From: apshah@bom3
Date: Thu Nov 20 2003 - 09:04:49 EET
We have tried various model with totally enclosed bubble and have got
successful RPT model on the Perfactory Mini RPT machine by Envisiontec GmbH.
The concept behind no liquid resin being enclosed in the block is that in
the perfactory RPT machines, the models are created upside down, thus due to
gravity the resin never gets trapped during the built and what we get is a
hollow built as required. As correctly noted by Larry, your problem seems to
in the modeling software.
Anuj Shah
Director
Sarto Electro Equipments Pvt. Ltd.
512 - Parekh Mansion,
S.V.P. Road,
Opera House,
Mumbai - 400 004.
tel - 0091-22-23823077
fax - 0091-22-23879457
email - apshah@bom3.vsnl.net.in
>
>
> At 04:33 AM 11/14/2003, you wrote:
> >Jonathan,
> >
> >Yes, you can build a cube of Swiss cheese with an SLA machine. The
totally
> >enclosed "Bubbles" within the block would build as a enclosed volume of
> >liquid resin.
> >
> >I believe the problem you are experiencing stems from your modeling
software
> >not the RP method.
> >
> >When you attempt to model a theoretical construct that contains only a
> >single twisted surface, you are creating the problem. Single surface
objects
> >don't exist in nature unless they are a solid shape like a sphere. Even a
> >soap bubble has a thickness, and therefore has an inside and an outside
> >surface.
> >
> >If the twisted surface that you are attempting to create wraps back onto
> >itself, most solid modeling software, by default, will assume the trapped
> >volume is a solid.
> >
> >When exporting the data for RP, the CAD modeler will follow the rules of
STL
> >file generation and export the STL surface data as a set of triangles,
each
> >with a single normal facing in only one direction.
> >
> >See if you can create your surface with a thickness of some small amount.
> >The modeler can then export the STL data as a pair of surfaces "back to
> >back" and may let you build the object as you envision it.
> >
> >Sincerely,
> >
> >Larry Blasch
> >Design Engineer
> >CAE Systems Administrator
> >
> >OPW Fueling Components
> >P.O. Box 405003
> >Cincinnati, OH 45240-5003 USA
> >Voice: (513) 870-3356
> >Fax: (513) 870-3275
> >
> >
> >-----Original Message-----
> >From: Jonathan Chertok [mailto:chertok22@hotmail.com]
> >Sent: Thursday, November 13, 2003 11:35 AM
> >To: rp-ml@rapid.lpt.fi
> >Subject: RE: Void Normal Direction
> >
> >
> >List,
> >
> >After a little thought on the responses to this question I am wondering
the
> >following:
> >
> >Could you build essentially a cube of swiss cheese using SLA RP for
> >instance?
> >
> >I understand that there is an issue with the fact that the voids should
have
> >
> >no draft type angles in the downward build direction that would trap
> >material.
> >
> >But would you need to put tiny holes through all the voids in the
"cheese"
> >in order to get it to build?
> >
> >I'm curious about this,
> >
> >Jonathan
> >
> >
> >
> >Universal Joint: Buildings + Digital Design
> >
> >Jonathan Chertok. Principal
> >Austin, Texas [512] 407 9628
> >
> >Full Service Design and Construction
> >
> >_________________________________________________________________
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>
> Dr. Ian Gibson
>
> Currently on study leave at
> National University of Singapore,
> Dept. Mechanical Engineering
> 9 Engineering Drive 1
> Singapore 117576
> Tel: +65 6874 1917
> Mob: +65 9087 3512
>
> "Everything really is stupidly simple, and yet all around is utter
confusion,
> don't look around to find the sound that's right beneath your feet"
>
>
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