Facets, the Next Logical Step #1: How hard can it be to make a Dodecahedron?

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Blog entry by shipwright posted 12-12-2010 03:37 AM 6629 reads 17 times favorited 17 comments Add to Favorites Watch
no previous part Part 1 of Facets, the Next Logical Step series Part 2: Planning the Base »

The next box in the series Oops!, A Llittle Cabinetree, and now Facets is on the build. It had to be started because I’ve been obsessing too much on the finish of Cabinetree and in order to amuse myself between coats I had been so bored I had started making micro plywood and then micro boxes and banding. It had to stop.
So the other day I started to think about what the next logical step would be keeping the theme and some of the aspects of the others but going a very different direction at the same time. It was obvious. The one thing that stands out as the same in the other two is a “square” box so let’s start with something else. So….. how hard can it be to make a dodecahedron?

It turns out it’s really easy. After all it is just a dozen identical pentagons and precision tools are all about making identical parts. This is the simple jig I set up to experiment with. Turns out it did the whole job without needing any adjustments. I don’t like to count on angles on miter gauges and the like. I prefer to draw the object, pentagon here, full size using simple geometry. and set my saw to fit this large scale angle. To me it seems to leave less margin for error. So, here the miter gauge is set up to run pentagons. Just cut, rotate and cut until they’re done.

Now that I know that the jig cuts perfect pentagons, I can go ahead and bevel the edges so they fit together. Here I had to trust the tilt scale and as the math told me I should try 31 3/4 degrees, that’s where I set the saw and it turned out to make perfect fits. I guess the old Unisaw is OK. Rather than move something that was working I just added a small shim to make the beveled cut a little smaller than the original pentagons.

At this point out came the packing tape to check that everything was close enough to bother going on. If at this point the fits aren’t just about perfect the whole thing will eventually go sideways for sure.

I decided that a hinge-up top would be fairly dramatic on this box so that meant some of the edges would have to have solid strips added to hide the MDF when it was open. To do that I just increased the size of the shim and cut two sides off square and shorter than the rest. The tricky thing here is that after you cut the first one you must rotate the just cut edge away counter-clockwise to make the next cut. Don’t ask me how I figured that out. This is because you are making two sides different from the rest.

Just as it was necessary to rotate counter-clockwise when cutting sides different, it is also necessary to rotate clockwise when cutting to make all sides the same. Sounds strange, I know, but think about it. It does make sense after a while.

Once I knew that I could make a dodecahedron it was time to figure out what to do with it. This is the plan I sketched up. I like it. I always thought that the square box was “harsh” in the organic flowing lines of the tree in Cabinetree. I’m not sure whether I like or dislike the discord that the contrast introduces. At any rate this is a chance to play the opposing side and have both options covered. This shape will suit the tree more sympathetically and the tree can play more of a visual role than just the “supporting role” that it played in Cabinetree. Sorry about the rambling on but this is how my “design process” works.

One aspect that I did want to carry over from Cabinetree was the dyed marquetry. I’m not finished with that idea yet and when I looked at the surfaces available here it was immediately obvious that they were made for a big maple leaf. Here a blown up photo of a big leaf maple leaf is fitted to a masking paper mock-up of the surfaces.

And in this photo it is wrapped onto the form. I think this will look really nice if I can pull it off.

Open wide and say AHHH. When I saw the way it opens I wanted to change the name to “Tridacna” (giant clam) and substitute branching coral for the tree but the leaf looks too good so maybe that one will be the next box. The hinge is a slight modification on a piece of prototype left lying around after Cabinetree was built. It will be much more strongly attached when it gets veneer on both sides.

As for Cabinetree, I should be taking it to the photographer on Monday or Tuesday. I’ll post it as soon as I have photos. Thanks for your patience.

That’s it for now I’ll update this as I move along but as this is a “real time ” blog it may not be every day.

Comments, critiques and questions make the world go around so don’t be shy.

Thanks for tuning in.


-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees.

17 comments so far

View RonPeters's profile


713 posts in 2904 days

#1 posted 12-12-2010 05:51 AM

Very cool project…

-- “Once more unto the breach, dear friends...” Henry V - Act III, Scene I

View FirehouseWoodworking's profile


708 posts in 3297 days

#2 posted 12-12-2010 06:02 AM

Way cool indeed!

The first thought that came to me is that would be a great graduation gift for a high school or college soccer (or futebol for our overseas brethren!) player!

-- Dave; Lansing, Kansas

View sedcokid's profile


2733 posts in 3622 days

#3 posted 12-12-2010 06:40 AM

You are way smarter then I am to figure this out!! This is a great project…

Thanks for sharing!

-- Chuck Emery, Michigan,

View BritBoxmaker's profile


4611 posts in 3060 days

#4 posted 12-12-2010 01:11 PM

Fascinating!. I admire your precision. An elegant solution. I can’t wait to see the, veneered, finished article.

I agree about the discord with the organic shape of cabinetree. Sometimes this ‘works’ though. In this case the organic Maple leaf form ameliorates this. I find a lot in common with your design process and my own. I love to ramble and this seems to spawn many different projects.

Incidentally the open clam shell looks like it would make an excellent display platform for another project, housed internally.

Veneering is going to be tricky on the inside of the dodecahedron or do you plan another one, pre-veneered (at least on the internal sides)?

ps Could you not combine the pentagon and angle cut into one, with the blade set at 31 3/4° before you start?

pps Sorry to disappoint Dave but the football (Soccer type) is based on a truncated icosahedron

-- Martyn -- Boxologist, Pattern Juggler and Candyman of the visually challenging.

View SPalm's profile


5320 posts in 3906 days

#5 posted 12-12-2010 02:58 PM

Fascinating brain you have there Paul.
This is great to follow along.

Like Martyn, I was wondering about the inside veneer. Is this thing just taped together at this point, so that you can disassemble and veneer all? If you are starting over, maybe put in an internal wooden patch to strengthen hinge attachment before veneering (?).

Love it,

-- -- I'm no rocket surgeon

View BigTiny's profile


1676 posts in 2912 days

#6 posted 12-12-2010 03:00 PM

Wild! Here’s an idea for a variation on the theme. Leave off the bottom face and extend the adjacent faces to a point, making it look like a diamond shape. Add a suitable base/holder and there you go.

-- The nicer the nice, the higher the price!

View patron's profile


13606 posts in 3365 days

#7 posted 12-12-2010 03:15 PM

this is sure a simple project
to pass the time

while the glue dries lol

looking good paul

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View terrilynne's profile


836 posts in 2917 days

#8 posted 12-12-2010 06:59 PM

Sheer genius! You see these things in your sleep too, don’t you. Can’t wait to see it finished!

-- Terri, Rocky Mountain High Colorado!

View tdv's profile


1188 posts in 3094 days

#9 posted 12-13-2010 09:23 AM

Shipwright has officially left the planet. Paul quite amazing you’ve got real drive & imagination can’t think where you go from here

-- God created wood that we may create. Trevor East Yorkshire UK

View shipwright's profile


7992 posts in 2822 days

#10 posted 12-13-2010 05:16 PM

Thanks everyone. I apologize, I answered yesterday but apparently didn’t click “post”.

Martyn, Steve has it right. It’s just taped together. I use a lot of packing tape and masking tape for preliminary setups and for glue-ups around my shop. It will be veneered both sides before it gets glue. And yes, the two operations could have been done at once, but I was feeling my way along at that point.

Steve, The hinge is butt glued to the MDF here but there is about 3/4” on each side that is thinned down to MDF thickness and will be veneered over on both sides like a sandwich. It will be very strong.

Big Tiny…. Thanks, good idea….. Just what I need right now …... more ideas. (lol)

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees.

View BritBoxmaker's profile


4611 posts in 3060 days

#11 posted 12-13-2010 05:58 PM

Yes, masking tape. I need shares in it.

-- Martyn -- Boxologist, Pattern Juggler and Candyman of the visually challenging.

View Dennis Zongker's profile

Dennis Zongker

2744 posts in 3616 days

#12 posted 12-13-2010 06:31 PM

That is really cool. Great looking Blog.

-- Dennis Zongker

View Blake's profile


3443 posts in 3898 days

#13 posted 12-15-2010 07:12 AM


I like how you think.

-- Happy woodworking!

View Napaman's profile


5526 posts in 4101 days

#14 posted 12-19-2010 10:17 PM

very cool!!!

-- Matt--Proud LJ since 2007

View stefang's profile


15881 posts in 3358 days

#15 posted 01-03-2011 07:02 PM

Great project and great blog Paul. I love the way you did the hinge too. It came our very well. I was late in seeing this and so I’m just trying to catch up now.

-- Mike, an American living in Norway.

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