How to do a hidden nut or screw

opaul

opaul

Well-Known Member
I have a basic concept of how this is done but have not actually completed one. I guess there are several ways to go about it. With the proper patience and measurements I'm assuming the tang could be threaded (female) and then the handle counter drilled on the butt cap and the handle affixed to the blade by using a bolt to fit up. Another way would be to thread the tang (male) and recess the nut in the butt cap by counter boring and then using a dyed epoxy fill.
Most of what I have been doing is threading the tang and then threading the butt cap and securing the handle this way. This leaves the bolt visible in the butt cap or on some occasions I have peened a small protruding section of the bolt over. I have also thru drilled and slotted a bolt to extend from the tang to the butt cap, which gives a little more flexibility in positioning the butt cap if it does not come parallel in the fit up.
I'd really like to do recessed method or hidden method.
What methods do you guys use when doing a through tang? If you don't mind sharing.
 
Turn the tang down to a threaded male end ( I do this ALL the time with only my belt grinder, a file and calipers. It takes about 10 mins if I'm really dogging it).

You could also braze or solder some all-thread onto your tang.

Then silver braze or solder a threaded standoff (sleeve) matching your tang end onto your butt cap.
 
I have two words- coupling nuts. Regular nuts are limited in the amount of threads you have to work with, so I always keep a good supply of coupling nuts, #10,, #12 and 1/14", on hand. I cut them in half that make them more useable and double my money, at which point they have about twice to three times, the threads as a normal nut would have. I always maintain the factory ends and work off them for squareness after the cut. You can also easily chuck them into a small three jaw lathe chuck (they are hexagonal after all) and turn them to whatever you want on the ends, but I strongly suggest roughly rounding them and using a threaded rod inside to hold them for lathing on center.

After I make my tall nuts, I center them on my butt cap material and braze them in place, being VERY stingy with the braze. If you have a non ferrous butt cap you will want to use a silver solder that is as close to the metals melting point without equaling it; the higher the temp, the stronger the solder. I have a turntable stand that I set the butt-cap on while I braze it so I can easily heat it 360°.

The vast majority of my tangs are threaded as John describes. I teach students to do it on the grinder. Let's say you are doing a 1/4"x20 thread. Using calipers first grind the end of the tang to a .250" X .250" square and then evenly knock the corners off to create an octagonal, then simply smooth it off to round and thread.

For a takedown style, you will have to leave some sort of nut with a purchase point outside the handle. My favorite is a recessed sleeve assembly. For this you can get a very short allen bolt the size of your threads and recess a socket into a thicker butt-cap to accept the shortened head. Turn a coupling nut to a prefect round. Pass the allen screw through the butt cap and thread it into the threaded sleeve at close as you can while still having free play, drill the sleeve and screw and pin them. You now have a butt-cap with a recessed allen fitting and female threads all in one assembly. You can also turn down a decorative finial on the end of the sleeve and simply pass it through a hole in the butt-cap, but I found people didn't like this as much on using knives, particularly hunters where the protrusion interfered with using the butt-cap as a leverage point.

Of course, for the top end knives you would want to turn down something cleaver and decorative for your nut so that it isn't just a allen socket.
 
I do something similar to Kevin, but take it one step further by using a clevis on the end of the tang, a piece of threaded rod, then an internally threaded "butt nut" that I turn/make myself (usually of the same materials as the butt cap...... the size I of clevis is usually a 4-40 (I use the SS variety, but this is the only example I could find on amazon at the moment): https://www.amazon.com/Sullivan-Products-4-40-Gold-N-Clevises-SUL528/dp/B0006O8O7Q/ref=sr_1_13?dchild=1&keywords=4-40+steel+clevis&qid=1588947826&sr=8-13

I use these because when I use regular coupling nuts, that are rigidly affixed, I would always have the butt cap or handle "pull" off somewhere.... leaving a gap (however tiny it might be) which meant I didn't have each mating surface "dead nuts" correct/even. With the clevis, it sorta of makes up for my inadequacies in having to have a "perfect" mating surface on every piece junction.
I trim the end of the tang, flatten it, and drill a 1/16" hole for the clevis pin to fit in. then I use 4-40 threaded rod from there, through the butt cap, and to the "butt nut". With a clevis, when I tighten the butt nut down, there's enough "play" in the clevis (in all directions) to prevent any part(s) of the knife from being "pulled" out of alignment. In fact, a clevis will make up for a lot of error on the mating surfaces, by pulling things together. The clevis is small enough to fit inside the handle, and the only real challenge is making sure the threaded rod is the correct length.... but it still give you about 3/8" of "wiggle room".

This is how I build the majority of my bowies, and any other knife that would benefit from using a clevis. Some will question the strength of the build..... which might be an issue if the knife is a "take down".....but I don't build those anymore. After having three "take down" knives wrecked by a clients, then wanting me to fix the knife for free, I quit building them. With the clevis, it's just an assembly method to hold everything until the Acraglas cures. :) I still have requests for "take down" knives, and my response is always the same.....Sure! I'll build a "take down" but before I ship it out, it will be permanently glued up!" :p
 
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I remember Ed posting a link to those clevis connections in the past. I ordered them and they sure do make hidden tangs easy. When everything is fully epoxied it works like a champ - Thanks Ed.
 
I do something similar to both Kevin and Ed,I use coupling nutst as well but also have found that if it's not a inline pull as in the but of the knife is not vertical in relation to the guard /spacer it wants to open a gap somewhere rather at the front or at the butt cap,the remedy I came up with is to slot a piece of all thread and then grind the end of the tang narrow enough to fit the slot or you can slot the tang and fit the all thread to the slot,then put this together by drilling and adding a roll pin.what you create is a a hinged bolt that self aligns with the vertical angle of the butt cap.
 
I know a lot of people work with articulated features on the tang, but long ago I came up what a method of lapping the ends of the handle material that always gives me an airtight fit, so I have never needed the added features. If I am using spacers, I only incorporate them after I have the seamless fit and then I simply account for the number of thousandths the spacers would add. One thing that allows me to do much of it is always trying to make my tangs as much of a straight line as possible, not straight as in inline with the blade, they always angle down a bit, but inline with the threads . Curved tangs are not only a problem for this fit, they also complicate hollowing out the handle to receive them.
 
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