Roughing out a design using BlockSCAD

My next project is a Jefferson Lap Desk:

Since this is rather complex, we first need something approximating a sketch, so we use BlockSCAD, which is fast and interactive, and just set up some variables/options:

All of which are hopefully self-explanatory.

We’ll skip joinery and just allow parts to intersect, working that out once we have all the proportions and part dimensions worked out.

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The basic structure is simply an open box on its side which we use some transformations, and a Part Spacing variable to make clear:

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The writing surface in closed position is quite straight-forward:

Managing open and the rotation will be a bit more involved — arguably first thing to do is to position the top relative to the bottom, so instead:

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Obviously the top writing surface needs to be differentiated by a part to hold books in place:

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And, because of where rotation happens, it’s easier to just re-orient the box left–right mirror image:

Which then argues for working out a fixed set of lid positions, one of which puts the front edge of the writing surface on the surface of the table when open — time for some trigonometry.

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The formula in question devolves to:

arctan(Height/Width)

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And of course, we need to use it to trim away the front edge of the lip:

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One position for the writing slope would be:

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Fantastic. Would love to get the file when you’ve finished. Looks like an ideal portable desk.

Adding the drawer is pretty straight-forward:

For the BlockSCAD code for this see:

https://www.blockscad3d.com/community/projects/1478506

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