Reference

Workbench tops: thickness first, then material

Thickness decides whether the bench flexes. Material decides how it behaves. Most listings publish neither, and the ones that publish thickness are telling you something.

A bench top is a beam. When you clamp work to the front edge and push down, the top deflects, and how much it deflects depends dramatically on thickness - beam stiffness rises with the cube of depth, so doubling the thickness of a top makes it roughly eight times stiffer, not twice.

That is why a 0.75 inch top and a 1.5 inch top are not two grades of the same thing. They are different products. And it is why thickness is the first number to look for, and why a listing that does not publish it has probably not got a number it wants to publish.

Three things, all of which you find out in the first week. Noise: a steel top turns every dropped tool into an event, and hammering on one is genuinely unpleasant in an enclosed garage. Marking: a painted panel laid on bare steel picks up whatever grit was already there. And cold - an unheated garage in January makes a steel top something you avoid leaning on.

None of that outweighs the advantages for automotive or metalwork, where solvent resistance and not setting the bench on fire are worth a great deal. The common fix is a steel bench with a wood or rubber mat over part of the top, which costs almost nothing and gets you both surfaces.

On a steel top, thickness is expressed as gauge and the same conversion applies: 14 gauge is 0.0747 in and 20 gauge is 0.0359 in. That is the difference between a top you can hammer on and one a dropped socket dents. The full gauge table.

Note the gauge on a steel top is a much thinner absolute figure than a wood top's thickness, which is fine - steel is far stiffer per unit thickness. What matters is what is underneath: plate spanning a frame behaves completely differently from a skin bonded to board.

If there is any chance you will fit a vise, check two things before buying. First, that the top overhangs the frame enough to get a backing plate behind the mounting bolts - without one, the bolts crush the top rather than clamping it. Second, that the material can take the load at all: MDF and steel-skinned board cannot, whatever the frame is like.

This is not retrofittable. A bench that will not take a vise will never take a vise, and finding out afterwards costs the bench. How to choose a workbench has the rest of the pre-purchase checks.

• Oil rather than varnish. A film finish chips and traps dirt underneath; an oil finish wears evenly and can be topped up in ten minutes.
• Do not seal the underside differently from the top. A top sealed on one face only takes up moisture unevenly and cups.
• Sacrificial layer for messy work. A sheet of hardboard clamped down takes the drilling, the glue and the paint, and is replaced for a few dollars.
• Flatten rather than replace. A cupped or worn hardwood top can be planed or sanded flat. That is the argument for solid wood over anything laminated.