Making a Toy Caterpillar Automata

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.

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Fixing a Toy Carousel/Merry-Go-Round (aka Giraffe Surgery)

I learned a few things with the last carousel I had built.  I had done a few smart and few not so smart things. The best thing I had done was cut out multiple disks for future carousels when I had my jig set up. When I went to make the next one, all I had to do was reach on the shelf and half my cutting was already done. I had also swapped out the camel from  the plans in John R. Nelson Jr's amazing "American Folk Toys" and had replaced him (her?) with a zebra. That was the transition to saying "Hey, I can put any sorts of critters on this that I want!"

I had made a series of rookie mistake in cutting out the giraffe and in how I glued the animals in place. I simply didn't allow for how the grain ran in the wood for the giraffe. Specifically in its legs. If the grain had run vertically the legs would have been much stronger, however it ran horizontally which made them far too brittle. I know... Woodworking 101, Day 1. Now, in fairness to me, that's the way the grain is shown on the plans and maybe that makes it less likely to have his snout break off but because I don't run a pole through the animals bodies to make it look like a Merry-Go-Round animal, it means the legs are pretty easy to snap along the grain. Which is exactly what happened... twice.

So I briefly discussed "putting him down" and replacing him with another animal since no way would a giraffe make it the wild with one, let alone two, broken legs. However, the owner's mom made it clear that the patient had to live. I try to keep my toys as close to 100% wood as I can so I went with very carefully drilling 1/8" holes through the legs and then inserting dowels to complete the surgery. It was touch and go there but the patient never said a word and the procedure was a success.

Now for the second mistake. Initially several of the animals had come off of the spinning base and I think it was because I had used spray acrylic on the base BEFORE I glued the animals in place. (As a certain Crawfish reminded me.. it is called wood glue for a reason.) Okay. So I left the surgical implants in a bit long so that they could become pegs to insert in the base. Then I made a little template out of some scrap clementine box wood and drilled 1/8" holes so I could line up the pegs with the holes.

I made sure that I wasn't going to drill too deeply into the base by using a flag/tag of masking tape that is just a little bit longer than the pegs.

Then I drilled one hole in the base and pegged it in place so that the next hole would be the correct distance. This worked surprisingly well... almost too well... if that was a possibility. Which it isn't.

Last step was to trim the pegs up a bit so they would fit in nice and smooth. I also scrapped the acrylic off where the feet and pegs will be glued down to be sure there would be good adhesion. All fixed and truly "better than ever."

Ultimately, this ended up improving the toy for me. On the next one I built, I pegged all the animals to the base using the same method and it was very easy and resulted in a stronger toy.

Necessity is the mother of invention but I guess failure is the father of improvement.

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Making a Toy Shark

Okay, right off the bat -this is not my design. It comes from the amazing mind of David Wakefield and is in his book "Toymaking Basics" That book is a great one stop shop for getting started making toys and has a few plans (including this shark) at the end. I highly recommend it.

This toy has an odd back-story for me. I think I started it about ohhhhh three or four years ago! Before you freak out, it is actually a very simple plan and can be made entirely with hand tools and knocked out in a few hours. What happened with me is that I used to have all my tools in my parent's basement and would just work an hour here or there when I was visiting or doing some work at their house. So, projects tended to go in fits and starts.

After my parents passed away we sold their house. My tools, and most of this shark, went into storage at a friend's house until our addition was completed and my shop space added.

One of the first things I did in my new space was look at the shark and try to improve him. I had everything cut out but as I was test fitting him, I saw something that I didn't like. The shark's mouth opens as the lower corner of its head is pushed up by pegs on the insides of the front wheels. It works great.

However...

Just like in real life, this shark can't go backwards.
Well, he can but the wheels lock up because the pegs can't move the sharks head from the front. It only works from the rear. My concern was that lots of times kids will move a wheeled toy back and forth rapidly. If the wheels were locking up and being forced, I worried that the pegs would break.

So, I made a test front 1/3 of the the body to experiment with. David Wakefield's plans have the eye sockets slightly larger than axle pegs that form the eyes and are anchored to the body. My thought was to have a solid dowel run from side to side and the hole in the body be more of an oval slot that would allow the head to slide up when being pushed backwards and then pivot up when being pushed forward.

How did it work? Well, I usually save every little scrap experiment but that test ended up in the fireplace. I found that the slot was going to need to be bigger than I though to allow the head to clear the peg.  It might work but it also takes away from the simplicity of the design. What can I say... I gave it a shot. It was worth a try.

So, instead the shark ended up being very straight from the book.  My one change is that I made the eye sockets 1/4" and widened the hole in the body to 5/16". Instead of pegs I used a solid dowel from one end to the other. The head needs to lined up as close to perfect as possible to make sure his (her?) head moves smoothly. Drilling both sides at the same time seems to be a must.

The body was from a 2x6 piece of pine and the sides of the head from my stash of Ikea bed slats. This shot is actually the test body before I tried cutting the slot. At this point it just has a slightly larger hole. (I figured the knot wouldn't matter since this was never going to be part of the finished toy.

Actually, having the kerf intersect the
side of the board allows the sawdust
 to escape and speeds the cut.

I like using the store bought hardwood wheels on a lot of my toys. While I can cut out wheels using my arsenal of hole cutting bits, I don't have a lathe to make them look as good as the pre-made ones. With this toy though, the slab, solid on both sides wheels, were the way to go for me. Just wanted to see how they'd come out. When cutting your own wheels, don't go all the way through. Go deep enough so you are past the 1/2 way point and the pilot bit has passed through the other side. Flip the board, line up the pilot and complete the cut. It makes for a much smoother wheel with no tear out. It is also easier to remove from the bit, which is very hot so look out.

The fins were from a different stash of Ikea bed slats usually reserved for the occasional stegosaurus. I got a nice tight fit on them and I liked how they looked but it made me rethink how I was going to finish the toy. I had originally planned on using Danish oil but I knew the contrasts in the woods would really show and perhaps be a distraction.


After a number of tests and focus groups among the family members, I settled on a two tone grey scheme with gills added on the suggestion of one of my daughters. Craft store acrylics with several coats and then gloss coated with a spray acrylic.

Clementine boxes...

... the onion of frugal woodworkers.

I painted some dowel caps to use as eyes but when I test fitted them, I wasn't happy with the look. It reminded me too much of Quint's quote in Jaws, "Sometimes that shark, he looks right into you. Right into your eyes. You know the thing about a shark, he's got... lifeless eyes, black eyes, like a doll's eye." YIKES! I'm making a toy not something to scare the poor kid.

I went with friendlier, but not too friendly, googlie eyes. They fit more into the toy vibe I was going for.

So here you go; the finished product. The lighting makes him look more blue than he really is.

It is a great design. Easy to make with hand tools but a drill press really helps. Again, I highly recommend all of Mr Wakefield's books. He sells his amazing, super high quality toys online now and you might want to check his site out. - http://www.wildlife-toys.com/

Like a nit-wit, I failed to get  a video of the shark in action before I gave him away. Oh well, I guess I'll just have to make another one.

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Making a Toy Carousel/Merry-Go-Round

This a fun, very straight forward project that can be adapted all sorts of different ways depending on who you are building this for. Any sort of animals, characters or vehicles could be used.

So the requisite history part...

FYI - Carousels in Europe go clockwise.
Carousels in the US go counter clockwise.

The word origin for carousel is interesting. It comes from the Spanish word carosella (meaning little battle) that was used to describe the battle practice or training games used by cavalry during the Crusades. Once back in Europe demonstrations of those skills included grabbing or lancing rings from horseback. Eventually "simulators" were set up at fairs so that kids could play along. So, that is why they have horses and that is why they have brass rings.

This toy has neither of those. (D'oh!)

And you may ask yourself... Is there a difference between a Merry-Go-Round and a Carousel?
Short answer... nope.
Just multiple names for the same thing like roundabout/traffic circle/rotary or dad/father/automatic daughter embarrasser.
(And you may ask yourself "Where is that large automobile?" or even "Am I right, am I wrong?" - sorry, can't help you other than to say "Same as it ever was..." However, if you ask yourself, "Well, how did I get here?" my guess is The Google or The Bing.)

The plans for this toy come from John R. Nelson Jr's indispensable "American Folk Toys" I highly recommend that book and have built a lot of great toys thanks to it. I've made some changes to the plans in that book for this project and I'll point out the differences as I go along.

The most difficult part of the build is getting the disks cut out. You'll need a total of three of these disks. Two that are 7" in diameter and one that is 5". The 7" disks form the base and the rotating platform. The 5" disk is used as the top of the carousel. The plans called for 3/4" pine but I went with 5/8" since I had a supply on hand.

You can use a coping saw to cut out the disks but I chose to bite the bullet and make a jig to do this with my band saw. Basically, you need a center pivot point so you can rotate the wood blank as the saw blade cuts. The edge of the blade needs to be perpendicular to a line running through the center of the pivot point.
I made a quick video to describe it:

Now you'll have three disks all with a 1/4" hole through the center. Two of the disks need four small holes drilled in them. These are the smaller top disk and one of the other larger disks that will be used as the spinning platform. The strings that will suspend the platform will be strung through these holes.

In drilling the four holes I took advantage of the 1/4" pivot and used it to mount the the two disks together so that the holes would be perfectly aligned. I also made a discrete reference mark on the two disks so I could be sure to align the four holes with the correct corresponding hole once the disks were painted.

I made a slight change in the plans here. I used a 1/4" Forstner bit to countersink the holes on the top part of the top disk and the underside of the platform disk. This allows the knots on the strings to be hidden and to be sure that they don't rub against the base when the platform is spun.

At this point, I tried a little something that ultimately didn't work out but was worth a try. In the plans (and in the way I ultimately made the toy) the four strings are all individual lengths. So that means all four pieces have to end up the exact same length for the toy to hang and spin properly. Four strings = eight knots. Not that big a deal but I decided to try and make it so that it was only two lengths of string, strung as big "U's." That way only the last of the four needed knots would be critical. I carved groves on the bottom of platform so the base of the string U's would be out of the way. In short, it worked but it allowed too much play with the platform and it didn't always stay level. So ditched the idea and the"mistake" is hidden anyway so no harm.

The idea was to make it easier to string but it allowed too much wiggle.

Mistake #2 - Should have lined it up with grain. Live and learn.

I painted and finished the disks with spray acrylic at this point because you can't do that once the toy is being assembled.

The plans called for a 5/16" dowel as the center post. I went with 7/16" to add a little more strength to the structure. This probably results in a few less spins each time it is wound up but, that was a trade off I was okay with.

The dowel needs to fit squarely into the base disk and into the top disk. The hole in the platform disk needs to be larger than the dowel to allow it to freely spin around it. I went with a 1/2" hole on the platform. One other bit of advise - Just because the dowel says 7/16" or 1/2"... don't trust it. Measure it and fit it into some test holes in scrap before you drill the holes in the top and base and permanently attach the dowel. Just saying that in addition to quality, there is considerable variation in how the dowels are made and labeled.

Here is the order of assembly I used for the three disks:

1- The dowel needs to extend an inch or two through the top disk and then be glued in place.	2- The platform disk is next. It needs to rotate freely around the center dowel.
3- The dowel is flush through the base and glued in place.	4- Check alignment to make sure it is square and lined up properly.

I used nylon string for this toy because it will hold up to a lot of use without becoming noticeably worn. One trick with working with this is that you need to melt the strings a little before you cut them. If you just cut them, they separate in a way that cotton strings won't. I use a candle and move the string close to it to allow it to melt but not all the way through. The melted part is easy to cut and the string does not fray making it super easy now to thread through the holes.

I made four generous lengths. Tied knots on one end of each string, trimmed it and sealed it with clear nail polish (being in a house with four females occasionally has its benefits.) I then strung them through the platform and out through the top. I also put 1/8" spacers between the base and the platform. That gap is needed for the toy to perform properly once all the knots are tied.

Then it was pretty easy to mark the sting where the knot need to be located. I pulled the platform up a few more inches and tied the knots exactly where needed before trimming and sealing the strings.

Last bit for the top was a ball to attach to the center post and some store bought "buttons" or plugs to fill the holes. I was going for an outside look with the green grass, blue sky, yellow sun and tiny white clouds.

A regular bead with a 7/16" hole drilled in it and glued in place.

Little wheels on table were used as spacers and then removed.

Okay. Now the "easy" part - the animals. I used the patterns from the book for all the animals except I swapped out the camel for a zebra. I made one of these about 10 years ago for my brother's kids and I used the camel on that one and he came out great. This merry-go-round was made for a friend's son and his room was decorated in a Africa theme so I thought a zebra would be more appropriate. I found one on clip art and sized him (or her) to roughly match the camel.

The animals were cut out using a bandsaw although a coping saw would have been fine. I used the same pine that the disks were cut out from for the animals. I did use a base coat of gesso to try and help with the coverage. It seemed to work fine. The giraffe still took 1/2 a dozen coats of craft store acrylic to get the coverage I wanted. Still, I think it helped.

The plans call for 1/4 dowels to go through the animals and into the platform so that it looks like the posts through the animals on a merry-go-round. While it would help secure the animals, I chose not to do it. I prefer the looks of the animals without the posts. They seem more alive. I ended up using super glue to attach them. The wood glue wouldn't adhere to the gloss acrylic finish of the platform disk.

So that was it. Time to take it for a spin. You just rotate the platform around the center dowel and the strings wrap around and then wind an unwind. It will run for about a minute. This is the second one I've built. Now that I have the jig built, I think more are in the near future.

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