This is a toy that looks complicated and seems like it demands real precision to work at all but honestly, it's pretty straight forward and there is a bit of wiggle room in the measurements. (Wiggle... caterpillar... never mind.)
The toy came together over several weekends of trial and error. Hubris and the occasional flying disk o' death off of the miter saw delayed me but I'm fairly confident that one of these could be made (but maybe not painted) in a day without too much grief.
So to begin at the beginning...
A few years ago I made my first caterpillar automata. Ultimately, I called it "The Very Hungry Caterpillar That Photographed Very Poorly." It was a gift for one of my nieces and it is still working today.
It had just six cams and I used five large beads for the body and a "doll's head" for, well, the head. There was nothing to prevent the body parts from rotating on their shafts, but that was fine.
I didn't have a set of plans for that one. It was just a proof of concept that became a finished toy. That was the same approach I took with this one; build and test as I went along.
I needed to make a toy for little one's school auction and for a friend's newborn. I wanted to try my hand with some more automata and I recently came across Woody Mammoth's version of a caterpillar toy on the web. I really liked the look of his, so it seemed like the way to go.
So... for those following along at home; here is Cam Terminology 101:
The cam is attached to a rod that runs through the pivot point. When the rod is rotated the cam turns pushing the follower up through the slide and then allowing it to fall as it continues to turn. So rotary motion gets turned into reciprocating motion. The follower is aligned over the pivot point and is always in contact with the cam.
Now on to the build.
The cams were cut from 1 1/4 pine dowel on the miter saw and are exactly 1/2" wide. They need 1/4" holes through their face that go all the way through. I used a jig that I usually use to drill offset holes in wooden wheels. The center of the hole is 5/16" from the edge.
I used a pine dowel for these. One batch seemed to have rougher edges that splintered a bit but a lot of factors can go into that. They cleaned up fine.
The case for the caterpillar was made with 1x3 (3/4" by 2 1/2" actual) pine boards. The case was 8 1/2" long (8" is fine as well). The holes on the top piece need to be right down the center and I used a 9/32" bit to allow clearance for the 1/4 dowels that will be the followers. I drilled the hole for the head at 2" in from the end and the first hole for the body at 3". After that, it was 8 more holes each 1/2" from the last one. ( I finally got smart and set up a template for this.)
The front and back pieces were 3" tall. They have a 9/32" hole right through their very center and need to line up since the rod need to go through both holes.
Once the holes were done I glued one end to the front of the top and the other to the back of the bottom to make two "L" shaped pieces. I put a coat of beeswax and mineral oil on them but was careful not to get any on the surfaces that will need glue during final assembly.
The followers are 2 1/2" long pieces of 1/4" oak dowels (I needed to make 10 of these.) The base of the followers were little pine blocks I cut that were 1" long (left to right looking from the front of the finished toy), 1/2" tall (up and down) and about 7/16" thick (front to back.) They each have a 1/4" flat bottomed hole drilled in them about 1/4"deep (using a Forstner bit.) I found that drilling the holes on either end of the stick already cut for thickness and height and then cutting to length on the band saw was much safer than cutting it to final size and trying to drill the holes.
I glued the followers together with their bases and checked that they moved freely in the holes on the top of the case. I hit the holes with a rat tail file to make sure nothing was too tight.
I took a 10" or 12" piece of 1/4" oak dowel and did a quick test to see where I could start safely lining up the cams. I glued the first one in place and then it was just a matter of lining up the next cam so it was a little off line from the previous one but glued to each other. I had a 1/4" difference in the rotation for each one.) The less the difference, the smoother the action. When finished it looks like a screw. I did double up on the cams for the head. I matched them for this one. On the other one I just cut one dowel 1" thick instead of 1/2" and drilled the offset hole in it. The thin disk at the front is used to help lock the rod in place so it doesn't move too far back and forth once the crank is attached.
So then there is some test fitting to see where that locking disk needs to be placed to have the followers line up with the cams. By having the bases of the followers be a little less that 1/2" wide and the cams exactly 1/2" wide, it makes it run pretty smoothly. I hit a few of the "feet" of the followers on the beltsander once or twice just to give a little more room. Once I was happy with the alignment, I glued the locking disk in place and the top and the bottom together.
Now the the body...
I purchased a 1 1/4" diameter poplar dowel from the local old school hardware store. I used it for the 7 main body segments. I also cut one disk each from a 1 1/8" and a 1" dowel for segments toward the tail. Each segment needs to be just short of 1/2" thick. The poplar dowel splintered a lot less than the same sized pine dowel I used for the cams and had a smoother,denser end grain after it was cut and sanded.
I experimented with using my bad saw to cut the disks and I was very disappointed with the results. They weren't a total wreck but they required a fair amount of time on the belt sander to clean up and they were uneven. After a little slip cost me a part of a fingernail, I finally was like "Not worth it!" I cut a new set using my power miter saw with a stop block. Super easy and super precise. One note though...DO NOT lift the blade while it is still spinning! I spit three of those little disks across that shop at about Mach 4 before I learned that lesson.
The body segments need a 1/4" hole drilled in the center of their edge for the followers. I used the same jig as for the cams but turned up on its side. I used a Forstner bit (thank you once again Benjamin Forstner) to get a nice flat bottomed hole. I made the holes 3/8" deep. You could probably make this with 3/16 dowels but I find the birch dowels I get in that size to be pretty fragile. Your millage may vary.
I used a pre-turned craft store piece called a "doll's head" for the caterpillars head. (It is 35mm across, about 1 7/16"ish.) I plugged the hole of what would normally have been its base with a length of 3/16" dowel and then drilled a 1/4" hole for a follower to fit in. I used the same jig as with the other pieces and left the dowel long so I could use it as a handle while drilling. Once the hole for the follower was done, I trimmed the dowel flush and sanded that part flat.
The smart thing to do now is to test your body segments to make sure they don't rub against each other too much AND THEN paint and finish them even though they will be slightly thicker once painted. Just be sure to keep the segments in the same order you test fitted them. 1/16" one way of the other really makes a difference. You don't want too much wiggle room between the pieces though since it can allow the followers to get out of alignment and interfere with each other. Don't let this stress you out. It's a toy. Not the engine on an airplane. It will work fine.
So, with all the pieces cut and tested, I painted them and gave them a coat of spray acrylic. Yeah... it looked a little creepy but this setup let me paint the full disks and have them dry out of the way. Also let me use the spray acrylic on both sides at the same time. It was a big time saver.
One thing I added before the acrylic was a shapely rear end for the caterpillar. He just didn't look right with a round head and flat butt so I rounded off a 3/4" dowel, painted and glued it on to the 1" body segment. Now... baby got back!
Last thing in the crank. I used a 2" hole saw to cut a disk of 1/2" pine from a board, sanded it up and painted it to look like an orange. A little 1/4" dowel became the stem/handle for the crank. It goes in the 1/4" hole where the leaves are.
I tested the fit again and the glued the body pieces on to the followers. Almost done.
I trimmed the front and back of the rod and added the handle. I left a tiny bit over 1/2" of the rod protruding from the front to attach the crank on it. I made sure to leave a little space so it wasn't constantly hitting the case. I guess a washer is called for here, but I tend to stay away from metal in the toys if I can help it.
Okay then.. all set.
Crank
Head
The full critter
And here he is in action. I did the cams slightly different on this one with an extended cam in the tail (not needed) and a longer cam for the head that worked as the locking piece as well.
My guess is that most parents of the last 40 or so years are familiar with Eric Carle's "The Very Hungry Caterpillar." It's a great book and it has a very distinctive style. I could never match it but I figured I could capture the vibe by using some of the same colors and shapes.
People really like the pleasant wiggle and whimsical nature of this toy. It really has whet my appetite for simple automata. Stay tuned.
In clearing off the digital camera I noticed some of my weirder projects from the last year or so and I just wanted to share some of the oddness. It is only semi-toy related but as I accelerate my journey from eclectic tinkerer through to eccentric old man, I feel it may be worth a post.
In short - as an allegedly semi-handy guy who makes some weird stuff, I for some reason get asked to make a lot of weird stuff for people. Funny how that works out.
These are "Bronze Medals" for an Office Olympics I helped organize over the summer. The little plastic medallions had "Yo Gabba Gabba "stickers on them before I hit them with the metallic spray paint. (The medallions were in the discount bin at the Party Store which is odd since Yo Gabba Gabba is basically timeless. It will always be good advice to not bite your friends.)
Bottom of a clementine box as my spraying surface. Each medallion was sitting on a plastic soda cap. Oddly enough, this was the second time in eight years I had done this.
I gave myself a Silver Medal for the performance because I probably should have peeled the stickers off before painting them. Oh well, Gold in 2020!
This one is sorta bittersweet. I've made a couple of toy boats and want to make more but these weren't intended to float. They were for a funeral. (YIKES! Way to bring us down Toy Making Dad!)
A colleague at work asked if I could make centerpieces for the memorial service of the brother of a long time friend of hers. It took me about an hour and a half to make the prototype but maybe only 2 or 3 hours to make ten of them. I actually made templates and it was easy to see how things like jigs and design simplicity are key to "mass" production.
The bases were 1x4 pine with a small cabin cut from the same wood and shaped on the beltsander. Masts are oak dowels. The finish is beeswax and mineral oil.
He had been an avid sailor and the family placed a sail on each mast with details about his life and a quote printed on it. Guests seated at the tables got to bring the boats home as a keepsake. They were very well received. The colleague's friend ended up paying me twice what I asked for making them. Toys make people happy even in sad times.
One other weird bit about "mass" producing these boats...
My eyes see this:
But my History degree sees this:
Okay, and now about the gnome. The Risk Management Team in my office was putting on a "Safety Month" for our organization and they wanted a mascot. I have NO idea how the idea started but someone suggested a garden gnome with a traffic cone on his head.
Seriously.
So my buddy Bill hands me a gnome and a little plastic traffic cone and says "Hey, toy-man. Can you cut off his hat and glue the cone on?"
Well, the short answer is "Yes" but as a wise freshwater crustacean once told me, "Why make it simple when you can make it complex?" Besides... I know I was told it was okay to cut his old hat off but I'd much prefer to fix things and not break perfectly fine things. (Also, not that I'm a gnome guy...but he seems alive and I don't want some weird woodlands curse coming down on me.)
So I cut a square of 1/2" MDF to be the base of the cone. I then took a hole saw that was pretty close to the diameter of the hat and got to drilling.
Once it was done, I then kept doing trial fits to see what still needed to be removed. I used a rotary tool to taper the hole and custom fit it to his head.
Success.
So I painted the base black with some gloss black latex paint and then proudly brought it back into the office to show we had achieved cone-headedness without destruction. Bill thought it looked great but the team felt that the hat HAD to be orange to be a "real" traffic cone.
Seriously.
So I picked up four different shades of orange from the craft store and settled on... well "Orange" and four or five coats later, viola! A non-broken gnome wearing a traffic cone for a hat.
I had Teddy perform a "Cat-Scan" to make sure it was safe before returning it to the Risk Management team.
Clean your room well; for good spirits will not live where there is dirt. There is no dirt in heaven. (Attributed to Mother Ann of the Shakers.) I'm a slob. Always have been... always will be. (Attributed to Toy Making Dad of the Sitters Around)
As a kid, Oscar Madison was pretty much my hero.
No fooling, my room was hit by lightning when I lived with my parents. Initially my mom didn't realize it had been hit since the normal mess wasn't all that different than how the room normally looked. What with a bookcase blown off the wall and a couple of holes in said wall.
As I often remind her even though she knew what she was getting into... my wife still married me.
Here is a shot of shop last month... not my proudest moment. I had to finally say, enough is enough and start squaring things away.
I couldn't get anything done. It was time to declutter and put things where they belonged. If they didn't have a space, it was time to make a space.
So let me start at the beginning...
I've had my shop space for about three years now and I always knew it would be a work in progress. It was the result of us putting a modest addition on our modest house.
It shares a room with a washer and dryer as well as a cat box (or two) and a utility tub. The space that is pretty permanently mine is a "L" that runs about 9 feet down one wall, 10 feet across the back wall (including the door and window) and then 7 feet up the next wall to the washer and dryer.
Since I didn't used to have ANY space, I really shouldn't complain about the space I do have. However, it's funny how many times I've wished I had just one more inch to get something to fit just right. Still, all things considered, space really isn't an issue. I build toys not pianos.
My first build was a long tool bench, 2x4s and screws with a plywood and hardboard top. In the event of an earthquake or rocket attack, it is a designated shelter spot in the house. It is solid. (Here is the post and the general plans.)
I have a tool cabinet that I inherited from my parents and it fit perfectly into the middle section (almost as if the middle section had been designed around it... just saying.) I labeled the drawers and have stuck to putting sockets and hammers and rulers back where they belong after each use. It has saved me dozens of hours. The mini fridge didn't last long. It went off to college soon after this photo was taken.
I added a wall mounted drop leaf table that I got from Ikea for like 166 or 250 Krona. I use it as an assembly and painting table. I've found that I've left it upright the whole time it has been there but a) I use it a lot and b) it's nice to know I could fold it down if needed.
Here is a rare shot of it cleaned off. The box for the shop vac may have to go at some point. I was trying to muffle the sound as recommended in some shop guides but it really doesn't fit that well thanks to the nature of the hose. Another project for another day.
On to the shop organization and lessons learned.
First off, there is only so much floor space so you gotta start hanging stuff on the walls. Thank's to a brother who was formerly in the retail beverage business, I was able to acquire a fair number of wooden wine crates. I've used some of the wood for toys (it is mostly 3/8" thick) but I've turned others into shelving. They are sturdy and they class up the establishment.
It seems that I've moved them all half a dozen times over the last three years. In general, I've come to what should have been an obvious conclusion - put the stuff you need close by and don't waste any wall space. (DUH!) Compared to my first attempts, that wall is now much "tighter" and practical.
I had planned on building a Roubo style workbench that would have made Chris Schwarz himself weep but alas... I purchased the Harbor Freight bench instead. I suck. The mind is willing but the body and wallet are weak. I think it was about $120 (On sale! Wow, how lucky was I to find something from Harbor Freight on sale, right?) It suits my needs for now although it is not sturdy enough to be used for planing. Well... at least not yet. I have some thoughts on that for another day.
The workbench is too long to fit in the space without blocking the aisle in the shop, so one end is tucked into one of the bays in the tool bench. (The floor of the bay has been removed.) It's not ideal but it gives me all the work surface I need and at some point the space may be reconfigured. Moving that power strip there has made things much easier when I'm using the rotary tool or palm sander.
An early get for my shop space was a used stationary belt-sander. Next to my drill press, I'd say it is my most used tool in the shop. We'll, actually looking at that picture, it is literally next to my drill press.
The drill press and sander both sit on the bottom base of an Ikea two piece cabinet that gave us 20 good years of service. (It may have been a Splurk or Rehnikl but I'm sure it wasn't a Jork.) The base is very sturdy and gave me some needed storage behind doors. The height on the drill press is fine but the sander was a bit low.
A log time ago I had made stackable crates as a shoe rack for our closet and after about 18 years of service, it was time for them to be replaced. They were still pretty sturdy so I cannibalized one and made the other into a very solid shelf into which I could fit little plastic bins.
The bins were salvaged from a piece of kid's furniture no longer needed to house Happy Meal toys from 350 movies we never saw. So the shelf raised the belt-sander just enough to make working on it more comfortable and gave me three "drawers" to house my drill bits and hole saws. Win-Win.
As an aside... check out the difference between a 1x3 furring strip sold now (on the left) and one sold in about 1998 (on the right). Sort of makes you think, huh?
With the doors removed from the top half of the Ikea cabinet, it really formed a nice hutch. I raised it a bit by making a big "C" out of 2x8s and setting it on top of that. Extra shelves have been easy to add and it sits on top of the tool bench and almost reaches the ceiling.
You can see the Western edge of "The Great Wall of Clementine Boxes" as well as my growing toy making library in that photo but here is the rest of the wall. There are still more clementine boxes on another shelf across the room and in the closet of our computer room... and on my desk at work but I swear I can stop saving them at any point.
The wall mounted little plastic bins are pretty much invaluable. I did get smart and made labels with the exact dimensions and part numbers for the pre-made wheels and specific parts I use.
It sounds stupid but the little labels really help around the shop. You can see things at a glance without opening cigar boxes and drawers to look for your priceless Allen wrench collection. As a bonus you get a a zillion of them for just a few bucks. You can even send them through your printer. Just saying.
The latest addition to the shop has been another wine crate wall shelf but this one has a sliding lid. Once I mounted it on its side, it turned it into a cabinet. I also added a pencil and marker holder under it and my clamps in another wine case above it.
I picked up some sheets of self adhesive dry erase paper and turned the door into a white board for notes and quick scribbles. (Robert Neville must have dropped by...) It's great because I can pull it completely out and use it at the workbench to work numbers and do rough sketches.
My shop is as clean as it has ever been. As each surface was cleared my tabby supervisor came in to supervise and comment on my work. This time it passed the smell test and nothing had to be knocked on the floor to test for gravity levels in the shop.
As I suspect it is the case with all weekend tinkerers, it isn't just my experience and tools that will change over time but so will my storage and work surfaces. They will all be a constant work in progress and that's not a bad thing.
I used a pine dowel for these. One batch seemed to have rougher edges that splintered a bit but a lot of factors can go into that. They cleaned up fine.
So then there is some test fitting to see where that locking disk needs to be placed to have the followers line up with the cams. By having the bases of the followers be a little less that 1/2" wide and the cams exactly 1/2" wide, it makes it run pretty smoothly. I hit a few of the "feet" of the followers on the beltsander once or twice just to give a little more room. Once I was happy with the alignment, I glued the locking disk in place and the top and the bottom together.
