Steve Maskery
Established Member
If you have an MFT then move on, you already have an excellent solution.
This is for the rest of us.
The first thing I ever filmed when I got my first camcorder was a gadget for checking a square corner. I never did find out what it was called, so I've called it the Square of Thales. Mr Thales was the first recorded philosopher, and is credited with being the first person to recognise that the corners of a triangle always add up to 180 degrees. This gadget works on that principle.
A Square of Thales is a pointed stick with a swinging arm. The points line up exactly at both ends. That's it.
When all three points touch, the angle is 90.00000000 degrees. It has to be. I can give you a mathematical proof if you want. But it is.
So it's great for checking an internal corner. If the big arm is too loose, the angle is too big, if the small arm is too loose, the angle is too small.
But I have long wanted to use it for an external corner. It's taken me years, but, like so many ideas, I've come up with a way that could not be simpler. I just convert the external angle into an internal one.
In this example I am trying to set my saw track square to an edge. So I have my track, my Square of Thales, and a length of wood with a rebate cut along its length.
1 Mark where the track is to cut, and align the track to that point.
2 Put the rebated strip up to the back edge of the track and hold it in place, either with a clamp or just with your manly thigh.
3 Push the Square of Thales into the corner and adjust the track until all three points touch
Job done. If you doubt it you can check with the biggest square you have, but it will be right.
I love it when a plan comes together.
This is for the rest of us.
The first thing I ever filmed when I got my first camcorder was a gadget for checking a square corner. I never did find out what it was called, so I've called it the Square of Thales. Mr Thales was the first recorded philosopher, and is credited with being the first person to recognise that the corners of a triangle always add up to 180 degrees. This gadget works on that principle.
A Square of Thales is a pointed stick with a swinging arm. The points line up exactly at both ends. That's it.
When all three points touch, the angle is 90.00000000 degrees. It has to be. I can give you a mathematical proof if you want. But it is.
So it's great for checking an internal corner. If the big arm is too loose, the angle is too big, if the small arm is too loose, the angle is too small.
But I have long wanted to use it for an external corner. It's taken me years, but, like so many ideas, I've come up with a way that could not be simpler. I just convert the external angle into an internal one.
In this example I am trying to set my saw track square to an edge. So I have my track, my Square of Thales, and a length of wood with a rebate cut along its length.
1 Mark where the track is to cut, and align the track to that point.
2 Put the rebated strip up to the back edge of the track and hold it in place, either with a clamp or just with your manly thigh.
3 Push the Square of Thales into the corner and adjust the track until all three points touch
Job done. If you doubt it you can check with the biggest square you have, but it will be right.
I love it when a plan comes together.
