Curved Molding on a Radial Arm Saw





Introduction: Curved Molding on a Radial Arm Saw

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first ...

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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    19 Discussions

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

    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

    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.

    3 replies

    The elevated table does not move.  It is clamped solidly in place.  It simply gives some clearance for the saw motor.  A radial arm saw allows the user to swing the arm to one side or the other.  I made use of that to swing the arm while the saw motor is running and the cutters are spinning.  I hope this helps.  Do not hesitate to pose your question again if I did not adequately explain.  Thank you for looking and commenting.

    I think I understand; Does the arm itself move sideways, or does the motor twist upon another axis?  It would seem using the radial arm as an axis would make most sense so you can make multiple different radius curves with different motor mount distances...

    sneaky sneaky!

    The arm can be moved sideways both left and right.  Normal use of a radial arm saw moves the arm and locks it down in a chosen position, as for cutting a board at an angle.  The motor can also be swiveled about an axis directly above it and then locked in a chosen position at 90 degree intervals.  These are useful for crosscut,  inrip, and outrip.   The  fourth position is not really useful, although I did make use of it in an Instructable on sharpening your lawnmower blade with a special jig and a grinding wheel on the motor shaft.  To add to the fun, the motor can move about another axis, allowing the shaft to be tilted for bevel cuts.  The bevel angle is selected and the motor is locked in position.  I did an Instructable that sets the motor shaft to a vertical position and attaches a sanding drum to the spindle on the rear end of the motor.  Then I used the sanding drum to put a straight smooth edge on a board for gluing it to another board so you can scarcely see the glue line.  I am feeling lazy and have not added links, but do a search for "radial arm saw," or check the Related Instructables listed at the bottom of this page and some of the related pages.

    Excellent ible! I'd always wondered how those were made, and I find woodwork really interesting. Well worthy of being featured :)

    5 replies

    PS I'm jealous... I want a tool shop. Maybe when I buy my first house I'll put a room aside for it.

    When I was in high school and college I wanted a bench or table saw so much, but could not afford it.  I saved money and bought a lathe while in junior high.  See another of my Instructables on making a Bench Saw Table for a Lathe.  I used it for a while.  One Christmas I received some money and bought a good circular saw, for which I made a table to make it an accurate table saw, and with it I made some furniture we still use.  (I have an Instructable on that ready to publish in a few days.  Please watch for it.)  The point is that you can get some decent tools for little money, even adapt tools to get more out of them.  A radial arm saw is a very versatile tool.  Many people do not know what they are because miter saws have pushed them aside in people's minds.  Often you can find a good radial arm saw for very little cost.  Check things like Craig's List.  Also, remember that once all of the things done with power tools were done with only hand tools.  Just learn the right skills.

    Thanks. :D

    My problem's not money, but space. I live in student accomodation so I have very little room to keep anything more than a draw full of hand tools. Good enough for a lot of things, but sadly lacking in a lot of ways. I really want a table saw at the moment. Or a bandsaw. Next year, when my degrees done and I have more money for rent or a house, I'll have room for the tools I want hopefully.

    Will subscribe to get news of that ible :)

    I remember student days and apartment living.  I was so jealous of people who had houses with basements or garages.  The possibilities for a workshop were so great.  Then I learned people who have houses spend a lot of time maintaining and repairing many things in the houses that do not require a workshop.  It is actually not quite that bad.  If you have a workshop, you will have opportunity to use it well.  I wish you well with your studies.

    Thank you for both of your comments.  All I can say for certain is this 'ible describes a home solution for making curved molding.  Woodworking is a very healthy hobby which you will never regret.  (I will make some further comments in connection with your other comment.)