How to Build the Tower of Hanoi - Two Lads With Their Grandad.




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It was the Easter holidays, off to the various parents' for a few days, and Grandad had a surprise for #1 and #2 son - he took them to his school workshop to use proper power tools.

Of course, they needed to actually make something, so he prepared the parts they needed to make a wooden puzzle - The Tower of Hanoi.

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Step 1: What You Need.

Wood, and tools. Lots of both. When Grandad works in a high-school technology department, you can get both quite easily.

The boys used 15mm-thick MDF for the base, 5mm thick MDF for the puzzle-pieces and 5mm dowel for the posts.

The tools they used included coping saws, tenon saws, scroll-saws, files, glass-paper, a pedestal drill, power-sander, band-saw, circular saw and a mallet.

Oh, and goggles.

Step 2: The Base.

Start with your lump of MDF, and drill three holes for the posts.

The holes need to be around 50mm apart to allow the puzzle-pieces to sit side-by-side.

Using the pedestal drill and a 5mm bit, drill the holes about three-quarters of the way through the base. If you are able to, set the stop on the drill to prevent it going all the way through.

After drilling each hole, knock the dust off the base, don't blow it off.

You will, of course, need to wear goggles.

Step 3: Shaping the Base

You could leave your tower with a plain rectangular base, but the boys ~~needed an excuse to use more tools~~ wanted to make theirs more interesting.

They drew outlines on the bases, leaving enough wood around the holes for strength.

They practised using a coping saw and a tenon saw on scrap wood, and decided they would rather use a power tool to cut out their proper bases.

So, roll out the scroll saw. Goggles on again, make sure the guard is placed to allow the base through without finger, and let Grandad hold the base firmly while you guide it through.

Step 4: Filing!

The cut-out shapes didn't exactly match what was drawn on them, and MDF had sharp corners.

Time to break out the files.

Files were popular - as noisy as a power-tool, without having to worry about where the emergency stop button was.

Step 5: The Posts.

Grandad used the scroll saw to quickly cut three posts for each boy, about 60mm long.

To help them fit in the drilled holes, and to allow air to escape*, he added a slight chamfer with the disc-sander.

The boys then smacked them into place with wooden mallets, and friction held them firmly in place.

* I didn't realise, but apparently square-ended posts trap air in the hole, which is compressed as the post is pushed in. This pressurised air can split the base. You can get away without doing it, but not if you are using glue in the hole as well.

Step 6: The Puzzle Pieces

Grandad had pre-prepared squares of 5mm thick MDF, one each of 30mm, 35mm, 40mm, 45mm and 50mm square.

The boys had to find the centres, drill holes fractionally larger than the diameter of the posts, and then smooth the edges and corners, and remove their pencil marks, with glass-paper.

Since the pieces were too small to clamp, they used a small hand-vice to hold the MDF during drilling.

Step 7: The Finished Product

There they were - done.

Both boys had, in about ninety minutes, turned scraps of wood and MDF into proper, usable puzzles.

They had experienced tools and techniques that most children don't get to use until they are years older (#2 son is seven - most UK schools restrict use of scroll-saws to age 13), and learned how to use them safely (they also had a go with a plane, and watched Grandad use a band-saw and a circular-saw).

Most importantly, they had a great day with their Grandad, and took another step towards getting their own accounts on Instructables (surely the pinnacle of any Maker's career?).

Some background to the puzzle.

If you don't want to build an actual tower, you can attempt the puzzle here.

I didn't do an awful lot except take photos, and help out with some of the more boring sanding (who can sand things when Grandad is using power tools taller than you are?)

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43 Discussions


9 years ago on Step 1

i just thought i should add the alternate names for us not living in the u.k. tenon saw = miter box saw, circular saw = table saw, glass-paper = sand paper, and pedestal drill = drill press.


10 years ago on Introduction

i got a math question with this never heard of it before and it had no pictures and not well described .so i never figured it out

Doctor What

11 years ago on Introduction

Wait, so there's more than one member of your family in the education "industry"? That must be painful for your kids. Especially when they get into high school.

14 replies
KitemanDoctor What

Reply 11 years ago on Introduction

Let's see ...

  • Kitewife and myself are teachers.
  • Their Grandad (Kitewife's father) was a teacher, now he's a technician (all in the same school he went to as a pupil!).
  • My sister is a teaching assistant.
  • Both grandparents on the other side (my parents) both used to lecture at college.
  • Kitewife's brother trained to teach, but gave it up.
  • #1 son's best friend's father is a teacher.
  • Kitewife's best friend and her husband both teach.

Yup, they're doomed...
Doctor WhatKiteman

Reply 11 years ago on Introduction

That must be 'orrible. Your family will always know when they are failing a class. Always know when they get into trouble. It's like a secret organization of spy-teacher-families.

KitemanDoctor What

Reply 11 years ago on Introduction

My boys don't fail anything. They constantly surprise us with just how much they know.

(#1 son, age 11, was helping me mark maths papers over the Easter break. His predicted grades for May's exams are equivalent to children 3 years older. #2 son has run out of books to read in his school library.)

KitemanDoctor What

Reply 11 years ago on Introduction

They're working on it - they're currently lacking in the strength and manual dexterity required for some of their ideas.

And the money...

("Daddy, If I bolted rockets onto the car here, here and here..." )

Doctor WhatKiteman

Reply 11 years ago on Introduction

They've actually wanted to bolt rockets onto your car? That's amazing! The apple doesn't fall far from the insane asylum.


11 years ago on Introduction

Ewww - the computer science memories are flooding back. What was it - recursion for the tower? Anyway - sounds like a great day - nice documentarianism!! (yes i see the red line below that, who says I can't make up words???)

1 reply

Reply 10 years ago on Introduction

I make up words too!! Like "ninja-tastic" and "buttkneed". Buttkneed it when you knee someone in the but. They got "buttkneed".


10 years ago on Introduction

Lolz, if it had not been for the teeth I would have thought that the kids were the same person!!