Re: one for the math gurus.....Squaring an Axis

> Date: Mon, 17 Mar 2003 12:20:15 -0600
> From: CL <datac@...>
>Subject: one for the math gurus.....Squaring an Axis
>
>Setting up an Axis to be truly square on a CNC machine has always been a
>challenge. It obvioulsy gets a little easier if one is fortunate enough
>to have a friend or a day job where you can borrow thier precision
>squares and straight edges.
>

Here is a technique that I have been tinkering with, it is developed from some inlay exercises that I have been doing over the last couple of years.

1) Mount a rail on your machine table and machine it parallel to the X axis
(Think 1 x 4 x 36 inches long on a router). Just skim cut it so that it is parallel on one side to the X axis, flush or below the spoil board.

2) Now cut out a square piece, 1/2 x 12 x 12 inches, leaving tabs on the sides if needed to hold it in place while machining.

3) Remove tabs, and rotate the square piece 90 degrees (about the Z axis) and clamp it firmly against the rail from number 1). Don't flip the part upside down as the error will still be parallel to the axis angle, instead of doubled.

4) Run a test indicator along the side parallel to the Y axis. Adjust the Y axis to remove 1/2 the out of parallel condition. That is if you have .030 TIR from one side to the other along the 12 inches, adjust the machine squareness so that the reading is .015.

5) Cut another square and check it the same way.

6) Throw away the first square, because it is not. ;-)

7) Machine a flat on the top of the spoil board, parallel to the X axis, wider then the square, then use the second square, standing on edge, to check the Z axis


For Metalworking, indicate a vise parallel to the X axis, machine a rectangular part parallel to the Y axis on both sides, rotate it 90 degrees about Z, and measure as above, assuming you have a way to adjust the angle between X and Y.

Let me know if it works. ;-)

Best Regards, Fred Smith- IMService

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