|Project by Gianni||posted 03-02-2013 12:53 PM||5229 views||12 times favorited||11 comments|
After seeing the super cool Metthias Wandel machines, I decided to make this much simpler version of the box joint jig. I used a 16 tpi threaded rod with a nut pressed into the outer box, and loctite-ed two nuts with large fender washers on the inside box such that it could turn freely with little or no play. The 16tpi rod makes it easy to translate turns into inches in standard increments for the dado stack.
The first attempts to cut joints advancing against a standard blade resulted in failure, and it took a while to figure out that the cheapo saw blade i was using had less than an eigth inch kerf. Frustrating. I put in the dado stack with no shims and measured it at 0.495. That setup gave me a very tight friction fit with zero gaps… Happiness, save a concern that the joints wouldn’t allow any glue (I had to knock apart the dry fit pieces with a mallet). I added a pair of paper shims and that resulted in the pictured joint, which had a sliding fit that squared itself up nicely with some clamp pressure.
I can’t go as fast as the Metthias Wandel jig, as i have to turn 16 cranks between cuts and manually crank all the way back between pieces to “reset” the jig, but I won’t miss an extra 5 minutes per project, so that’s fine by me. I cut test pieces holding only the outer box and with my fingers over the edge of the inside box to put sideways tension on it during the cut. I thought this might make a difference to take out any slop in the lead screw, but it didn’t seem to matter – the shimmed blade leaves about a 1 mil spacing in the joints which seems to be adequate to account for any slop in the jig.
I’m very happy with the results, and thanks to Mr Wandel for the inspiration. His machines are nothing short of amazing.