Re: New machine zeroing trick with laser

Seems like a waste of time to me. If the fixture is used
repeatedly, why not pin it to the machine's table? You would only
then have to measure it once and record the fixture offset values.

The next time the job is setup, you put the jig on the table, slide
the pin in to register it (With far greater accuracy), enter your
fixture offsets and start cutting. If the control software has the
G10 function like MACH, then you can have the CNC program
automatically load the fixture offsets so you don't even have to
type them.

This message paid for by hands on experience, no spam follows :-)

Chris








--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Fred Smith" <imserv@...>
wrote:

>
> I don't know if it is really new or not, but it is new to me.
>
> While talking with one of our many happy customers who have
> converted their CNC machines to DeskCNC control systems, the
> conversation drifted to limit switches, fixture offsets and zero
> setting on table based machines. Their method of finding a

fixture

> zero was interesting to me, and I thought I would share it with

the

> group.
>
> They have installed a laser pointer onto the Z axis, aimed at the
> table below the spindle. The laser pointer is offset somewhat

from

> the spindle centerline, so it stays mounted during machine
> operation. They have placed a pin-hole aperture over the laser
> pointer lens to reduce the size of the spot projected below.
>
> The work holding fixture has a target hole made by driving a small
> finishing nail into the wooden base, then removing the nail. To
> zero the fixture, the laser pointer is turned on and jogged over

the

> hole. As the spot is positioned over the center of the hole, it
> disappears. Moving the laser pointer, just a couple of

thousandths

> off the center of the hole and the spot reappears in that

direction

> of movement. This is apparently sensitive enough to provide the
> fixture location with in a few thousandths of an inch(plenty good
> for woodworking). It repeats reliably and permits fixture setting
> without cutting tool contact or removal.
>
> Any others incorporated/designed/used similar devices in your CNC
> machines?
>
> ------------------------------------------
>
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> Fred Smith
> http://www.cadcamcadcam.com/hobby
>