Monday 9 July 2018
This apple puzzle is very quick, simple and inexpensive to produce. Just three turned, wooden parts and a small, metal pin are needed to produce a puzzle that is intriguingly difficult to solve. It even looks attractive while it is sitting there waiting for inspiration to strike the puzzler. When well shaped and well turned, apples are most appealing objects. This apple, like many garden-grown apples, contains its own little visitor. The tiny, wriggling grub, peeping out of its hole, has begun its meal, but has it ruined the whole apple? Just remove the core to see if this apple is good or bad inside.
1. For the apple body, cut a 65mm long by 90mm square piece of your chosen wood. Make sure that the wood is cut accurately and square
2. For the apple core, cut a 110mm long by 30mm square piece of good hardwood
3. For the grub, cut a 20mm length of 9mm square close-grained hardwood
1. Threaded mandrel
2. 200mm length of 9mm threaded bar
3. 4 nuts and 2 washers to fit the threaded bar
4. Two 25mm diameter – plus a little bit – rubber bungs or doorstops
5. 3 pieces of wood to be turned to 25mm diameter with a centrally drilled 9mm hole
6. Length of 3mm metal rod
7. A 7.5mm drill
8. A 3.5mm drill
Placing the apple on the mandrel
Begin by taking the block of wood for the apple body. Using a pencil, mark diagonals across one end-grain face of the block
Set the block on a pillar drill in which is fixed a 25mm drill. Drill through the block at the centre point where the diagonals cross
Fit and lock the apple body block onto the mandrel. Hold the mandrel end in a chuck at the headstock and support the other end at the tailstock
Bring the tool-rest up to the work and rotate the work by hand to ensure that nothing catches
Use a roughing gouge to turn the piece down to 85mm diameter. Make sure all cuts are well made, and avoid tearing out the grain (A)
Shaping the apple
When turning fruit shapes, it is worth looking at the particular fruit you wish to copy. Take a long look at a nicely shaped apple. You will notice that its largest diameter is two-thirds up from the base. There is a tapering curve down to the base which flattens out. Try to follow this shaping using a gouge (A), turning into the wooden plug on the mandrel
From that largest diameter two-thirds of the way up the apple, use a 9mm gouge to turn a fluent curve, rolling it over towards the mandrel. It is important to keep the apple diameter as close to 85mm as possible to help the puzzle work effectively
Turn a hollow in the top of the apple, continuing the shape into the wood plug of the mandrel (B)
When satisfied with the apple shape, clean up thoroughly. Go through the grades of abrasive paper to produce a lustrous finish. When satisfied with the finish, remove the mandrel from the lathe and the turned piece from the mandrel
For the apple, I used some wonderful old mahogany cut from a large table leg I was given many years ago. As it moves and the light plays on its surface, this mahogany ranges in colour from a rich tawny red to a pale auburn brown. I first saw the laburnum from which I turned the core when it was being cut down in a front garden. The trunk was 45cm diameter, a magnificent piece. I spoke with the person removing the tree and he was only too pleased for me to take the trunk and any other usable pieces. Once I had the piece home, I split it into quarters, sealed the ends and allowed it to dry in a well-ventilated, covered area in the garden. The heartwood of that laburnum is so rich and dark and of such wonderful quality that it would compete with any of the world's great hardwoods.
Turning the core
Take the 110mm long by 30mm square piece of laburnum and set it between centres
Turn it down to 25mm diameter. Now, test the core inside the drilled hole through the apple. It should just be a sliding fit. Replace and turn, remove and test, until it is a sliding fit
Measure the exact length of the hole in the apple. It will be around 65mm long. On the laburnum piece in the lathe, measure that same distance from the tailstock towards the headstock. Mark a pencil line
In the area between the pencil line and the headstock, the stalk may be turned. At present, only turn it down to about 9mm diameter
At the tailstock end, undercut the base of the core then sweep back up towards the tailstock centre to give the appearance of the underside of an apple
The core remains partially turned until the 'locking' hole has been drilled. It can then be returned to the lathe to be polished and the stalk cut at an angle (A)
Drilling the apple and core
Remove the core from the lathe so that it can be positioned inside the apple and a hole drilled through both. To support the apple and core while drilling, choose a mug or cup into whose hollow the apple will sit so that it is firmly held with its central hole running horizontally
With the apple now sitting in the cup and its central hole horizontal, measure from what would be considered the top curve of the apple – where the stalk comes out – 27mm along the top surface. This will be at about its largest diameter. At this point, use a 7.5mm drill to drill vertically down to a depth of 9mm precisely. Make absolutely sure that the drill is aligned so that a vertical hole is drilled (A).
Using a 3.5mm drill, drill down through the original hole and into the core to a total of depth of 40mm from the top surface of the apple. This will drill only partially into the core.
Before removing the apple and core from the mug, mark on the waste wood at the stem, using typist correction fluid to indicate the top surface and the direction from which the drill entered.
Remove the apple and core from the mug, then remove the core from the apple.
Using the 3.5mm drill, complete the drilled hole through the core.
Replace the core in the lathe, between centres, and turn a 6mm wide band around the drilled hole in the core, down to 23mm diameter.
On either side of this 6mm band, turn a 6mm wide band down to 21mm diameter. Carefully clean up the core.
Turning the stalk and grub
To complete the core, turn the stalk. At 25mm away from the core body, the stalk should be 6mm diameter, tapering down to 3mm diameter where it joins the core.
Using the dot marked in white typist fluid on the waste end of the core as a guide, cut the stalk at an angle so that it slopes down towards the hole in the core (A). The sloping cut will begin 25mm away from the core. If the hole in the core has been drilled slightly off, don't worry. The sloping cut on the stalk will still ensure that the hole in the apple can be precisely lined up with the hole in the core, enabling the puzzle to be solved.
Clean up the sloping cut using abrasive paper.
Turn a small grub, which will fit into the hole in the apple. It must be 7.5mm diameter and about 15mm long. Shape the last 6mm into a grub's head.
Polish the apple body, the end of the grub's head and the top and tail of the core. Do not polish the inside of the core.
Assembling the puzzle
Cut a 23mm length of 3mm steel, measuring the hole depth to confirm the pin length (A). Small nails are ideal, as they are both cheap and sufficiently robust.
Fix the core in place, level with the top and bottom of the apple. Twist the core to make sure that its hole will not line up with the apple hole this time.
Drop the pin into the grub hole. Push the grub into place, but do not glue yet.
Try the puzzle. It should be possible to raise or lower slightly the core, but not to remove it. The steel pin will drop into the channels above and below the core's grubhole – but not into the drilled hole in the core unless by some fluke – preventing the removal of the core.
If the core cannot be removed, even though the pin can be heard to drop into the central hole in the core, then the pin is too long and needs to be trimmed.
If the core can be removed when the apple is held horizontally with the grub face down, then the pin is not long enough. Cut another which is a fraction longer and try again until successful.
When everything works properly, the grub can be glued in place. It can be a fine balance between the pin being exactly the right size, slightly too long or too short, but once you have got it this puzzle is a real brain buster.
Solving the puzzle
To remove the core, hold the apple horizontally with the grubhole uppermost and the edges of the core in line with the top and bottom of the apple. Rotate the core until the slope of the stalk points towards the grubhole. Slowly move the core until the pin drops into the hole at its centre. The core can now be withdrawn.