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Strap hinges and pintles.

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Speaking as someone just starting out even with the guy that was an awesome video particularly for the difference in colour between the welding and the regular forging.


I still have one small question how do you ensure that the bolt and the nut match in size? As in general diameter do you round of the bolt end first then match the punch for the nut from the rounded end of the bolt. Coming at this from 20 years ago in machine shop class of machineing stock to a set diameter messured by a micrometer then tapered slightly before cutting the threads. Sorry if this was stated in the video the host was driving me nuts.  

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Welcome aboard Cowboy, glad to have you. If you'll put your general location in your header you may be pleasantly surprised to discover how many of the IFI gang live within visiting distance and nothing will get you down the smithing road like having a smith show you.


Ever forged a tennon? If not, learn how. Once you've forged and shouldered your tennon you'll need to swage it to correct dia. I make this kind of top and bottom swages by drilling between two pieces of square stock with a bit of spacer between them, I use a business card or matchbook cover. The space makes the hole slightly under size but of the correct diameter. Ease all the edges of the holes or it'll make cold shuts.


Now take a good heat on the tennon (bolt blank) high orange or low yellow are good, get below mid orange and you'll be sweating all day for poor return. Before you put the bolt blank in the swage brush it clean of scale or it'll be driven into the blank and you might as well make something else from it. Put it in the swage and give it sharp smacks with a goodly sized hammer rotating the blank 1/4 turn between blows. Rotating is IMPORTANT for even results. MOVE QUICKLY THE SWAGES WILL DRAW HEAT VERY QUICKLY so you'll only get a couple few blows before loosing heat.


Sure, you'll need at least three hands to do the above so make a spring swage, a quick search here will yield plenty of plans.


So, now you have a properly sized bolt blank, thread it at least the bolt's length and at least three threads. Once you have the bolt, punch your nut blank and DRIFT it to the correct dia to tap. For instance a 3/8"x24 fine requires a 21/64" hole. (I just drilled and tapped some 3/8-24, I am NOT a drill-tap chart <grin>) To make a proper drift it needs to be tapered on both ends so it'll pass free once driven past the sized section.


Once punched and drifted it's ready to tap. Heck, give a tap from your tap and die set a shot. If all the above was done properly with the proper % of luck it may all work. This is a can't hurt, might work situation at this stage so what the heck. Hmmm?


If you need the "right" size tap to work you'll need to make one. Thread one of your bolt blanks 2-3x as long as you need for the nut. Use a hack saw to cut a slit lengthwise across the threads. If you're a good hand with a peanut grinder (4-4.5" disk grinder) you can do this with a cutoff blade. Tip it slightly AWAY from the direction it'll screw INTO a bolt. If you use a hack saw, flile a LITTLE away from the slit to give relief for cutting threads. The relief MUST be on the side opposite of the cutting faces. If you envision it cutting as you tighten the bolt (chasing tap) the sides of the cut threads that are biting are is cutting side while the threads on the other side of the cut are dragging without cutting. THIS is the side to file relief in as it won't effect cutting. The filing needs to be clean so once you've cut the "flute" run the die down it to clean the threads.


Cutting a "flute" in an existing bolt is an old field expedient for chasing buggered threads I learned in Jr. high shop class oh those many years ago. It's a trick I used pretty frequently in the field.


Anyway, that's the easiest way I know of to make matching bolt and nut in the smithy. Of course you CAN make taps and dies old school but. . . (I MAY be OLD but I'm NOT that old! <grin>)


Oh okay, so I do know how making a tap is done but it's a buttload of work and can go wrong so easily it'll drive you to drink. Okay so that's something in this method's favor. <sigh> Here goes, Buy a set of machinist's, watch maker's or die makers files. You'll need the 60* triangular file, NO NOT a triangular rat tail!


You'll need some high carbon stock because you'll need to harden the tap and die. Spring steel may work, I don't know.


Now decide on the thread's width and find or make a tape, light metal is best for repeatability, cloth will work, etc. For instance a 24 TPI tap will require a measuring tape 1/24" wide. What you do next is wrap the tape around the die blank in an even helix, now take a scribe and carefully mark the tap blank BETWEEN the tape where it meets. Be CAREFUL ANY wobble and you have something that won't cut threads at all!


Now for the fun, using your 60* triangular single cut file carefully CAREFULLY file the threads in the tap blank till the outside of the threads meet in a nice clean EVEN ridge. NOW you have a hand made bolt needing only to have the flutes FILED into it. Follow the standard model, it's tried and true and file 4 flutes.


Hardening will be an interesting exercise in preventing scale formation. I'd flux the tap before putting it in the fire. Flux will allow you to see the color so you can judge critical temp with a magnet. Covering it in clay will protect it from oxy but I don't know how to judge temp under a layer of clay. Okay, once it teaches critical (non-magnetic) quench it in the appropriate quenchant. Do so on the raising heat for best results. Once cool, clean till shiny and temper it to dark straw in the oven. I know there's a temperature chart here but if I go looking for it I'll have to re-write this whole lengthy ramble so take a look around if you really want to do this the hard way.


Okay, imagine you've made a good working tap, now you need a die. Punch and drift the right hole for the tap size in a blank of high carbon steel about 3/4" thick and at least 3x the dia . of the bolt dia. Tap the die blank with the newly made tap. now you get to do more filing! WOOPEE!! Eh? Take a look at a die and file your freshly tapped UNHARDENED die blank so it looks the same. harden and temper it to match the tap and.


CROSS YOUR FINGERS!! Hopefully they'll make matched threads.


If you're lucky you can use the taps and dies from a set and avoid all the hand work and fingers crossing stuff.


Frosty The Lucky.

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First read through Frosty`s post ``Hmm it`s like he is speaking english but not.`` Few web searchs later ah okay, I still don`t get it, third time was the charm. Not that your explanation wasn`t excellent just been a while since I looked at this stuff, like 20 years. :blink:


Think I will be doing the first method making my own taps and dies is just a little above me for now and by the time I get to that skill level I`ll already have bought some more tools to do that work. However the explanation was very educatiional


Hope you don`t mind I cut and pasted that text and moved it into a document in my blacksmithing file along with a few other explanations I`m finding here. I`m hanging on to till I get the forge and anvil up and or sourced. Don`t worry if I ever posted it I will give full credit. :D

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Yeah, I sometimes think I'm speaking in a foreign language. I get too wordy on a good day, trying to make directions of something I learned to do like 45 years ago would've been a challenge before the TBI.


Sure, go ahead save my ramblings and spread it around if you wish. Credit is a good thing. I'm thinking if a person could find a 1960's metal shop classroom book, all this stuff is  laid out in language a teen can understand.


I'm sure someone with more practical advice will speak up presently.


Frosty The Lucky.

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