Finger joints

[Templatetom]

Here is a challenge taken from another forum
How was this joint produced all those years ago?

The boxes were for storing amnunition and dragged over the ground, once the base and lid were added they could not come apart. One of the members wished to produce a few of the boxes for the AUSTRALIAN LIGHT HORSE INFANTRY in Adelaide; exactly as they were constructed

 

[Dangermouse]

Well they must have been made on a machine, such a thing would not have been hand made, even in Victorian times. As to how one could make it now, you'd have to have a box in front on you to figure it out I reckon.

 

[Random Orbital Bob]

I reckon he had a flipping big chisel!

 

[lanemaux]

Hi Tom , quite a poser.
If it were me trying this , a radial arm saw equipped with a dado blade set up to work with a modified table and registration peg set at an angle much like a box joint jig , but incorporating the angles the joint possesses . Set a compound angle cut on the saw and cut away. The table would be heavily modified so the workpiece could register from below the registration pin and lay flat to the fence (perhaps a slot cut in the table?) Clamping to the fence for each cut . Not elegant , but as close as I can come to wrapping my head around it .
Edit: and then the blasted bottoms would be skewed , blast , back to the drawing board.

 

[monkeybiter]

and then the blasted bottoms would be skewed , blast , back to the drawing board.

That's the difficult bit, I was going to suggest using a jig on the TS :tongue9:

I had thought you could do it on a morticer with a compound angled false table/fence, but you'd hit the same problem. On a dedicated machine you could have trapezoidal or rhomboid cross section morticing chisels that would allow for that slot.

 

[ColeyS1]

Have a router table set up with two routers - similar to doing ordinary finger joints. Have the first router mounted at the correct angle (with just a flute) then after that pass have the second router(mounted behind) with a dovetail cutter in it. The dovetail bit would have to be the right angle to avoid hitting the previous bit done with the flute cutter

 

[Chrispy]

A spindle moulder, with spindle canted back at about 20d, a set of comb joint cutters that increase in diameter as they progress up the shaft and have the same 20d angle so that with the spacing they all aline, then the work piece needs to be held on a fence thats at 20d to the vertical but ie thicker at the bottem than the top this fixed to a sliding table like a tenoning table would I think cut this joint.
after you have spent a week setting it up you would want to make a lot of boxes, and seeing the end use they probably did!
Thats the theory, in practice there is such a thing as a box combing machine that I'm sure would have been modified to do this cutting more than one at a time.

 

[xy mosian]

Ammo boxes? With a need to make a lot, then specially produced cutters would be used surely? I am thinking about a slitting type of cutter with the edge formed at an angle to the plane of the cutter. This would cut the slots in one pass. Such a cutter could be designed for use on either a Spindle moulder or even a machine similar to a Table saw.
xy

 

[Templatetom]

Here is the details from Router forums for those who may be interested in the searches that were made also the machine that was used fro the purpose
http://www.routerforums.com/
compound angle box joints
P.S. Look under Jigs and fixtures

 

[andersonec]

Twisted dovetails.

Here are a few which may help

http://www.blocklayer.com/woodjoints/dovetailtwist.aspx

http://lumberjocks.com/projects/45357

Example with the corners curved (check some of his other joints)
http://www.eurus.dti.ne.jp/~k-yazawa/ne ... table.html

Andy

 

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Probably used a bandsaw with a tilting table (or ramp), then finished with a chisel. My guess is that the operator started out with a stack of boards cut to dimension, then made a single cut on each board (on both ends) before resetting his jig and repeating the process. He would then have to chisel out between the cuts to make the fingers.