Cheating Device Spotlight - Shapes, Flats and Edge Work

Crooked dice of the mis-shaped variety. Explanations of many different ways crooked dice players use to alter the shape of a die to gain an edge over the house.


10/2/20224 min read

Shape Types

Shapes aka flats or bricks are dice that have been shaved or squeezed to alter the size of certain faces of the dice. Making one or more sides longer or shorter than the others. After the treatment the dice will be more rectangle shaped than a square. The side with the greater surface area is more likely to land on it’s face. These gaffed dice are often made to favor the ace or six, known as 6-ace flats. These rigged dice are known as mis-outs, since more 1-1, 6-6, 1-6 combinations will be rolled. Shapes are a desirable gaff because when kept to under a 3% variance they are not detectable without using a measuring instrument like a micrometer. The downside for shapes is that they struggle to get the money. A self-proclaimed dice cheat I spoke with told me he gave up on shapes because they just didn’t make a profit for him and his crew. I decided to test the idea and dropped a 27/1000 shape. The FBI in 1976 recommended tossing a die at least 10,000 times, but in the interest of reality I dropped mine 920 times. I still found some very interesting results with a high degree of confidence.

Looking at the Chi-Squared table, we see these dice are indeed gaffed.

Laying odds is somewhat effective, but to really make the most of this particular gaff a cheat would be the proposition bets (one roll bets) hard two and twelve where the advantage for the dishonest dicer is around 24% and 30% respectively.

The die I dropped is off by 2.66%, just under the 3% threshold for being detectable by the naked eye. An interesting and logical effect of shaving off part of a die is the reduction in weight for the die (see chart).

Shaved dice offered by the some of the old cheat catalogs often sold extra light – 5/1000, light -10/1000, and medium 20/1000. While other offered up to 40/1000 off. The die I dropped is just over “medium” strength. The Dice Detective, MacDougall claims for flats to be effective they must be between 20/1000 and 40/1000 off. Those 40/1000 off on a ¾ inch die is a 5.63% variation in size while the 0.65-inch die is off by 6.56%. These shapes would stand out to any careful observer.

In order to augment their work and create more profitable betting opportunities, cheats often combine shapes with beveling or edge work. Unsurprisingly these gaffed dice are known as “combinations” or “combos.”

Suction - Concave dice are dice with the center of a face lower than the sides. The theory is the dice will tend to land on the side with the hollowed-out center due to a suction effect. If the five face is concave, fewer fives and more deuces will emerge face up. Suction die are opposite gaffs, whatever number has the gaff, the opposite number is desired.

Beveled - Convex dice with the center higher than the sided. Some claim that 5/1000 bevel is as strong as a 10/1000 flat. Beveled dice will tend to roll off the rounded side and land on the flatter die faces. The rounded sides are more likely to appear face up compared to the flat side. If the one, two and three faces have been rounded, expect more fours, fives and sixes to roll. Convex shapes are commonly found alone and in combinations. Weight and bevels are natural partners, so are bevels and flats. Remember the beveled face is the number desired.

Edge Work - All the edges on a fair cube are the same style. Dice with asymmetrical edges are gaffed.

Rounded Edges - Rounded dice will have some edges cut at 90 degrees and edges will be rounded. The rounded edge rolls more freely than a sharp edge. If the all the edges on the six face are rounded and the other edges are 90 degrees, the die will favor the 2-3-4-6.

Cut Edges – Dice should have all their edges cut at the same angle. For razor edge dice that angle is 90 degrees. To gaff a die using edge work some of the degrees will be cut at 45 to 60 degrees.

Raised Edges - The edges on the desired faces are increased slightly. This change gives the favored number side a larger surface area. These dice are also known as trip edge dice, used in whip cups.

Burred Dice - A burred die is one with a portion of some of the area of the die face has a small burr or protrusion. The burr is designed to catch on the throwing surface and favor the numbers of the dice with burrs. Two dice with burred spots on the 4-5-6 favor rolls of 8-9-10-11-12. They have been part of gaffed dice for centuries. Burrs were known as gords and bristle dice in 16th century, today this gaff is almost unknown. In the more modern burred dice, the imperfections on the spots are allowed to remain rather sanded and smoothed off. There has always been debate on how effective they are.

Slick Surface - Slick Surface dice are not really shapes, but they are definably outside work so I put them in with this chapter on shapes. Simply put slick dice are notably smoother on some sides than others. The rougher faces control the outcome like burred dice. The rough surface grabs the layout and makes the smooth face more likely to end up on the bottom thereby favoring the rough side. SandedSanded dice have had a face or faces roughed up to grip the table as they are land.