Prusa Mendel PLA Coupling

by Griffin_Nicoll, published

Prusa Mendel PLA Coupling by Griffin_Nicoll Mar 20, 2011
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After repeated failures of the standard z-axis rod coupling, a need for a more robust coupler was determined. This coupler has separate clamps for the 3/16th drive rod and the motor shaft, centering both without stretching the PLA too much. Additionally, it has recesses for the nuts, allowing very easy tightening and adjustments. This design however uses 4 bolts and nuts instead of 2.


The given values are for the SAE Prusa Mendel. You will need to modify settings for metric. Also the screw holes are a bit larger then they need to be, but it worked great for me. If your layer thickness is 0.4 or greater, you may need to increase the size of the bridging layer. You will probably also want to saw off excess screw after tightening around your rods, as the 1" #6 screws will be too long.

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Prusa Mendel PLA Coupling by Griffin_Nicoll is licensed under the GNU - GPL license.

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Easily the best z coupler avail. Thanks for the great, simple, functional design.

Ive made a parameterized version. http://www.thingiverse.com/thing:15633http://www.thingiverse.com/thi...

It however does not have the cut on one side which I can add if anyone wants. Just ask.

Parametric Shaft Coupling

My Nema 17 has a 5mm shaft connected to a 9.5mm shaft, do you happen to have something that might fit this configuration? =-X

Oh yah sure let me make that parametric and clean up this crappy old code. Sorry about that. Im busy today but I'll have it done Wednesday.

Is the drive rod 3/16" or 5/16"? I thought the SAE Prusa was 5/16"?

Very nice , i used these (modified for metric and smaller diameters of rods and axis), on a "rusty" huxley prusa, and they work great ! when sufficiently tightened , they don't slip! well done :)

I tightened up the "nutR" (nut radius) to 5.2 to get more infill around the nuts and a press-fit. Otherwise I had some trouble with nuts slipping.

Well done. You've also hit the nail on the head as to describing why belt-driven Z axis assemblies are my preference.

looks like another good option to try. Thi is a tough part because gravity is always working against it. I had to put some cross notches in the motor drive shaft to get it to hold on. if it fails again I may jbweld it together :)