Making Large Finger Joints

[Dell Littlefield]

I am building a blanket chest from spalted sycamore following plans in WOOD magazine no.194, November 2009. The plans present three options: 1 using cherry with dovetail joints and a traditional american base, 2, using pine with rabbeted joints and square nails and a "country-fresh" base: 3, using ash and walnut with rabbeted joints and plugged screws and a "casual-contemporary" base. My sycamore is not clear, it has a lot of knots, voids, etc. so I am going for the "country-fresh" look. However, I feel the rabbeted joints will not be strong enough to withstand the ravages of time and use. The chances of blowout of nails and screws are also pretty high since there is some pretty wild grain involved. In my opinion, the dovetails would be the best of the three options for durability and strength yet, they seem a little formal for use in this wood. I do not have a dovetail jig. I am thinking about making 2 inch wide finger joints to provide more strength and still retain the "rustic" look. I would like comments on how this would look Also, I am looking for suggestions on the easiest way to make these. The front and back panels are 16 X 45 so I don't want to try any vertical holds. I have a 14 inch bandsaw and a large router table. Thanks for any help you can provide.

[John Tallyn]

I think given the type of wood you are describing, large finger joints would be a great look, maybe even pin them with some contrasting wood. You can make a template and cut them using a router table or freehand them with the router. Make a template, then use a top mounted bearing flush trimming bit to route out the waste, routing to a depth of about 1/8 on each pass. When you get done with the router, simply square the corners up. Good luck with the project.
John

[Peter Quinn]

I did a series of out door furniture pieces for a client about two years ago at work which involved large finger joints. The species was teak, the largest panels were 45"X38", most of them were 18"X38", all 1 1/18" thick. The finger joints were 1 1/4" spacing, which I found pleasing for the scale of the project, but the design is not mine, simply followed the plans as drawn by the architect. I did all these on a table saw using a 3/4" dado stack and a shop made sled. I have no pics of the sled, but it was basically a 2 runner cut off type sled with a tall back fence, maybe 14" tall, made of a 1 3/4" MDF lamination with triangular strong backs behind the fence to connect it to the 3/4" BB base. Two maple runners complete the sled, which was roughly 25" side to side, 20" front to back. Imagine a shop made band saw resaw fence mounted perpendicular to the blade acting as the sleds fence, that is the jig.

I tuned the dado to EXACTLY .750", then made a spacer that was EXACTLY 1/2". Add the dado plus the spacer, you get your 1 1/4" in two passes. You set the fence up much the same as any other finger joint jig, by making an initial cut and then moving this a set distance from the cutter or blade, just that you must include your spacer in this calculation. You could certainly make bigger fingers using the same idea and more passes, but I'd mock it up full scale first before cutting anything, because 2" starts to get a little large visually IMO, but your design may support that? In use the sled was quite safe. It is heavy, but that adds needed stability for long work pieces, and the stout fence gives a place to clamp. You could adopt the same idea for the router table, though I would probably remove most of the waste with a BS or jig saw in that case. I prefer the TS for speed and accuracy with minimal set up. In order to get the square shoulders required for finger joints you will have to attack the pieces from the vertical plane, but you could certainly do this with a mortising style jig and plunge router from the end grain if you are uncomfortable standing the work up on the TS or router table. Or you could basically make a single purpose dovetail style jig for this project from BB. Remember the original dovetail jigs were shop made, not fancy aluminum and stainless creations!

If you any questions feel free to ask. Unfortunately like most jigs for custom jobs it has long since been cannibalized and morphed into something else, so pics of the original jig are no longer possible, but it was really not complicated, just rather large and heavy.

[Dell Littlefield]

Thanks for the replies, both ideas sound like something I can do. I just finished milling the lumber and have to wait a while for it to finish acclimating and then I'll tackle it. Good idea for a full scale mockup too. That thick teak must have been a real wrestling match!

[glenn bradley]

A neat method by a talented guy, David O. Wade: http://www.youtube.com/watch?v=ZHGuqXUI-eg

[Dell Littlefield]

Another great idea! Thanks!

[John Tallyn]

Hope you will post some pics as the project moves along, I'd be interested in seeing how the finger joints come out.
John

[Curt Putnam]

Consider pinning the fingers with Miller Dowels