Re: digitizing

From: VandenBerg, Bert (
Date: Mon Jun 03 1996 - 22:38:00 EEST

The method takes as input point data from any sort of input device.
 Typically the
idea is to reduce the time required to produce an accurate part, while
occasionally a more accurate part (with less attention to cost) is the

If you care about a few features, you need to measure enough points to
characterize their shape. If you care about the entire part's volumetric
error then lots of data is a good idea. Any sort of point gathering device
can be used. Clearly the improvements to the shape cannot be more
accurate than the data-inaccuracy.

      Bert van den Berg
      Integrated Manufacturing Technologies Institute
      National Research Council of Canada
From: rp-adm
To: rp-ml
Subject: Re: digitizing
Date: Monday, June 03, 1996 5:29AM wrote:
> Bert,
> I found your post interesting, and would appreciate if you could elaborate
> on one point you made. You said you measure the resulting shape of the
> part. I would think you would need many measurement points in order to
> apply selective shrink correction factors in the next step of you process.
> This would imply to me that you are probably not measuring the cast parts
> with hand metrology equipment or a contact CMM. This leaves one with


I'm wondering why you believe a contact CMM is insufficient for gathering
point data. In my
experience, this is still the most accurate digitizing tool and it allows
to take the
points in a more "strategic" manner, with higher density in more convoluted
areas. At the same
time, you can measure features (form and position), a necessity if you're
comapring to known


Steve Farentinos
PML, Inc.
201 W. Beach Ave.
Inglewood, CA 90302
310 671-4345
310 671-0858 Fax
310 671-1862 BBS

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