The router table has always been particularly good for cutting a groove, particularly in smaller items (such as making boxes).
The orientation of the blade to the timber for one, the diameter of the blade (vs a tablesaw), the speed of the cutter, the accuracy in setup.
The one frustration I have found is having to accept the width of the groove is limited to the width of the cutter of the router bit, or having to take multiple passes. Unlike a tablesaw, the concept of a dado blade is foreign to the router table.
Well until now that is.
Toolstoday.com have available a really interesting router bit indeed from Amana Tool. It is an EZ Dial Slot Cutter, and unlike a tablesaw dado blade stack, this router bit does not have shims, or even need to be taken apart and reassembled.
Looking at the anatomy of the router bit, from the top-down. The top threaded section is the range of adjustment of the router bit, and there are two types available – a 1/8″ – 1/4″, and a 1/4″ – 1/2″. Next is the locking nut – once the width of the slot is set. The knurled knob is the adjustment for the router bit, and is then locked in position with the locking nut.
The blade is next – it is a four-flute router bit, but because of the adjustment, each side of the trench is cut with two of the flutes. As the knurled adjustment knob is turned, two of the flutes move with the knob, and the other two remain fixed.
A bearing then sits under the flutes – useful when following curves, and other times a router fence is not in use. Just below that is a section with two flats – this is useful if the locking nut is too tight – a spanner can be fit on this section so it can be undone without having to risk damage to the router chuck or shaft lock.
Finally, the shaft is a finely finished, accurate 1/2″ shaft. (An inaccurate shaft is either difficult to fit the router collet if too large, or at risk of slipping if too small).
I was working with the 1/8-1/4″ router bit, but the concept is the same. In the above image, the two opposite flutes move, the other two are fixed. That dial-in adjustment is remarkably liberating. Being able to set the width of the resulting slot to accurately match the material that will fit in it (whether that be another piece of timber, a sheet of glass etc), and also easy to add an accurate amount of clearance if required.
The quality of the router bit is obvious, as is the finish that is achieved.
Not only can the width of the slot be set, but it can be adjusted with the router bit fixed in the router. (So long as you intend to remove more material – too hard to put material back!) Rather than trying to work out the range to move the router up and down again, a test cut or two, a dial-in of width, and your accuracy and flexibility of the table is increased dramatically.
Once you experience the convenience of a shim-less, dial in width of slot for a router bit, you’ll be wishing a tablesaw dado blade was as easy, as infinitely adjustable, and as accurate.