightly bigger pattern because it was a pain to get them distributed along the circles in Illustrator. I think I could do a better job now knowing more about pattern brushes, but I was just using the Offset Effect, and getting that with perfect spacing was a pain.

Some of the miter work on the maze walls. Lots of tiny herring bones.

Here are some more parts glue drying getting ready for assembly.

Here you can see how easy it is to make a mess of wooden washers (left) and wedges for the tilt floor (right). This is enough for all 6 labyrinths.

I was originally going to drill/bend brass wire loops to attach the drive train to the pivoting frames, but that was going to take FOR EVER to do, so I opted to just my staple gun. This was terrifying because I was stapling into fully finished things on Christmas Eve. So being off and having a staple come splintering out would be VERY bad. So I practiced on some scrap first. I used this brad to keep the staples from fully seating so you could then tie strings/ attach tensioning springs to the staples.

Here you can see one of the springs attached.

And the way that the spring tensions the string as it wraps around the rod.

A closeup of the two rods in place with the strings on and tensioned.

That’s the full view of both rods in place and strung up.

The knobs for the first size mazes are sprouting like strange flowers from a pink bucket. (glue drying stand.)

My brass control rods are 5/32″. Thankfully they make 5/32 locking collars for some sort of hobby use, so I was able to buy them for cheap. Here are enough locking collars for two mazes.

A closeup of one of the collars before I put the set screw in.

This is a closeup of one of the knobs with it’s spacer washer and locking collar in place.

The bottom of the box screws into place just inside the corner feet that that box has.

Both frames and the knobs in place for the first time. Time to play test! The first play testing happened at 9pm Christmas Eve, so it was good that it worked because there wasn’t time to make any major changes. I did end up re-tensioning things to deal with some stretch in the strings/knots.

Then it was time to sew up some black velvet bags for the ball bearings to go in.

There the bag is turned right side out.

The three balls on the velvet bag.

The maze opened up so you can see the maze surface.

I made a video of the laser cutting, and the kiddo’s playing with it on Christmas Day.

The final finished box. I managed to make 3 by 2:30 am Christmas Eve.

Building a Motorized Iris Diaphragm

August 9, 2010 by Kurt

There’s something cool about a mechanical iris. The opening expanding and contracting like magic, the nice radial symmetry. Very fun. Lawrence and I had built the Solar Plotter, and although the output was very nice it has some limitations. Because we were using a large cheap magnifying glass the output lines were pretty fat. I thought it would be cool to have some sort of dynamic line width control, and what would be more steam punk and fun then a magnifying glass with a motorized iris.

The First Build

I started by making a laser cut prototype. I used poster board for the shutters and 1/8″ acrylic sheet for the control rings. The whole thing was pinned together with a few 1/8″ brass pins. The iris worked fine, but there were a few problems. One was that the range of motion for the control levers was not that large, and because it had a sort of snap action it seemed like it would be hard to get fine grain control of the hole’s diameter. Also because there were only 5 shutters the opening was a pentagon, and that might well show up in the final drawing. (If you look closely at the burned wood output of the Solar Plotter you can see little discs stepping along in the ash.) I’d designed it this way to cut down on the number of identical brass sheets I was going to have to eventually hand cut to make the final (longer lasting) shutters.

The Second Build

So I canned that design, and went with a different style of iris. I saw this page about a different iris design. The new design has 12 arc shaped shutters with a pin that sticks out one the bottom at one end and on the top at the other end. I was originally thinking of biting the bullet and snipping these things out of brass sheet, and soldering down short segments of brass rod to act as the pivot and drive pins. As I tried making them it became clear that getting all those parts flat again after all that snipping/soldering was going to be a real pain, and I worried that if the shutters weren’t super flat they’d interfere with each others motion.

All that brass was going to add a lot of weight that I didn’t really want. Of course nothing is more steam punk then a brass motorized iris. But it was time to give up on the complicated hand fabrication of 12 shutters and instead figure out something that I could cut directly on the laser. So I went back to the poster board. The great thing about the new design was that there was very little stress on each of the shutters, so all I really needed was a good way to glue the drive and pivot studs onto the thick paper and I’d be in business. It would have been nice to use very thin plastic sheet for the shutter blades, but I can only cut acrylic on the laser, and that doesn’t seem to come in super thin sheets. (Or at least Tap Plastics doesn’t have it.)

I redesigned the drive plate and bottom pivot plate so they’d accept much larger pins so the pins would have a larger glue area in contact with the paper. I used wooden pins thinking that I trusted Elmer’s Glue and wood bonding much more then some other random glue and acrylic. That was an OK decision, but if I had it all to do again I’d user acrylic pins. All that sanding and champfering of 1/4″ wooden pins was fiddly work and burned more then an hour of time.

The result was a very nice smooth acting iris driven by an RC hobby servo.

Here you can see the gear that goes on the servo motor (center) the drive ring with it’s distinctive drive slots, and the two arc pieces that make up the back wall of the iris.

Here you can see all the shutter blades still in the laser cutter. Only 12 are used, but for this kind of thing it’s always a good idea to make extras. The rounded end it the pivot end, and the other end is the driven end.

Here you can see the basic layout of the drive ring. On the right the servo would turn that gear, and the drive ring rotates in the cup of the back wall. Each of the slots drives the end of one shutter blade around. It’s a bit wonky to have this motion without a nice central pivot point but that’s the nature of be beast.

Here you can see the pin around which each of the shutter blades pivots. I’ve just glued all 12 of them. You can see how I had to sand the ends/edges to get rid of any splinters left from cutting them on the band saw. That was a fiddly business and I highly recommend just using laser cut acrylic discs. You’d only have to sand one face, and then use some sort of glue you trust to do a strong acrylic to paper bond. I’m going to do some glue experiments and figure out what works well for this situation.

Here you can see I’ve flipped over the shutter blades and glued more drive pins onto the other end of each one.

Here you can see all the shutter blades in place on the bottom ring. Each overlaps the other around in a ring. Because the shutters go less then half way around the circle there is never a thickness of more then 6 shutter blades at any one point, and the thickness is always very uniform. The hole in the foreground is where the brass pin will eventually pin the semicircular back wall to the base.

Here you can see me taking the iris for a spin. I put the drive ring over all those pins and gave it a twist. The action is very smooth and controlled. The first layer of the back wall is just set (approximately) in place for this photo.

This is an old servo that I had lying around. It has some little screws that will self tap into those holes to hold it in place.

Here’s a bottom view of the iris with the motor in place. When I mounted the motor I realized there was something wrong! The gear didn’t mesh right. I was off by a whopping 0.075″ Crazy talk. I was very worried because I didn’t know where the problem could have crept in. Had I had more stuff selected when I was nudging elements in Illustrator? What else might be wrong? Then I realized what was wrong. I had flipped the design for the bottom plate so that when it cut out the side away from the laser could be the “top” I’d done this because the holes are always smaller at the bottom side (because of the somewhat conical cutting action of the laser) and I wanted the edge that would be contacting the pins to be as close to the base of the pins as possible. However I had forgotten to flip the motor over, and it was now off center. (accounting for some of the extra space.) Phew!

I flipped it back over and we were good to go.

Here’s the final assembly. There’s still a little bit of play (you can see the gap between the drive ring and the back wall) If I end up cutting a new base ring, I’ll bump that motor bracket in an extra 0.04″ and that should be perfect. It runs nice and smooth. But there’s a bit of a problem. The servo rotates more the 180deg. I had designed the mechanism for 180 of rotation plus some modest amount of slop, but on this motor it seems like it might be an extra 15 deg or more. So much for believing something I read on the internet! The problem is that if the motor can forcibly drive the iris past it’s comfort zone (where the wooden drive pins have bumped up against the outside of their slots in the drive ring) the iris might be damaged, and since we don’t know how good the control will be for the servo we have to assume it will frequently be run to it’s limits in both directions. We really should make sure that the iris is OK in those situations.

The easiest solution would be to make the slots a tiny bit longer. Another solution would be to make the drive gear a little bit smaller and scoot it over some. It’s surprisingly difficult to find exact rotation range number for this model of servo. I guess most RC folks don’t care at all.

The original page in the Internet Archive.

Building a Mechanical Cryptograph

January 8, 2010 by Kurt

This year I’m building an encryption device for my Retrotechnology Society. If you recall last year 6 of my friends/relatives were “antecedently” inducted into a secret society. The only down side being that the society was so secret that I never heard back from anyone. This year I’m going to change all that by providing them with this encryption device, so they can communicate with me (and one another) in cipher. Functionally it’s based on the 1850’s Wheatstone Cryptograph, design wise I’m working on spicing it up a bit.

These images are of the very first prototype. It’s totally rough. I want the basic shape to be the Retrotechology Logo of the 11 toothed gear with an eye in the middle. I’m trying to design the eye so that it “looks around” as you encode/decode messages. You turn the thumbwheel at the upper right, and that drives two gears which turn two rings of letters which are visible though two openings in the face of the device. The eye design is really rough, and various spacings will be adjusted, but this is mostly just a proof of concept to make sure things are actually going to be functional.

These were laser cut out of clear 1/8″ acrylic. Later versions will have to have clearance areas etched into various parts, etc. (to prevent binding) and I’ll have double brass sleeves acting as the bearings. (right now it’s all just jammed in 1/8″ brass rod to hold it together enough to make sure things were working out.) I like how it’s coming out, but I think the aesthetic of the eye design really has to be worked out some more. Still I think it’ll be fun. The final color scheme is going to be black, with white disks inside. I haven’t deiced yet what to do with the back. I could add some cutouts that would expose the gearing a bit. Kind of a skeleton Cryptograph, but that might make it less functional. “keep your fingers and crud out of those holes!” so I haven’t decided. Maybe just a redux of the eye.

I wrote the code to generate the gear profiles in python, and then imported that into illustrator and did all the rest of the work there.

Ok, so then it was time to cut out real versions in the right colored plastics, etc. I used black for the outer casing and “Ivory” for things like the friction wheel, and the lettered discs. In the design the black front/back called for gold and white lines. I thought this was going to be a real pain to do, but I came up with a trick. I used a little rubber squeegee (cut from a Speedball rubber pad) and was able to squeegee gold paint down into all the lines and curves in a jiffy.

This squeegee system reduced the amount of paint used, and really speeds up the whole process. The fills are more uniform too. I don’t want the fills to be perfect because the device is supposed to look sort of old, but the amount of time I was saving painting all that stuff made using the squeegee super important.

Once the splops were on, it was just a couple of strokes to fill every line.

I did have to manually clean out the center hole. It doesn’t matter if there’s a bit of extra gold paint in there since it’s going to have a brass tube pressed in, but we can’t have a thick blob.

If you look closely you’ll also see that I have scraped the outer ring free of most of the gold paint using a paper towel and my fingernail. Then I painted white over the top.

These are the faux Ivory thumb wheels with their special strate knurl, and inlayed arrows. (Done with the same painting technique)

I would have rather had the gears be “ivory” but since they’re not actually visible, I was able to cut them nested inside the other black components, and save a lot of material. I’ve toyed with the idea of making a fancier gear and a “skeleton” version of the Cryptograph, but decided to punt. The dark rings and little “tabs” you see in this are places where I’ve etched extra clearances on the gear/outer wall of the device so that friction wheels can run more smoothly without their knurl making their action feel “notchy.”

I also did some initial tests of burning a deep deep hole in a book. I’ve had people tell me it’s impossible to laser cut books, but you can. You simply have to clamp the pages together so they aren’t as prone to catching fire. I laser cut a clamping jig, and the first cut went well. (Probably 1/4″ easy) but subsequent cuts are bad because the loose paper and forced air cause a lot of burning. (I remove the inner paper, but the walls aren’t as well clamped as they were before and there’s a lot of smoke and mayhem. So I think I’m going to have to change the way I index the rig and flip pages/reclamp after each cut until I get to the needed 5/8″ inch depth. Still here you can see a piece inside a book with only minimal effort. I don’t think I’m going to glue or do anything extra. Just cut the hole so the device can be tucked into the book for safe keeping.

I did this test on a volume of a Funk and Wagnalls New Encyclopedia. (Millions were given away free in super markets back in the day, and it’s hard cover with gold outer trim, so it seemed like a good call.) I really need to find some uniform nice looking old hardbound books that no one wants/cares for. Not sure how I’m going to do that, this thing was $4 at Goodwill. I have no idea why anyone but me would buy such a thing, and that’s a kind of steep price! If I could have snagged 10 volumes of this F&W I might do that, but I’ll have to keep looking.

So this morning I started assembling a final unit. Here’s the parts mostly laid out. They gray part of the eye is supposed to look a bit rough like that. I want the device to seem a bit old, not super crazy snappy new.

Here’s the body assembled with its 11 pins in place. (11 pins! I have to cut and deburr all those by hand, 1/8″ is a bit small to automate on the lathe. (Kill me.) You can also see the super fancy inner pin that drives the middle disc via a square drive shaft that passes though the center of the other gear.

Here’s a closeup of the friction wheel on it’s shaft. You can see it’s inner brass sleeve.

Here you can see the most complicated brass part for the project. Most of the 18 brass pieces are just bits of rod or tube, but the central drive shaft is made up of a brass rod, and square brass tube, and then a custom machined brass tube (the needed to be machined so that it nested to the outside of the square tube and then nested properly inside the 1/4″ brass tube sleeve that is in the center of the upper gear. This shaft lets the bottom gear smoothly drive the lettered disk that is on top of the upper gear.

I was originally going to solder the bits together, but they pressed together so nicely all I really had to do was add a dab of JB Weld to eventually fix the central rod to the inside of the square shaft. This let me adjust things up/down slightly on assembly. Which was nice.

Another device nearing completion.

Here you can see four of the devices, three done, and one just needing to have the bottom paper pealed off. You can also see last years wax seal, and some sealing wax because I’m about to put the devices in their books and package them up for shipment.

The process of cutting the books was a real messy pain. In order to be able to cut a lot of pages at once I had to make this book press which clamps 80 some pages at a time, and lets me do alignment of the cut. You can see the little ‘L’ shaped page alignment guides for positioning the corners of the page.

The problem with cutting so much paper is that you have to go slow, and the compressed air blowing in the machine makes the paper char a lot more then it would for cutting just a few sheets. So there’s a lot of char and mess, and although you only spend maybe 3 mins in the laser doing each cut the time it takes to do a cycle (take out the old paper, clamp up the new paper, and tape things up so various pages don’t fly around while the laser is cutting, etc. eats up a lot of time, and you have to watch the cut like a hawk to make sure it doesn’t go to open flame, or something comes untaped and is flapping around, etc. Nothing I’ve ever done on the laser before was “messy” in this way.

In the end I did manage to cut 6 books before Christmas.

I was lucky to get this 1909 lavishly illustrated 12 volume set of “Adventures in Bookland” which was great because they were all the same size, which simplified alignment. I got all of them (plus some more books) for $5 at the Friends of the Library book sale. So it was a great deal, but I paid a heavy price in terms of guilt. It was horribly Fahrenheit 451 and I felt awful cutting though all the stories I knew like Robinson Caruso, etc. I’ve kept all of the cut out illustrations for possible future use, but my hands have run black with the blood of many an old book and that made me feel bad.

Here is an image of the device in a book. I love the way it looks like the device has burned its way into the book.

Here’s a close up of it in the book. The “top” page here is quite burnt because it was exposed to the most compressed air laser action. Intermediate pages were much less burned looking, but every sixty pages or so theres are a few really burnt ones because that was the next layer I cut. Alignment between the layers isn’t perfect, but it’s decent. You can see I added a faux window reflection that holds still as the eye looks around. I’m really proud of the way this turned out. Now to see if I get an encrypted messages!

Spider Costume Halloween 2009

October 30, 2009 by Kurt

Sometimes back in the day I’d just put up a bunch of pictures without a writeup. So sorry, no write up.

Paper Lanterns for Mom’s Birthday

September 29, 2009 by Kurt

The other day my son Pioneer brought home a paper lantern from preschool. Around that time we also got some pastries in an interesting paper to-go box that had four sides and folded up into a nice curved shape. That got me thinking that I hadn’t done any paper projects in a very long time.

As a kid I had access to a few super useful project resources. There was scrap wood out in the shop, the pile of used twine loops in the neighbors barn, and a drawer that had a never ending supply of 8.5″x11″ paper. These were great resources because they could be used on a whim to make anything I wanted. I once even tried to stretch a piece of paper around the outside of the house buy cutting it into a very thin spiral strip. I only made it about 2/3 of the way. Paper cranes, paper palm trees, expanded paper mesh, paper chains, paper, paper, paper. It wasn’t until much later in life that I realized our miraculous bottomless “drawer of paper” was closely tied to the fact that that my dad was a high school teacher.

So early on I did a lot of paper projects. In high school I got into origami, and did a lot of book driven Origami projects. Probably the best book I built out of was John Montroll’s Animal Origami for the Enthusiast. Then my work with paper more or less ceased for a long long time. So suddenly seeing Pioneer making a paper lantern made me think back to all my early paper cutting/gluing days, and I realize that the laser cutter at TechShop would be an incredible paper cutting tool. I resolved to make some paper lanterns for my mom’s up coming birthday.

The first prototypes with a few sheets of legal paper and some scissors.

I initially thought I’d make a lantern a bit like the one Pioneer had made, but with much more detailed cut outs. I produced a few little prototypes out of construction paper. I didn’t get a picture of the better lighting bolt themed one, but I did take a picture of this green and yellow one, but wasn’t satisfied with the way they looked kind of spindly. So I thought maybe I’d make a more enclosed lantern a bit like the to-go box I’d seen, but with nice patterns formed by using two layers of paper with the pattern only cut into one of them. I experimented with various patterns, and also started looking for the right overall shape. With paper, scissors and tape I made a number of 4 sided prototypes, and then a 6 sided one. That seemed more pleasing, and I second 6 sided one that I eventually went with.

It’s a joy to do prototyping with paper. Want symmetry? Just fold it over before cutting. Want three exact copies? Just stack the paper up before cutting it out. Wrong position? Unstick the tape and try again. You can try out a lot of major design changes in a twinkling.

I knew I didn’t want to deal with actual candles, and thought LED candles would be excellent replacements, without the risk of fire and design constraints that would impose. I found Pier 1 Imports selling 4 small LED Candles for $5, so that’s what I went with. When folding up the various paper lantern shapes I realized it was important to do that with a light inside the paper so you could see the patterns that the paper overlaps where forming. I eventually made a prototype where the overlaps formed a flower, but because I was later constrained to some fairly opaque paper for the colored layer of my lantern I didn’t take that prototype any further.

I did however decide on some nice flared fins on the outer edges both because they looked nice, and because I was starting to have fantasies about the lanterns spinning in the breeze.

Paper paper who’s got the paper?

I went to the local art store and found nice colored paper, but it was all very opaque. Not ideal for fairly dim LED Candles. I looked a bit on-line, but it’s nigh impossible to determine a papers opacity from a web page. The only paper listing opacity was Shoji paper (used for Japanese screens) but it didn’t seem to be available in bright colors. So eventually I just went with the art store paper even though it meant that the lanterns weren’t going to be as bright as I’d hoped. I did buy vellum for the inner layer of paper to at least maximize the amount of light getting out though that part of the lamp.

Multi Colored Laser Cut Confetti.

Time was running out, so I did a quick pattern design based on a leaf, and thought I’d get cutting/gluing in no time. However I ran into a problem. The super detailed pattern took about 30 mins on the laser at it’s highest speed. (Enough pieces for two lamps) I thought I could avoid this bottle neck by stacking up a bunch of paper and cutting it all at the same time. However the massive amount of air flow in the laser chamber and the direct stream of compressed air at the cutting point made it so the paper would not all lay perfectly stacked up, they’d puff apart and chads would fly, and all this mayhem made it ineffective at cutting more then two sheets at a time. I ruined 3 extra sheets of paper on that first run because the lower sheets were somewhat cut, but not well enough cut that the chads would drop out. It was horribly time consuming to try and hand poke/trim out all these suck pieces, and so I decided I really could only cut two sheets at a time.

I had to reserve the laser for extra time to try and make up the difference. I’d originally wanted to do 20 lanterns, but only ended up making 14 because of these problems.

Two kinds of paper and three kinds of glue.

Then I had to assemble things things. For each lantern there were 6 pieces. Three patterned colored outer pieces and three vellum inner pieces. I used a glue stick to attach the inner and outer pieces together in pairs (only gluing at the top/bottom). I did this because glue stick doesn’t cause the paper to wrinkle/warp the way Elmer’s glue does. Then when I had 3 pairs glued up, I’d glue the base rings of the 3 together with yellow Elmer’s wood glue. (for strength) I’d glue the LED Candle to the center of this stack with hot glue. (Quick, and with good gap filling.) Then after that had set up I did the final gluing of the upper sections. (again with Elmer’s) The final glue step was the most painstaking, but not too horrible.

Pivots at the last possible moment.

My friend Ken pointed out that the lamps would look nice either sitting up, or hanging upside down. And with them up-side down they could spin in the breeze. The trouble is that I was having trouble tracking down the fishing line pivots I’d imagined using for this, and I was running out of time. I had struck out at K-Mart. As luck would have it on the 4 hour drive to Cambria (where my mom’s birthday party was going to be) we pulled off the highway to get some coloring books for the kids, and I dashed into a sporting goods store, and finally managed to find the swivels I’d been looking for. I used some chain nose pliers and gold colored wire to bend up nice hangers for the lanterns as we drove down. We arrived in Cambria with the Lanterns done without a moment to spare, but they were totally untested.

Thankfully they spun easily in the light breeze in the yard. Success. *phew*

Here is a video of some of the lanterns spinning in the breeze about half an hour after we got down to Anne’s:

Here are some photos of the process:

And a few photos of the final results:

I ended up making quite a few of these lanterns in a short period of time and I was pleased with the results. This last photo isn’t mine, it’s one by Laura Mappin. I have a bunch of other shot-in-the-dark photos, in groups, and not, but this one seems to just have a nice glow. I’ve been toying with building a bigger led lamp based on this design using more powerful leds and and Arduino. My friend Lawrence and I have done some interesting software prototypes for a virtual candle based on info we’ve collected from actual candles. Hopefully I’ll get around to writing that up some day.

The original page in the Internet Archive.

A Totoro Step Stool for my Son

January 18, 2007 by Kurt

The japanese director Hayao Miyazaki has produced some of the world’s best animated films. His “My Neighbor Totoro” is one of my favorite kids’ films. It came out in 1988, but didn’t really make a showing in the US until much later. Around 1990 a friend of mine who is an Anime fanatic introduced me to Miyazaki’s work. We would watch the movies, and someone would read the text translation as the movie progressed. How primitive! One of the great things I noticed about Totoro in that setting was that it was universal. Pastoral beauty, kids being kids. It needed no translation.

Disney has finally decided that Miyazaki movies have a market in the US and has produced some decent dubbed versions of his movies on DVD for the US market.

Now that I have a son of my own I want him to grow up loving Miyazaki’s work too. So for his second Christmas I gave him My Neighbor Totoro, and Kiki’s Delivery Service on DVD. I also decided to make him a wooden step stool that looked like Totoro.

The Sketch

So I did a sketch. That’s the problem with a lot of the projects I do. I’ll do one or two quick sketches, and then I’m off slavishly producing that exact thing in wood/metal. Not exactly going with the flow and following the inspirations provided by materials at hand, etc. I did the sketch. I went down to shipping and receiving at work and snagged some cardboard boxes. I blew the sketch up on the photocopier and used that as a pattern to cut out a full-sized mock up. Doing a mock up is good. It’s something you can do in 30 mins with office tape and scissors that’ll warn you about things that you wouldn’t otherwise discover until 2/3 of the way though the project.

I decided on an overall scale for the project, and I was off to the races.

Totoro’s an Owl?

I took the cardboard Totoro home. I sort of hid it by tucking it vertically under the bench, but the next time my son came out to the shop he went straight to it. I guess even the clutter and chaos of my shop has enough pattern to it that he was able to pick out the “new” object in a flash. He went right over and grabbed it. He was 20 months old at this point. “Whaz that?” He said excitedly. He put his arms around Totoro’s neck. “Eye. ‘nother eye!” he said with his face only an inches away from Totoro’s eyes. “Ear. ‘nother ear” he said grabbing the ears. “Owl?” Apparently Totoro was an owl. I hadn’t thought about it before, but he does rather look like an owl. At this point, he’d never seen the movie. He had no idea what Totoro was, but I could tell by his excited reaction that the Totoro project was going to be a success.

The construction plan

I wanted to use natural wood colors for the various bits of Totoro. I don’t know why I do this except that I rather like wood’s natural beauty, and many of my staining projects seem to come out somewhat blotchy. So I went to the Minton’s lumber to get some darker looking wood. I settled on Alma Rose. I have no idea what kind of wood that is, but it was brownish, with even grain, it wasn’t heavy, and it was comparatively cheap. (Less then $2 a board foot) So I was all over it.

I biscuited it together, and low and behold the joints weren’t that flat. So I spent a good chunk of time hand planing and then random orbit sanding with a 60 grit disc to get it flat.

I hate veneer

I had originally thought I’d do his belly using some spare white formica that I had left over from a counter top. Then I had this “good” idea. Instead of using formica I could put a light wood veneer on, it would look more natural, and I’d still be able to route through to produce the darker chevrons on Totoro’s chest. I got some veneer and some veneer glue, and I stuck it on. Now it is at this point dear reader that I noticed that the clamping force recommended in fine print on the glue’s label was something like 200 lbs per square inch! Now that was going to be something like 14 TONS of clamping force. I started to get a bit worried. I noticed that the piece’s shape made it hard for me to get clamps to reach many of the edges of the veneer. I worried more. I put the board on the shop floor with a board over it, and then piled layer after layer of concrete block on top of that. Still probably had less then half a ton total on the board. Not good. The next day I unpiled the stack only to discover that the veneer had rippled horribly. I had to sand it all away again using a 60 grit pad. Tediously back to square one.

Resawing is hard

So I thought I’d glue down thicker wood. I had some nice figured maple and I thought if I resawed it into 3/16 boards it would look really nice. However I didn’t have a resaw blade, and I quickly discovered that resawing figured maple is a lot harder then just sawing thin strips of wood off a pine 2×4. The blade wandered and pretty much destroyed the piece of wood I was trying to resaw. The smell of burnt wood, the destruction of one of my nice chunks of maple. All the hallmarks of a “learning experience.” What the heck was I going to do? Time to go back to the wood store. I finally decided to go with some very thin plywood. It looked nice, and glued down without a ripple. Not as nice as solid wood, but hey Christmas was coming and I was working with a deadline.

Totoro starts to take shape

His belly was on. So I traced and cut out his outline. I cut the outline on the bandsaw. Now he was starting to look like like something! I used the belt sander to round the various contours, and then a drum sander chucked in the drill to round some of the harder to reach inner corner edges. Then there was lots and lots of hand sanding to refine what I’d done with the belt sander.

My son wasn’t in the dark about this project. If I’d been spending this much time out in the shop without him getting to see what was up, he would probably have exploded. So he came and checked out how things were progressing.

Router templates are fun

So then I made a router template to cut the chevrons on Totoro’s chest. I did a sketch on paper, cut the outline onto some 1/8″ acrylic sheet, and drilled/filed the shape out. Then I’d clamp that into position for each of the chevrons and routed away. I used a ball end bit, and would do a “once around the outside,” and then a series of evenly space vertical passes to route out the interior. I didn’t want to have to finish the bottoms of those things and I figured that sort of pattern would provide an interesting look that wouldn’t need much touching up.

I also used a router template to route the recesses in the back of Totoro that would hold the treads of the step stool. That exact pattern took quite a bit of trial and error filing because the treads were somewhat cupped and I wanted the holes to match the boards rather closely. I also did a routing trick on the feet to make it so that they overlapped the bottom of the belly plywood. That way there was no visible edge just above the feet.

At this point I also needed to work on the other side of the stool. I didn’t quite have enough Alma Rose left to do it out of that, so it was back to the wood store for the third time. They didn’t have a nice Alma Rose board, so I opted for some Australian Blackwood that was a similar hue, and quite a bit denser. That had the advantage of counter balancing the bigger Totoro side of the bench.

I cut the treads from more figured maple that I’d snagged by picking carefully through the boards at HomeDepot. It’s amazing what you can find there if you keep an eye out. Don’t tell anyone! I cut a nice curve out of the upper tread, and echoed it in the piece I put underneath to provide more diagonal reinforcement.

Horror and Heartbreak

So I routed the Totoro side. Then I took careful measurements and routed the hole for the treads on the other piece. I SHOULD have taken a piece of paper and a pencil and made rubbing of the routed recesses to make the pattern on the other side. What did I actually do? I took some careful measurements and laid out the other side. After routing those holes I tried putting it all together only to discover that the bottom tread was off by exactly 1/2″ back to front. Horror! I was forced to route another opening, and make a 1/2″ curved patch to put into the extra gaping hole on that side. I don’t know where that 1/2″ went, but it was so big, and so exactly 1/2″ I can only assume I screwed up my measurement somewhere. So some time was lost making the patch, but the end result isn’t that bad looking. It’s not easy to pick out at a glance. An imperfection to show the hand of the maker and placate the gods.

Burn your face

So I used a wood burning pencil to burn Totoro’s face on. Always a bit hairy because with a wood burning pencil there’s no erase. (Well short of gouging out a fair amount of wood.) So that was a bit ticklish. Thankfully I was able to follow my original sketch’s lines reasonably well, and his face came out fine.

I had decided to burn on of the Soot Spirits on the other side of the stool, but then decided that such a spirit would be much more at home hiding in a dark corner on the underside of the stool. That would have been a lot easier had I done that before gluing the whole thing up. Oops. Still I managed to burn it without any big screwups. Even if it was 3 times harder because it was in a corner. He just feels safer and more comfortable down there.

Finishing “Sticky …. sticky… sticky”

So then it was off to put various coats of polyurethane on the project. The hard part was that I couldn’t finish it out in the shop. It was too cold and damp and dusty to have it finish in any sort of time, and I only had a few days left before Christmas. So I put the finish on it in the house. That seemed to be going reasonably well. I had put on the last coat and was kicking back when I heard a bad sound from the other room. “Sticky … sticky… sticky…” My son was saying “sticky” over and over. I could only think of one thing is that room that was probably still sticky. A great big half-dried Totoro. Oh no! So Cheryl and I went in there. Cheryl washed off his hands while I tried to deal with the hand prints. I ended up putting on another thick coat right then and that mostly hid them, at the cost of a few drips that cleaned up with a razor blade.

Ready for Christmas by a Whisker.

Well Christmas came, and our son was flooded with gifts. The Totoro had been a more or less constant presence at our house for the past few weeks, so it wasn’t exactly a surprise. Still he was excited to be able to clamber all over it (finally). He used it to get on his new train table. Thank goodness it was done, or very nearly done. There were a few finishing touches that I put off until the new year. Felt pads on the feet, painting the background of his eyes white, and putting on his whiskers, but by Jan 3rd it was well and truly done. phew.

Here is the original page in Internet Archive.

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