Dumb/awesome idea of the day: screw-driven CoreXY

[Ryan Carlyle]

Build a squarish CoreXY gantry with spectra line or steel wire rope. 

Take a pair of screws each with travel = about 75% of the X or Y axis length. 

Attach a pulley to the screw nut to make a 2:1 compound pulley / block and tackle.

Screw travel produces 2x line travel.

CoreXY gantry requires sqrt(2) = 1.41x line travel per nozzle travel.

Thus, a screw that fits within the frame can produce full CoreXY gantry travel. 

I suspect you could jury-rig a way to use the Y axis (stationary) CoreXY rails for the screw nut carriages by adding some rail length. Which would look rather interesting. But hiding them in the bottom of the frame is probably more reasonable. 

[Whosawhatsis]

Not sure why you would want to use an indirect drive like this for X and Y, but I've proposed something similar for Z to allow you to get the resolution and power-off-holding characteristics of a screw-driven Z axis combined with the anti-wobble decoupling of a belt/cable-driven axis. Also, if you're going to implement a passive cable sync Z axis, switching it to indirect screw drive requires almost no additional parts, and likely allows you to place the screw in a more advantageous location (maybe even horizontally, depending on the aspect ratio of your machine).

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[Ryan Carlyle]

Yeah, your indirect screw Z was the source of the idea here. Applying it to XY is more of a comedy value thing. Like “why on earth would you do that” kind of design to attract eyeballs.

Belt Z and screw CoreXY... maybe that’ll be my next printer...