In this topic, I'm passing on considerations that came to bear in my own planning, as well as a few general thoughts. The subtopics that are covered here are:
Location
Determining the Cabinet Size
Number of Drawers
Drawer Height
Internal Separators and Drawer Dimensions
Choosing the Drawer Runners
Mounting on a Pedestal
Lighting
Appearance, Cost, and Effort
Location
In my case the house, including the basement, was already full. In the cold climate in which I live, the garage was out of the question. Fortunately, I had in my basement workshop an old but solid oak desk which had become the place to pile up things that needed to be fixed, but never would be. As it happens, this turned out to be the ideal spot for supporting the cabinets, providing a good working height.
The position of the desk would also give me good working space, good lighting, and immediate access to the workbench where I do my cleaning, splitting, sorting, and organizing of new material. I regularly move drawers to the workbench to work with the contents. The combined weight of the fully-loaded cabinets is now about a half ton, but this presents no problem for the desk or for the concrete floor.
Determining the Cabinet Size
The width of my cabinets was primarily determined by the width of the egg cartons I planned to use as internal separators (see the subtopic Internal Separators and Drawer Dimensions below). It was also qualified by the available space above the desk. A single wider cabinet would have been cumbersome to build and to move.
The height on the right side was restricted by enclosed overhead ductwork. I took advantage of all of that height, and chose to make the leftmost cabinet identical.
I find that the optimal position for drawers is between your thighs, to minimize bending, and your shoulders, for good visibility and easy drawer removal. In my own case, I decided to go higher. The uppermost three drawers on each side are a little too high; however they help to provide needed capacity.
Number of Drawers
The number of drawers is not only related to what you need to store the collection (see the following subtopics on Drawer Height, and on Internal Separators and Drawer Dimensions), but is a question of how many drawers of your chosen height you can fit into a given-sized cabinet without excessive space being wasted by the design of the cabinet, specifically the gliding mechanism and the space between drawers.
The approach to cabinet and drawer construction was something that I had been pondering for years. Traditional cabinets, dressers, and desks use wooden dividers between drawers, but with shallow drawers this approach would waste considerable vertical space. Nor would rock-laden drawers glide smoothly over wood.
It made sense to use side-mounted metal drawer runners (a.k.a. drawer glides). Also, I attached each drawer bottom beneath the other drawer components, rather than nesting them into recesses cut in the sides, front, and back. These two steps resulted in the 1/4” drawer bottom itself being the only vertical space unavailable for storage.
Although attaching drawer bottoms in this manner is generally considered taboo in the world of cabinetmaking, it actually works well with metal drawer runners, because the runners support the drawer from beneath. See the subtopic Choosing the Drawer Runners below.
Drawer Height
My history with rock and mineral collecting started at the age of ten with a school project for which I acquired two sets: “Forty Prospector’s Mineral Chips” and “Forty Prospector’s Rock Chips”. These included a variety of minerals, ores, and rock types, each measuring about 1” to 1 1/2” in length. As I collected over the years, this became my idea of “the right” specimen size – and of course, miniatures like these are lighter, less voluminous, and much less expensive than larger (hand) specimens.
The drawer height should be carefully chosen to accommodate the vast majority of the collection.
Internal Separators and Drawer Dimensions
Consider first the size and weight of drawer that you would be comfortable lifting from the cabinet. Also, consider your internal containers. For example, if you use 2” x 3” fold-up boxes, you could select internal dimensions of slightly more than 16” x 18” in order to hold 48 boxes in each drawer, minimizing wasted space while not squeezing the boxes. Grid structures of wood or cardboard with slots of one or more uniform sizes are another approach.
I decided on using two types of internal separators: transparent plastic egg-cartons with the top flaps removed, and horizontal strips. We had to buy the right eggs and save our cartons for a couple of years to do this, but the additional benefits were not only that we reused packaging materials, but also that we got lots of Omega 3.
Internally, my drawers are 23” wide by 22” deep. Each is designed to fit two opened egg-cartons across, and up to two and a half front-to-back. As each opened egg-carton provides 24 slots, each drawer has up to 120 ready-made storage positions, with enough room to spare for a row of additional specimens behind a horizontal strip near the back. An egg-carton slot usually holds one item, but often will house two or more smaller (and usually similar) specimens.
All the drawers have vertical grooves cut in the sides at uniform intervals for inserting removable horizontal strips. These are used to separate rows of specimens too large to fit in egg-carton slots. Even a specimen 6" or longer can fit into a shallow drawer provided that its profile is low enough when lying flat. The strips can be placed in adjoining slots for smaller specimens, or for wider specimens, further apart.
While some drawers use only horizontal strips, most use a combination of the two types of separators, as shown below. I generally like to place the egg cartons towards the front.
In drawers in which I store slabs and other thin specimens, shallow removable trays resting on half-height lower strips allow the capacity of those drawers to be nearly doubled. You can see this in the photo below,.
Choosing the Drawer Runners
I selected low-cost metal runners (glides), specifically Blum Standard single-extension runners available from Home Depot. Sold in lengths from 10” to 32”, these runners allow drawers to be extended up to 75% of their depth and to be removed easily.
Some definitions: On each side, a bracket (called the cabinet profile) is attached to the cabinet, and another (the drawer profile) is attached to the drawer. Each profile includes a smooth-running synthetic roller, and together, they provide a double-warning lift-out stop. Full-extension side-mounted drawer runners, which include a third bracket on each side (the intermediate profile), are also available. If cost is not a constraint, you might prefer full-extension runners.
Drawer runners are rated for a maximum load. The 22" single-extension runners I used are rated at 55 pounds per drawer, and have provided smooth operation for several years without any problems. The drawer profile supports the drawer bottom from beneath, so even when fully loaded with heavy rocks, there’s no danger of the bottom falling out. See Tips for Building the Cabinet and Drawers for further considerations related to the size and installation of drawer runners.
Mounting on a Pedestal
I placed the cabinets on top of a low pedestal, in order that any objects placed on the front of the desk will not obstruct the lowermost drawers. Open at the front, the design of the pedestal (shaped like the letter “E” rotated clockwise) also allows storage under the cabinets, in the open sections of the "E". The vertical in the "E" supports the full length of the cabinets at the back, and the three crossbars support both cabinets at their sides.
Although you can't see it in the following photo, the pedestal, which is about 3" high, is visible in the first photo in this topic.
Let There Be Light
A storage cabinet will also be a display cabinet. Good lighting will bring out the best in a collection, and may also influence where you place the cabinet. In my case, fluorescent lighting was already built into the ceiling above the rightmost cabinet position, but there was insufficient light above the other. A flex-arm lamp above that cabinet provided the answer, nicely illuminating the contents of any open drawer beneath it. Full-spectrum bulbs are preferable. (In the following photo, only the flex-arm lamp is turned on.)
Appearance, Cost, and Effort
If you want a fine piece of furniture to store your collection, by all means use the best materials and construction techniques. A museum cabinet may deserve fine-quality hardwoods, dovetail joints, and french-polishing to perfection. One-third lapping the drawers with the cabinet frame may enhance the appearance of your cabinet by concealing gaps, but note that without wooden dividers, there will always be gaps between drawers - so I chose not to do that.
In my case, function (rather than appearance) was the overriding need, but I also wanted the cabinets to be reasonably attractive beneath their light layer of workshop dust. However, recognizing that one day we will move to a condominium, I tried to make the cabinets presentable so that a single cabinet might be retained when we downsize.
My criteria included low cost and moderate effort. To reduce cost, I decided not to use full-extension drawer runners. I made drawer fronts from leftover pieces of oak hardwood flooring, and made 60 oak handles. I used medium-density fiberboard (MDF) for the drawer backs and sides – not the best building material, but inexpensive and up to the task. Finally, I put a minimum of effort into sanding and varnishing.