Benchmarking Parts .. ER .. Just plain parts

From: George Sachs (
Date: Fri May 02 1997 - 06:28:08 EEST

I should have known that the term "benchmarking" is a loaded one. From now
on I will refer to such test parts as just "real world parts" (or
parts-is-parts). Elaine is correct in pointing out that Clemson does have a
site where such parts can be found, I have looked there in the past but have
not been back there in a few months and I noted that there were quite a few
new additions. I have also looked at the parts located at Carl Denton's site
and there too you can find some good ones. Unfortunately, between these to
sites there are only a few parts which would be regarded as both high
quality and reflective of real world uses for RP. Most of these lack
descriptions, sources of origin, design system information, tolerance
information or any information regarding what type of RP (if any) was
attempted on the part. Some parts appear to have been converted from DXF or
OBJ formats and so may not have been optimally tesselated or cleaned up (no
information available), still others appear to have serious flaws. Also
depending on how tolerant your modeler is, you may have difficulty reading
in some of these correctly, since some contain bad triangles, degenerate
triangles, some are binary others ASCII and some of the ASCII files are
upper case and some others are lower case. In general then, there seems to
be some quality control problems and lack of scrutinizing of these parts
before they are made available to the public. This alone is one reason to
have a site devoted to professional RP users and researchers.

Never the less, I found at least the following to be fairly good looking and
I think anyone who responded in favor of having more parts available or
interested in helping to contribute to a site hosting a collection of high
quality "real world" parts should look at the following sites FIRST, and
then comment on whether what is there is sufficient to meet their needs.

Reasonably good looking Clemson Site Parts:

accav, accor2, ansitbbot1, bottle, brain-gear (challenging?), distributor,
esfvalvs1&4 (2 bad!), skin (plane), spacer-retro,

Reasonably good looking Denton Site Parts, not included above:

cavity, connecto, core, cover, foot (coarse), hammer, klein, skyscrap, spring

Since for professional service bureaus and long time users of RP, the supply
of parts is not a problem and this issue is of no great interest to them, I
suggest that those still interested in this and having already commented on
this issue publicly please contact me by private mail and we can pursue the
matter further if there is "sufficient" interest. I would also like you to
provide me with a "wish list" of parts you would like to see (hopefully
objects which would have broad application ). For instance I would like to
produce one or more engine manifolds, engine blocks, motor housings, and
other automotive components. I would also like more medical models, a few
consumer type items and maybe a few toys, etc. I remain willing to produce
at least 1-2 of these, although at this time I do not have anything ready
and I would have to spend at least a few days working on any one of these
I also agree that there should be standards for these parts and I also agree
that perhaps there should be an oversite committee of volunteers to ensure
that anything contributed is really public domain and of high quality and
applicability (i.e.. written permissions for use would have to be obtained).

But perhaps we should keep such parts at Clemson or some other university
since their greatest benefit would be for students and others just
interested in learning more about RP? Comments (negative or positive OK as
always ).

George Sachs

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