Re: [CAD_CAM_EDM_DRO] Re: Fab@Home

On Wednesday 10 January 2007 11:32, Phil Mattison wrote:

> > A laser cut perspex CNC router with a syringe. It seems silicon
> > sealer might have been the nearest to an engineering material it has
> > laid down. Not getting overly excited here but I do like efforts
> > towards low cost rapid prototyping.
> >
> > Graham
>
> This raises the same question I have about the RepRap project. While it
> looks interesting and maybe can duplicate itself, I have to wonder at the
> utility of being able to make a wide variety of shapes from one or two
> types of thermoplastic. Even the really expensive 3D prototype machines
> have a very limited range of applications, which is part of the reason they
> are so expensive. Seems to me none of these machines can make anything
> useful for more than a conceptual model without at least some subtractive
> post-machining. The example shown of the first RepRap component made for
> itself looks like it could have been made easier from a chunk of plastic
> with a drill press and a scroll saw. If all I want is a conceptual model
> I'll content myself with a 3D virtual model and keep my $20K, or however
> much it is.
>

You're correct that he could have done it more easily with a drill press and a
scroll saw. But he made a shot glass a few days ago:
http://reprap.blogspot.com/2007/01/cheers.html
You can't say that that's not useful.

More seriously, if you can make plastic gears and other widgets, you can make
an inkjet printer with a RepRap and some off the shelf parts. Or a robot, or
maybe a sewing machine. Or prostheses:
http://openprosthetics.org/

The really expensive 3D prototype machines are making parts out of steel,
plastic, ceramic, or rubber, using a laser to sinter (fuse) various powders.
We're not at that stage yet. We're looking at depositing ceramic and metal
powder green bodies and fusing them in furnaces, as well as doing lost-wax
casting with wax or thermoplastic. (Note that "We're looking at" != "We've
accomplished", but I'm confident, especially about the lost-wax casting.)

It's a fabrication machine with a build cost of < USD$500, simple enough that
a child could use one. It's not going to be perfect, but it should be
useful.

> It reminds me of a conversation with some friends at dinner once. He owns a
> Bridgeport mill for hobby use and was telling his wife that a milling
> machine is the only machine that can duplicate itself. She looked dubious,
> so I added, "That's why every guy needs one, just in case he evern needs
> another one."
> --
> Phil Mattison

I shall have to try that on my wife.

Regards,
-Sebastien