Introduction: Slot Joint Adjustable Bookshelves
We love our loft apartment, but it only has one closet. So we have to get creative with clothing and book storage. A large shelf was a good solution for stacking folded clothing and other things. Living in a loft we were able to make a 8ft tall shelf.
I found some inspiration from New Zealand designers Pedersen Lennard (shown above in the two staged photos) I adjusted the design to meet my needs, which were to make a simple shelf that is "quick and easy" to make and requires no hardware. The intention was to hold clothing (for now) and later become a book shelf, so an adjustable shelf is perfect.
This shelf is made entirely out of Apple plywood, a dense high grade Russian birch in 3/4" thickness. The shelf I made is 8ft tall by 5 ft wide and 14" deep. All joints are slot fitted and have dog-bone fillets for ease of assembly.
4 Sheets of 4x8' Apple Ply - $493.88
Brass Brackets $11.10
Polyurethane Satin Coating + Misc rags, brushes. $45
SHELF TOTAL COST $550.00
Step 1: Cut Out Vertical and Horizontal Slotted Parts
I wanted to cut these shelves on a ShopBot (CNC Wood Mill) not because the design requires it, on the contrary the shelf pieces can be easily made in a traditional wood shop, but because I wanted to get comfortable with the Shopbot work flow and make something that would be easy to generate code for and cut.
I drew up the the shelf plans in Fusion360 and exported them as .DXF files. I imported it and generated .Sbp files with my tool settings, and particular feeds and speeds. * I highly suggest doing this process on your own and generating new G-Code to make sure its correct.
Since this piece requires no hardware and needs to have slot joints that are snug but not too tight, you need to measure and adjust your tolerances on all the slot gaps after measuring your plywood with calipers. I find that 3/4" ply can vary quite a bit, even when ordering a new batch from the same supplier. If your tolerances are too tight later you will need to sand the slots for a while which takes extra time.
I have included drawings so you can look at my exact measurements if you like.
Step 2: Sanding, Sanding Then a More Sanding
I wanted a smooth finish on all surfaces so I sanded every piece with 220 grit and 320 grit using an orbital sander. The important part is the sides where the cuts were. They are a bit trickier to sand and require a bit on hand sanding between the cuts. I also tested my small shelf to make sure the shelf tolerances fit together.
It took a while to sand between each slot and on all sides.
Step 3: Sealing and Assembly
I used Minawax Poly-urathane satin finish, applying 2 coats to each side with a foam brush, sanding with 220 and then 320 grit between coats, sealing each side 3 times. This took several days and was not easy to do right on first try.
Pro Tip* I found that using a wipe on poly-urethane or an oil/wax based finish like (Rubio Monocoat) is better then the foam brush application which will drip and streak. If you have the option use a wipe on sealer and apply several thin coats with a cotton rag to get a smooth finish. Light sand with 400 grit for final smooth finish if necessary
As always, safety first! Wear gloves, a respirator and apply any chemical finish outside or in a well ventilated area.
Once all parts are fully dry, allow at least 24 hours to fully dry.
Assemble shelf and voila!
Pro Tip. If your shelf slots are too snug and require force, grease all joints with a bar of soap and try assembling then.