Step 3: Cutting Mortises and Tenons

This is the fussy step. I started by cutting a prototype tenon, about 1/2 inch deep, and slightly shorter than the full width of the 1x4. Note that my tenon has round edges because I cut the mortise with a 3/4 inch router bit. You could use square edges if you use a chisel or dedicated mortising tool. Next, I had to layout 3 3/4 inch holes spaced 120 degrees apart (if you're clever you can do this with a compass). So I started with top shelf, and marked the hole centers about 1.5 inches from the edge. I stacked the top shelf disk on top of the bottom shelf and centered them, and then carefully drilled 1/16 inch holes through the top into the bottom to transfer the layout marks. I marked the holes A, B, and C on both disks. I then used these holes to center a 3/4 inch spade bit, which I used to drill some starter holes about 1/4 inch deep. Remember that the mortises go on the top of the bottom shelf, but on the bottom of the top shelf. You want to use A, B, and C markings to keep track of the corresponding holes for the top and bottom shelves. That way, if the initial spacing was slightly off, you aren't compounding the error by changing the orientation of the top and bottom shelves.
I have always thought I wanted a lazy susan for books, but have contented myself with bookshelves and bookends over the years. The advantage of a round lazy susan for books is that there are no corners to catch on anything when it revolves. The disadvantage is that some books lean in a strange way that invites them to fall out of the lazy susan. I have always thought the ideal configuration for a lazy susan bookholder is that of a swastika, whether in the German pattern (arms radiate clockwise) or the Swiss pattern (arms radiate counter-clockwise). A swastika pattern does leave corners that can catch something moved too close to the bookshelf. Lest a swastika seem too politically incorrect, I have a commercial CD case that is actually a swastika configuration, but has a top on it so you do not see the swastika layout. Your is nicely done. Thank you for it.
A swastika (in plan) arrangement does seem to make a lot of sense. If you place it on a disk, and position an imposing sculpture of an eagle on top of it, other objects will stay out f it's way, and the corners won't be an issue.
I am sorry, but I do not know what else to call the pattern but a swastika. It would not be placed onto a disc, but the base of the bookholder would be square. It yields four open spaces for books to fit neatly with no unused space. As concerns a sculpture of an eagle, I am not going there.
Yeah, I'm only joking. A swastika shape or some variant of it would be good, especially if the object is to be placed not directly behind but behind and to one side of the monitor slightly. That way the only part of it that could be seen readily would be the compartment that faces you.
A very good idea!

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More by jcohen:Build a "working" tricorder lazy susan bookcase tiny table: an adjustable keyboard tray 
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