scale and warpage of sls

From: Miller, Michael W (
Date: Sat Mar 31 2001 - 01:29:36 EEST

Dear rpml,

I'm looking at using my sls2000's to make some simple tooling out of Duraform GF. My experience so far has been that the process is not quite accurate enough. I'm looking for suggestions that might improve the parts.

1) Curl- The parts I'm making our relatively bulky.... 1 inch section thickness. Even though the build looks dead flat, the finished parts are warped or curled. I feel that this is an endemic, direct result of the process, adding heat on top of the part and then subsequently having it cool and shrink. Any thoughts on how to reduce this persistent phenomena? I know orientation on a corner helps a little. What about designing the parts for reduced mass without sacrificing stiffness by using a web and flange philosophy... like I-beams? Alternatively, has anybody had much luck with the outline feature? My experience has been that it's unreliable, at least on the 2000's. Perhaps shelling the part with outline but filling the core with lightly sintered material would alleviate the 'curl'. Unfortunately, on the 2000's, this is quite slow because of the delay while the scanner loads with new parameters. Are the 2500's fraught with curl?

2) Scaling- Has anybody developed non-linear scaling parameters? I utilize a one dimensional Z-scale as a function of Z. For the GF I vary Z scale 1.012 @ Z=0, 1.010 @ Z=3, and 1.008 @ Z=5. For X and Y I use a constant scale, 1.023. Has anybody tried varying Z scale 3 dimensionally... as a function of X,Y and Z?

3) Z adjust- I believe the z-adjust parameter in the 2000 software is lousy. Horizontal holes do not come out round. Solid View has a z-shift function that is fully adjustable as a function of downfacing angle that results in much rounder rounds. Concur?

4) DTM- Does DTM have anything in the works to improve accuracy?

Thanks for your insight,

Disclaimer: Engineer and out the other!
Experience is something you get right after you need it.
Michael W Miller (
The Boeing Company M/C 17-PE B-2T65
Propulsion Experimental Hardware 206-655-3289
Rapid Prototyping 655-4366 Lab 655-4365

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