Two “Rules of Thumb” for choosing cutters are:
- Cut-to-cut: Most pin tumbler locks have a cut-to-cut spacing greater than 0.140”. This is the cut-to-cut spacing minimum for using a symmetrical standard cutter.
- Spacing: If the distance from the shoulder to the center of the first cut is less than 0.100”, use special or asymmetrical cutter. General Motors and Mitsubishi use .098” spacing from shoulder to first cut. If the depth of cut is greater than two a standard cutter will cut into the key blank’s shoulder.
Manual key originating machines have two methods for determining the spacing and depths of cut. “Card Type” Key Origination Machines including the Ilco Universal II use specialized cards that provide space and depth information by lock manufacturer or code series. A card will also include the appropriate cutter for originating the key. The Universal II machine comes with the T14MC and TCW-1011 cutters.
Note: Code cards and cutters are interchangeable between the Ilco Universal II and competitive “Card Type” code machines. However, the “47” cutter is larger diameter and the spacing and included angle is 0.032” offset compared to the symmetric (i.e. 1011, 14, etc.) cutters. The symmetric cutters cannot be used in the place of the “47” cutter.
Framon 1 & 2 code machines use spacing blocks for the cut-to-cut positioning and a micrometer for the depths. Each spacing block has a number of different cut-to-cut dimensions for locating the cuts. Spacing blocks are available for cylindrical, automotive, and flat steel keys.
The depth crank has a dial with 0.001” increments. As the dial turns, the pointer moves along the scale with indicators starting at .100” to .350” in .050” increments. Once the depth is at the correct position, the straight-in feed vise has the key blade perpendicular to the cutting wheel insuring a flat cut.
The Framon 2 code machine comes with three cutters: the FC8445 standard cutter, the FC8735 foreign automotive cutter and the FC8615 Medeco cutter. Framon cutter part numbers indicate the angle of cut and the flat. For example, the FC8445 cutter has an 84-degree angle of cut and a 0.045” flat. All cutters have a 2.375” outer diameter with a 0.0005” tolerance.
Most modern code machines are preset. They depend upon all of the cutters being the same diameter. When the first cutter become dull, a decision must be made as to whether to purchase a new cutter or to have all of the cutters sharpened at the same time. (This excludes the asymmetrical cutter TCW-47MC.)
When the cutters are sharpened, the outer diameter becomes smaller, resulting in the need to adjust the machine for depth. If cutters are of different diameters, the machine must be adjusted each time the cutter is changed. This can often be forgotten and result in an improperly cut key.
Originating certain key blanks using a rotary key origination machine can be a problem unless the machine has multiple position vise jaws or modified vise jaws designed for specific key blanks. For example, Framon offers an automotive/interchangeable core vise, part # F2SH050.
If the key blade is not held properly in the vise jaw, when the vise is tightened, the blade can flex or twist, resulting in a mis-cut key. This is more likely to occur if the key blade is relatively thin.
If the key blank does not seat properly into the vise jaw, problems can result because key blank will be tilted within the jaw, not contacting the cutter at the proper position, having the cuts off angle. Most Best keyway interchangeable core key blanks have an uneven blade base. This off angle position and the angle of the cutter of a pivoting machine can result in a key out of factory tolerances. For originating Best style keys, the use of a dedicated keypunch machine may be the best choice.
Keypunch machines originate keys by punching a single depth of cut in one operation. These machines have a fixed punch mounted into the handle portion that goes into a die mounted into a carriage. Most machines have a triangular punch that has the pin seat at the tip. The two sides of the punch have a sliding fit within the die to ensure accurate keys.