A bench belt sander or belt and disc sander is a shaping tool as much as a sanding one. With the work resting on its table, it squares the ends of boards, takes a part exactly to a pencil line, rounds corners and smooths curves that a saw left rough. A few habits make the results accurate and keep your fingers away from the abrasive.
Set the table first.
Check the table with a square against the belt or disc before accurate work, and use the mitre gauge for angles. On a belt and disc sander, set the disc table square for end grain and tilt it only for bevels.
Which surface for which job.
- The disc, for end grain and angles. Use only the half of the disc that runs down towards the table, so the work is pressed onto the table rather than lifted. End grain and mitres come out clean and square here.
- The belt over the platen, for flat edges and faces. Hold the work flat on the table and against the belt; move it from side to side so the belt wears evenly.
- The belt off the platen or over the end roller, for curves. Many machines let you sand inside curves on the end roller and gentle outside curves on the unsupported part of the belt.
Sanding to a line.
Saw just outside the line first, then bring the work to the sander and remove the last millimetre. Approach the line gradually, with light pressure, and check often. For several identical parts, clamp a stop block to the table or use a jig, so each part is sanded to exactly the same size.
End grain.
End grain burns easily on a fast belt. Use light pressure, keep the work moving across the disc or belt, and use a sharp, coarse enough abrasive. A burnished, dark end is a sign of too much pressure or a worn belt.
Keeping it safe.
- Hold the work firmly on the table with your fingers well back from the abrasive.
- Don’t wear gloves near the belt or disc, and keep sleeves and hair away from it.
- Use a holder for small parts: a scrap block with a notch, or a clamp, rather than holding them with your fingertips.
- Never sand metal and wood with the same dust collection if the metal throws sparks; see dust extraction.