Re: STL settings in Rhino for MM2 output.

From: Bathsheba Grossman (sheba@protoshape.com)
Date: Fri Sep 29 2000 - 07:35:54 EEST


On Thu, 28 Sep 2000, Paul J. Burr wrote:
> Any one out there using Rhino to design parts for Sanders MM2 output?

Every day. Twice on Sundays.

> I not fluent in Rhino. But, I have two customers who are trying to have us
> build their very first RP parts using Rhino They are also "newbie" Rhino
> users. Problem is, the STL files are shot full of errors and won't build
> properly.
>
> Anyone have some suggestions on how to get these people points in the right
> direction?

My first question would be, are they checking that their solids are
good to start with, i.e. no naked edges, no self-intersections?
Usually if I start with a solid that passes Rhino's 'enaked' test and
doesn't do other obviously illegal things, I get a workable STL file
from it.

Rhino offers some STL verification tools, explained in the online help
under the STL topic, which customers can and should use to spot most
problems themselves.

Another good thing to read is the "Diagnostics" help topic, which
lists a number of practices that are easy to fall into but lead to
troubled models.

I don't know if it applies to your customers, but it's sometimes hard
to convince people that intersecting solids are not allowed in Sanders
models, they have to boolean-union them before exporting as STL. This
causes particular problems for Rhino users, because Rhino's union
function isn't all it could be, and cleverness is often required to
make it work.

I don't enjoy dealing with this one, because it's my understanding
that the limitation isn't present in a number of other prototyping
systems. People quite justifiably say "well, this worked when I had
it done on a ZCorp (or FDM) machine", and I have nothing to say.

Of course, I'm not sure what you mean by "shot full of errors" -
perhaps things are worse than I'm imagining. Anyway, let me know if
that helps.

-Sheba
Bathsheba Grossman (831) 429-8224
Digital sculpture www.bathsheba.com
Creative prototyping www.protoshape.com

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