Re: [rp-ml] Query

From: <>
Date: Wed Sep 15 2010 - 23:13:24 EEST

In a message dated 9/15/2010 2:52:53 P.M. Eastern Daylight Time,
_adler@a3dm.com_ ( writes:

Can anyone tell me the expiration date of the 3D Systems Quikcast patents…?
Read Today's Blog at

Steven Adler
_www.a3dm.com_ (
_adler@a3dm.com_ (

The earliest patent is probably this one:
5256340 : Method of making a three-dimensional object by stereolithography
INVENTORS: Allison; Joseph W., Valencia, CA Richter; Jan, Los Angeles, CA
Childers; Craig M., Santa Clarita, CA Smalley; Dennis R., Baldwin Park, CA
Hull; Charles W., Santa Clarita, CA Jacobs; Paul F., La Crescenta, CA
ASSIGNEES: 3D Systems, Inc., Valencia, CA
U.S. CLASS: 264/022
ABSTRACT: An improved method for stereolithographically forming a
three-dimensional object wherein ordinarily solidified internal walls of the object
remain at least partially unsolidified. Any unsolidified medium within the
object can be drained from the internal walls of the object prior to
post-curing so that a hollow three-dimensional object is formed. The object is
formed on a layer by layer basis with the internal portion of each layer of
the object formed as a grid of solidified portions and unsolidified
portions wherein the solidified and unsolidified portions are different on each
layer. Objects formed in this manner can be used as patterns in investment
casting. XX
Issued October 26, 1993
Back then the term of a patent was 17 years, but there can be extensions
and other differences. Nothing apparent on the PTO, however, and it
probably will expire shortly.
There are 67 patents that reference this one and you should take a stroll
through at least the early ones. This patent also references other
material and there have been similar methods patented by others more recently.
I am too lazy to dig further.

Ed Grenda
Castle Island Co.
_EdGrenda@aol.com_ ( (email)

The Worldwide Guide to Rapid Prototyping
_www.additive3d.com_ (
Received on Wed Sep 15 23:06:51 2010

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