Disentangling Dick Hess’s “Pendulum”

PendulumWhen I approached Richard Hess about an interview for this blog I asked if there was a particular puzzle he wanted to discuss. One of his three suggestions was Pendulum, a disentanglement that he noted was an improvement on an older design of his. The improvement? The addition of a small wooden bead.

This seemingly innocuous addition – which serves to make it an even more difficult disentanglement – is something Dick found while exploring variations on the puzzle. This style of searching for new puzzles through an extensive examination of variations on basic disentanglement structures is characteristic of Dick’s modus operandi.

This can be clearly seen in his “Compendium of Disentanglement Puzzles”, which in its current edition catalogues over 10,500 of them arranged according to the structure of the puzzle and the solution method. His interest in disentanglements can also be seen in his enviable collection of over 30,000 mechanical puzzles in which disentanglements form a large part.

Dick was educated as a physicist (at BS Caltech and received his PhD from UC Berkeley) and spent his professional career at defence computer contractor Logicon, Inc, retiring some years back as a Vice President managing a unit of 300-400 people. Being an avid tennis fan and having played the game most his life he travels to grand slam and other tournaments every year. In between traveling, Dick took time out to answer some questions on Pendulum via email.

Saul Symonds: In your “Compendium” this puzzle appears with the name Improved Finnish obstacle. How did it get this name? (Editor’s note: the puzzle appears under the category “Type 1 Finnish Trapezes” with the alphanumeric handle “G558”.)

Richard Hess: A Finnish puzzler, Markku Vesala, first introduced me to the Finnish Trapeze structure and I added many embellishments from there.

SS: When did this happen? Was the Finnish Trapeze created by Vesala or does it have an older origin?

RH: This happened in the late 80’s. I don’t know if Markku invented it or got it from somewhere else.

SS: The solution to this puzzle involves two main “steps” or “movements”. When creating it did you start with the combination of these movements and create a form that embodied them or did you start with the finished shape?

RH: I started with the finished shape and managed to solve the puzzle.

SS: So you have to discover the solution to the puzzle in the same way as everyone else?

RH: Yes.

SS: How long does this first solve usually take you?

RH: From a few minutes to perhaps 30 minutes.

SS: And do all your wire puzzles follow a similar creation method?

RH: Normally, yes.

SS: Can you walk me through the process for creating the shape of the puzzle. Do you make sketches first or just start playing with wire shapes?

RH: Occasionally I make drawings but normally just build from wire straight away.

SS: Pendulum is a reworking of an earlier puzzle of yours, adding a green bead to one of the wire pieces. Can you explain how this complicated the solution process?

RH: The bead doesn’t fit through the slot so one has to figure out how to get the ring past the bead.

SS: You create wire puzzles that are very difficult to solve – is the difficultly of a finished puzzle something that you factor into the design/creation process?

RH: Yes.

SS: So how do you go about ensuring the required level of difficulty? Is it through adding more steps; sticking to moves that are counter-intuitive; finding new shapes for the puzzle; etc.?

RH: All of what you list can be involved. Often it’s tuning the sizes so that moves only barely can happen.

SS: You have an encyclopaedic knowledge of wire puzzles and the various ways of solving them, do you still come across ones that you find difficult to solve?

RH: From time to time, yes.

SS: What was the last one you found difficult?

RH: The last difficult one I produced is Keys to the Kingdom, which will be my exchange at IPP34.

SS: When creating disentanglements, how do you go about “disguising” the solution, so to speak, so that even an experienced puzzler will find it a challenge?

RH: Making the pathway for solution as small as possible increases the difficulty.

SS: A lot of your work with wire puzzles seems to be about exploring variations on a theme. For example, Five Keys shows how five handles, all with minor variations, are placed on the same puzzle in different ways. Do you find these variations through trial and error or do you have a more directed approach?

RH: Mostly by trial and error.

SS: In that puzzle you presented the solver with five “keys”, have you made other puzzles with more than one key but discarded them?

RH: No. I made the “Five Keys” from noting five different methods of putting a key on the trapeze shape.

SS: You have more than just a casual association with wire puzzles, as your compendium of over 10,000 of them clearly shows. How did this interest begin?

RH: My father had a collection of about 25 wire puzzles. As a 7-year old I was curious what they were and started with the bent nails, learning how to solve each until I could solve the Chinese Rings as a 10-year old. In high school I designed my first extension of a wire puzzle, which is A019, the Triple Compound Trapeze.

The collection of wire puzzles that first intrigued Dick Hess in a cigarette box (Photo courtesy Dick Hess)

The collection of wire puzzles that first intrigued Dick Hess in a cigarette box (Photo courtesy Dick Hess)

SS: In 2003 you published the seventh edition of your compendium. When did you publish the first edition and how did the idea start?

RH: The first edition came out in 1980 and was suggested by Jerry Slocum. By 1982 I had over 500 wire puzzles so a second edition came out then. Subsequent editions had 1400 (3rd), 2600 (4th), 7000 (5th and 6th) and 10500 (7th edition) puzzles.

A book that influenced me greatly was Wire Puzzle written by Yu Ch’ung-en in 1957. I have met his son and grandchildren, who were selling wire puzzles in Shanghai into the 21st century.

SS: Your compendium is interesting for the way it categorises wire puzzles according to both the parts of the puzzles and solution methods. How did you go about identifying and breaking down these categories?

RH: That was quite arbitrary.

SS: In Jerry Slocum’s puzzle classification system wire puzzles are just one category of disentanglement. What do you see as the major significant sub-categories of disentanglement?

RH: The subcategories of wire puzzles are quite arbitrary but I use the following:

4.2A Wire Sets Boxed
4.2B Wire series and Packaged Sets
4.2I Hard Wire and Bent Nail Type
4.2J and L Large Blacksmith, Tavern, Bortolazzo and the like
4.2K. 3D Wire Puzzles
4.2 M Chinese Rings
4.2 N Miscellaneous Wire Puzzles

SS: Are there types of solutions that you gravitate towards when creating wire puzzles?

RH: Not really. I look for as many varieties of solution technique as I can find.

Pendulum can be purchased directly from Dick Hess.

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4 Responses to Disentangling Dick Hess’s “Pendulum”

  1. George Bell says:

    Nice interview! Pendulum is a personal bugabear of mine. I managed to solve it once but have never managed to repeat this. Did you manage to solve “Pendulum”?? As I remember his Compendium does not have any solutions.

  2. saulsymonds says:

    Hi George, I did manage to solve the puzzle but it is easy to get lost in it and I’d have to try it again to see if I still remember the solution. What edition of his Compendium do you have? In the 7th edition he has a new section that describes 20 different “solution principles” and for each puzzle he then tells you which principles are required and in what order. It’s not exactly a solution but it may help put you on the right track if you’re stuck without giving too much away. Saul.

  3. saulsymonds says:

    It was very useful. It helped me to gain an understanding of how particular parts of a disentanglement puzzle change the solution path. This is actually one of my favourite books on mechanical puzzles.

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