I finally got my toggle clamps and digital angle gauge in the mail. The Wixey gauge eliminated all the fiddling and guess work. What a great tool!
Soo... cut another 16" chunk of maple and started again down the box making road.
Planning to 3/8
I then rebuilt my crosscut sled and tried to eliminate all the slop in it. I added my new Chinese toggle bolts and clamped a stop block at 3". Clamping before had been downright scary with a 3" side and 45 degree bevel. Not anymore.
I wrapped a couple pieces of mdf in packing tape as my cauls for the 3/8 box sides.
Result? Really nice and tight miters! (a bit of tear out, but I can fix that)
Next weekend, on to the spline cutting jig!