Add "Z" Axis to lift each extruder indipendently, it's feasible?
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Hi everybody,
i'm starting to design a dual extruder printer and this will be for me the occasion to start to use a Duet, being a mechanical designer i decided to draw all the machine from scratch and now i'm working on the layout deciding between cartesian, CoreXY and H-Bot, now this is not so important at the moment because in any case i will have a X , Y, Z system as usual, my concern is about the feasability of implementing an additional indipendent lift-system for each extruder.
The idea is to interpone 2 additional axis ( linear systems with rail/screw/coupling/stepper) between the X carriage and each extruder that now i will call "U" and "W" axis for semplicity.
In general what i would like to do is:
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Retract the extruder which is not working or,vice versa, lower the extruder that have to print. (mechanically indifferent but i want to understand if one if preferable than another considering the firmware)
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Indipendent sensorless probing for each extruder (contact of the nozzle with plate) done moving the U or W axis down against the plate which is stationary ad his top dead center (Z=0).
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Have the plate that move only down (Z+) during print, and having the U/W axis that lift up the extruders when g.code call for Z-hop.
This last "feature" allow to downsize all the linear motion system of the plate/Z-axis because the plate is quite heavy and considering high print speed/accelerations is more convenient to move up/down 2kg of extruder group than all the plate. Obviously the plate has to come back again to the top but this will be done before the print start at very low sped/acc so is not necessary to have high torque & stiffness.
Now i'have not yet a duet and i'm a beginner in terms of programming so before to procede in this direction what i want to understand if it is feasible, yet implemented, hard..impossible, etc
Any help, comment or suggestion are welcome =).
Thank you
D. -
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@danb If it was me, I'd use a "see-saw" arrangement with each hot end mounted on a beam that rotated about the centre. So when one hot end is lowered, the other is automatically raised. You could probably drive it using a servo motor or a simple solenoid with the necessary commands in the tool change macros. An arrangement like that wouldn't need any additional axes, steppers, lead screws or other paraphernalia that you mentioned.
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@deckingman said in Add "Z" Axis to lift each extruder indipendently, it's feasible?:
paraphernalia
Thank you for reply!
I know the system you're mentioning and you'd be right if you think about "standard components", for many reason long to explain here it's not feasible, the project is not intended for a standard size printer with commercial extruders.Briefly imagine for example what's happen on the carriage overall dimensions in X direction if you use a very long extruder (eg 200mm), wherever you place the pivot point between the two extruder you have increased the x-size in vain.
D.
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@danb said in Add "Z" Axis to lift each extruder indipendently, it's feasible?:
..........Briefly imagine for example what's happen on the carriage overall dimensions in X direction if you use a very long extruder (eg 200mm), wherever you place the pivot point between the two extruder you have increased the x-size in vain.
D.
Not necessarily. The pivot point would need to be on a centre line between the two extruders, but the "see-saw" beam/mechanism itself could be above the extruders negating any need to increase the spacing between the extruders. That's how I'd do it anyway................
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I tried to promote my idea of a "mini-z" axis several times. I needed to control z-hop and mesh levelling for each toolhead individually.
So far it is still a wish, not even on the devs ToDo list. -
@deckingman do you have a link or example of this see-saw type dual extruder? I tried searching for it but came up empty handed.
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@wwak84 said in Add "Z" Axis to lift each extruder indipendently, it's feasible?:
@deckingman do you have a link or example of this see-saw type dual extruder? I tried searching for it but came up empty handed.
No I've never seen one. It's just an idea and how I would do it if I wanted to achieve what the OP wants to do.
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Something like this?
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That looks like the mechanism described, its pretty neat but adds a good deal of complexity. Wouldn't a dual nozzle extruder like the e3d chimera be a better solution?
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@wwak84 The problem with multiple nozzles is that it is almost impossible to prevent oozing filament from unused nozzles being deposited on the print or cooling and causing a head crash. I'm not the OP, but I'd guess that's what he is trying to avoid. Personally, I prefer to use multi input single output hot ends which have a single nozzle. The other alternatives are a tool changer or a multi-filament unit.
