Machining Mouldings from Flexible Stock

Running flexible moulding stock through your machinery is doable, but problematic. October 15, 2010

I recently ran a custom casing for a customer who now needs some curved casing for a couple of arched windows. I am looking for a flexible rubber or composite blank that I can run through my moulder and then bend around the arch. Is there such an animal out there, or am I better off making a template and having the work done on a curved moulder? In our area a lot of the trim is painted, and I run into this more than I used to. If there is a flexible blank out there, I would sure like to find it.

Forum Responses
(Solid Wood Machining Forum)
From contributor M:
The problem with using rubber for radius casing is that you're bending the material the wrong way. It isn't going to bend along its width very well.

From contributor J:
I think you can buy blanks from Flex Trim.

From contributor I:
Yes, you can buy straight, flat flex stock. You can buy formed curved flex stock. You can order your straight molding made into radius flex stock. You can do any of these things, but it's usually easier just to make the curved casings from wood or order it from someone (right here on WOODWEB).

Running flex stock through your saws or molding machines is a nasty, brutal business and I don't recommend it. It will ruin knives, dull carbide saw blades, and fill the machines and dust collectors with clinging shavings and particles.

From contributor D:
You can also buy lineal PVC mouldings from companies like Gossen, which are designed to be heated until soft, then bent around your form.

From the original questioner:
Would the PVC moulding already be profiled, or could I run a blank through my moulder and then bend it?

From contributor D:
The mouldings are already profiled. The finish is harder and glossier than inside the plastic. In other words, if you were to buy the non-profiled stock and machine it, the surface would be the lower density stuff with air bubbles in it. The exterior is designed not to be painted, but can be sanded and painted anyway.

Note that this is feasible only if you have a long oven, so unless you plan on doing a lot of this, it may be impractical to have someone else bend it for you every time.

From contributor R:
I ran some flex molding through my molder once... Once! I made my own knife, and ran several hundred feet of poplar molding. It was a pretty big profile, but the Woodmaster handled it in one pass. I needed 30 feet of the Flexmold. It took three passes and I had to re-sharpen the knife 6 times to finish the job. It was a nightmare of the first order.