A short time ago set up a finger joint bit on my wood router table to see how it worked, having never used it before. A number of people asked how it compared to other, less expensive finger joint bits, to which I had no experience, so I ordered one from Gearbest.com  and here are the results of that setup and testing.

Watch it on Youtube: https://youtu.be/IIdhe5PLjF0

This bit is quite a bit bigger and heavier than the last bit I tested and has much coarser teeth. In the world of finger joint bits, there are a variety of sizes and one size is not better than another, but different sizes would be selected for different kinds of work that need to be done. This coarser tooth would obliviously be used for larger pieces of wood in joint them together.

The bit I used is a half inch shank because I wanted to use a router with sufficient horsepower to drive the bit and a collets size that can grab a bit diameter securely. This is another bit that requires a router table in order for safe, accurate cuts. Unlike some other bits, this version also has a large top mounted bearing, which is easier to set the bit up with when aligning it to the router table fence. 
Finger Joint Bit

Very often with larger bits like this, I will take 2 or more passes before making the final cut, but the wood I was using, Red Alder, is somewhat soft so I decided to try cutting this wood with just one pass. As it goes, with his density of wood, that turned out to be fine. With harder woods like oaks and maples 2 passes might be required for these larger, more aggressive teeth.

For alignment I used a 1/8th piece of clear Plexiglas, just to give the bit a starting point for alignment later when I need to make the mating cut. I put the Plexiglas sheet on the router table and aligned the bottom of the lower tooth to the Plexiglas sheet,  Next I aligned the fence so that it was even with the bearing and finally set the sides of the split fence of the router as close to the finger joint bit, without touching it, as I could. 

Running Perpendicular wood Through The Router
Some people who watch the process of running vertical pieces of wood through a router table expect that the best way to do this is with a miter gauge. That is NOT THE CASE. Just as with a table saw, you never use a miter gauge in conjunction with a fence. The best and safest way to push perpendicular pieces of wood through the router is to use a backer board or push block. This ensures the wood you are pushing through the router bit is supported, so it can't kick back, it's even with the fence so it gives a good cut and there is no way it can jamb part way such as it can with the miter gauge. The only time to ever use a miter gauge on a router table is after the fence has been moved back out of the way or removed from the table altogether. 

Router table joints

To make backer boards or push blocks for my router table, I just use 3/4 inch plywood scrap, about 8 inches square and absolutely 90 degrees on all 4 corners, and that will give you excellent, safe results when pushing wood through the router. 

First Pass and Setting Up
The first pass I made through the finger joint bit was fine, with the exception of a bit of tear-out where my plywood push block was not quite as high as the wood I was pushing through, but this is a small consequence in this instance.

Next, I needed to align the second cut so that it would fit nicely into the first.  As it turns out, this can be done quite accurately just by eyeing the first cut and raising or lowering the bit so that the second bit will slide nicely into the second cut.

After cutting off my first cut, I ran the second cut through at the new bit height and checked the fit. Reversal finger joint bit

The 2 pieces of wood aligned ok but did not fit snugly into one another. There are clearly gaps at the base of the cuts, that is at the bottom of each gullet on each side. The actual side did match somewhat and for the purposes of joining wood, after the glue was applied to each side, there is probably enough wood contact make a fairly strong bond, depending on what you are doing. None of these finger joints that are being cut into end grain wood are immensely strong when compared with their industrial counterparts that are done with much longer finger joint teeth, which of course makes for longer, stronger joints. 

Uses  Decorative Edging
Because the teeth on this bit were so large, it gave me the idea of running a couple of contrasting woods through the bit but this time, with the grain, to see what some decorative edging could look like. I used some light colored Red Alder and some Black Walnut and cut some matching pieces and glued them together.

A few hours later I cut the edge of my routed pieces to see what they looked like, and it gave me a very nice strip of parallel, contrasting woods that could be used for a wide variety of applications and decorative detailing. 

Just another idea of what can be done with wood router bits to add a bit of unique style to your woodworking projects.

Copyright Colin Knecht

Reversible Finger Joint Router Bit - Coarse Tooth Finger Joints