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finger joint router bit

604 Views 10 Replies 4 Participants Last post by  weepee
New member here. :)

So I bought a finger joint router bit similar to this many months ago. (1/2 shank not 1/4) for the router table. Is there a setup method so that surfaces match up? Seems it always take a long process many cuts adjusting the height of the cutter. Some YouTube videos instruct flipping the second board 180 deg. That hasn't worked for me. I've resorted to adjusting the tooth on the cutter (by eye) so it matches the tooth of the first board. Then do trial cuts on scrap (same thickness boards) with micro adjustments.


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What thickness wood are you working with? I've never used a bit like that but I think to use it as perscribed flipping it, the wood would have to be 13/16" or 1 1/4".
Sorry I should have included that. 1 1/4 inch mostly.
I have the same bit and yes, it’s a bit fiddly. You have to run all the first parts, then dial it in with scrap of the same thickness.

I thought about measuring the width of a tooth and using a height gauge to raise lower the but that much.
I've gone through the same steps. Measured the tooth pitch (.310). Made the first cut, raised the bit 1/2 the tooth pitch, flipped the second board 180 degrees. That didn't work for me. Repeated with different cutter heights on the first board, etc. I suspect the bit is designed for 1 1/4 inch boards and 13/16 inch as mentioned by Steve. That I haven't tried yet. After all the time spent I finally resigned myself to eye balling and a few minor adjustments. Yet it should be easy if you look at the following link. Same cutter AFAIC tell.

This works for me. The workpieces all must be the same thickness. I scribe 2 lines on the endgrain of one piece, one off each surface, so they are slightly off center and symmetric. Then I set this on the machine table and against the finger joint cutter and adjust the cutter height, so a sloped face of the profile is centered between the lines as shown:
Font Brand Graphics Logo

The distance between the scribed lines may not exactly match the sloped edge of the cutter. What is important is that it look centered.
I make 1 trial run on a pair of scraps, flip one, and adjust the cutter height by 1/2 the offset of the 2 surfaces. After this, any 2 pieces of this thickness will align when one is run face up and one run face down.
I mostly use this to attach hardwood end grain caps to sugar pine core stock for veneering. I allow 1/16" for surfacing both sides (1/32" each side) to bring the banded cores to final thickness, and I haven't had any skips in the faces at the finger joint lines.
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Thanks. I kinda tried that method. I didn't use two lines just tried to center on the slope. It makes sense but somehow never worked for me. I'll give it another shot. Like your drawing. How did you manage that? :)
Early on it was drummed into me that while a designer might be thinking in terms of locations like the mid-point of a slope, the guys who actually have to make the part need drawings with references to features they can accurately locate with measuring tools. A very simple but powerful insight.
Thanks. I kinda tried that method. I didn't use two lines just tried to center on the slope. It makes sense but somehow never worked for me. I'll give it another shot. Like your drawing. How did you manage that? :)
Did you ever get this figured out? I was thinking you could line up a tooth about half way, route two and tweak it till they fit flush. Then you would be able to flip a board.

Can‘t get my mind around what @JohnGi said, but looks good.

I gave up on mine and ended up glueing it, jointing and planing flush. No good if the parts are final thickness!
No haven’t had chance Been too busy with other things. Hope to do that in next couple days. Looking at that picture it should work. If dealing with final thickness it will take some tweaking as I’ve already learned with my work around. Takes several tests on scrap
Ok spent a few minutes in shop to test John's method. It worked like a charm on 1 1/4 inch stock. It's listed as 1 1/4 so sort of expected that. Next I planed some scrap to 1 inch. Reset the router again using John's method. Just eye ball. Results first try almost right on! Only a few thousands off. Just the slightest tweaking should be a perfect match.

Thank you JohnGi


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