I have done lots of hand cut dovetails and I decided to step out of my comfort zone (Chris), and cut some through mortises. I am not done yet, but, they are roughly 2" by 1/2". I wanted to make sure that I was cutting through squarely so I went looking through my collection of stuff.
It feels like I own lots of squares; but I know people (Steve) who have demonstrate that I do not know the meaning of "lots". That said, my narrowest blade is probably 3/4". None of these were working well because the blades were just too big.
It was difficult for me to find something smaller. I went to a Rockler and a Woodcraft store, and neither had what I wanted. The best they had was a Starrett 14D Double Steel Square (https://www.amazon.com/Starrett-14D-.../dp/B000VDTDTU) with a single blade; the largest one shown at the Amazon link. I already own a Lee Valley 4" precision double square (http://www.leevalley.com/us/wood/pag...79&cat=1,42936), I really like it, but, it is just too wide for this.
The Lee Valley small double square (http://www.leevalley.com/us/wood/pag...936,42941&ap=1) was a lead contender. It is well reviewed, and the price is right.
Lee_Valley_Square_15n0501s03.jpg
Although this would work for me, what I really wanted was to have both of those blades and then one more that did not have two different sizes. You know, like what Vesper tools sells
https://www.vespertools.com.au/vespe...ouble-squares/
vesper_tools_square_455451.jpg
Someone pointed out on the forum here that you can also buy that from Highland woodworking (https://www.highlandwoodworking.com/...le-square.aspx).
Some people that I respect greatly love that little square from Vesper tools. For example, Patrick Chase (https://www.highlandwoodworking.com/...le-square.aspx) and
Derek Cohen (https://sawmillcreek.org/showthread....-Double-Square). I would probably have been happy with the Lee Valley version, but, I really wanted that third blade.
Now I wait and see how long it takes to arrive.