How to get things rolling
Choose the right caster for the load
If your workshop isn't quite large enough -- and whose is -- you can alleviate a lot of annoyances by making shop equipment mobile. Need to make the best use of your limited space? Want to handle materials more easily? For these and many other problems, the solution just might be as simple as putting something on wheels.
Photo 1: The stem on a typical light-duty furniture caster snaps into a socket like the one shown in the cutaway leg.
Casters provide a great way to make equipment movable, but using the wrong ones can bring you to a screeching halt. Here are five questions to help you choose the right casters for the job:
1. How heavy is the load? Begin your quest for the correct caster by determining the weight of the load you'd like to roll around. You don't have to accurately calculate the weight down to the last ounce; a realistic estimate is good enough. When you're estimating, though, be generous. (The manufacturer's shipping weight is a handy figure to use for tools and equipment.)
Take everything into account as you calculate the load. Include not only the weight of the tool, motor, and stand, but also the weight of any accessories -- outfeed rollers or table extensions on a tablesaw, for instance.
Consider your usual shop practices, too. If, for example, you routinely flop full sheets of 3/4" plywood or particleboard onto your tablesaw for cutting, figure on another 100 pounds of load on the casters carrying the saw.
Once you've determined the total weight, divide it by the number of casters you'll be using -- probably four -- to find the minimum load rating necessary for each one. If you want to put four casters on a tablesaw weighing 270 pounds, each will need to support 67 1/2 pounds. You'd be safe buying casters rated at 75 pounds, but ones tagged for a 50-pound limit probably wouldn't hold up well under normal usage.
Determining the caster load this way assumes even weight distribution. But, the weight may be biased. For instance, the headstock end of a lathe weighs more than the tailstock end. To put the lathe on four casters, play things safe by dividing the weight by two or three instead of four. Generally, you can't go wrong choosing heavier-duty casters for any application.
2. How do I attach the casters? Casters commonly mount with either stems, as in Photo 1, above, and Photo 3, below, or plates, Photo 2, below, and Photo 5, next page. Which style to use depends on the item you're mobilizing.
Plate-mount casters are just the ticket for attaching to a solid flat surface, such as the bottom of a box or platform. Legs usually take stem-mount casters.
For a steadier stance, mount the casters as far as possible from the center of the load. Often you can improve balance and stability by attaching them to outriggers, as shown in Photo 4, next page.
To install plate-mount casters, simply position the caster, mark the mounting holes, and drill them. Then, attach the caster with nuts, bolts, and washers.
To install the socket for a stem-mount caster, drill a hole the size of the socket's outside diameter straight into the bottom of the leg. Drill about 1/4" deeper than the length of the caster stem. Drive the socket into the drilled hole, then snap the caster into it. Non-socketed stem-mount casters fit into a hole the same size as the stem diameter.
Photo 2: Plate-mount casters, available in fixed-wheel and swiveling styles, mount with four bolts. Plate size, hole size, and hole spacing vary among different casters.
Photo 3: Here are three types of stems you'll find. The one at left fits into a hole without a socket. The split ring on the shank holds it in place. The threaded stem screws into a 3/8 - 16 thread on many manufactured items, but could be installed through a hole with a nut and washers. The plain-stem caster fits a socket that has a retaining ring inside.