Tuning a framing square
This is in response to a question in another thread. I didn't see any thread that addressed this so thought to post it separately. There are couple of videos but they really aren't that good.
Framing squares are notorious for being off. I have 2. One was very close but the other was way off. You can tune the square to true by using a machinist's center punch. The kind used for making a mark before drilling a hole.
Get a piece of sheet material with a straight edge. I used 1/4" melamine. It should be sized to at least fit your framing square 2X in one dimension and 1X in the other (for an 18x24 it should be 36x24). The long edge must be dead on straight.
Line up the short side of the square with the straight edge and draw a perpendicular line in the middle of the sheet. Flip the square over and align it with the edge and line you drew. If the line you drew is parallel to the square's edge, you are done. If not, hit the punch on either the inside or outside corner to adjust the square. (Do it some where other than on the sheet material.) If the square is less than 90 deg, punch the inside corner. If greater, punch the outside. Draw a new line and repeat the process as needed. I used the outside edge of the square. The inside and outside edges should be parallel but use which ever you use the most for the best accuracy.
This worked really well for me. I lightly tapped the square that was really close and it took about 5 hits to bring the other one to square. Now, both are spot on.
By the way, if you drop your square, it wouldn't hurt to check it for true.
Last edited by PhilBa; 02-13-2015 at 10:20 AM.
Reason: typo patrol