Last time I build the two squares which form the main body of the X and Z axes. This time I’ll print out the parts that connect these squares, and use them to attach them together. This will be the first step where we attach stepper motors also.

This step requires printing out 4 new parts, all of which are quite large.

You can download the STLs for these parts – the links are:

The top mounts look like the piece shown below:

z-top-drive-left-cura

The motor mounts look like the piece shown below:

z-motor-mount-right

I printed out each of the top mounts, and inserted two 608ZZ bearings (608RS bearings are fine also, I just happened to have 608zz bearings handy). ZZ bearings have metal seals on each side, where as RS bearings have rubber seals. You can see this in the photo below.

Top Mounts

I then printed out each of the motor mounts. These require a little bit of extra work before attaching the motors:

  • I needed to insert a knurled insert nut in one side (using a soldering iron). This is so I can use an M5 thumbscrew to adjust when the Z-axis limit switch is triggered;
  • I also needed to insert an M3 knurled insert nut on both sides – this allows me to insert an M3 bolt to secure the vertical slider rods;
  • I inserted 4 M5 x 10mm bolts on each of motor mounts through the two holes on the left and right sides, and I threaded an M5 T-nut on each of the bolts. I did this to make it easier to thread the 2 squares I made last time onto these parts. The alternative is putting the nuts into the central grooves on the aluminium extrusion and trying to find them with the M5 x 10mm bolts. This would be pretty difficult, as there’s very limited space inside these printed parts;
  • Finally, I inserted two 608RS bearings into the large holes on both sides;

You can see the printed parts in the photo below.

Motor Mounts

The next step is to attach 2 NEMA-17 stepper motors to these two motor mounts. Each motor requires 4 x M3 x 12mm bolts. These are pretty straightforward to attach – I’ve shown this below. One thing to remember is to make sure that each motor is oriented in a consistent way – they might look symmetrical, but the 4 wires emerge from a side. I decided to orient the motors so that the wires came out at the back.

Motors with Mounts

The next step is the tricky part – there’s nothing technically difficult, but the size of the squares makes connecting the parts awkward. I found the best method was to lay one square on its side, and attach the four corresponding pieces onto the square frame, as shown below.

It’s really important to remember that the frame has a top and a bottom – the top of the frame will have the central groove threaded to accept an M6 threaded bolt.

Frame on side

Finally, slide the second frame onto the 4 parts. I found it easiest to slide from the top down.

Attaching second frame

I tightened the bolts on each of the top mounts, and rotated the frame into its normal vertical orientation. I pushed the motor mounts down to be flush to the ground, and then hand tightened the M5 bolts in the two motor mounts.

Finished frame

Next time, I’ll print and install the mounting points to attach this frame to the Y-axis (which I made in the first 3 parts of this series).