Non-Linear Z axis?

Does anyone know of any experiments with non-linear Z-axiz, or even support for such in any firmware?

I'm thinking specifically of a screw drive scissor-lift style of Z axis to act as a mechanical multiplier. It may be similar to the changes made to accommodate a delta design?

-Rob A>

Never heard of anyone actually trying it. What's the advantage? Lead screws are simple and already pretty rigid.

Dale Dunn Wrote:
-------------------------------------------------------
> Never heard of anyone actually trying it. What's
> the advantage? Lead screws are simple and already
> pretty rigid.

Mainly to allow the printer to be smaller when not in use. Rather than a gantry style, I'm imagining a core-xy style where the entire X/Y frame can be elevated using a scissor lift. This would give a much taller build envelope without requiring such a large machine.

-Rob A>

Edited 1 time(s). Last edit at 09/05/2012 01:22PM by RobA.

This machine uses a scissor lift mechanism.

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I'm glad to see someone thinking along the same line, I'm even happier to see someone referring to my work, thanks Sublime, sorry about not posting any updates, I'm a bit busy and the lift mechanism is quite tricky specially at the targeted overall size

I did a small modification to a Marlin firmware for the purpose of testing the mechanism, in my case the bottom side of the scissor-lift is closed or relaxed by a regular screw fixed horizontally, since the z-axis values are passed in the gcode in absolute values - I use slic3r don't know about others - I can convert the vertical displacement to horizontal using basic Pythagoras' theorem, with the length of the scissors' arm as the hypotenuse, something like:

z' = z'0 - sqrt( arm^2 - ( z + z0 )^2 )

where " z' " will be the absolute horizontal displacement of the bottom moving hinge of the scissors
z'0 is the initial horizontal distance between the two scissors' hinge points at the same horizontal level at home position ( when the tip of the extruder is touching the printing bed )
"arm" is the length of the scissors' arm measured between the hinge points at both ends
z is the absolute z-axis value from in the gcode
z0 is the initial vertical distance between the two hinge points on the same vertical line at home position

the resulted " z' " should replace the original " z " at the earliest possible point and the original firmware will be suitable, I can't find my modified firmware now and don't remember where did I inserted the equation exactly but I remember is had some comment about "calculating axis positions in absolute steps"

hope this helps, let me know if my explanation is not clear, and please keep us updated on your work