Making an Adjustable Try Square is a pretty staight forward build, here are the parts:
I chose rosewood for the handle, approx. 4” X 1/12” 1/2”
Some brass, 5/16” rod,1/4” rod and 1” flat stock (about 1/16”)
Brass inserts and screws 8-23 X 1 1/2” long.
The handle must be flat and square if you want a square that is square on both the inside and outside reference. Check the width with calipers and get it exactly the same on each end, then do the same for the blade.
Next cut the slot in the handle for the blade, I get as close to center as I can then flip the handle over and cut again. This helps to center and widen the cut as the saw kerf is not wide enough for the blade.
Use a card scraper and sand paper to clean up the slot and fit the blade.
Now lay out the holes for the adjustment screws. I just measure in about a 1/4” or so and mark lines on all sides, this comes in handy at the drill press.
Using a vise, clamp the handle as shown for drilling. This is a good spot to slow down and make sure everything is lined up exactly as the bottom of the hole needs to center on the blade slot. Remember to keep pulling the drill bit out and cleaning off the waste to keep the bit from wandering.
Here is what you are looking for, a straight hole centered with the slot.
Now cut the connecting rods to length then sand a slight crown on the ends, I sand up to 400g to be sure there will not be any binding.
Don’t forget to insert the connecting rods before installing the inserts (don’t ask) but a tang on a small file fits and will work as an easy out. ;-)
I started out with a phillips head screw but switched to an hex head screw to put the inserts in. In case you don’t know, the slots on the inserts are not for a screwdriver but are to cut the threads in the wood.
I enlarged the hole about 1/4” deep to house the screw head, the insert will also be 1/4” deep.
Put a clamp on the handle to prevent splitting when screwing in the insert. (see don’t ask above)
Cut the adjustment screws to the proper length and install, all that is left is to sand and finish.
-- Good judgement comes from experience and experience comes from poor judgement.