Mike J. ( B9-0002 )

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10/29/2004 - Building the Donut Assembly

The Donut, lazy susan and waist plate form a single assembly. There's an optical switch and interuptor plate also attached, it is used to determine the straight ahead position.

 

First, we drill out and tap eight 5/16" holes in the outer ring of the lazy susan. The outer ring will be stationary and the inner ring will turn.  Eight 3.5" long support rods are cut from 5/16"-18 threaded rod stock.

 

The inner ring gets six 1/4"-20 holes drilled out and tapped.  Use the six counter sunk holes already present (the counter sunk side is the bottom).

 

Cut a strip to act as the interupter for the optical switch from 1/16 aluminum sheet.

 

Use clamps to hold the strip in place, it should be flush with the top of the lazy susan.

Bottom view:

 

Drill and tap 4-40 screws. Note how these line up with the unused pre-drilled holes.

 

The alignment is critical. The leading edge of the interuptor should line up with the support post as in this photo.
After it's mounted trim the trailing edge to be exactly 180 degrees offset.  Paint it flat black to reduce reflections that might cause false signals.

 

Here are all the fabricated parts prior to assembly

 

Lazy Susan assembly complete: Top View

Bottom View

 

Here's the optical switch with a fabricated mount made from a 1/4" piece of acrylic.

 

Here's a shot of how the switch interacts with the strip.

 

Here's the donut with 8 hole drilled to allow the 8 threaded rods to pass through it. Also, 8 screws are in place to act as spacers to raise the lazy susan to the correct height.

 

Here's the waistplate with 8 holes drilled for the support rods. Note the counter bored holes to allow for nuts that are flush with the bottom of the waist plate.

 

Lazy susan in place in the dount.

 

Waist Plate in position, held there by nuts on the threaded rods.

 

Optical Switch Mounts on threaded rod.

 

Central Support Structure (CSS) bottom plate. Fabricated from 1/8 aluminum plate.

 

 

Drill the torso to match the CSS plate.

 

Make sure the torso rotates without binding. There should be about 1/16" clearance between the torso and the donut.

That's it for now!

 

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