This is a small part that you use to fix the Z-Stage on the four threaded rods. Cupcake CNC developers only included 4 of them, fixing the Z-Stage from the top. However, it is useful to fix it also from the bottom to prevent it 'jumping off' the nuts. I found the DXF on thingiverse, however for some reason I failed to convert it to STL miserably. :)

So I created this part myself using a real-world ruler and openScad (openScad is a damn cool piece of software that uses simple programming language to create 3D parts). Here is the openScad source if you wanna play with it:

r=2; // mount hole radius (m3)
t=5; // part thickness

difference() {

union() {cube([30,10,t]);translate ([0,10,0]) cube([15,10,t]);translate ([0,20,0]) cube([30,10,t]);}union() {translate([5,5,0]) cylinder(t,r,r); // holestranslate([25,5,0]) cylinder(t,r,r);translate([5,25,0]) cylinder(t,r,r);translate([25,25,0]) cylinder(t,r,r);translate([5,5,0]) cylinder(2,3,3); // nut placeholderstranslate([25,5,0]) cylinder(2,3,3); translate([5,25,0]) cylinder(2,3,3); translate([25,25,0]) cylinder(2,3,3); translate([30,30,0]) cylinder(t,3,3); // side arcstranslate([0,30,0]) cylinder(t,3,3);translate([0,0,0]) cylinder(t,3,3);translate([30,0,0]) cylinder(t,3,3);translate([15,15,0]) cylinder(t,5,5); // center arc}

}

The part is basically a 30x30mm thing with 10mm whole in the center, 4 holes on the sides (5mm away from part edge), and 4 nut placeholders. I included the placeholders so that we could use the bolts that came in original batch, otherwise you'd need longer bolts.

Enjoy!