My idea is to remove the extruder motor from the Y carriage and place it on the X idler, opposite of the X motor. This has already been experimented with; http://garyhodgson.com/reprap/2012/01/experimental-off-carriage-extruder-motor/. This would decrease the total mass of the y carriage and allow greater printing speeds. But instead of using a rod for the drive gear, a belt is used to drive a pulley, to which the drive gear is attached. See attached image.
Obviously, some logic will have to be implemented for the extrusion, as the extruder must now counter the movement along the X axis.
Do you think this is worthwhile?
cool idea, maybe some CoreXE approach? one belt 2 motors, just like CoreXY but only with X axis and Extruder.
Probably need to draw that out to see if it is worth implementing.
One belt 2 motors is h-bot not corexy, corexy uses 2 belts 2 motors.
You are right, I didn’t looked into details of those mechanisms.
Its a nice idea, I wonder if having it in a H-bot style setup (e.g. run both motors in same direction to move the axes, opposite directions to move the extruder) would be better or if the difference between required extruder and axes torque would cause issues with that setup?
I’d like a lighter/faster X carriage but don’t want a bowden setup, so this does seem like an ideal setup to achieve that!
@Liam_Jackson Yes I’m a bit curious about the extruder torque as well. But I guess if that would be an issue you could smack in NEMA23 instead along with a driver that could accommodate higher torque through higher current output?
And like you I didn’t quite want bowden just yet, so I came up with this. I think the idea of having a single motor for both x axis and extruder has been drafted somewhere though…
Just going to tag in @Joshua_Rowley and @Tim_Rastall here…
@Sanjay_Mortimer Yep, saw this :). I Also saw your comments on the original design back in 2012.
@Mike_Miller What if they started looking for the hash tag and targeted that stuff to steal first just to really piss us all off?
Sooo could anyone please implement and share the result? 
Will have a go at this once I complete other pending projects and share the result here. I have two other ideas, a positioning feedback system and a linear rail, which I’m looking to share very soon. BTW, is the Makerbot threat real, i.e. do we risk getting our ideas shared here stolen?
Still interested in feedback, criticism etc. on the above idea, just so you know!
I’ll just go ahead and claim first here: http://forums.reprap.org/read.php?151,99646 (Image missing for whatever reason, @Mike_Miller prior art as of October 2011).
The belt path as pictured in this post is not going to work as the motors can’t turn independently. A hbot or coreXY-style setup would work, but it still increases the load on the X motor. Adding gearing on the extruder carriage would shift the working point of the motors towards higher RPM and less torque. Steppers can maintain their torque up to a certain RPM and then drop off, so you’d have to figure out a sweet spot where the motors work at their maximum power output when printing at full speed.
@Imko_Beckhoven_van coreXY still only uses one belt, but has a belt crossing to prevent racking: http://corexy.com/theory.html
No one seems to have read the text on the drawing. The belt pictured only drives the extruder. There is another belt that drives the carriage. I still do not think it is a good idea since the extruder motor would fight the carriage motor and amplify the slop in the carriage, with movement along the axis of travel and a torque on the carriage itself.
@Wylie_Hilliard right, it does say idler.
@Thomas_Sanladerer yes its crossing over but i’s also connected at 4 points front / back and left and right to the extruder. For refference http://corexy.com/theory.html
