Lab Shelves

2x4 and plywood shelves for the test equipment
June 12, 2022
lumber lab shelves

As I expand my collection of test equipment, both in variety and backwards in time, my office has been running out of horizontal space. The top of the cable bin was covered in VTVMs and the holiday decorations were buried under signal generators, with a shelf in the laundry room dedicated to repair projects. After visiting a particularly productive garage sale, I filled the last shelf and ended up with a floor ‘scope. Something had to be done.

After measuring my office, some quick CAD work in OnShape produced a viable design. The original concept was a full wall-length shelf with alcove in the middle for my soldering cart and reading chair, but I ended up building them as two separate shelves which made everything easier. The wall-length concept would have had to be assembled inside my office, which would have meant removing my desk and the server rack. With separate shelves, I had to move my desk over but was able to build and position them one at a time.

After being split, the frames are 80" tall, 44" wide, and 27" deep (203cm tall, 112cm wide, and 69cm deep). The shelves are 41" wide and 24" deep, with the cross braces adding the extra 3" of depth. If I were to redesign them, I would try to integrate the cross brace under the shelves to provide some support across the length and reduce the depth, so the shelves are flush on the front and back. I tried to keep the design fairly simple, with three different parts and a single kind of fastener - not Phillips.

One trip to Home Depot with a van was enough to get all of the lumber: 2x4" whitewood studs and 4x8’ sheets of 3/4" maple plywood. I priced out a few options for the shelves and the sande plywood was the cheapest option in both the 1/2" and 3/4" categories, but after looking at what they had in stock, I sprung for the maple. It has a very nice surface and was easy to cut, even though I am not a skilled wood worker by any means. Almost everything is attached using 2-1/2" star drive wood screws, except for the corner brackets and leveling legs, which use their included screws.

Once I had the first frame cut, I brought everything down to the basement and laid out a moving blanket to assemble it, with plenty of help underfoot. These shelves won’t fit up the stairs once fully assembled, but the cross braces can be removed without completely taking apart the side ladders. The first frame was very close to level, but not as square or rigid as I wanted, so I picked up a dozen corner brackets and put them down the back of each frame. I may add some more to the front later, but reinforcing the back and adding shelves made the frame much more stable. To fine tune the level, someone in Discord suggested a set of heavy duty leveling legs, which should be able to hold the weight I have planned.

I tried cutting notches in the corners of the first shelf, but forgot to calculate the triangle at the bottom of the next support (about 41.87"), and the shelf wouldn’t fit. Luckily I was able to trim the ends down and use that piece, but the rest are simple squares. For the heaviest ‘scopes and tube gear, I plan on adding some braces across the middle of the shelves, but according to The Sagulator calculator, the 3/4" plywood should be able to handle about 50lbs per shelf without fixing the sides or bracing them in the middle. Fixing the sides would probably be good enough for about 100lbs per shelf, but with a center brace reducing the span to 22", they can handle something like 200lbs. Combining the two would make sag a non-issue and the load limit would be structural, the frame or my floor.

The space between the shelves is the same width as my repurposed AV cart with the wings up. When I’m not soldering, it is a well-lit alcove for having a nice whisky and reading datasheets. There is a dual-purpose rug for foot comfort while reading and carpet protection while soldering, suggested by the garage sale fellow, from whom I got the Hallicrafters power supply and matching set of Heath gear. I need to get a vertical power strip to reduce cable clutter, and maybe talk to an electrician about a dedicated circuit. My isolation transformer and variac are within easy reach on the right, behind the OWON power supply. I have most of the parts for a compact dim bulb tester, which will be a future project.

Parts

Each shelf frame is made up of three different lengths of stud. The 2x2 furring board used for the bottom shelf can be replaced with 2x4 if you are not worried about clearance from the floor, but I wanted to make sure our Roomba could fit underneath.

The shelves are 7 pieces of 41x24" plywood, 1/2" or 3/4" thick.

This is for each frame, double for a pair as shown. Each side needs at least 10 studs and 2 sheets of plywood, plus the furring board and metal parts.