best way to tune old try squares?

[Mac Houtz]

I have several old try squares, as many of us probably do, the type with a steel blade set into a wooden and brass pinned handle. They mostly end up being shop ornaments because I know them to all be slightly out of square. I'm not sure how they all get that way, as none of mine seem to be loose at all.

Anyway, I purchased some tools from a guy yesterday and among them was a much larger version of the same tool, the mahogany and brass handle is probably twelve inches long and the blade is about 18 inches. I think this would be a great tool to get back into shape for use in the shop, but, like its brethren it is also out of square by at least a couple degrees. the blade/handle joint is still securely pinned, with no movement at all. What is the best way to go about tuning this thing to get it dead on? I have a couple of ideas but before I re-invent the wheel I thought i would see what others might have tried. Thanks for any help you can provide.

[David Keller NC]

Mac - I've tuned a slightly out of square wood, steel and brass square by careful filing. Fortunately for me, the blade wasn't hardened. My procedure was as follows: Using a wide board that I'd just jointed with an accurate #8, I placed the square with the stock on the jointed edge, I drew a line on the outside blade edge with a very sharp, single-bevel knife, then marked the position of the stock. I then flipped the stock 180 degrees and compared the outside edge of the blade against this line. That determined whether more metal needed to be removed near the tip of the blade or the stock. Then I carefully clamped the blade in a front quick-release vise, "painted" the edge with a black marker, and draw-filed the edge in a sequence much like one would use to correct a board whose thickness was out of parallel with a previously jointed face.

Specifically, my first stroke started 2" from the tip of the blade, the second 4" from the tip, etc... until the last pass was the full length of the edge. I then repeated the sequence, and re-compared the filed edge with my previously established reference knifed line. This was an 18" blade square that was out about 3 degrees (about 1/16" at the tip of the blade). The sequence was repeated about 4 times, and took about 20 minutes.

I trued the inside by using a wheel-marking gauge (a tite-mark) to score a parallel line to the just-filed outside edge, and used a similar procedure with the file to true the inside.

All told, it took about an hour, which was definitely not worth it from the labor point of view (it would've been cheaper to have bought another antique that was actually square). But, an 18" wood-stocked try square isn't all that common, so to me it was worth it.

Note: I would definitely not recommend this for something that has collector's item value. Collectors definitely do not appreciate bright metal on anotherwise patinated tool.

[Mac Houtz]

That's exactly what I am thinking. I have never bothered to do it with my small ones since they are so common. I would like to tune this larger one though. I am not that worried about collector value on something like this, I would much prefer to have it as a user.

[Tony Shea]

I also would consider lapping the outside edge of the blade on granite reference plate with sandpaper. And keep more pressure on the side that needs more material removed. It could also be done on the inside as well but with a little more care to not mark up the handle part of the square. I do like the idea of using a marking gauge for a parrallel line. Just a thought as getting your filing perfectly flat may be a bit tricky. I have never personally done this before and am by no means qualified, just throwing suggestions to the wind.

[Jim Koepke]

I have also done this by way of the filing method.

Another way is to apply a quick rap to the blade.

Since these often get out of square by being dropped, a reversal of the process seems like a workable plan.

Calibrating the amount of "rap" to be applied is the difficult part of the equation.

jtk

[John Coloccia]

To make the angle bigger, hit the inside rivet. Smaller, whack the outside one. When you're happy, lock it with the center one. IMHO I would put away the file but I can't say that won't work.

By the way, I should add that I'm not sure why this works, but it was shown to me years ago and has worked on the handful of squares I've tried it on. Maybe someone with more knowledge of how it works can expand on this c