Dual extrusion firmware

Quote
pras_pune
I am currently looking into defining a fifth axis parameter 'Q' so I can print simultaneously using: G1 X-- Y-- E-- Q-- etc. Though I am stuck with several errors in the firmware as I am trying to update.

Also, checkout the M160 code for multiple mixed material printing: [reprap.org]. Maybe this helps. And were you able to figure out how to use E0 & E1 to print simultaneously?

Quote
from our programmers
Hi All,

William and I have manage to get the firmware to controlled each extruder independently via G-Code.

G1 X10.000 Y34.000 Z22.00 E32.00 I32.000 J12.000 F100.0000

[github.com] (Make sure you are using the bioprinter branch)

A couple things to note:
* Board doesn't require you to have a thermistor plugged in.
* Cold extrusion is now enabled by default
* There is no longer a concept of an active extruder, they are all active. So the T command does nothing.
* You now can have up to 5 extruders to independently control, if you board physically supports it. They are labeled as such E, I, J, K, L.
* Designed to work ONLY on a cartesian 3d printer.
* Some 3d specific things such as ADVANCE settings or COREXY have been disabled.

Instructions for configuration.h changes:
[github.com]
1. MOTHERBOARD - should be changed to your board
a) BUAD_RATE - if you need to.
2. EXTRUDERS - max number of extruders your board can support
3. NUM_AXIS - this should be number of axis (x, y, z) + EXTRUDERS
4. HOMING_FEEDRATE - each number represents an axis just make sure you have a default value there, 0 is fine. There should be a total of NUM_AXIS values.
5. DEFAULT_AXIS_STEPS - same thing as HOMING_RATE but the default should be the last value in the enumerable.
6. DEFAULT_MAX_FEED_RATE - "
7. DEFAULT_MAX_ACCELERATION - "

The code is litter with "NOTE" comments indicating we were unsure what was suppose to happen here.

Especially here: [github.com]

It is the Euclidean distance in mm for all the extruders. I believe the distance is use as a basis to determine the rate at which all the axis should travel.
So does N-dimension distance formula makes sense for N-extruders?

Known Issues:
1. Sometimes your G1 command will do nothing after a couple of commands especially if you are only issuing commands to move the extruders.
I believe this is a failsafe mechanism to prevent over extrusion of material in one spot, I still need to investigate this further.
A workaround of now is to issue a G91, G90, or G92 before your G1 code and it should reset the extrusion hard limit.
2. Steps per mm for extruders needs to be mapped to the ratio with syringe pumps.

Feel free to fork the source code (or make a pull request).
Feedback/bug finds are encouraged

Thanks,
Chris