Extrusionless MGN12 gantry for Duender

Allows for a length of MGN12 rail to be used instead of cutting a 2020 extrusion down for the X gantry. Up to 3 mounting points are available each side for mounting the rail, and 2 points each side you mounting onto the Y carriage.

My build measures 302mm between the faces of the Y carriages, and the design allows for rail up to 302mm long. The rail does need to be cut roughly at the midpoint between mounting holes, but there is some allowance for adjustment. My rail measures 299mm and each end is ~11mm from the nearest hole centre.

2 rail mounts on each side are intended for use with M3 nuts; the third, in the captive end, is intended to be drilled and the screw tapped into plastic. It will foul on the carriage mount screws if drilled too deep.

I've allowed for 2 heatset inserts on each piece for mounting to the Y carriage - use M5x7x5mm. I don't like that they're mounted on the ‘wrong’ side, but the layout of the Duender mounting holes means I can't have them both pulling through.

I've printed this out and mounted it but my build is not yet ready to run - as such, please keep in mind that it is presented AS-IS, warts and all.

BOM:

MGN12 rail - 300mm x1

M5x7x5mm heatset insert x4

M3 nut x4 (plain or nylon locking both work. Apply a small amount of superglue with a toothpick to help hold them in place while doing them up, if required)

M3x12 screw x4

M3x8 screw x2

Update 24 Feb '25:

• squared up the outer edges to allow additional x travel and easier homing
• simplified geometries to make Duender belt paths smoother

Inspired by Vampire Bat but redrawn from scratch to suit MGN12 rail. Mounts where the Duender 2020 gantry extrusion would.