Model an egg shape

I drew an outline of the elevation of an egg, by intersecting two circles, drawing a smaller circle in the center, and an even smaller circle on top of that. I rotated the election using the Rotate3D command, then added horizontal circular sections along the Z-axis. Then come up with solid object through the loft command.

I then sliced the egg horizontally, and subtracted a small sphere for the Yoke through the boolean difference command.

Making the ribs

To make the ribs I used the contour command which is really useful and safe a lot of time. By selecting the solid this command allows you to slide the object with planes, at a set distance. I decided to do this diagonally instead of orthogonally.

After producing the contours of the ribs. I extruded them but the thickness of the plywood, 15mm. And grouped and intersected both sets of planes running perpendicularly to each other.

Making the Waffle joins.

To make the waffle joins I copied the intersecting planes and used the Boolean intersect command to isolate the areas of intersections between the planes. After which I split the intersected geometry, which was basically a set of rods, at the midpoint of each using a small horizontal plane I drew. I then made two groups. An Upper and Lower part of the interaction.

I then used these two groups to subtract from the Waffle planes. Using the Booleon difference command I subtracted one set of the waffle planes from the lower intersections. And the other set with the upper intersections. This produced a perfectly fitted Waffle structure along the egg geometry

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Prepare CAM file

After ‘nesting’ the pieces on the profile of the stock. Making sure the pieces have a good distance between each other and from the edge. I use the Make 2D command to create a 2D drawing of the upper profiles of the ribs.

This file is then ready to go into Rhino CAM where it will be prepared for CNC cutting.

Rhino CAM Settings

To prepare the CAM file we first need to make sure we have the layers organized correctly. In my case there are three main layers. 1. Stock 2. Outcuts 3. Screws

In each layer hold important information for the cutting.

After setting up the layers, we then set the machining operations. In this case it will be a 2-axis operation since we are cutting a planar surface and the Z axis is not variable. Within the 2-axis cutting there are many options ie. Roughing, Facing, pocketing, profiling etc… In this case we will set up engraving and profiling operations.

Engraving

In the screw layer we placed points at a distance from the cut pieces. This is important to hold the board down while the machine is cutting. We select the curve/ edges first then set up the rest of the parameters.

Clearances plane: is the plane where the machine moves along the piece. It is set higher so not to crash into the work piece. Set to 20mm Tool: We choose a flat head mill Feeds and Speeds: 15000RPM - 2600 for the rest Cut Parameters: Tolerance to 0.03 - Cut Direction: Natural - Location of Cut geometry: At top - Total cut dept: 3mm.

2-Axis Profiling

Clearance Plane: Tolerance:0.03 - Cut Direction: Down Cut Feeds and Speeds: 15000RPM - 2600 for the rest Cut Levels: Location of Cut Geometry: At top - Cut Depth: 15.3 Rough Depth/Cut: 3.1 - 15.3/3.1 = 5 ?