In my opinion, the elliptical archway is the most beautiful of the radius (or curved) openings in homes. Some homes and architectural styles call out for full radius (half circle) or segmented arches, also known as eyebrows, and those can look very nice also. But the well-done elliptical opening is the most graceful of all. Perhaps because it is more difficult and costly to produce, it is rarer and more exciting to see.
Quick Geometry Review. To understand radius mouldings, we’ve got to understand some basics in geometry and some terminology of the trades. The geometry for half circles and segmented arches is quite simple, since those shapes only have a single radius (the measurement from a single point to the inside of the curve – picture a stretched string pinned on one end or a pencil compass). In such a single radius, the curve of the moulding stays the same throughout its length.
In the case of the half circle, the radius measurement is half of the opening width. For the segmented arch, the radius depends on the width of the opening and the “rise” of the arch. The rise is the height difference between the top of the arched opening and what is known as the “spring line”, where the straight legs of the door casing give way to the curve of the radius moulding. For half circles and ellipses the spring line is intended to be subtle, whereas the segmented arch results in an abrupt corner angle, or “dogleg”.
Ellipses are actually one half of an oval (a circle that has been stretched or viewed from a different plane). An ellipse technically has a continually changing radius throughout its length. While you may hear the term “true ellipse”, and I’m sure in the world of geometry such a thing exists, such a curve is very difficult to reproduce in wood. As a result, unfortunately, one will often gaze at an elliptical opening and silently (hopefully) wonder what in the world is wrong with that one?!
Common Problems for Elliptical Millwork. Here are the most common problems with elliptical casings and jambs:
• Flat spots – part of the curve goes straight
• Dog-legs – sharper angles that stand out (usually at outer edges of opening)
• Shepherd’s staff – radius portion is wider than opening and bows back in for legs at spring-line
• Mismatch with jamb – reveals vary over length, or install is racked
• Unnaturally small rise – sharp curves on corners and long almost flat in middle
With all of these potential pitfalls, very few carpenters or millwork shops have the necessary experience and equipment to consistently produce beautiful elliptical openings.
The Radius Solution. Beautiful radius openings require proper measurements, deep experience, the right equipment, and labor-intensive attention to detail. Davis-Hawn Architectural Millworks boasts state-of-the art facilities, including CAD systems, CNC router, and Mikron radius moulder and Weinig traditional moulder. In addition, their craftsmen possess the expertise and knowledge of how to use them well - having produced over 5,000 radius openings for satisfied customers across the region.
So if your building or restoration plans call for some wonderful elliptical or radius casings, jambs or other architectural pieces, trust them to North Texas’ experienced leader in radius millwork and avoid the potential problems highlighted above. For more information, check out our Millworks Page.