Curved Molding on a Radial Arm Saw





Introduction: Curved Molding on a Radial Arm Saw

I made two six-sided enclosed end tables for our home and wanted a decorative feature on each table's two doors.  I wanted to use molding to make a raised design.  The photo shows the top portion of the design.  The smaller radius molding was done on a lathe.  But, the larger piece of molding has a radius of 8 inches, and my lathe cannot handle a faceplate almost 17 inches in diameter.  Bending straight molding after steaming it was a possibility, but with complications I wanted to avoid.   I found a way to make the larger radius curved molding I needed on my radial arm saw.

Step 1: A Few Accessories

One of the handiest things I have for my radial arm saw is an auxiliary table to raise work about 4 inches above the regular table surface.  I use this auxiliary table to hold things I want to drill with the spindle on the rear end of the motor.  

Also shown in the photo is a set of molding head cutters.  You can see the knife I used for the curved molding on my end tables.  It is called a clover leaf and screen mold pattern. 

Step 2: Begin the Setup

I installed all three knives in the molding head, secured the Allen screws that lock them in place, and fixed the molding head on the saw shaft.  I turned the radial arm saw's motor to the inrip position.  The saw's fence has been removed and the back table piece has been secured to the saw's frame with "C" clamps.  The motor is locked down on the saw arm so the center of the molding knives is 8 inches from the center of the saw's column.

Step 3: Attach the Work

The work for this demonstration is a piece of soft, clear pine.  I used oak for my end tables.  A harder wood, like oak, is a better choice.  Near the end of my demonstration photos the soft, open grained pine molding I had nearly completed broke away and I lost a nearly finished piece of molding.  That is much less likely to happen with a quality hardwood.

I had to put another thickness of wood on top of my auxiliary table and under the work piece so the motor would clear the auxiliary table near the end of the process as it is lowered farther and farther for cutting.  Notice the dark piece with the white paint blotches.

It is absolutely essential that you swing the arm before you start the saw motor to make certain the spinning molding head knives will not strike the "C" clamps.  Notice that I have turned the handles on the clamps so they cannot come in contact with the knives, even if vibration causes them to move.

Step 4: Swing the Saw Arm

You will swing the saw arm from left to right after lowering the saw's motor a tiny amount below the surface of the work piece.  To swing the arm, loosen the arm's locking knob and pull the arm's indexing pin lever toward yourself.  (My palm rests on the locking knob and my fingers are curled over the indexing pin lever.) 

Step 5: After a Few Passes

In the photo you can see the piece of curved molding is beginning to take shape.  Take a very light cut on each pass.  Always cut in the direction that the knives attack the wood.  Never make a cut while dragging the spinning cutters backwards into the wood. 

Step 6: Get the Thickness You Need

The work piece is thicker than what is needed for the finished molding.  Even though the finished profile appears in the work piece, continue removing wood from the work piece until the thin sections of wood holding the curved molding to the rest of the work piece are very, very thin.  That would be thinner yet than what you see in the photo. 

Step 7: Finished

This is about as thin as you can safely make the portions still holding the curved molding to the work piece.  Break the curved molding away from the rest of the work piece and sand the sides smooth.  If the molding is still a little high for the pieces of straight molding in your design, you can sand the back of the curved molding.  Miter the joints so you get a nice meeting of all of the features on both pieces of molding.  Glue the pieces of molding in place.  People will be amazed.

Your power miter box may cut miters faster than a radial arm saw, but just try making curved molding on a power miter box!



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    I could never imagine to do it with a radial arm saw! Thx for sharing.

    I had no idea a RAS could be used thusly! Wow! Ingenious.

    Trank you. For things like this I try to think about all of the things that could go wrong so nothing moves or pulls my hand into a moving cutter or blade, and I try to make a safety back-up for myself.

    hello phil,nice to see a fan of ras out use mine for molding also, i have a large selection of blades for my dewalt ras.also i use the molding head with cutters,peole should now there is more to the ras than meets the eye, it can do alot more than people may think. the trick is know you saw can do and do it the right way and the safe way.thanks, shinju

    Phil, you are great!!   ...I envy your skills.

    You are very kind, Osvaldo.  Thank you.  (You need a radial arm saw.  You need a radio arm saw.  You need a radial arm saw.)

    I WILL MAKE ONE OF THEM!! Maybe 2010, maybe 2011...

    Of course, the "poor man's" version.

    Here is an advertisment from 1968 for a radial arm saw made by AMT (no longer in business).  It used two pieces of square tubing for the arm, a bearing mandrel with shaft for the saw shaft, and a mount for almost any standard electric motor to power it.  I think there was one main casting where the arm met the vertical column.   I tried to find an exploded diagram, but could find only this advertisement.   It might give you some ideas for making your own.

     Thanks, Phil. 
    My  "mental design" has square 2 inches iron tube arm and tower, ended in a round washer (one end). Obviously, details will come later. The washer is graduate and has screws to hold it in position.

    Very good instructable with great pictures!  One thing I'd like expanded (for my understanding) is how the elevated table mounts to pivot around the spinning cutter.  Very neat - I always thought it started as straight and was steamed/bent to shape.