Testing a new machine

[analogman]

Hey all, I am near completion of my all aluminum data-cut router. I was wondering what kind of tests I can perform to check out its accuracy/repeatability and how to perform the tests.

Here are some thoughts:

(1) testing square in x, y and z
(2) testing for backlash (if any)
(3) testing for precision across the table

For testing for square in X/Y, I was thinking of a series of 6"x6" boxes around the table, then measure with calipers.

For testing square in Z, mill a deep thru hole and measure roundness (not sure if this will be of much use if the table is a bit out of whack.

I suppose for testing precision across the table, I could just make small boxes with a precise pen in the tool holder at the extremes of the table. Repeat them and see if they line up.


thoughts? comments?

[Northboy]

The way I checked mine was

For XY I drilled four holes using manual jog at the four furthest corner points and used a piece of scrap mdf and vernier calipers to measure diagonally for square.

To get my Z tool square I just used a square and my eye (not the best way to be sure, but with a long tool and a decent square it's okay)

For table level (my table is adjustable) I put a dial indicator on my z axis and measured in many places.I intend to surface my spoilboards before I start serious cutting to get this even better.

For backlash I used a dial and manual pulled the axis by hand with reasobnable force to look for any deflection at all,then jogged VERY slowly to watch for differences between mach3 and the dial

For repeatability I set up a dial on each axis to a fixed point (one at a time), zeroed the dial and Mach3 and just kept jogging back and forth to be sure they kept hitting zero together


Northboy

[BobF]

I picked a convenient spot on my table and milled a 1/8" wide slot in it about 3/16" deep. I run this a good ways along X. Then I do the same along Y. This gives a 90 degree groove in theory. I can then put 2 pieces of 1/8" thick aluminum strip in the groove to use a setup point for flat stock.
So what does this have to do with alignment? Just measure the resulting grooves with good square (the larger the better). If you put the aluminum strips in its easy to see even small errors.
One way to tell how square the Z is is to use a large center cutting straight bit to surface your spoil board. If it is out of square you will get a stair step pattern. Use a large stepover to magnify the error.