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box joint pliers / general box joint question

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I'm trying to figure out how to make box joint pliers as the title implies. I should first note I'm trying to figure it out without much reference. There's one thread on here but it's not helpful. Anyways, I've based my forgings off an image (see below), and a video of Peter Ross doing the assembly (but not the actual forging). I *think* I have the actual forgings where they should be, but here's is my main problem. When I drift the punched piece, by the time I can squeeze its pair in, it's over stretched and the result is not clean looking and doesn't work great. I made a little sketch explaining what I mean, as I don't have images of pre-trashed attempts of mine, so see attached. I imagine a solution would be to make the punched piece half the length (in the punched) area, and generally bigger than its partner, but in the video they look the same size.


I also imagine the hole needs to be punched at an angle. Which seems to stretch the metal even more. I'm only maybe 6 full attempts in, but I'd figure I'd ask about this. I should also note I've been grinding / filing a little bit before the fitting to make sure everything is flat enough, etc, so avoid any issues with that. And on a few I filed the hole to have a slight angle. I've also tried with 1/2", 5/8", and 3/4" square starting stock, but I imagine it wouldn't matter as long as you do it right.

So any advice would be appreciated. There's surprisingly little online. Thanks!

Reference image of forgings I found - 067ab4d002ad5a2e3de97591acb6370c.jpg


Peter Ross video with assembly (and shots of forgings pre-assembly) -




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I haven't seen the video, or watched Peter forge one of these in person.  However, it looks to me as though he forge welds two mirror image sides to create the "box" portion of the pliers, then uses the various drifts to refine the opening and open it out for the assembly.  Possibly he has something tricky figured out for the minimal amount of stretching that takes place during the temporary opening for assembly, but I expect it should be quite minimal to just barely allow the handle width to pass through the box.  Looks like a fun project, I'll have to try it sometime.

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Ive only seen box joints done by punching. Not meaning its the only way. Without a good "how to" to go by, then trial and error and taking notes is how I would do it. 

Your material will stretch. When you come up with a proper procedure, measure after slitting, then measure the opening after fitting the two halves together. Then on your next try, make your initial slit that much smaller. That should get you pretty close.

Im pretty sure there is a Peter Ross vid on box joints around somewhere. 

Also in some of the old last century text books there are some pretty good descriptions of how to do this. I believe " Plane and Ornamental Forging", Schwartzkopf, has a good lesson on these. This is available in a number of places on line. When I come across my copy I will check, In the meantime, should you buy it, its a great source and worth the money anyway.. It was a text book for the NYC school system circa 1900. 

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yeah, I guess I'll just keep trying unless anyone else shows up with some ideas. It just sort of perplexes me, if you watch the first ~45 seconds of that video, you see the two parts, and the finished product, and it doesn't look like its stretched much at all. Unless finished one was a different starting size for some reason. I do have a hunch it has less to do with that initial punch, and more related to the amount of drifting needed compared to the size of the second piece.

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  • 3 weeks later...


I've successfully made a pair of tongs this way. I used 5/8" square stock.  I started by making the boss area more perpendicular to the handle which I left straight.  That allowed me to slit the boss working down towards the edge of my anvil.  Once I got it punched, I put a rectangular drift in, and bent the boss area closer to 45 degrees.  That got me the angled hole without needing a special bolster.  Then, I forged the set downs for the inner jaw, being careful not to let the jaw dimensions exceed 5/8" in cross section.  I took a short section of 5/8" square stock, and forged a taper working from opposing corners.  I kept the width at the chisel end at 5/8".  The resulting tool is what I used to convert the rectangular hole into a more square opening. It didn't stretch the sides very much at all, because there's very little surface contact.  If it get's hard, tap the jaw end towards the handle like you're upsetting .  When inserting the inner jaw, there's a fair bit of fiddling because the outer hinge surfaces need to be brought in as soon as the jaw passes through the opening.  A longer slot doesn't hinder performance, especially if you're going to drill and put in a rivet.  

I hope that helps.

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