Fixed Problems with SL 5220

From: Chris Sutcliffe (
Date: Thu Feb 25 1999 - 12:35:59 EET

Dear List,
At the University of Liverpool we have recently installed 5220 on our SLA 250 with a doctor blade recoater. As some of you might have read earlier in the year we were having enormous difficulties building parts from this resin on our system. I posted mail on the RPML asking for advice on how to fix the problem (many thanks to the people who replied and built example parts for us on their machines). We have now found a solution to the problems we were having and I feel its only fair to tell the rest of the community how we fixed them.
The fix was, turning the DH Flag "ON" in the .sty file. Which enables Downward Hatching. Turning this flag "ON" means that you draw both hatch and fill on downward facing surfaces which eliminates the quilting and delamination issues.
The use of 3 boarders also seems to help as does building the part in thinner layers.
We tested a whole array of parameters trying to find the solution before the DH flag was set; none of them seemed to work which seems to suggest that 5220 is highly tolerant of unoptimised parameters which I guess is a good thing. The problem seems to come about because SL5220 has is slightly softer in the vat immediately after scanning and hence on downward facing surfaces problems can arise with cured scans sagging.
May I say that it goes to show the usefulness of the RPML that this problem was sorted out with many people's help and may I also thank unreservedly the 3D engineers in the UK who were most helpful and patient with me at this time of extreme stress.

We have now built several customer parts in 5220 and will not be switching back to 5170.
Once again thanks to all particularly the people who built samples and the Guys at 3D UK
Dr. Chris. Sutcliffe
Product Innovation and Development Centre
Department of Engineering
3 Brownlow St.
Liverpool L69 3GL

(0151) 794 8022 Direct
(0151) 794 8021 Secretary
01893 209 556 Bleeper

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