GearHeads Forum

Nice work, thanks for sharing guys.


Cheers
Bob

I did one of those some years back, but I used a different joinery method. I cut box joints, cut off the ends of the fingers at 45 degrees (I used a disk sander), and glued it up. After glue-up, there was another nub sticking out from each finger to trim off.

"Bevel box joint" is probably as good a description as you're going to find for it...let's see if this drawing makes more sense, looking down from the top edge:

  As I finish a new kinetic art piece I want to share my experience creating a laser cut octogonal box. The box is 6.3" across the flats. Laser cutting the top and bottom was straight forward. The side pieces had to be cut at a 22.5 degree angle so that the edge of one side would butts perfectly with the adjacent sides when glued. To do this I laser cut a fixture for the 22.5 angle. I was pretty simple. First I taped down a scrap piece of 1/4" ply and had the laser cut two .2" wide by 2.625" long slots. Next I cut the 2 22.5 degree uprights that fit into the slots and position the length of each blank. This perfectly orientated the 22.5 angle to the X axis  and 90 degrees to the Y axis. I then cut the 8 side blanks a bit long and last place each blank with the grain horizontal on the fixture. I then lowered the cutting surface using the Z axis control to the correct focal point. Using the test feature of Laser Works 6, I jogged the X axis to the starting point for the cut on one edge and using a Y axis line cut the first side. Next I simply turned the blank around and place it back in the fixture to cut the other bevel.
With all the pieces cut next came making a another fixture so that I could butt glue one side to the next and hold them in alignment while the glue cured. With all but one side glued the last step was to glue the 7 sides to the base which houses the motor, nicad batteries and electronics. The 8th side has the control panel for a charging connector and switches. It is removable for servicing.
I hope to have some pictures and video of the finished piece in the next week. The only thing I would do differently on a similar project would be to cover the fixture in the area of the laser cut with a aluminum foil so while the laser cuts the blank the 40 watt setting is enough to burn the fixture also.

Dan Mauch