Mission Table Design: 3D Modeling the Double Tenoned Shelf

As stated in an earlier post, when modeling a multi-sold layout part, it is a best practice to reference only the skeletal geometry wherever possible.

.As you may be able to see in the image below, the yellow shelf plane was created via the line and point method at a point on the main elevation sketch that represents the top face of the shelf. The shelf boards were laid out early in the design process on the Layout sketch down at the bottom of the image. I always lay out all of the boards when designing Mission Furniture because generally the boards are book matched and often have butterfly splines between them. The boards in this case are book matched, but have no butterfly splines.

The modeling process for the first shelf board, as shown below, is simply to create a sketch on the plane that was just created, project the geometry that describes the board up to the sketch, and finally, extrude the shelf downwards to the point on the elevation sketch that describes the bottom of the shelf. That point on the image below is the next intersection down from the plane shown…

As can be seen in the image below, the plane for the shelf tenon sketch (pink translucent square) is created by line and end point on the representation of the tenon on the Layout sketch (plan view). If you click the picture to enlarge it, you can see that the tenons are laid out using construction geometry that cross references both the layout and main elevation sketches. There are no dimensions whatsoever. You can also see the board division –the vertical line near the center of the tenon. ..

…this marks the division of the book matched half shelf that will be created before mirroring the book match over to the other side. As per usual, the tenon was extruded back to meet the main body of the part, and I used the extents option ‘To’ again, and chose the same point on the elevation sketch as was chosen to terminate the shelf body extrusion…

Next I chamfered the end of the tenon and created the shelf tenon pin mortises and pins as these features need to be present before the mirroring of the tenon to the other side. The pin mortise is just a ¼” hole drilled through the bottom of the stretcher and through the tenon. To create it in the model, a sketch was created in the usual fashion on the bottom plane of the stretcher, a point was placed on the sketch in roughly the correct location, and a circle was created using the point as its center. The diameter of the circle was set to a parameter named Tenon_Pin (1/4″). Reference geometry was then projected from the layout sketch, and the point was constrained to that geometry. The hole creation itself is pretty straight-forward, with both the stretcher and tenon participating in the procedure…

…the point was found and used automatically by the hole command for the centerpoint, and the diameter was set to the same parameter as the circle was —the Tenon_Pin parameter. For the depth , I created another parameter called Tenon_Pin_Depth .

Now for the pin. The circle from the previous sketch is used to create the extrusion, and the depth is, of course, the Tenon_Pin_Depth parameter used to set the depth of the hole…

Although there is no need to show it, the chamfer was then created on the tenon end, then the tenon with the hole was mirrored over to the opposite side using the YZ origin plane. The result can be seen in the image below…

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Mission shelf half