Re: [CAD_CAM_EDM_DRO] Measuring accuracy

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>Gregory Kamysz wrote:
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>>What kind of test does one run on a mill to define it's accuracy? Is
>>there a standard code or method used to do this? Or do I just run some
>>parts and see if I've made scrap or something useful?
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One of the other tests I do, with no special equipment, is checking
orthogonality
of the spindle to the actual X-Y plane of motion. (My table is banged up
enough that there is no way to easily place a flat on the table repeatably.)

I wrote a CNC program to move in a complete circle of some diameter.
When done, it returns to the center of the circle.
I use a 1/2" end mill to cut the circular track in a piece of scrap. I then
mount a dial test indicator on a copy of an "Indicol" holder, and sweep
the circle. If the height is the same all around, the head is "trammed"
correctly. If not, the head needs to be realigned.

Because of concave wear on the bottom of my table, I get a saddle shaped
curve to the circular track. It is a small, but detectable defect in this
65 year old machine.

Jon