Check the width of the slots on your big Al. They should be an inch wide. I put the blade of my Starrett combo square into the slots on both of mine, and it's sloppy. Maybe 1/32? I've gotten used to it, and know how to compensate for it. CB.
I just checked my Big Al and yes my 1" framing square tongue is sloppy in the slots between the bars.
But I guess it comes down to a question of accuracy or tolerance. How accurate does it need to be?
If the tenon is laid out 1 1/2" off the reference face and then 1 1/2" thick using a Big Al. And the mortise is laid out 1 1/2" off the reference face and then 1 1/2" wide with the same Big Al aren't they the same?
If they are both off the same 1/32" more or less, does it matter?
They should both line up and go together, with the faces flush to each other. At least that's my opinion, that they should.
And I have just tested two timbers, here and now. One is a 3x5 brace with the 1 1/2" layout of the tenon. And the other is a 6x8 tie beam and it's mortise is 1 1/2" off the reference face and 1 1/2" wide both laid out by the same Big Al. And when put together the reference face of both timbers are flush.
My point is if you use the same layout tool for both joints and they are both off by 1/32" or so, it shouldn't matter.
Jim Rogers
