How to Assemble the Prusa i3 Y Axis 3D Printer Frame

By Kalani Kirk Hausman, Richard Horne

The first part of construction for your 3D printer is with the Y axis frame. The frame is made from four printed corners, with M8 and M10 threaded rods and nuts, and this forms a rectangle of smooth bars along which the Y axis can move back and forth, driven by a stepper motor.

To build the Y axis frame, follow these steps:

  1. Assemble the Y axis frame side:

    1. Take one of the 380mm M10 threaded rods, and thread an M10 nut into approximately the middle of the rod. Slide two M10 washers and thread on another M10 nut to make a sandwich of washers in between the nuts, all in the middle. Do not tighten.

    2. Thread another M10 nut onto each end of the M10 rod about 45mm in.

    3. Slide an M10 washer onto each end, then fit the printed Y corner onto each end of the M10 rod. Check orientation of the Y printed piece: The M8 grooves to hold the smooth rods should be facing up and inwards.

    4. Slide an M10 washer onto each end of the rod up against the printed part.

    5. Thread an M10 nut on each end of the rod. Now you can hand-tighten the parts so the printed ends are secured by the M10 nuts and washers.

    6. Repeat the mirror image for the other Y axis side.

  2. Assemble the idler bearing mount:

    1. Slide a M4 washer onto the 25mm M4 bolt and insert into one side of the idler mount, while holding two 624ZZ bearings in the middle of the mount. Push the bolt through.

    2. Slide another M4 washer on and secure with another M4 nut.

  3. Assemble the Y axis front and back frame sections:

    1. Take two of the 210mm M8 threaded rods and thread on an M8 nut about 45mm onto one end of each rod, then slide an M8 washer onto the rod against the nut.

    2. Insert the ends of the M8 rods into the Y axis, printed corners-up, against the two M8 nuts and washers.

    3. Use another washer and M8 nut on each rod end to hand-secure the rod against the printed Y corner.

    4. Slide a nut and washer into the middle of each rod, then slide on the Y motor mount so it faces inwards.

    5. To secure the mount, use another two washers and nuts to sandwich the printed part; hand-tighten.

    6. Repeat steps a–e on the other end of the M10 rods.

    7. For this end you need to slide on the printed idler mount, again facing inwards. Repeat step e to secure the idler in the middle of the rods.

    8. You will need to add the third and fourth corners to the other ends of the rods using steps a–e.

  4. Measure and tighten the frame.