Hot Wire Foam Cutter Attachment: Bow & Guide

Extending the reach of a hot wire

A hand cutter with a resistance wire will manage accurate small cuts, but with a large block of foam it comes up against two limits: the width of the reach and the ability to hold a plane. The bow with a guide deals with both. A wire tensioned in a firm frame does not bend and a cut therefore runs straight even across a whole board.

The dimensions of the cut

The bow opens a path 11.4 cm wide and 15.2 cm deep. In practice that means it goes through a standard board of insulation foam in one go and there is no need to turn the block over and join the cut from the other side, where a step always arises.

The guide enclosed serves for angled cuts. The angle is set and it holds the wire along its whole length, so a slope under a line or an embankment has the same angle from the beginning to the end. A cut led by hand practically never has that property.

The conditions for safe work

A hot wire melts foam rather than cutting it, and during the melting fumes are released. The manufacturer therefore expressly limits the use to its own foam materials, whose composition is known; with an unknown foam there is a risk of poisonous fumes being released. The work should be done in a well-ventilated room and with extraction or at least with an open window.

The wire is a consumable part and is replaced with the special resistance wire of the same brand. An ordinary wire from a household supply does not have the resistance needed and either does not glow or burns through.

What you need to have

This is an attachment, and the cutter itself is bought separately. Without it the bow is of no use, because it has neither a power source nor a handle.