http://www.shapeways.com/forum/index.php Shapeways: Bring your creativity to life in 3D http://www.shapeways.com/forum/index.php?t=rview&goto=42495&th=7932#msg_42495
I am drawing in AutoCAD 2002. The parts I am drawing will eventually be patterns for sand casting Live Steam Locomotive parts using brass and cast iron.

When I export the parts to an STL file format the curved faces have large triangular facets in the curves.

For one will these facets show up in the actual RP part and if so can anyone give me advice on reseting my AutoCAD to a higer density on the export to STL


]]> pipescs 2012-01-22T15:10:07-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42499&th=7932#msg_42499
As a general rule of thumb, aim for faces on curves that are half the minimum detail size. i.e. A 2mm diameter cylinder printed in WSF, 60 edges around the circumference and 1 edge for the height ( = 120 triangular faces for the cylinder walls) this works out to be just over 0.1mm edges on the curved areas. (with FUD, aim for 0.05mm)

The limit for (regular) upload is 1 million triangles, surfaces constrained to the regular axis of a model should be ok at whatever size triangle, however surfaces that transistion from one axis to another or are on a diagonal need to be pretty detailed to avoid 'printer stepping'... so the more triangles you can get into your model the more accurate the final print will be to your model.

Paul

[edit] sorry, I forgot my manners. Welcome to Shapeways!

A handy tip when modelling, turn off all smoothing - smoothing is a visual thing for us human-beans, printers cannot see




]]> stop4stuff 2012-01-22T16:36:06-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42506&th=7932#msg_42506
Sadly I am not educated enough yet to understand all you have said.

The part I uploaded is is a tapered cylinder that is 3.5 inches in diameter and one inch high

Where can I find a definition of WSF?]]> pipescs 2012-01-22T20:20:36-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42521&th=7932#msg_42521 White, Strong and Flexible.]]> JamesSaunders 2012-01-23T02:52:48-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42522&th=7932#msg_42522
So as I understand this I need to increase the number of Facets up to the max allowed of one million.]]> pipescs 2012-01-23T02:57:49-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42525&th=7932#msg_42525
I would suggest designing with at least 1/2 or 1/4 of that size as your maximum. You don't want to be bigger than that or your facets are going to show.
]]> stonysmith 2012-01-23T03:19:34-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42545&th=7932#msg_42545
The parts I am designing are to be used as patterns for doing sand castings to make brass and cast iron parts on a 1.6 inch to the foot model locomotive.

This is an example of a part that is around 8 inches long that was cast in sand haveing used WSF as a pattern




Changing the part size is not an option

Thanks for all the help so far. Quite a neat website.]]> pipescs 2012-01-23T12:51:17-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42550&th=7932#msg_42550
I don't know specifically how to change your facet resolution in AutoCAD, but Google sent me here: http://books.google.com/books?id=I49AEJAsa98C&lpg=PA352& amp;ots=2N5mrKzUuu&dq=facet%20autocad&pg=PA352#v=one page&q=facet%20autocad&f=false

Might be a good place to start.]]> JamesSaunders 2012-01-23T14:31:56-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42568&th=7932#msg_42568
Paul]]> stop4stuff 2012-01-23T17:40:09-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42570&th=7932#msg_42570
Type these commands in AutoCAD's command line:

1. Set DISPSILH to 1

2. Set ISOLINES to 0

3. Set FACETRES to 10

4. Relocate the object to the positive X-Y-Z octant

5. REGEN

Export your STL again to overwrite your first file.
I would recommend opening your stl file in Nettfabb to check, repair or scale.

http://www.netfabb.com/basic.php

http://solidwild.posterous.com/cad-guide-to-stl-export-for-3 d-printing

]]> JACANT 2012-01-23T17:52:35-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42629&th=7932#msg_42629
After changing the settings



]]> pipescs 2012-01-24T01:59:29-00:00 http://www.shapeways.com/forum/index.php?t=rview&goto=42657&th=7932#msg_42657 If you open a new file and change all of these system variables plus all your layers etc. you can save this as a drawing template file '.dwt', then when you come to open a new drawing all these variables will already be set.
If ever you get stuck with Autocad give me a call. Always pleased to help.]]> JACANT 2012-01-24T16:20:29-00:00