Eleven Grooved Box Step by Step – Part 5: Making the Splines
Making the Splines
See the original “Woodwright’s Shop” video here.
Splines are made cross grain. This makes the strongest joint, but the thin blank will be fragile before gluing into it’s ultimate home. I like to use contrasting wood, Walnut for these Cherry boxes, Aspen for a Walnut box. The first step is to rip down a piece of scrap leaving slightly more than an eighth of an inch of wood. If you’re careful you can get three splines at a time out of a 3/4″ board.
Move to the miter saw and slice off the end of the block to make blanks a little wider than a quarter of an inch. Contrary to what Roy says in the PBS video, it’s OK to be a little bit off as these will be planed down on both sides anyway.
Also it’s OK if the blanks are somewhat short. Just cut them in the middle and when gluing, spread the two pieces out so the empty space is in the bottom half of the box where it won’t show. Ideally, you want the spline long enough to protrude about 3/16″ from the ends while gluing so you can plane down to a clean end after the glue sets.
My jig for sizing the splines is very similar to Roy’s. I had a piece of Apple wood from the back yard and used the Stanley 45 plow plane to make two grooves, one for thickness planing, the other for width. I first glued dowel pins in the grooves to make end stops but an improvement later was to make the stops removable. Sooner or later the jig surface gets shaved down too much and you have to recut the grooves. Don’t Ask Me How I Know This. After the blank is planed to thickness in the wide groove, it is rotated and moved to the narrow groove where it’s planed to width.
It’s difficult to read the grain of these small strips, I just try different orientations in the jig and use the one that planes the best. It’s common to break a strip while planing. That’s OK if the break can be placed in the bottom half of the box where it won’t be seen.
Another photo of the sizing fixture with blanks in each slot. I fine tune the jig grooves by inserting strips of paper cut off the sticky end of a large Post It Note. That block plane BTW is not a Stanley 18, it’s a knockoff Craftsman 5256 probably made by Miller Falls.
The best way to check a finished spline is to insert it into the dry fit box. This is a bit loose, but if using water based glue, the splines swell as soon as they have glue applied so you don’t want them to fit too tight at this stage.
Finally four sets of four box splines trimmed to size.
Note to self: Next time cut the blanks closer to final size so don’t have to plane off so much.