Are Molding Cutters a Good Buy and Safe?
Issue: Issue 1.06
Posted Date: 7/4/2000
Ian Kirby, Rob Johnstone & Ellis Walentine
Q: This woodworker has seen them at Sears and from Delta but wonders if these adapted blades for table saws - that do what a shaper does - are a smart buy? Do they work well and are they safe?
Ian Kirby: "The origin of these molding cutters was the dado molding head, a device designed long ago. Here's where it comes from. A round column is frequently mounted on a square sectioned pedestal. The pedestal has a base molding at the bottom and a cornice molding at the the top. The square black between is the dado. It was frequently enriched with an applied molded frame. Saw blade makers realized that they could make a molding head to fit a table saw ? for those woodworkers who didn't own a shaper but wanted to make the piece of molding.
In the U.S., the word dado is used to describe a square or rectangular channel on the face or edge of a piece of wood with a saw or router. In the U.K. a channel going with the grain is called a groove and going across the grain it's called a housing ? the term dado is reserved for the cutter head.
Do they work and are they safe? The cutter block is just one link in a chain. Yes, they work and, yes, they are safe if the setup is done right. That's up to the operator.
Begin by checking that the cutters are exactly the same profile. The stock has to be held down fore and aft of the cut as it passes the head. It has to be held tight to the head and tight to the fence. The best result comes from an automatic feed. Whether you have an automatic feed or not, the heads and fences should be smooth and waxed with paraffin. What you can't do is mount the cutter and feed the stock with your fingers as if you were ripping a wide board in two.
Rob Johnstone: "Let me start by saying that I have never used one. Let me also say that the reason I have not is because there are better ways to skin this cat. Three (independently adjusted) cutters spinning through the arc of the table saw blade cannot be as accurate or cut as cleanly as router bits. (I don't know if they are dangerous ... but they are scary.) I would use a hand held molding plane far sooner than I would the table saw molder."
Ellis Walentine: "Tablesaw molding heads work quite well, considering the relatively low speed of a typical table saw as compared to a shaper. With a reasonably slow feed rate, you should get perfectly acceptable results. For the cleanest cuts, sharp edges and accurate cutter alignment are critical.
One particularly nifty use for a molding head is for cove cuts. Use round-nosed cutters in the molding head and angle a wooden fence across the saw table (on the operator side of the blade) to get the cove profile you want. This setup produces much smoother cuts than a sawblade, which is cutting with the sharp edges of the teeth.
I'm convinced that molding heads are no more dangerous than dado heads, provided the cutters are securely locked in place. I recommend using featherboards to keep the workpiece as tight to the fence and table as possible to reduce the chatter that you can expect with only three cutters. Feed the stock as slowly as possible for the smoothest cuts."