The Topsy Turvy Clock by Andy Clark

Andy Clark of The Workshop Shed blog made this, The Topsy Turvy Clock, after being inspired by a kids TV show, featuring a clock with numbers in the wrong places.

Andy Clark explains:

I saw a clock with the numbers in a Topsy Turvy order and wondered if I could actually make it work. After concluding it would be too much of a technical challenge to make it entirely clockwork, I decided to use stepper motors and software control. I wanted it to look like an original mantel clock so the brass mechanism and style of numerals were key. I had the numbers laser cut in card by a company who normally make wedding table decorations so the what I call "antique white" is actually "champagne". I started planning in late November last year so it's been a long build with mechanical, electronic and software challenges. I finished it just this week after a month of fine tuning and completing the software.

Here is where you can learn more about the Topsy Turvy Clock. It's also been entered in the Atmel Simply AVR Design Contest, so be sure to vote for it!

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BIRDSONG, with found feather -- a mechanical sculpture by Martin Smith

Check out BIRDSONG, with found feather, the latest mechanical sculpture by Martin Smith. Wonderful!

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Cabaret Mechanical Movement - The classic text on automaton-making in Kindle edition!

One of the all-time best books on the art and science of making contemporary automata, Cabaret Mechanical Movemen, is now available in a Kindle edition. This is great news, because the original paperback edition can be somewhat hard to get and used copies of the softcover book are quite expensive. Published by Cabaret Mechanical Theatre, a museum that pops-up all over the world to delight its visitors with some of the finest examples of the automata makers art, is largely responsible for the existence of the genre. As such, they are a name to be trusted.

From the book description:

Making automata is hard. Making other sorts of three dimensional objects can also be hard, but the extra dimension of movement seems to add a disproportionate amount of difficulty. For most people, especially those untrained in engineering skills, getting to the point where making mechanical devices is easy, can be a long and frustrating task. Then again, there are many people who have a sound understanding of engineering but can’t even draw a horse.

These things can be learnt. This book does not teach you how to draw a horse, but it does remove the mystery that surrounds the world of mechanisms and the business of making things move. Cabaret Mechanical Movement contains a lot of theory but it’s also packed with practical tips and ideas for making your own automata, moving toys or mechanical sculpture.

Chapter titles include:

• Who, What, Why?
• Some Principles
• Levers
• Shafts
• Cranks
• Cams
• Springs
• Linkages
• Ratchets
• Drives & Gearing
• Control
• The Checklist
• Bibliography
• Index

You won't find step-by-step plans to make an automaton, but you will learn a lot about the basic mechanisms that make most contemporary automata tick. You will also get valuable constructions tips for making moving toys and automata. The book includes over 200 black-and-white illustrations. I would say that alone, it may not be enough to get you started making autoamta, unless you have some previous woodworking experience. That said, it is an indispensable book on the subject and should be among the first those new to the field acquire.

Here is where you can get the Kindle edition of Cabaret Mechanical Movement: Understanding Movement and Making Automata

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"Serpina" -- an electromechanical wooden rolling ball clock by Christopher Blasius

Christopher Blasius wrote to let us know about his latest creation: an electromechanical wooden rolling ball clock. Check it out!

From the creator:

I have designed a new clock. Her name is "Serpina" and it's a electromechanical rolling ball clock. Instead of a pendulum, a ball rolls down an inclined plane, which takes 20 seconds. Then the seesaw then tips in the opposite direction and the process begins again.

For more information please visit his website at http://www.holzmechanik.de.

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Blast from the past: aging an authentic wood catapult kit, part 2

This is the second in a two part series reviewing the working wood catapult model made by Pathfinders. In the the first part, I reviewed the the kit and gave you some assembly tips. In this part, I'll tell you how I went about making the catapult look like it truly belongs on a medieval battlefield.


What is the Kit and Where Do You Get It?
The catapult kit is sold various places, but can easily be found from Amazon as the Pathfinders Medieval Catapult Wooden Kit.

Getting Ready to Get Old
Once the kit is assembled, you should have a bit of fun testing it out. I recommend throwing small grapes at a pyramid of empty aluminum cans. If you would like to make your catapult look old, read on. For this process, I used the following tools and materials:

* Carving knife
* Small wire brush
* Furniture finish touch-up markers
* Coarse twine
* Elmer's glue
* Sandpaper - 100 grit
* Minwax wood stain - Early American
* Round wooden disks
* Wooden wheel pegs
* Popsicle type "craft" sticks
* Soldering iron with wood-burning tip
* Gun bluing
* Portable hand drill
* Ball-peen hammer

None of these things are essential. You should feel free to use whatever tools and materials you have on hand or can obtain easily.

Making the Catapult's Wood Beams Look Old
The first thing I did was removed the string and washers from the model.

I used a carving knife to take the corners off of the straight edges of the wood. I didn't remove a lot of material because I didn't want to compromise the strength of the wood.

I just shaved off small, irregular shavings to make it look a little less perfect and perhaps as if the beams had been hand-hewn. I also rounded the spoon-shaped end of the throwing arm.

Next, I added the wood knots to the beams. I have a set of three wood finish touch up markers. I used the second darkest color. By gently resting the very tip of the marker on the unfinished wood, pigment from the marker is drawn into the wood fibers in a way that looks something like a real wood knot. Use the underside of the model to perfect your technique.

The knots may look a little too dark at this point, but don't worry. After placing knots of various sizes on the beams, I gave the entire model a coat of Minwax wood stain. I used "Early American" simply because I had some around. You can use whatever color you like, so long as it is considerably lighter than the knots you have made with the marker. This allows the knots to show through the stain. At this point, you should give your catapult some time to dry.

Later, I used a wire brush to give the catapult some scratches and wear marks to make it look like it had been used for years. I also used a wood-burning tool to add some grain lines and cracks to some of the beams. Make sure these lines follow the grain of the wood so that they appear natural.

I dipped the the string that comes with the kit in the Minwax and wiped the excess off with a rag. This makes the "rope" look old too.

Adding the Twine to the Crossbar and Throwing Arm
I am not sure if it is authentic or not, but I thought some cordage wrapped around the throwing arm and crossbar would look good. I also figured this would provide a bit of cushioning. I used a coarse three strand twine for this. I unraveled the strands so that I had a single strand. I tied one end of twine around the crossbar.

Next, I spread some Elmer's glue on the section where the twine was to be placed. I then wrapped the twine in a tight coil around the crossbar. I tied off the end and put a drop of glue on it to keep if from coming off.

This process was repeated on the throwing arm where it meets with the crossbar.

Making the Wooden Wheels for Your Siege Engine
I purchased a set of round hardwood discs that are 2 - 3/4 inches in diameter. I also purchased some wooden toy axle pegs and some craft sticks -- really they are just Popsicle sticks. All three items can be found at craft stores.

I used a soldering iron with a flat wood burning tip to create parallel lines on the wheels to make it seem as if they were constructed from individual planks. I also burned the edges of the wheels a bit to simulate wear and wood grain.

Next, I glued two short lengths of Popsicle sticks to the outside of each wheel to model the boards that would hold the wheels together.

I drilled a 1/4 inch hole in the center of each wheel and in the four corners of the catapult base. I sanded flat sides on the axle pegs and darkened them with marker.

Using the toy axle pegs, I mounted each wheel to the catapult. I glued only the holes into which the pegs go, so the wheels can move freely. Finally, I gave the wheels a coat of wood stain.

Finishing Touches to The Antiqued Catapult
The catapult was starting to look pretty old at this point, but the bright metal washers on the outside ruined the effect. I used the rounded end of a ball-peen hammer to dent one face of each washer. I then rubbed some gun bluing on the surface to give it a dark, oxidized look. DO NOT get this stuff on your tools.

In the end, I spent 30 to 40 minutes making the basic functioning catapult kit, and 4+ hours making it look old! I had a lot of fun doing it.

Where to Get the Kit and Other Supplies
Most of what you need can be found at your local hardware store, craft store, or hobby shop. If you have any difficulty finding these items locally, here are some online sources:

* Pathfinders Medieval Catapult Wooden Kit
* Wood carving knife
* STEEL SCRATCH BRUSH
* Sharpie Touch up Markers - 3 pack
* Sisal Twine
* Elmer's Glue-All
* 100 Grit Sanding Sheets
* Minwax Wood Finish - Early American
* Wood toy wheels
* Wood toy wheel axle pegs
* Cuisipro Frozen Pop Sticks
* Woodburning and soldering tool set
* Perma Blue, liquid gun blue kit
* Cordless drill
* Ball peen hammer

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Blast from the past: building a wooden catapult kit, part 1

 

 

This is the first in a two part series reviewing the Pathfinders Medieval Catapult Wooden Kit. In this first part, I will tell you about the kit and give you some assembly tips. In part two, I'll tell you how I went about making the catapult look like it truly belongs on an ancient battlefield.

The kit comes with nearly everything you need to assemble the catapult. The only material you need to provide is white Elmer's-type glue. The kit comes with a small swatch of sandpaper and suggests that you have a ruler and scissors available. The kit arrived in a slender cardboard box with instructions and parts separated into two plastic bags. No excessive packaging, no impossible-to-open-plastic-clamshell. I like that.

The kit contains just over a dozen wooden parts, two washers, some string, a small bit of wire, and some soft Play-Doh type clay -- otherwise known as "ammunition".

The wood is a clear-grained pine. Just one of the pieces of my kit had a medium sized knot in it. It had been filled with a little plastic-wood type filler to keep things solid and smooth.

How were the instructions?
The instructions are printed in black and white on 8 pages. There are instructions in English, French, and German which is nice, though they are intermingled in a way that requires a bit of scanning and rescanning. I found the directions to be very good, though there were a few vague spots. I'll address these very minor pitfalls in the next section. The line drawings in the instructions are simple and clear and serve as the primary means of instruction.

What helpful hints do you have?
Overall, the kit itself took me a little over half an hour to make, though they suggest that you set aside 1 to 2 hours. The kit is suggested for ages 9 and up. That sounds about right to me.

Here are a few helpful hints for the assembling the catapult kit:

1. Read the entire instruction manual all the way through, paying attention to the drawings. This won't take long and this will prevent any possible confusion.
2. At first, I wasn't sure how to tell the crosspiece that the holds the trigger from the upright braces. It's quite simple really: just read the directions (I hadn't yet). Note that they have thoughtfully placed red marks on the crosspiece and the base with which it mates.
3. The kit is held together with pegs that are glued in place. There are 18 total. Be sure to sift through the lot to find the two that a just a bit longer than the others. These are used to add tension to the string.
4. I found that the pegs fit rather tightly. The glue helps to lubricate them a bit. I gently used a nonmarring hammer to tap the pieces together. Alternatively, you could use the included sandpaper to slightly taper the ends of the dowels and ease their entry.
5. Add a safety/trigger - The trigger arm didn't always want to hold the throwing arm in place when under tension (OK, yeah...so maybe I have it wound too tightly). I rigged up a small diagonal piece of wood that fits in a notch to keep the trigger arm from swinging. By pulling this diagonal piece out, the trigger arm is free to swing and the catapult will fire. (See image below for my safety/trigger addition.)
6. A small hobby or razor Saw is handy if you want to trim some of the dowels that are left a bit over the surface of a few parts.
7. Consider staining and/or sealing your model to increase its beauty and lifetime. More on this in part 2 of this series.

So...does it work?
The packaging claims that the catapult can throw a soft clay ball over 15 feet. This is absolutely true. I easily achieved distances over 20 feet and don't think I have put undue strain on the model. Should you choose to add extra horsepower to your model (and this is just my speculation), I believe some added string and a reinforced crossbar would allow you to throw a grape twice as far as advertised.

The Verdict?
This is a well proportioned and historically accurate catapult. More specifically this is a mangonel variety of catapult that uses twisted fibers for its power source. I gather that many had a sling on the end rather than the spoon shape we typically see. (You can learn more about catapults from The Art of the Catapult: Build Greek Ballistae, Roman Onagers, English Trebuchets, and More Ancient Artillery)

Everything that was promised was delivered and the model outperformed the advertising copy. When was the last time you purchased a product that did that?

I give the Pathfinders Medieval Catapult Wooden Kit high marks.

What's next?
In the next installment of this article, I'll show you how to the catapult model look ancient and ready for a siege.

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Gear boxes, motors, vehicles and track drives from Tamiya

The Tamiya company produces a whole line of interesting mechanical components for model makers. These can be really useful for understanding key concepts better -- gear ratios, worm gears, and drive trains. Better still, they can integrated directly into your mechanical projects. Here are a few of my favorites:

Tamiya Tracked Vehicle Chassis Kit
Use this kit as a stand-alone or combine it with other accessories making a more complex machine with more capabilities. The gear box can be built with two possible gear ratios-Standard: 203.7:1 or High Speed 58.2:1. The motor is included.

Tamiya Planetary Gear Box Set
The Planetary Gear Set from Tamiya features a highly versatile system for reduction of high RPM electric motors to high-torque low RPM applications. RC-260 motor operates on 3 volts. Combining the gearboxes in various ways enables 8 different gear ratios -- 4:1, 5:1, 16:1, 20:1, 25:1, 80:1, 100:1, and 400:1.

Tamiya 70168 Double Gearbox L/R Independent 4-Speed
Suitable for use with remote controlled robots. Left/right independent design means you can set different gear ratios for either side. This set can be assembled for 1 of 4 different gear ratios -- 12.7: 1, 38.2:1, 114.7:1, and 344.2:1

Tamiya 72008 4-Speed Worm Gearbox H.E.
The gearbox features four gear ratios (84:1, 216:1, 555.4:1, 1428.2:1). The gear ratio can be easily adjusted by altering the middle and final gear attachment positions.

Tamiya 4WD Chassis Kit
The 4WD Chassis incorporates a four-wheel shaft-drive system similar to those in full size 4WD vehicles. A hex shaft transfers power from the center gear box to the outer gear box giving 4WD power.

Here's a full line of tools, materials, and kits offered by Tamiya.

[ Thanks Mike! ]

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