puzzle that almost fits together

The idea of creating multiples of an object instantly made me think about identical pieces that could fit together in some way – wooden puzzles came to mind. I did some research to get references of what was already out there, and find puzzles that needed identical pieces, but not too many. Turns out there's websites dedicated to this sort of thing (obviously?)

I was initially thinking of the wooden star puzzle, but just getting a good sense of the exact shape of each piece wasn't easy, since there's so many cut angles. Apparently this shape is also known as the "Escher Solid", and can be tessellated on all 3 axes. (credit to this video)

wooden star puzzle

After some more research I realized that this was a variation of the diagonal burr puzzle, and the triangles / cuts at the end were just decorative – the puzzle mechanism was the same

diagonal burr puzzle

There seems to be a lot of people who are into making the puzzles, not just solving them. I found a bunch of resources for techniques to make them (like this and this). Despite Ben's warning about the lack of precision with the shop tools, I wanted to give it a shot and see how far I could take it.

a single unit of the puzzle
"square" dowels from home depot. one of them is clearly warped

Ben helped me figure out a 45 degree jig and a way of holding the dowel down to pass through the band saw

I needed to make a method of drawing out the angles on the dowel, so set out to make a small jig – after a lot of time figuring out the required trig

jig for drawing the triangles
sanding down some wood from the junk pile to 45 deg
my jig setup for the band saw, clamped to the miter gauge 

The miter gauge is not accurate.. and it was hard to make get the lines of the triangle to line up using the band saw

the band saw was not going to work

I then tried using the vise with the japanese saw, and hand-sanding the triangles down, but that proved to be pretty inaccurate as well – it was hard keeping an eye on the angle I was cutting with the handsaw, and hand-sanding created a bumpy surface since it depended on where I was putting pressure more / less.

clamped with the vise
bumpy jagged cuts with the handsaw + hand-sanding

I then went on to try the scroll saw, which seemed to be the most promising tool so far.

scroll saw, gripping the dowel with both hands, using the wall of my jig
scroll saw cuts – almost there
things seem to fit pretty well

I decided to go forward with this, and measure out my pieces. Aside from the limitations of the tool itself, there's also limitations of the space around the tool which one needs to account for. The dowel I had was 36", which was too big to cut in one go. I also needed to ensure that I left enough place to hold the dowel with both hands, on each side, while trying to be economical with material.

dowel is too long. probably a good thing the pillar was in the way, using such a long piece would have been hard to control, with too much give.
all measured up and ready to go.
not perfect, but not the worst cuts. at least I didn't cut out too much 
using the band saw to cut off the ends that I was using for grip
sanding down the ends

I still needed to figure out the best way to get the notches to be more precise – Ben to the rescue again. I learnt about a much better alternative to hand-sanding – using a file, which allows me to get flat surfaces.

marking out the areas that needed to be filed down, after testing each piece with multiple other pieces for fit
clamped up with some sacrificial wood to protect the surface of the puzzle piece.
post-filing, pre-sanding

The pieces still didn't fit together – probably because of the imperfect squares as well as the imperfect notches. I sanded the pieces with the straight (band?) sander, and tried to soften the edges a bit.

the sander can eat up material if one's not careful! this was more than I intended for
the straight/band sander isn't entirely flat either – the ends are sanded more since that's where my hands were putting pressure, and the middle of the sander is more flexible
the (almost) finished pieces ... 
... almost fitting together. it sits like this at least!

I would still like to work on this more – try to gently sand down the side a bit more to see if I can get a better fit. And since I over-sanded one corner, perhaps try to create the star puzzle by sanding of pyramids from the 2 outside corners of each piece. I also want to try some kind of finish – oil or wax or paint.

Overall, I'm pretty pleased with the results, however imperfect they are. I got to try a bunch of different tools and learn more about what they are and are not good for, and made two jigs. Angles are hard, I need a better protractor.