RepRap: Blog

To give the μRepRap Axis Driver true linear motion (as opposed to the current very-flat-arc motion) I've suggested using a pantograph mechanism to do the movement reduction. The point of this is to allow common CNC or 3D Printer software to drive μRepRap without having to do maths to get the absolute positioning right.

To create a pantograph using flexures I need two things: First, there can be no shared pivot points; basically every pivot only has one moving arm sticking out of it. Second, the areas where the drive screw and stage attach must have a level land - I cannot directly attach the drive screw or a stage to a pivot point.

So I noodled around with FreeCAD and came up with this 1 DOF-constrained concept, based on having the drive screw on the left flat, stage attached to the middle, and the right flat firmly anchored:

As you can see, this functions as a 3:1 reducing linear pantograph, and you'll note the flats at the bottom remain parallel to the X axis. Printable design left as an exercise to the enthusiast...

Those understanding constraints might notice it relies on the drive screw being linearly constrained, but that can be handled with the same sort of parallel flexure as the Maus C stage uses, so I've cheated and left that off for clarity.