PLA isn’t particularly strong, especially in small sections under high stress:
MPCNC – Cracked Z Motor Mount
I tried solvent-bonding + clamping the break, didn’t expect much, and wasn’t disappointed.
Z Upper Motor Mount
It adds a festive touch when done up in orange PETG:
MPCNC – Reinforced Z Motor Mount
The attentive reader will note the missing head of the screw anchoring the mount to the left Z rail. Apparently a #32 drill was a bit too small to let the randomly chosen self-tapping screws thread themselves into EMT; they probably anchored a PCB to the plastic case of a long-forgotten lump of consumer electronics.
It should last long enough for something else to let go …
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#1 by Jason Doege on 2018-01-30 - 09:09
Many of the pieces of the MPCNC look pretty trivial to mill out of aluminum when they inevitably succumb to stress. Are you thinking about doing that?
#2 by Ed on 2018-01-30 - 09:30
Ryan designed the shapes specifically for 3D printing, so they’d be awful to chew out of solid stock with a simple milling machine. A guy on the MPCNC forum showed off his lost-PLA aluminum cast parts, although IIRC he didn’t do much in the way of post-casting cleanup.
Bulking up the existing shapes seems the least-awful way of reinforcing them, although the screw fittings on the circumferential clamps still look like the weakest parts.