RE: [CAD_CAM_EDM_DRO] Making a rapid prototyper

HI Sebastien,

I found and mentioned the RepRap project on this list just last week! A bit
after the bevy of posts on self-replication of a few weeks ago.

I hadn't seen the 2nd generation RP head, just the first. Sounds like a
step forward! I'll give it some study. (I wish you'd publish PDF's.)

RepRap is using lower temp materials then I was considering. We recently
purchased a ProtoPulsion Dimension SST RP, and it uses ABS "wire". I'm told
it melts at about 165C, a little warmer! And, the inside of the enclosure
for the RP is heated. Lovely machine!

How hard is the Poly material you're using when it's cooled? The ABS is
fairly hard. And the .07" ABS wire (1.77mm) comes on spools already (no
need to make your own PolyMorph rods! I'm told I can have the tail-ends of
the spools; they leave quite a bit on them in the magazines.

I've designed and have been building a "Baby PCB Router", which at 12" x 12"
x 12" high overall might be an appropriate size to take an extrusion head.
It's currently designed with a 3.25" x 5" tooling plate on the Z axis, and I
have a bracket for DeWalt DW670 trim router mounted on it.

Although I'm currently implementing USB with the PIC 18F4550 uP, my Step4
controller program runs under DOS. I don't yet have a convenient driver for
USB under DOS. And I am a LONG way from getting Step4 ported over to Windoz
(if ever). I am investigating USB-CNC, a windoz controller program. The
extruder control program could run as a windoz program as well! All we'd
need would be some simple handshake between the two processes (I think, help
me here).

I think "self replication" is a long way off (Star Trek, NG), I'm simply
interested in being able to explore a new fabrication method.

Have you considered a two-material extrusion head? The SST also has a dual
extrude head; the second material is a water-soluble structural support
material.

A sintering head would really be making progress! I know nothing about the
process, but expect it needs higher heat and pressure that a hobbyist can
easily handle. Please prove me wrong!

Can't we make the extruder out of METAL? Would that make it smaller and
more compact? I'd also consider a stepper motor for the drive. As I
mentioned, I'm really not targeting self-replication. I'd make the best use
of materials available to me.

Alan KM6VV
Central coast, CA, USA
SherlineCNC list

> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Sebastien Bailard
> Sent: Monday, July 31, 2006 10:54 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Making a rapid prototyper
>
> Hello all,
>
> I've been lurking here since mid July. I apologize for not jumping in
> during
> the self-replication thread, but I'm still catching up with my email.
>
> I'm Sebastien Bailard, the junior-most developer for the RepRap project -
> a
> rapid prototyper (rp) we're trying to build. It is basically a glue gun
> on a
> three-axis CNC device. The glue gun extrudes hard plastic,
> polycaprolactone,
> which is much like nylon but melts at 70C.
>
> The RepRap makes plastic parts, and is made of plastic parts, so it can
> make
> copies of itself. (At least, once you add ground drill rod, bushings,
> steppers, pcbs, etc...). We're looking to put down a 0.5mm thick filament
> with 0.1mm precision, a build volume about 20cm-30cm on a side, and
> keeping
> the total (pre-fabrication) cost under about USD$500. We're _hoping_ to
> achieve self-replication within 2 years.
>
> We'll be building the RepRaps using commercial or home-built rp machines
> (like
> a RepRap itself). Most of the developers are building what they
> call "RepStraps", essentially homebuilt CNC machines, which will move an
> extruder head around. I'm lazy, so I'm going to just use my Taig mill as
> a
> RepStrap. (I suspect that's how most people on this list would go about
> it.)
>
> Extruder head write-up:
> http://reprapdoc.voodoo.co.nz/bin/view/Main/Version2OfThePolymorphExtrusio
> nHead
>
> General info:
> http://reprapdoc.voodoo.co.nz/bin/view/Main/WebHome
>
> Project Blog:
> http://reprap.blogspot.com/
>
> Print file community and database (will be at objects.reprap.org).
> Currently
> this is just a functional, anyone-editable wiki-powered wishlist.
> http://www.dubsen.org/twiki/bin/view/
>
> We also want to design a ceramic/metal slurry depostion head to do
> additive
> fabricating, sintering the slurry object in a furnace, along with a
> ECM/EDM
> head.
>
> The group is figuring out how to control it via a serial port and USB,
> while
> writing the controller in Java, but I'm going to be building in parallel
> port
> and emc control as well, probably.
>
> My setup: right now, I've only got as far as milling "Hello world" in a
> bit of
> boxwood using my taig, by flicking bits on the parallel port and having
> crude
> stepper motor controllers (breadboarded L297 + L298 chips) move the mill
> around. I'll be setting up EMC over the next couple days, and then
> machining
> an extruder head out of plastic.
>
> If you're interested, please take a look and tell me what you think. I
> would
> be happy to answer any questions about the project, either on list or off.
>
> -Sebastien Bailard
>