October 11, 2009

Laser-cut Puzzle Box

Unfortunately, I didn't (and don't currently) live within easy access of any power tools, so my ability to build new puzzles was somewhat limited. I was searching the internet for fabrication labs, places where you can pay a fee to use various tools that could be used for prototyping, and discovered a place called the South End Technology Center at Tent City. This is a non-profit collaborative venture between the Tent City Corporation and MIT whose purpose is to provide free or low-cost access and training in most aspects of computer-related technology.

This might not sound particularly exciting, but in addition to classes on a number of aspects of technology such as word processing and web design, they also have two laser cutters and two CNC routers for open use! All you have to do is show up during Open Access Fab Lab time (Thursdays 5:30-8:30pm or Saturdays 1:00-4:00pm), and they have volunteers there who can get you started. Pretty cool, eh?

Well the first thing I thought was that it would be really cool to try to build one of Bruce Viney's puzzle box designs using a laser cutter, since his designs consist mostly of cutting plywood at 90-degree angles. This would make it fairly easy to create in a computer so a laser cutter could cut it out.

For my first project, I decided to try making Modified Matchbox by Peter Wiltshire, which is an alteration of Matchbox by Bruce Viney that makes the proportions a cube. I wanted to try making something more complex, but I thought it would be best to try something simpler to get the hang of things first.

The lab uses a program called Inkscape, which is a vector art program, to create the files that are sent to the laser cutter. Before I went to the lab, I created an Inkscape file that would cut out all the parts for Modified Matchbox, so when I arrived I just had to pop in a piece of wood and set it to print. The whole process was quite easy, and a few minutes later I had all the parts cut out. Now I just had to glue them together!

The results were decent but not great. I had assumed the kerf of the laser would be negligible, but unfortunately it was not, so each piece was slightly too small. The final box still worked, but it wasn't as good as I had hoped. You can see in the photo above that the top panel is slightly higher than the top of the front panel, which isn't ideal.
I finished it using some stain and wax, which unfortunately turned out a bit duller than I hoped it would. I was hoping that the stain would highlight the grain a bit more to give it depth, but no such luck. I had used plywood, so you can see the plys at the edges which also don't look too great. It would probably be better to use a proper wood that has been planed down to the right size, at least on the outside panels.

I tried another attempt a weeks later that turned out a bit nicer. I scaled up the pieces to account for the laser kerf and was quite careful to focus the laser before I started cutting. This helps reduce the width of the laser. I finished it just with wax, which I think looked nicer.

One of the biggest problems with using a laser is that it burns the wood rather than cutting it, so you are left with an ashy residue on the edge that must be sanded off. This isn't too bad when you just have a few pieces, but it is a bit of a pain having to sand every edge by hand. With the plywood I used, this residue is a bit sticky as well, so it is important to remove it for smooth operation.

Despite the mixed results, it was a lot of fun being able to build puzzles this way. There are a ton of interesting puzzles that can be built just with a laser cutter, so I just had to decide what I wanted to try. I'll write about some other attempts in later entries. Unfortunately during the summer the lab was only open on Thursdays, so I had to wait a whole week before I could try some more designs.

Tomorrow I'll write about two more interesting Hanayama cast puzzles.

1 comment:

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