Re: home brew rapid prototype machines

"bfp" <bfp@...> wrote:
Subject: Re: home brew rapid prototype machines

Andrew Werby wrote,

>
> [It sounds like one could make a head for a small milling machine that
> would substitute the modified glue dispenser for the spindle, and just
> raise up as the part grew. Deriving the contour lines is fairly simple (in
> Rhino, anyway), and converting them to g-code isn't that tough, but some
> sort of batch program would be needed to feed these successively to the
> machine with the correct vertical interval interposed. Then swap back to
> the spindle head and machine the wax to specs.]
>

wouldn't using only the contour lines produce hollow shell parts?

[Right. For most purposes, hollow shell parts would work as well as solid
ones, and would take much less time and materials to produce.]

this is why I had mentioned using solid models from the cad system
each layer would have to be made up of filled contours to get a solid part
like I was saying,the software side needs some work :)

[Why do you need these parts to be filled in solid?]

the hardware is well within the home shop range
I just wish I had the time to put into it

Brian

[I wish you did too...]

Ian wrote:

Hi Andrew,

You've touched on something here which has been puzzling me for a while.
Just how would you go about deriving the g-code for a slice of a 3D model in
Rhino. I can see how you could fairly easily get a perimeter cut but how do
you do the fill-in?

Ian W. Wright
Sheffield UK

[By hand, or with software? Rhino just does modeling, not g-codes. For the
machine I was proposing, (the "glue-gun" head on a mini-mill) one would
have to calculate the width of each bead, then space ones beads the correct
distance apart so they neither stacked up on one another nor were so far
apart that they didn't adhere. A cutting operation would be the same, in
reverse. In DeskProto, which I use to generate g-codes from models, this
would be a simple matter of defining the area (as a plateau), typing in the
correct value and pressing "OK". If you were doing this by hand, I suppose
you would lay it out on a piece of graph paper, and stop each bead when it
intersects the contour, sending it back in the other direction, and
repeating. If you have some other piece of software to figure out your
g-codes, it should be able to fill in a flat surface bounded by a closed
contour with lines a specified distance apart- this isn't a very
complicated task for a computer.]

Andrew Werby
www.computersculpture.com




Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com