Finger/box joints by hand

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  • #680019
    Stephen Tyrrell
    Participant

    I recently attempted to make a small sliding lid box from one of Doug Stowe’s books. It’s about 9in x 3in x 2in, 3/8inch thick all round. The sides were assembled using 1/8 inch finger joints which I cut by hand. I found this very difficult with such small joints, which may be my lack of skill, but I wonder if there is a minimum size finger joint that can be made using hand tools.

    I finished the box but it ended up being more of a practice exercise than anything I would want to use. If I were to repeat the design, I would probably scale it up a bit to make the joinery (and the set out) a little easier.

    #680034
    Larry Geib
    Participant

    I don’t think Doug Stowe cuts finger joints by hand. His work is mostly done on a table saw with various jigs.

    Thinking about it though, I’d probably approach making 1/8” box joints by hand by first making a saw that cuts an 1/8” kerf.

    It shouldn’t take too long to cut a few inches of teeth on a piece of 7/64” O1 tool steel and hammer set them. I’d start with maybe 12 TPI slight fleam and a relaxed rake. (5°?) You probably could get away without hardening and tempering, at least until you figured out the tooth profile. I have a plane maker”s edge float and just tried it, and it works, but the float teeth are too coarse and too agressive a cut.
    I get my 01 locally, but McMaster Carr Will have what you need. Spring a couple bucks extra for Starrets precisión ground stock would save work.

    The other thing you would need to do is make some sort of appliance to regularly space the fingers. There are step and screw fixture plans for table saw spacing that could be easily adapted . Just turn them upside down to make sort of a miter box.

    I have a screw spacing appliance for a table saw I use occasionally for quick storage boxes. The advantage of screw spacing is the finger size is quite variable by changing the number of turns of the screw. ( a 3/8” all thread rod is 16 turns per inch, so four turns would position each finger for an 1/8” kerf and 1/8” fingers)

    Or you could just spring for Bridge City Tools’ Jointmaker Pro, which would make accurate box cuts a breeze. ( google it) . It’ll make you smile, anyway.

    #680041
    Colin Scowen
    Participant

    Last time I did finger joints by hand, I set the finger width to the chisel I would use, and knifed either side of the chisel blade. Not sure if that helps at all.
    If you wanted a saw blade to cut them, then you could maybe get some hacksaw blades with the holes in the ends, and double side tape them together with a bolt through the holes for alignment. Probably have to make your own handle for something like that though.

    Colin, Czech Rep.

    #680099
    Stephen Tyrrell
    Participant

    Thanks Larry. I will investigate the tool steel and jointmaker pro. I live in Brisbane Australia and sourcing some of these things can be a little challenging.

    #680101
    Stephen Tyrrell
    Participant

    Hi Colin, I did try using the 1/8 (actually3mm) chisel as my guide in one prototype and it was not all that successful. On reflection, I should persist and try again.

    #680256
    sanford
    Participant

    This is an interesting question. First, I sorta thought the finger joint was a joint specifically designed with machines in mind. Am I wrong about that? They are very quick and easy on a table saw or a router table. I used to make them on my router table (before I turned to hand tools) using home made jigs with a little indexing thing — plans for that sort of jig are easy to come by I think. But although I have never made them by hand I see no reason why they would be any harder (probably a lot less hard) than dovetails.

    I have seen videos of hand made finger joints for craftsman style things that look nice which I may try some day, but they were not the tiny joints Stephen is describing.

    From the post, I think the real issue is not the finger joints themselves but rather the tiny size of the finger joints Stephen is trying to make and the thinness of the stock — 3/8. The same issue arises for really tiny dovetail joints in thin stock. The boxes Paul makes use thicker stock and larger joints. I remember making finger joints on machines with thin stock, say, for very tiny boxes. But I wonder about doing that by hand.

    I could use some help here too. Suppose you wanted to make a small jewelry box, maybe sized for a single ring. Or maybe it would be a bunch of small boxes designed as organizers to fit into a larger box. You might want 3/8 stock or thinner. Maybe 2/8 or 1/8. What sort of joinery would you use? Tiny little dovetails? Itsy bitsy finger joints? Maybe simple miter joints held together with keys (is that what they are called)? Are there standard approaches to this?

    Oh, I just thought to look at an old jewelry box my wife has. It has a tray that sits in the larger box. The tray is made out of roughly 1/4 inch stock and has dovetails holding it together. They are 1/4 at the wide point of the tails.

    #680399
    Colin Scowen
    Participant

    I suppose another thing to consider, and apologies for taking this away from the original intent of the thread, is that finger joints have been used as the basis for knuckle hinges. Granted they are not glued, and are generally larger than the ones we are discussing, but I suspect that type of joint has been cut by hand a lot.

    Colin, Czech Rep.

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