Kitco Cutter

Kitco Cutter Information for builders  by Robert Haus

What is a “Kitco Cutter?”

The Kitco Cutter is a hotwire cutter designed for cutting neon tubing, It was marketed in the 1980s and 90s and was later offered through Daco and Monarch.  Unfortunately this tool has been out of production for a while now, and this has coincided with the increased use of lead-free glass.  In my personal experience, this was always a neat tool that could save one’s bacon in certain situations but I never really used it much…..until lead free glass came on the scene.  With the lead free, it is still  not something I use all the time, but I do use it more often than I did with the standard glasses from before.  Apparently I am not the only one who feels this way and in recent years there has been a periodic stream of requests for this tool and even a few instances of people attempting to get them back into mass production.  The latter has not yet worked out, in part because our industry is rather tiny in the grand scheme of things so the demand, while there, is not necessarily great enough to make it a workable proposition for a manufacturer.  Therefore, I am providing this set of photos and notes so that you can replicate the device yourself. 

How does it work?

The function is very simple, a small loop of nichrome wire is placed tightly around the tubing and when powered, the heat causes a localized thermal stress in the glass and the tube snaps off in that spot.  The low voltage used and the convenience of the handle design makes this a simple and safe tool to use.  When properly used, it is possible to cut off 1/8” lengths of tubing if you want! 

Handle Design

The handle consists of a hinged assembly with brass sheet sandwiched between sheets of plastic.  The loop is attached to the protruding ends with thumbscrews, with the lead in wires entering at the hinge point and soldered to the brass.  One of the two brass parts is severed such that a push button switch in that side of the handle will move a piece of spring steel to complete the power circuit to the nichrome loop.  The provision for the switch button and lead in wiring is accommodated by routed channels in the plastic material.  The hinge point is given a flat washer and is held together with a sex bolt.  An important, but easily overlooked feature is the stop screw and spring.  The stop screw prevents squeezing the protruding blades together to the point of contact.  If they did contact, a short circuit would result.  The spring aids in making it easier to spread the jaws apart.  The effect is subtle, but significant when in use.   A look at the following series of photographs should make the design self-evident.   

Materials
Brass sheet and the miscellaneous hardware are readily available at any good hardware store, for the plastic, a sheet of micarta would be ideal, but plexiglass or lexan would work too. A jeweler’s saw will make easy work of cutting out the parts.

Power Supply
A couple of different variations of power supply were used with these over the years. My example uses a tapped transformer, others made in recent years used a single output transformer and then had a set of wound resistors to provide these taps. The purpose of these taps is to provide different power output levels for different needs. For what it’s worth, the multitap transformer is a superior way to achieve this rather than adding extra resistances into the circuit, but both methods work. The overall output is not terribly critical, and when measured I found my unit to provide about 7.2v maximum, dropping to about 4v under load, depending upon which tap was being used. The current flow was in the 10-14a ballpark. Taken at the maximum for purposes of calculation, this puts it in the 90-100w range. If you were wanting to replicate this, a variety of good options exist, including using the transformer from an old style automotive battery charger or tube radio filament transformer, or even a 100 or 150w toy train transformer (which would offer the adjustable output via its speed dial. In any case, for safety, NEVER use any high voltage direct to the handle!

Nichrome Loops
The nichrome loops were sold in a variety of sizes based upon the tubing diameter to be cut. The factory ones were offered for 8, 10, 12, 13, 15, 18, 20, and 25mm tubing and were made with 0.026” nichrome wire. Today, you can obtain similar wire from mail order suppliers and simply bend your own loops to fit as required.