Rapid Prototyping - Fabathome / Reprap - On bridging the gap?

[ostranenie]

Hi there,

There are two (that I'm aware of) low-cost rapid prototyping systems out there - Reprap and Fabathome. They are three-axis positioners with a head that instead of cutting or drawing or probing, successively builds up layers of glue or some other material to build an object in three dimensions. These systems also have software that figures out the positioning and extuding code based on 3D models. As far as I can see, their dedicated software controls the machines "on the fly" so it builds as it goes (i.e. no G-code type output for the machine to follow--they seem to have eliminated that step entirely).

The obvious question is - how hard would it be to engineer a retrofit for an existing three axis positioner? To slap an extruder head on it and call it a "fourth axis?" G-code has been around a long time and works pretty well so it would follow that with some additional logic, you could extrude material (frosting, glue, whatever) without a terrible amount of difficulty since all that engineering has been done up front (as in, timing on "when" and "how fast" to extrude versus "where" the head is at a given time). Then you'd have a multi-tasker instead of a dedicated "fabber" as they call them.

What are your thoughts on all this?

[svenakela]

Google for "3D printing" and you'll get heaps of info and producers.
I've been working with Stratasys machines. The software sliced a solid model in layers and every single layer was then created with - G code!
This was more than 10 years ago and it might have changed, but I think the software still translates the models into G-code but keeps it internally. The biggest challenge is to make a workable heater nozzle, and to get a plastic that works well. They usually have two nozzles, one for the primary plastic and one for supporting plastic that is shot where the primary plastic has no support (angled surfaces etc).

And BTW, as the machine creates the model in layers, there's no need for a fourth axis.

[jcoats]

It seems that STL is the format choice for 3d modelers. In the RepRap they did a lot of code to make sure the STL were closed structures, so they could rasterize them without 'holes'. Once that is done, the gcode should be 'pretty simple'.

As far as the machines, even a CNC Gantry could replace a spindle with a 'fabber spindle' and it should work. If you want something taller than your
normal table, you can do what both RepRap and FabAtHome do and make your
table 'drop', rather than just be limited to the height of your z-axis.

Now, how can we generate our 'sawdust' from a router into 'fabber fluid' to deposit to make 3D models?