Optical illusions and their first cousins, unattainable objects, have beguiled humanity for millennia. Twenty 5 hundred years in the past, Aristotle and different historic Greeks debated the character of optical illusions. More just lately, Oscar Reutersvärd launched what has come to be referred to as the Penrose Triangle (Figure 1). This intriguing creation could be depicted as in the angle drawing proven, but it surely can not exist as a strong three-dimensional object, regardless that two-dimensional variations in wooden exist (see Figure 2, for instance). The unattainable Penrose design is featured prominently in the works of artist M. C. Escher, of which “Waterfall” (Figure 3) is one instance.

Line drawing of a Penrose triangle
Figure 1: Penrose triangle

2-D Penrose triangle in ood
Figure 2: 2-D model in wooden

Escher’s “Waterfall”
Figure 3. Escher’s “Waterfall”

I just lately made two variations of what I imagine is a beforehand unknown variation of the Penrose Triangle that’s concurrently an intriguing puzzlement and an uncommon woodworking challenge. To my eye, the brand new model appears significantly extra three-dimensional than commonplace (Figure 2) examples. Although development of this new object seems comparatively difficult, its achievement is definitely simpler than it might appear.

Two 2d triangles that look 3d
Figure 4; the woods proven are wenge, bloodwood, and both maple or crimson oak.

Construction particulars

Exploded view of wood pieces making a triangle
Figure 5. Exploded view the meeting. The use of various woods and/or dimensions simply results in a wide range of potential merchandise.

All items had been reduce from 1/8-in.-thick inventory. For the instance on the highest of Figure 4, the inventory was ripped into 11mm-wide strips on a small tablesaw (for the underside instance the strip was 17mm huge). The strips had been then reduce into particular person horizontal lengths of seven.zero and 5.7 cm (10.1 and eight.zero cm for the underside instance) utilizing a small miter/chop noticed set at an precisely 30° angle. Apart from the three diamond-shaped corners, the six different items come in solely the 2 lengths given due to the threefold symmetry of the design. The diamond-shaped items of finish grain start as 1/8-in. slices off the ends of boards or turning inventory. The slices of finish grain are then reduce into 11mm (or 17mm) huge strips, one finish of which is mitered to precisely 30°. To keep away from harmful proximity of fingers and sawblade, the diamond-shaped items had been trimmed to remaining dimension solely after that they had been glued in place.

The 2d pieces being assembled to make the triangle
Figure 6. Order of Assembly (left to proper)–Before glue-up, double-check the match of the six longer items and trim accordingly.

Since slight misalignments severely detract from the general impression of the piece, a vertical belt sander was used to realize good angles, dimensions, and match. Sanding and ending (Minwax Clear Semi-Gloss Fast-Drying Polyurethane was used in the examples pictured) full the challenge.


The writer. T. Ross Kelly is a retired (Emeritus) Professor of Organic Chemistry at Boston College. Woodworking has been one in all his hobbies for a few years. He obtained the Teacher of the Year Award in 2004 and greater than 1,000 of his college students have gone on to turn out to be physicians. With the collaboration of two undergraduates (now physicians) he created the web site “A Scientist’s Curiosity Cabinet (https://sites.google.com/a/bc.edu/curiosity-cabinet), which has attracted >110,000 web page views. Kelly has printed greater than 100 analysis articles in chemistry, together with his fundamental curiosity being the development of molecules.

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