Puzzle Making for Woodworkers

Donald BellSFW Meeting, January 2011

Email : donald@marchland.orgWeb site : www.bellwoodwork.com

Puzzle Making for Woodworkers

What makes a good puzzle?- It should be easy to describe- Fairly easy to make (either one or many)- Not trivial to solve, but not dauntingly

difficult either (solving time between 10 and 30 minutes, perhaps)

- The “look and feel” should be attractive- There should be a surprise – either an

“Aha!” factor or several puzzles in one

Puzzle Making for Woodworkers

The puzzle-maker’s progress

- Solving other people’s puzzles- Copying other people’s puzzles- Modifying other people’s puzzles- Creating original puzzles of your own- Developing the manufacturing processes- Documentation, packaging, sharing …

Different kinds of puzzle illustrated here

- put-together puzzles (2D)- put-together puzzles (3D)- "steady hand" puzzles- sequential puzzles

Also (but not shown here)

- take-apart puzzles- (especially "burr" puzzles)- scroll-saw puzzles- sliding block puzzles- secret compartment boxes

More kinds of puzzle illustrated here (back cover of same book)

- put-together puzzles- "steady hand" puzzles- sequential puzzles

Also (not really puzzles)

- magic tricks- games of skill

The “Blockhead” Puzzle- Easy to describe- Not hard to make- Not trivial to solve- Definitely an “Aha!”

moment when you work out how to do it

A Brief Tour of the Workshop

Band SawRecord Power BS 350 1½ HPcut depth 230mm, throat 340mm

Woodturning LatheRecord Power, Model CL3¾ HP, 5-speed belt drive

Record Power TS200SB2 HP, 4000 rpm250mm (10") bladeSliding Beam(605mm travel)

Table Saw

Sliding Beam, Mitre Fence, 45 degree tilt

Disk Sander Clarke CDS 300

300mm diameter1 HP, 1450 rpm

Radial Arm Drill PressAxminster AWBRD550¾ HP, 5 speed belt drive

Portable Router

Clarke Contractor CR23 HP, 21000 rpm½" collet

The Puzzle Maker's Toolkit

A few puzzles for you to play with – this is a secret opening box (there is something under that thumb!)

Four small cubes can be put together in eight different ways, including a straight stick and a square. The other six pieces, plus a 3-cube L-shape, make up the Soma Cube Puzzle.

Easy to make and not too hard to solve. There are 240 solutions

Alternatively, take away the L-shape piece and use the other six pieces to make a big L-shape twice the size. A bit harder.

A well-known, easy to make puzzle

The "Soma" Cube

Conways's Curious Cube

Six of the pieces are 2" x 2" x 1" blocks.

And there are three 1" x 1" x 1" cubes.

They can be assembled into a 3" x 3" x 3" cube, but there is only one way of doing it.

(John Horton Conway is a mathematician who has produced many wonderful puzzles)

A puzzle with an "Aha!" factor

The Fifth Chair Puzzle

The four chairs are the same shape, but different sizes.

Two small, one medium, one large.

Use them all to make a fifth (giant) chair, the same shape as the others.

Can you ALSO discover the mathematical principle that makes the puzzle possible?

Here are the dimensions of the chairs in mm.

Height Width Depth

Small 63.0 50.0 39.7

Medium 79.4 63.0 50.0

Large 100.0 79.4 63.0

Giant 126.0 100.0 79.4

Easy to Make, Very Hard to Solve

Professor Hoffman's Cube27 identical blocks of wood (often made in 27 different types of wood)

If they were all perfect cubes, 5x5x5, they could easily be packed into a 15x15x15 cube.

But these are 4x5x6, so each one can have one of six orientations.

A 4x5x6 block has 4% less volume than a 5x5x5 cube, so there are a few small gaps in each layer

Here are the three layers of one solution, but it is hard to find