Running Radius Mouldings on a Standard Shaper

Tips on making curved mouldings with jigs, ingenuity, and a shaper. December 6, 2008

I don't have an arched shaper. What is the best way to run casing through a standard shaper? I do have a CNC to cut the blanks. What are my options?

Forum Responses
(Architectural Woodworking Forum)
From contributor A:
Mikron multi moulder works great for us.

From contributor C:
Create a form matching the outside radius of your finished arch with a cutout for your cutterhead and set your feeder accordingly - (dry run it) and run the moulding.

From the original questioner:
Should the power feeder then be on the top side with one wheel pulling the stock across the cuter head?

From contributor D:
No-lay the feeder flat with a little down angle pushing against the fence. One wheel wont hold. As contributor C said make a form but make sure its about 1/8 thinner than your moulding so your feeder has more pressure on the moulding than the form. Also it sounds like its your first time doing this so stand back. If you glued the blanks up with the grain going one way either the front or the back can blow apart.

From contributor L:
Be sure to give yourself lots of extra length because the moulding won't be supported well on the out-feed side after much of it has been cut away in profiling. This also increases the chance of having a major blowout at the end of the part. Figure on the quality of this molding being a bit less than that of a molding supported by the table since the cutter head will be pushing the molding out with each rotation against the spring load of the wheels. With nasty grained wood this will also increase the chances of tear out.

I used this method for several years before finding a used Stegherr arch shaper. Its an ok machine but has its limits. The US Concepts machines are of a similar but improved design. There are two different power-feeds made for feeding arches on a regular shaper. One of them has a single large diameter wheel that feeds from the top edge. This allows you to use a solid back-up fence to decrease the bounce.