I need to build some shop furniture, mostly roll-round utility tables, but I will also need stands for things like the drill press, grinders, etc. Rather than re-invent the wheel every time, I decided to settle on a single design I can use for a variety of applications.

Back in 2005 when I moved my office from our first 700 square foot building on Whittier Ave to a 1,500 square foot unit on Monrovia, I spent Memorial Day Weekend building five workbenches out of structural Douglas fir, some pine boards and 5/8 inch sheathing:

Image

It’s a very basic design. I didn’t see it anywhere, it just seemed a natural way to build a bench. Those were assembled with deck screws; later I would use 1/4 inch lag screws in most places. I covered the benches with sacrificial 1/8 inch Masonite (hardboard) that can be removed and replaced after it gets worn, a trick I learned from my father:

Image

When that photo was taken, there was only one person working in the warehouse: me!

Those benches are still in use, and I made a few more five years later when we moved across the parking lot to Unit B1. When we moved across town to Baker St I asked my production manager if she wanted to get fancy proper workbenches and she said she liked the ones we had, so we made some more. I think we have ten of them now.

In the meantime I also constructed some big 8×4 foot worktables of pretty much the same design (with no shelves) for use in the shipping and receiving area. When we moved to Baker St I made some more, but fitted them with casters so you could move them around the shop easily (note the assembly benches in the background):

Image

This proved to be a remarkably useful innovation. We have four of those big roller benches and we use them constantly. It’s incredibly productive to be able to stack stuff up on a bench in your working area and then simply roll it out to the shipping area, or vice-versa. Which reminds me of an anecdote from Nassim Nicholas Taleb concerning wheels on airport luggage . . .

So I decided that from now on utility benches would have casters.

For my woodshop I am looking at a different design, this one of 3/4 inch birch plywood. It’s something I have seen around on YouTube. Also, the woodshop next door to us when we were on Baker had a bunch of these (they later added casters to them after they saw our roll-around benches). All my projects are assigned random project names (from a spreadsheet, natch), and this project is called Jade:

Image

I’ve been trying to work out how large to make my Jade bench(es). The big 8×4 foot bench is too big for my space and anyway the eight foot span probably tests the strength limits for this particular bench design. Luckily, my design software, SolidWorks, lets you easily develop what it calls configurations, that is, variations on a single basic design that differ by dimensions or other changes. So after designing my Jade bench, I whipped up a number of different configurations by changing the main table top dimensions, which are all at a 2:1 aspect ratio (that is, the width is half the length):

Image

SolidWorks would allow the widths of the stretchers and legs to be changed for each configuration to make them more proportional, but I wanted to keep things simple, so in all cases the legs and stretchers are five inches wide.

Of course, there’s a spreadsheet at upper left in the illustration. That’s to work out the bill of materials (or more specifically the cut schedule) for each bench. The green tinted cells are variables, that is, dimensions that might be specific to a particular bench size. Once those are entered the rest is calculated automagically.

Non-USAn readers might note with dismay and alarm all the fractions that appear in the Length and Width columns of the spreadsheet. These are truly the American Man’s Burden, and what set us apart from the rest of the world far more profoundly than rampant gun nuttery. In fact, I have often wondered whether any other culture in the world besides the US and the British use fractions at all, for any reason (and the British are migrating away from them now too). The worst part is when you have to do math with fractions. Luckily, we have spreadsheets for that.

Naturally, going metric for this sort of thing would be practical, but here is why I won’t:

For my mechanical design work I use decimal inches, no fractions. This is easy for me and easy for the machinists, who just punch decimals into a CNC program. From that point of view, calling out 2.763 inches is no easier or more difficult than using 7.018 cm.

Mathematically, fractions can be more accurate than decimals. For example, 5/32 is much more precise than, say, 0.156, which is rounded up from 0.15625. But today computers and calculators just work with the floating point, so fractions don’t give you anything when doing calculations. And when measuring you are subject to tolerances anyway. If I want to use a dimension of 5/32, it will be called out as 0.16 if I can live with a tolerance of 0.015; and 0.156 if I need it to be accurate to within 0.005. I never get to 0.15625, practically speaking.

The problems occur once a tape measure gets involved. All the tape measures I have ever seen are in fractions of an inch. So are the yardsticks and just about every other device for taking linear measurements except a few engineering scales I have laying around (my digital micrometers can switch at will, of course). So anything architectural, or in the woodshop, uses fractions of an inch.

If I really cared (and maybe if I was raising kids I would care more), I could round up every tape measure and ruler in the house and in the shop and trade them all in for metric equivalents. Within a week of using a metric tape measure I suspect centimeters and millimeters would be as natural to me as inches and quarter inches. After all, it didn’t take long for me to find driving in the UK as natural as driving in the US.

But there is no compelling reason for me to make the switch, especially as I can do the math with Excel, when necessary.