Rotating base for Meccano builds

My dad had big plans for cranes and merry-go-rounds made with Meccano and had a thrust bearing he wanted a purpose for. He asked me to print a 120 mm disc and a large gear that could form a rotating base to build these projects on.

Printed parts

• Bottom plate
  A 120 mm disc with holes spaced like those of a Meccano plate, allowing fixing it Meccano structure underneath. I did update the hole pattern after printing, hence why the uploaded model has a few more holes than the print shown in the pictures.
• Top plate
  A 135 mm disc with 8 holes for threaded inserts, also spaced for mounting Meccano on top. It has notches for the gear to slot into.
• Gear
  200 teeth spaced to interface properly with a Meccano gear mounted on a Meccano structure on the bottom plate. This gear is combined with the top plate. Having this as a separate part allows for more accurate print settings for just this part and for easy replacement when it fails.

Required hardware

• Small bearing
  Outer diameter: 24 mm
  Inner diameter: 8 mm
• Three-part thrust ball bearing
  Outer diameter: 78 mm
  Inner diameter: 52.4 mm
  Height: ~20 mm
• M8 sleeve nut
  Outer diameter: 10.8 mm
  Flange: 2.0 x 14 mm
  Height: 17 mm
• M8 bolt
  Minimal length: 37 mm
• M4 heated inserts (8x)
• M4 bolts (8x)
  I decided to use metric bolts rather than Meccano bolts to attach Meccano parts to the plate, as metric inserts were easier to find for me.

This was the hardware we had at hand at the time, but some of these might be hard to source. So if you would like to use other hardware and need adjustments to the model, feel free to leave a comment.

Printing

• Bottom plate
  Layer height: 0.28 mm
• Top plate
  Layer height: 0.28 mm
  Supports enabled
• Gear
  Layer height: 0.16 mm

Assembly

1. Melt the heated inserts into the small holes of the top plate
2. Press the gear over the top plate
   You might need to file the notches a bit to make it fit snuggly.
3. Press the small bearing into the centre of the top plate
4. Press the top of the thrust bearing over the center ring of the top plate
5. Press the sleeve nut into the center of the bottom plate
6. Press the bottom of the thrust bearing over the center ring of the bottom plate
7. Stack the plates, sandwiching the balls of the thrust bearing
8. Use the M8 bolt to link the plates