I had never heard of a molding cutter for a table saw until I inherited my dad's old Craftsman 113 table saw and read that it was an optional attachment in the manual I found online. You can pick these up on ebay for $50 or less. There are two versions, one has a single blade and the others have three. From what I hear the single blade ones work fine, but I can imagine that you'd have to push the wood through a little slower. The single blade models can be found used with 18 different profile blades and are usually under $30 online. Many of the different profile blades are still available used online and a company called Corob makes new cutting heads and profile blades.
These blades can also be used on radial arm saws.
Step 1: Safety
I'm probably sure that these things fell out of favor because of negligent people getting hurt by them. As you can imagine they have a huge potential for kickback, especially if you are trying to take off too much material in one pass. The keys to safety with these things are getting to know how much you can take off each pass with each different blade and getting a feel for the speed you can push it through. Also very important is hold down support to keep the wood in full contact with the blade and unable to get kicked back at you.
I've heard a lot of people online say that people thought these things were scary, but to me it's no more scary that a regular table saw blade. In fact, the high pitched whine of a carbide blade is more unsettling than these molding blades. They make a lower pitched hum when running. You could probably use them without hearing protection. I wouldn't, but in actuality it probably wouldn't be a problem at all.
Step 2: The Set Up
The cutting head comes with a spacer and an adapter bushing so it'll fit a 5/8" arbor. If your arbor is 3/4" you won't use the bushing, of course. The groove on the cutting profile blade will be facing away from you as you look at the table saw from the position you use it. This particular blade--and all I've see online--will be clearly marked to tell you the rotation of the cutter head and orientation of the profile blades. Put it on the arbor as pictured: washer, spacer, cutter, washer, nut.
Always disable your saw when changing blades. I always unplug mine and leave the plugs in my field of view for peace of mind.
Step 3: Make Your Own Fence and Insert
I don't think this is really optional if you want to use this safely. Some profile blades you could probably get away without it, but I wouldn't. You could seriously damage your fence and have flying shards of profile blades going everywhere if you ran your metal fence into while running.
My old saw's design makes it a little tricky to make a wooden zero clearance insert so I made one that sits on top of the table and is part of the fence. You could easily make one for each of the different profiles if you wish, but I just made this one with the 1" straight edged joiner profile blade so that any of the blades would work with it. I made the wooden fence 1" wide. 1" wide fence add-ons make it easier to do the math when you still want to use the fence's measuring tape.
The only thing to be careful of is where you put your screws in this thing. None around the blade's path, naturally.
My saws dado insert would have worked fine, but I wanted a little extra support after the wood came out of the blade.
Step 4: Making Your Insert
Lower the blade to below the table and turn it on. Slowly raise it up through the material. Repeat this, moving your fence each time, until you get it as wide as you need.
Step 5: Profile Blades
All of the blades are 1" wide. That makes finding the middle pretty easy. This 3 flute profile will go down the middle of my wood.
Step 6: Support
I love featherboards. Here I've used one that mounts in the 3/4" slot on my saw. This one will keep the wood firmly against the fence. For downward support I put the wood on the table and then screwed in a piece of scrap on top of it. I put a piece of paper folded on itself a few times between the workpiece wood and the scrap support piece to make a slight gap before screwing so that the wood could slide through smoothly. I plan on adding another adjustable featherboard for the downward support eventually.
Step 7: Cutting
Adjust the depth of the blade to take off just the right amount of wood. You don't want to take too much as this will slow down the speed you can put the wood through. Use a test strip to get your depth set right or to figure out if you need to make the cut over several passes at gradually increasing depth.
If you've got multiple pieces of molding to make you'll want to run all of it through the setup before making any changes. For example, if you have to make multiple passes at different depths, then run all of the wood through at each adjustment so that it remains uniform. If you run one piece, then adjust and run another you may not make the depth or position correctly and have molding that doesn't match up.
Hear I set the depth to just make the flutes on one pass and barely take away any wood at the highest height of the flute so I didn't have to make multiple passes. I then changed the blade to a cove profile and for each outer edge. I took off so little material that this happened in one pass as well.
Step 8: That's It
This particular molding is to cover up a cut line in my wooden soffit on my house from where I removed material to add more venting. I doubt anyone will ever notice it, but it made a good excuse to show off the molding cutter on Instructables. Their are many many uses for this thing, just be safe and mindful.
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