Quote
uncle_bob
slop:
The other driver for the metal shaft on a large printer is to drop the hub diameter. If you scale everything up, the hub gets fairly large.
I imagine that some things don't need to be scaled, and can be accounted with a variable change or code modification.
You should be able to modify the g-code preprocessor math to account for a portion of the design to be not scaled (original design intent),
such as the pivot distance of the hub/end effector, and if necessary the lead screw nut pivot distance from the lead screw.
I'm making changes that will necessitate modifications to the g-code preprocessor math:
I'm eliminating the arm pivot off sets, this will place the arms in-line with the lead screw and end effector (math reduction).
I haven't studied the math so I don't know what the function is doing at this time,
but it might be that I only need to delete a portion of the math.
From this
return [z+thetas+math.sqrt(arm_length**2-(ds-hub_offset-shoulder_offset)**2) for i in range(3)]
to this
return [z+thetas+math.sqrt(arm_length**2-(ds)**2) for i in range(3)]
I want a double shear joint vs. a single shear joint.
By moving the lead screw nut pivot out, and away from the lead screw (toward the hub),
you can gain enough room for the arm to drop nearly vertical.
This modification may reduce the effective build area, but it's a design goal of mine to increase the stiffness/rigidity,
and the weight bearing capability of the arms.
So I'll have to make some g-code preprocessor changes to account for the new locations of the arm component pivots, and lengths.
I'm not designing this just for me, I want others to be able to use it for more than 3d filament printing.