Hey,
if you want to draw a right angle on your table top, there is the method of calculating the diagonal and then apply this measurement from the first two marked points.
The diagonal in a square is the root of two multiplied by one side:
diag_square = a × √2
or in programming:
diag_square=a*sqrt(2)
That lets you construct a right angle geometrically.
But it would be simpler to directly mark the holes for the most exterior screws of the feet of the machine. But they do not form a square, but a rectangle. I use this method:
Squaring the machine on assembly:
At first I would mark the holes for the two most exterior screws on the front. Usually you know how much distance you want to have your machine from the front edge of your table top. So at that distance, you simply measure the width between the two holes:
If you have your machine already, and you have X Axis mounted on top of the Y Axes, so you pin a center punch into the two most exterior screw holes of the front feet and then you measure the distance between these two marks. This gives measurement x.
Be sure to hit the exact center of the screw hole in the aluminium block of the foot.
If one doesn’t have his/her machine yet, according to ‘Woodworker Dimensions’ on page 15 of the manual, the distance between the two most exterior screws on the front is (in inches):
44.069 - 2 × 0.419 = 43.231
(NOTE: One should check if these statements are true, as in this posting (Machine Dimensions) first number is 45.519 instead.)
This gives the distance between the to most exterior screw holes of the front feet of the machine. I mark these two with a center punch (at the distance from the edge of the table that you like).
For the third hole, for a rear foot now, which shall be the the hole for most exterior screw on one of the rear feet, we first need the distance between the most exterior screw holes of the Y Axes:
If you have your machine already, you take one of your Y Axes, pin a center punch into the two most exterior screw holes and measure this. This gives measurement y.
Be sure to hit the exact center of the screw hole in the aluminium block of the foot.
If one doesn’t have his/her machine yet, one would need to calculate the distance between the two most exterior screws of the Y-axes’ feet:
According to ‘Woodworker Dimensions’ on page 15 of the manual, the distance between the two is (in inches):
42.347 - 2 × 0.344 = 41.659
(NOTE: One should check if these statements are true, as in this posting (Machine Dimensions) first number is 42.597 instead.)
As we can see, this is no square, since the dimensions differ, so it’s a rectangle. So in order to calculate the diagonal of a rectangle, we use the pythagorean theorem:
c² = a² + b²
so we need to calculate c:
c = √(a² + b²)
or, in programming:
c=sqrt(a^2+b^2)
Here we go:
x=44.069-2*0.419
y=42.347-2*0.344
diag_rectangle=sqrt(x^2+y^2)
diag_rectangle
60.03658586228900474983
Result: The diagonal between the most exterior screwholes of one front foot and one opposite rear foot is 60.037 inches.
So, the third hole we want to mark is on the intersection of one line backwards from the first marked front hole with length y, and one diagonal line measured from the other marked front hole with length diag_rectangle.
If I apply these measurements accurately, the result is that the angle between x and y is a precise right angle.
The (good) question is how to measure this. Good roll-up tape measures have a pin for drawing circles. That’s the one I use:
After all, when done with assembly and first run, accuracy can be checked with a two-sided job or a tiled cut (e.g. see “Tiled cut issues”)
Thanks,