Coated abrasive belts

Belts are specified as width by circumference, for example 50 x 2000 mm or 100 x 915 mm, with circumference taken along the inside. Length must match the machine because the tensioner only compensates a small amount. Read the size printed on the back of the current belt rather than measuring a stretched one.

The arrow shows the running direction, which relates to the joint. A lap joint must run the correct way so the splice edge does not peel, while a taped butt joint usually runs either way and more smoothly. Fitting the belt backwards is a frequent cause of splice failure.

X weight is lighter and more flexible, conforming to contours and suiting soft platens or contact wheels. Y weight is heavier and stiffer, handling higher belt tension and grinding pressure on industrial belt grinders. Heavy stock removal on thick material calls for Y weight or an equivalent polyester backing.

Adjust tracking so the belt runs centred, tension it to the machine's specification and run it unloaded for a few seconds after fitting. Store belts dry, hung over a large round support without kinks, since cloth absorbs moisture and curls, causing poor tracking. Grinding in one spot grooves the belt, so move the work across the full width.

Yes, hang belts in their original packaging on a peg of at least about 5 cm diameter in a place with stable humidity. Folded or crushed belts crack at the joint and backing. Before using belts brought from a cold or damp store, let them settle to workshop conditions for about a day.

Common causes are folding in storage, excessive tension, mounting against the arrow direction, or a joint that has dried out through poor storage. Lap joints are usually stronger than butt joints but can cause slight vibration. If breaks repeat at the same point, check belt tension and the drive wheels.

A rubber cleaning stick held against a running belt can remove wood dust and resin build-up and extend the life of woodworking belts. On metal, belts that are loaded with swarf and glazed usually cannot be restored this way. For soft materials such as aluminium, use belts with an anti-loading coating.

Speed depends on the material: mild steel is ground at high speed, while stainless, titanium and heat-sensitive materials need lower speed to reduce burning. Belt speed must not exceed the maximum marked on the belt. Refer to the manufacturer's recommended speed chart for the grain in use.