Tony, basically you start with either a nice thick slab and resaw it into two pieces that are oversized to the pens you want to fit inside, or start with two thinner slabs that are sized the same as each other, again slightly oversized to the pens. You also need two side ‘straps’. The same edge dimensions (or slightly oversized) to the thicker slabs (pre-resaw), and about 1/4” thick. In the pics below, these ‘straps’ are of Osage Orange and stand out against the walnut, and I left them fat to be cut down later…I don’t do that anymore, I just start with 1/4” thick straps and call it good.
You need to route recesses for the pens on the inside of both slabs. These need to be carefully laid out and routed so they match, since they will create ‘tubes’ when the slabs are closed against each other to hold the pens. This last box I made I flocked the recesses before assembly, just for a nice detail, but that’s not needed at all.
Once the recesses are routed, one slab needs to be cut, cross grain, at somewhere around the 1/3 mark lengthwise, at about a 45° angle. I use a thin kerf, Japanese pull saw and an angle block to get it clean…but you could honestly introduce some curve to it intentionally for an interesting aesthetic, and just use a band saw with the piece on its side. As long as it lines up when it closes, you’ll never see it…so it doesn’t need to be perfect. Now you have one full slab, and another slab cut into two pieces, roughly 70/30. Carefully align and glue the 30% section to the full slab. After curing, the 70% section just sets on top, filling the obvious gap. You need two hinged pin holes drilled in the fat section of the glued slab, centered in the seam, and the same distance from the end. On the slab portion, this can be as deep as you want, but on the strap pieces it needs only be about a solid 1/8” deep. Just make sure you size the pins to the slab body and let the protrude just less than 1/8” from the sides when seated. Otherwise, if there’s extra room behind the pins, they may back themselves into the slab and the straps would slip loose. Also, the strap-side hinge pin holes must be carefully aligned or else you end up having to cut everything down to flush the sides later. I mark the pin holes on the slab with an awl, then tape a super small 1/32” ball bearing into that dimple. Then I carefully aligns the straps on both side and press them into the sides of the slab (as they’ll look when glued up). The ball bearings dent the straps and give an aligned starter location for the pin holes. Using a super small ball bearing leaves the perfect indent for a Brad point bit. I start the pin holes in the straps with a Brad point on the drill press, but immediately change to a twist bit once I get the hole started so I don’t punch the Brad point through the visible side.
In this pic can you see the red line shows the 70% slab separate from the rest o father body. I put wax paper in between the slabs and cover the main body when I glue in the straps so any squeeze out doesn’t try to glue the main slab body to the straps as well. There in NO GLUE touching the main slab body anywhere, only on the 70% section. Put the pins into the pin holes on the body (I just use metal dowel, usually 1/8” is more than fine), then place glue on the sides of the 70% slab only!! Then press the straps into place over the pins and clamp the whole thing together. When it cures, you’ve to the 70% slab glued to the straps, which are holding the pins, hidden, in place in the large slab. This creates a pivot and the two slab sections can rotate through each other. At this point, you can trim down the side if you want, and shape the ends/edges however you’d like. Square, radiused, angled, whatever…it’s cosmetic. Finish it however you’d like, I like oil and wax, but anything works.
For what it’s worth, if you have cleanly drilled hinges pin holes and the pins don’t fit loose, and you clamped everything together tightly during glue up, you don’t need magnets at all. The natural tension in the pin holes and the friction of the straps against the slab hold things shut just fine, I’ve found. But there’s nothing wrong with a magnet or two.
Hope this helps some!
Ryan/// ~sigh~ I blew up another bowl. Moke told me "I made the inside bigger than the outside".
