Rotary Engraving Cutters
Index Of Selected Cutters
Before talking about specific cutters it is first important to talk about what cutters are made of. The two most common cutters are high speed steel (HSS) and Micrograin carbide. Each of these cutters have different characteristics, and thus suggested applications for a particular engraving job. There are generally three characteristics that cutters are judged on: hardness, toughness, and abrasion resistance. Hardness usually means the ability of a cutter to resist fracturing during engraving. Toughness refers to the cutters resistance to stress and breakage. Abrasion resistance refers to the cutters wear due to friction.
High Speed Steel – high speed steel cutters are made of a steel alloy which contains a small amount of manganese which gives the cutter a high degree of hardness. This cutter will resist stress and breakage under heavy loads. These cutters are used primarily for engraving stainless steel and aluminum. However because this cutter is low in abrasion resistance when cutting into phenolic a HSS cutter will dull very quickly. Because of the overall ability of Micrograin carbide to engrave a variety of materials HSS cutters are only available in a half round conical design and are used in engraving only tough materials such as steel
Micrograin Carbide – introduced about seven years ago, Micrograin carbide cutters have given the engraver the ability to engrave a number of materials and decreased the need to resharpen cutters as much. These cutters tend to be very abrasion resistant (they hold their edge longer) and their strength is almost that of HSS. Because of their flexibility most of the specialized cutters that you see in the preceding pages are made of Micrograin carbide.
Typically many engravers have relied on the conical, half – round rotating cutter with a 60 degree included angle. The only difference between each job was the tip size and possibly variations in the cutters speed.
As many publications have pointed out …” One cutter is simply not designed to handle the wide array of tasks an engraver is faced with”.
Today manufacturers have designed a number of specialty cutters for the engraving industry. With a little bit of practice these cutters can help make many of your jobs a lot easier.
Conical / Tapered Cutters
As discussed conical cutters are the most common cutters available. These cutters come in either half round or quarter round configurations. Most lettering and surface engraving are done with these cutters.
Although half round cutters have been the most popular conical cutter, quarter round cutters are becoming the choice of many engravers. Although quarter round cutters are not as strong as half round cutters they have been recommended more by manufacturers because they clear out the engraved chips quicker. When engraving in plastic this cuts down on the melting of the plastic, while in metals this cuts down on the breakage of cutter tips. In metal it is the chips that will ruin a cutter before the edge becomes dull.
To make cutters stronger and last longer a gold coloured titanium nitrate coating has been applied to these cutters. This makes the cutter last longer on both the initial cutter and on subsequent resharpings.
Parallel Cutters – these cutters are used to create an engraved groove with vertical side walls. These cutters are used mostly for profiling, slotting and hole cutting where a vertical side wall is desired. These cutters can be resharpened.
The previous two cutters are classified as single fluted cutters, that is they have one cutting edge now we are going to introduce a multi fluted cutter.
End Mills – although parallel cutters are very important many engravers have found that if at least a 0.090 cutter can be used they would prefer to use an end mill. Just like the parallel cutter, the end mill will give you a vertical edge on your profile or cut out design. However unlike the parallel cutter, the end mill will give you a smoother edge finish especially on acrylic and metal. Another positive point for end mills is that because they have more than one cutting edge (they have multiples in 2,4,6,8,etc..) They will cut faster than parallel cutters. One more important factor is that end mills are stronger than parallel cutters.
One downfall to end mills is that they cannot be economically resharpened. It is for this reason that we suggest titanium coated end mills as they will last a lot longer under normal conditions.
Ballnose Cutters – used mostly for engraving in acrylic, the ball nose cutter will give you a vertical side and a rounded bottom. This gives a very smooth and decorative 3 dimensional look. As with parallel and end mills ballnose cutters are available in a single fluted design or a two fluted design. Both have the same properties as parallel (single fluted ballnose) and endmill (two fluted ballnose) cutters.
Beveling Cutters – as with ballnose cutters, beveling cutters are available in a single fluted conical design or in three fluted design. Single fluted cutters are very common, however a three fluted beveling cutter will give you a smoother cut on your edge (it produces a 45 degree cut). This cutter also works well in spot drilling.
Also available is a cutter beveler. Thus, instead of cutting and beveling in two steps you can do it in one step with this cutter. This cutter can profile and bevel all at once i.e. Badges. Cutting nameplates out of sheet stock.
Burnishing Cutters – burnishing cutters are normally used to engrave lacquer- coated metals. Used in conjunction with a “featherweight”. This cutter floats on top of the material and strips away only the lacquer coat. The over all effect is excellent. Burnishers are used also when you need a thicker line than you can get with a scratch engraving tool. Just as with conical cutters, burnishers come in varying widths i.e. .025, .030,.090 etc.
Traditionally burnishers have been solid carbide, however there is a new burnisher on the market which incorporates a diamond to do the cutting. Initial results show that this tool is superior to the solid carbide burnisher in cut and life. It also cuts better into aluminum. It does a good job in anodized aluminum.
Deep Wood Cutter – this cutter was designed to engrave in wood . Not only does it give you a deep cut but it gives you a nice straight cut in on the edge of the wood.
Dovetail Cutter – these cutters were designed for the specific application of cutting a dovetailed slot i.e. a slot/channel that has angled side walls (just like the slotted channel on a pantograph copyslide). The most common use for this cutter is in creating sign directories. This cutter is used to cut a series of slots in a plastic blank. Once this is done you can side in a beveled piece of plastic into each of the “slots”
Fly Cutters – this cutter is used when you want to engrave a letter over 2 ” and you do not want to use a multi-line font (especially if you want to engrave fast or hate those “grooved” cuts in the letters).
A fly cutter contains a cutting tip that is larger than the shank diameter. The cutting tip is offset and thus a 1/8″ cutter can make cuts up to 1/4″.
Glass Cutters – the most common type of cutter used for this application is a diamond burnisher. A long with coolant a good look can be achieved.
Stencils Cutters – this cutter was design to cut stencils out of thin brass or plastic.
Pyramid Cutters – this cutter was designed to help the engraver engrave into some of the new and harder surfaces that are commonly found on higher quality pens and pencils
This short discussion shows that their are a number cutters available to help you the engraver achieve the best look to your job with accuracy and ease of operation. However, remember that the recommendations of these cutters come from discussions with manufacturers our own experience and the experience of other engravers. Thus what works for one person might not necessarily work for another.
I hope this article has been educational to you. For further reading there are a number of good articles in the Engravers Journal which deal with cutters and their applications.