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.


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


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:


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


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:


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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:


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:

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