Hands-on
The workshop bench
A live wood surface you can work. Sand it through the grits, plane it flat and watch the shavings come off, cut a kerf with the saw, pare with a chisel, then stain and wax it. The surface is simulated from a height field, so every stroke genuinely changes the material.
What the simulation does
Six tools, six different physical effects
Sanding
Each grit has its own bite. Sanding reduces the surface roughness value and shaves the peaks of the height field, exactly as abrasive paper cuts the fibres. Coarse grits leave their own scratch pattern.
Planing
The blade takes a full-width shaving and leaves a genuinely flat surface. It removes far more material per stroke than sanding and throws a curled shaving that arcs out of the cut.
Sawing
Drag in a straight line and the saw cuts a kerf along that line, removing material as it goes. Let go and start again and you begin a new cut, because a real saw cuts in a straight line.
Paring
The chisel leaves faceted marks that catch light on one edge and shadow on the other, which is why a pared surface reads differently from a sanded one even at the same depth.
Staining
Pigment soaks into the pores. Rough and porous areas take more colour, raised grain stays lighter and the low spots go darker — which is why blotching happens on soft species.
Waxing
Wax builds sheen rather than colour. It reads as a specular highlight that follows the light across the grain, and it sits on top of everything rather than soaking in.
A sensible working order
Try the sequence in this order
Plane first, sand second
In a real shop you plane to remove the machining marks and get flat, then sand to refine the surface. Try it here: plane a few strokes, watch the surface flatten, then step through the grits. Sanding a surface you never flattened just polishes the bumps.
Do not skip a grit
Switch to P60, work the board, then jump straight to P220 and watch the roughness value. It will not drop as far as you expect, because the coarse scratches are still there. Now step 60, 120, 180, 220 properly and compare the reading.
Stain after the final sanding, not before
Stain behaves completely differently on a rough surface and a sanded one. Reset the board, stain half of it, then sand the other half to P220 and stain that. The difference in colour absorption is the reason the grit progression matters.
Cut before you finish
Cutting a kerf after you have stained shows you why the sequence in a real build is cut, assemble, then finish. Sawdust and cut fibres ruin a finished surface.