Re: [CAD_CAM_EDM_DRO] Re: [DIY-CNC] Horizontal Planes

----- Original Message -----
From: "Graham Stabler" <eexgs@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, July 04, 2006 10:02 AM
Subject: [CAD_CAM_EDM_DRO] Re: [DIY-CNC] Horizontal Planes


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Peter Reilley" <micrio@...>
wrote:
> Here is a better explanation of how they work;
> http://www.davidsonoptronics.com/poa.htm
>
> Pete.
>
>

thanks for the link, that's really handy. I actually own an
autocollimator although it needs a new light source. I rescued it
from certain doom but have never used it or really known what to do
with it. I'd be quite interested in looking at making my own if I
didn't have one, the optics look relatively simple and the CNC builder
really just wants to minimize error rather than measure an angle.
With the tiny and cheap webcams available I'd say an electronic one
would be pretty easy to knock up too.

Graham

I forgot to mention that the light source is just a flashlight (torch to you
over there)
bulb. It does not need to be too bright but it should be as close to a
point
source as possible. Most ordinary 3 volt flashlight bulbs are fine.

If you must make a holder for the bulb (they frequently get lost) it is
important
that you can move the bulb in and out. You want the filament at the focal
point of the lens. It is easy to adjust by looking through the
autocollimator
at a target. At the proper setting the image will be the brightest and the
crosshairs will have the best contrast.

Pete.