QuickCast swelling, Tapered shrinkage compensation?

From: Luper, Harold (HLuper@SOLIDIFORM.com)
Date: Tue Apr 04 2000 - 00:16:32 EEST

Has anyone else experienced swelling of QuickCast patterns, especially on
larger parts which are in the vat for extended build times? For example,
when I build a 12" box shape on our SLA5000 (SL5195 resin), it will always
measure larger at the bottom (at the platform) than at the top. Most of the
time this is a significant amount of variance (.015 - .020"), and is fairly
consistent from build to build though perhaps effected differently in other
specific geometry detail which may be included in a given shape. The only
compensation I am aware that I can apply is for overall shrinkage, and I
must resort to "splitting the difference" to compensate.

I realize that the ultimate solution to this is to develop a perfectly
accurate process and materials, but until that time arrives perhaps there is
a software solution. I wonder if any of the various stl file software
vendors could include a tool to apply "tapered shrinkage" to a file to
compensate for this? Is this idea even feasible?


    Harold Luper

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