Side cutters for modelling: what matters and what does not

Why not scissors or a knife

Sprue cutters cut cleanly with less stress on the part than scissors, and with far less risk of slipping than a knife. Reaper's assembly guide warns that using a knife alone to free parts raises the odds of damaging the part, or yourself.

Double blade or single blade

Most sprue cutters are double-bladed: two sharp edges meet and pinch through the plastic. They are robust and handle thick gates, but the pinching can compress the plastic and leave a pale stress mark, known as stress whitening, on coloured plastic.

Single-blade nippers have one sharp edge closing against a flat anvil, so they shear the plastic rather than crush it and leave a cleaner, flatter cut. Sprue and Brush notes they are finishing tools: the thin blade can chip on thick or hard material, so do not use them on metal or thick sprue.

The two-cut method

How you cut matters more than which cutter you own. First cut through the sprue gate a little way out from the part, leaving a small stub. Then trim the stub flush with the flat face of the cutter against the part, or shave it down with a knife or file.

Cutting flush in one go puts all the stress on the part itself, which risks a torn or whitened attachment point (Sprue and Brush).

What does not matter much

Common bench view: price beyond a point. An inexpensive flush-cut cutter used with the two-cut method gives a better result than an expensive one used carelessly.

Common bench view: matching the cutter brand to the kit brand. Any good flush cutter works on any polystyrene sprue.

Look after them

Never cut metal wire or pins with hobby cutters; it notches the blades. Use a separate wire cutter, and wear eye protection, as Reaper warns that cut metal can fly.