Re: [CAD_CAM_EDM_DRO] Test Peice for 3D finishing

CNC Crew:

At 08:36 PM 10/9/00 +0800, John wrote:

>Hi list:
>Is there a G code file / 3d test piece that is suitable for to
>comparatively assess the software and controller performance during 3D
>finishing?
>
>Recently there has been discussion on EMC for engraving and also MaxNC
>for finishing, both regarding the "need for speed" for 3d finishing.
>
>My thoughts are a standard test piece say 50 mm (2") by 50 mm (2"),
>consisting of a hemisphere that would be cut by 6 mm (1/4") ball mill.

This opens a whole can of worms. Specifically, how do you qualify
a CNC machine? If you call a machine house and say I want a XYZ
Machining Center and I want it installed here. A month later it is
installed but now I want to know if it meets specs before I write a
check. How do you go about this?

This is similar to comparing machines and controllers. If you can
measure performance you can compare systems. I do suspect it will
be a combination of CNC software, drivers, motors and driven machine.
But the question is the same, how to measure performance or qualify
a CNC machine?

The simplest I've read of (and one of the only) is a bar connected
to the spindle and to the table with ball joints. The bar has a
sensor to measure extension/compression. The CNC is then directed
to "cut" a sphere (or circles) about the ball joint on the table.
Any deviation from spherical is an extension/compression of the link.
By monitoring the sensor you get a one dimensional indication of
the 3D (or 2D) motion of the CNC. This could be run for different
rod lengths and speeds.

What other methods are used in industry to determine CNC performance?

Thanks.

Hugh Currin