Re: SLC File format for 3D printer

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "vrsculptor" <vrsculptor@...>
wrote:

> I reluctantly have to agree with you that the SLC format is the way
> to go for 3D printing.

My opinions are hard to resist :)

> I spent a lot of time exploring different hacks up
> to and including Java3D, Sketchup (Ruby, too slow) and a couple of
> other CAD programs with no luck. I did find one interesting one,
> Boxford RapidPro, which does almost what we need, but not quite.

This turned up on make today:

http://www.evilmadscientist.com/article.php/candyfab

They have made a hotair sintering sugar printer for large low
resolution objects (I don't know why they did this but I like the
giant screw). They say that they slice there objects with povray,
this makes some sense as rays that pass through objects could be used
to create the layers. I've not used povray but it may be an option,
the import formats may be an issue.

> Can you point me to a layout of the SLC file? I haven't had much
>luck finding it.

There is not a lot of info but these seems reasonably accurate:

http://rpdrc.ic.polyu.edu.hk/old_files/slc_introduction.htm

Its fairly simple, an ascii header containing not very much followed
by binary data built up as stated on the page. For each MODEL layer a
z height is specified as well as the number of contours, then each
contour is listed in turn starting with the number of vertices and
followed by a list of x,y co-ordinates of those vertices the CW/CCW
direction of the contour specifies it as internal or external.

The printer generally repeats this layer until it meets another model
layer so the printed layers may be thin compared to the model layers.

However to get Rhino to read the SLC files I created I had to add an
extra two blank longs at one point in the file, this may be a fault in
the web page or even Rhino, Objet a company that make a polymer
printer I may be using are going to check my resulting files so I
should find out then.

In terms of turning the SLC file into a bmp it is much easier than
doing the opposite, I could knock out a matlab program in no time,
that could then be ported to become a proper windows app.

> There is a vtkSLC reader but I'm reluctant to learn yet
> another technology. Java3D in a day was bad enough.

I know what you mean! Also be aware that I have seen files described
as SLC that are totally ascii, these are not the same files as far as
I can tell.

> PS. I bought a bundle of 5 new Lexmark injets on Ebay for $49. I'm
> going to have plenty of spares. I'm not going to start the hardware
> until the software is done.

I'm of the opinion if you build it, it will come :)

On the subject of hardware, I've been trying to get my HP working as a
flatbed, unfortunately I forgot to put something in the slotted opto
and so it thought there was a paper jam, now it seems impossible to
persuade it otherwise. I'm unsure at the moment if the printer has
some special methods it uses to detect paper or if I have too much
friction on what was the paper feed. Either way I'm not too happy.

Graham