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Working with Flexible Trim, continuedCutting floppy crown. I cut crown in position whenever possible, using a curved jig to hold the material upside down (see Figure 1).

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Figure 1.This radius jig allows the author to cut flexible crown molding in an upright, upside-down position -- just as you would solid crown. The flexible plywood fence is screwed into place so that it can be relocated for varying radii.

It takes a little while to make the jig, but once you've made it, you can reuse it for other radii. I usually make the fence 4 feet long, but the curved support can be as short as a foot or so. Orienting the plywood's grain vertically makes bending it easier.

Once I determine the miter angle with a Bosch Miter Finder, I place the jig with the cut line, which I call the "diameter line," at 90 degrees to the fence and close to the blade. On most saws, you have to set the miter angle first, then position the jig. After I make the first cut, I hold the molding on the wall and mark the second cut. A series of nails along the wall and ceiling can help support this unruly material (Figure 2). In most situations, I cut inside miters long and snap them into place.

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Figure 2.Finish nails help hold the crown in place and free a hand for operating a nail gun. Because the author uses MDF moldings, inside corners are mitered not coped.

Backer blocks. I highly recommend putting backing behind crown joints. When you push on the face of flexible crown, it collapses and may not spring back. So I carry triangular backing blocks, just like the ones I use on the cutting jig, to support the void at the joints and serve as a gusset for splices (Figure 3). These blocks don't necessarily have to be attached to the wall. If there's a slight difference in the thickness of the two materials, I'll use shims to raise the thinner piece into place (Figure 4).

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Figure 3.Triangular blocks keep the crown from bowing in, provide nailing at joints, and make transitions to regular crown molding easier.

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Figure 4.MDF is often thicker than flexible molding, so shims placed behind the flexible molding smooth the transition.

Fastening crown requires greater care than fastening other types of flexible molding because nails easily damage the crown's thin edges. Using 18-gauge brads prevents bumps and damage along the edge, and the thinner wire size also allows some tweaking for tight joints and miters.

Like curved casing, flexible crown made for a fixed radius cannot be straightened (Figure 5).

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Figure 5.Crown molding can't be bent in place like baseboard, and there's little room for error when ordering. Manufacturers require a specific radius or template, and, although the material fits in a small box when shipped, it won't fit around a curve with a different radius.

That means finding the transition point between the curve and a straight run is critical. Using a straightedge, I check to see where an outside-radius wall falls away from the straight run, or where an inside radius lifts the straightedge. I join those transition points with square butt joints backed with the triangular blocks. It's a little easier with an inside-radius piece, because the material can be cut slightly long on the jig and snapped into place. I cut outside-radius pieces as square as I can with a circular saw, then carefully fit the rigid molding, relying on a slight back cut, some whittling, and patience.


Ross Welshis a finish carpenter subcontractor in Sacramento, Calif.

Sources of Supply

Flex Moulding, Inc.

800/307-3357

http://www.flexiblemoulding.com

Complete line of flexible molding, including Superflex and fire-retardant flexible moldings

Flex Trim

800/356-9060

http://www.flextrim.com

Makers of Flex Trim and ZzzzFlex flexible molding

ResinArt

800/258-8820

http://www.resinart.com

Makers of DuraFlex brand flexible molding