multiple point printers?

are there rep-rap designs with multiple guns on the plane
i guess this is analogous to SLI graphics cards,or multiple "tile renderers" in computer graphics

e.g. deposition happening on 2 points on the same XZ plane
or
a row of nozzles that can vary on X, adjusted independantly on Z, all constrained to the same Y* (for fast printing of height-field type object.)
i guess this might require different deposition speed

if so please post images
if not please explain the disadvantages or lack of reasons to construct such a thing
(Y = vertical, X&Z=horiz)

Edited 1 time(s). Last edit at 08/29/2009 07:33PM by ceti331.

RepRap is still relatively new. I think that significantly increasing cost and complexity to gain some speed would be premature at this point.

If you have build a single-nozzle machine and find that it is not building parts as quickly as you want you should probably just build a second RepRap. That way you can make two objects in parallel and don't need any software changes, either.

It wouldn't be especially hard to do, especially if all that you're doing is allowing parallel printing(ie set two extruders up with their nozzles about 10 cm from each other).It would reduce the maximum size of the printing parts (cos the axis controls would run as normal, just the extruder would be printing two sets at once). Though you wouldn't be able to make one part faster, just make duplicates easier.

As for two x axis at once, that would be considerable harder, especially if you're working on two parts of the same object.

If you have a long X then it might make sense to have multiple extruders to build duplicate objects. CnC mills typical have a more generous X then Y.

I am working with some high school students who's repstrap is going to be such a mill and we are looking at working with multiple extruders and should have some form of initial report by October.

We are using a Sanguino which only has six PWM driver channels so it becomes a design tradeoff if you use them for feed motors or heater control. Others have reported that simple on/off for heater control works well so some flexibility for pin reassignment is envisioned.

The firmware design for the extruder controller has been interesting as the variables are DC motor verses stepper motor feed, selecting/deselecting active extruders, monitoring multiple extruders for temperature targets, heater control and digital I/O to the mill.

Here's a blog about our progess before the begining of the summer break. Haven't gotten much done during the break other then refining the mill mount, building more electronics and starting the interfacing to the mill.

You can see in the last picture the beginings of two extruders on each side of the mill head.

[builders.reprap.org]

>>It wouldn't be especially hard to do, especially if all that you're doing is allowing parallel printing(ie set two extruders up with their nozzles about 10 cm from each other)
hah ok, crude "mass production" generating N copies of the same part side by side.

Whats the relative complexity of the actual extruder relative to the rest of the machine (e.g. compare N independant printers to one printer with N duplicate heads with same control)

does this give you a worthwhile intermediate between the bespoke one-off print & mass produced parts..

SYMETRY - I suppose another restricted DOF configuration that might be usefull would be simultaneous print of an object & mirror image via some sort of linkage, then you glue the halves together ?

Edited 2 time(s). Last edit at 08/31/2009 05:44PM by ceti331.

Hm, I've been printing multiple parts side by side on my Darwin anyway; Skeinforge has an option for multiplying out the Gcode. Here's an example:

[picasaweb.google.ca]

Darwins have a lot of repeated parts, so it makes sense to make multiples at the same time.

Slapping a second extruder on would double my print speed, at the cost of having to align two print heads, and double the extruder failure rate. Still, might be useful - adding a second extruder is easier than adding a second reprap.

Wade