woodturning, project, Woodworking

Locking box project - competition entry

Last Monday was the first woodturning competition of the Hampshire woodturners association. Well I say first, it was the first in a new run, done differently than previous. Certainly the first competition of any form I have been in. The format of the competition was that every entry was for one of four categories, defined by phrases. A) boxing clever B) one night stand C) bowled over D) the big apple you could choose to interpret these any way you like. Rather than specific judges, everyone got to vote for their top three choices. They could vote based on any criteria they liked. The results were summed up to find the first,second and third place entries.

I didn't win, or come second, or third.

However I really enjoyed competing. I spent quite a lot of time thinking around the phrases to come up with ideas to enter.

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Ultimately this is what I made

It's a 'clever' box, in so far as it has a locking mechanism in the lid. If you turn the knob on the top it causes two pins to move in and out of the sides, locking and unlocking the box.

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This started life as a rough prototype

here I turned a small disc to put on the end of a dowel, and two small wooden pegs to atatch via panel pins. This was inside a cylinder with two holes for the pegs to pass through. Turning the dowel causes the pegs to pivot and retract through the hole. Turning the other way pushed them out again.

This prototype made a couple of things clear, I didn't need such a large range of motion, and certainly didn't want so much lateral motion, as the holes for the pegs could be snug. This was a good thing as it meant if the dowel section was just wide enough, I didn't need a disc, I could pin directly to the end of the dowel.

I knew that one issue would be grain matching the lid and the base. Normally with boxes you try to remove minimal material to preserve the grain match. Ideally with lid in place it should look like no material has been taken away. However my mechanism would require at least 10mm of overlap.

Fortunatle when I turned my chosed block of wood, some Indian rosewood, it looked like this:

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right at the point I wanted to take the lid, all the grain runs straight for about 50mm. Absolutely perfect for my needs!

I proceeded to part into lid section and base, hollowing the base as usual for a box. I left the base unfinished, and on it's spiggot as I wanted to turn the lid and find out how things would fit together before comitting myself on the base.

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I turned the overlap section of the lid, checking the fit against the base. Then hollowed enough space for the mechanism to fit. I also drilled the 5mm holes for the pegs to go through. And finally a broad hole through the whole lid for the main dowel to pass throguh. I finished the lid much as you would expect and reached this stage

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next i needed the knob for the top, with it's dowel section to pass through the lid. I turned it with the dowel section first to check the fit against the lid as I went.

This let me make it so the dowel section came exactly level with the top of the holes for the pegs. I marked a ring on the end of the dowel section, and drilled two small holes for the panel pins to go into.

Then I chopped some small sections on the bandsaw so that I could turn two small pegs, to fit in the 5mm holes

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with it still on the lathe I could check the fit through the side holes. I could also drill a hole for the panel pin to go through.

Finally I could assemble the mechanism. It required some fettling to sand the peg ends to allow them to pass past each other enough in the tight space.

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there was also a lot of fine adjustment of length such that fully retracted they stayed in the holes, but fully extended they locked nicely in place.

I then remounted the base on the lathe, and measured the depth to scrape a recess in the wall for the locking pins to latch in. This was quiet delicate as the wall was already pretty thin.

Finally everything was in place and working. This just left me to turn a cover piece to hide the mechanism, and properly finish the base.

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I am really pleased by how this design worked out. Not everything went perfectly, but basically the concept worked.

Whilst I didn't win the competition, I did get some encouragement from our local professional woodturner Les Thorne, who urged me to refine the idea. For the first time in woodturning I think I will. Until now I've tried all sorts of different projects. But this feels like something I'd like to do more of, and get better at.

So watching this space for more turned mechanisms!