Developing Syringe print head as second extruder

[kvones 5]

Hello All,

I am trying to develop a syringe print head extruder based on the stepper driven Fab @ home design for the model 1 single syringe extruder for my Ultimaker +.

http://www.fabathome.org/wiki/index.php?title=Model_1_1-Syringe_Tool#Model_1_1-Syringe_Tool_Assembly_Diagrams

This design works with a non-captive shaft linear stepper motor driving the plug inside the syringe directly and pushing material out in a very similar way to the filament deposition method. I know there are a few designs out there just using the filament melted directly onto the plug of the syringe, but I am interested in the more precise stepper driven approach, also with a view to using it as an alternative dual extrusion head. Now my questions to the forum:

I believe the dual extrusion kit won't work on the UM+ because of the heat generated and the power load drawn by the hot end. This will not be an issue for the syringe extruder. Is there enough space/power on the electronics of the UM+ to drive an additional stepper? If so, which port should be used, and what specifications in terms of current and load should the stepper have?

Would either one of these two work?

http://www.zappautomation.co.uk/electrical-products/stepper-motors/linear-stepper-motor/sy17sth0404-100tr8x8-non.html

http://www.zappautomation.co.uk/electrical-products/stepper-motors/linear-stepper-motor/sy8sth30-0504-100tr35x061-non-non-captive-linear-stepper-motor.html

Finally, how might I be able to tell the UM which extruder to use at what point? Would this be handled by Cura?

Any help/input would be much appreciated!!!