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hey adam here from tested in my cave and today we’re going to talk all about taps uh a few weeks ago i did a build in which i was tapping something and i used uh well i used a device called a tapping guide in order to tap straight and a few people tweeted and wrote in the comments they were wondering what i was using and so i thought i’d show you one how to make a tapping guide two how to make a tap and tap drill holder which is a useful thing for any makerspace and it’s a great little project and then lastly i’m going to show you some of what i know about tapping tapping for those of you who are uninitiated is a process of using a thing like this to put threads into a hole so you could then screw a machine bolt into that hole so this is a thread cutting tap made out of hardened steel and tapping is a sort of dividing line for makers uh like a whole bunch of makers are terrified of tapping and rightfully so we’ll talk about some of the pitfalls and the ways in which tapping can ruin your life um however what you should know about me is that i love tapping i find it super meditative and super relaxing and yes i’ve broken my taps uh and had to redo work because of it but the mindset that tapping requires is one i find very pleasurable to tap into and by the time i’m done with this video hopefully you will too a little tapping 101 a tap is a threaded rod with grooves cut out of it to allow the threads to obtain a cutting surface so if you look really closely at this you’ll see where the grooves are carved out they create this sharp edge on the tap and what that does is that peels metal as it goes in and as such the entire tap is tapered it’s a little narrower well it’s definitely narrow up here and then it’s narrower here than it is here and this is to allow it to pull threads out slowly now there are many different kinds of taps if you’re doing a blind hole i.e a hole you can’t see through to the bottom of you use a normal tap and then use a bottom tab and this is all stuff that we’re not going to cover in this video this tab specifically is a kind i love which makes the job of tapping very easy and it’s called a spiral point and if you notice this little interesting cut at the tip so normally what happens with tapping is as you are turning these little edges are peeling parts of the metal out and they’re curling up and so the normal part of tapping that everyone was taught when i was a kid was that you turned one full revolution forward and then half a revolution back and the reason you turned back was to clear the bits of swarf that you were creating inside the hole with the spiral point that’s less necessary i’m not going to say it’s not necessary because you can get into trouble but it’s less necessary because the specific angle of the cut up here pushes the swarf forward and out of the hole you’re going to see what i’m talking about but that’s just the initial tap 101 the second part of tapping 101 is the tap wrench and if you bought a tap set which has a lot of crappy things in it um you’ll have gotten a tap wrench that looks like this and so what it’s got is a pair of jaws here that can squeeze down and they can grab taps of various sizes for most model making tapping for most beginning makers this is like this should be your big tap wrench this is for quarter 20 and up so this is a quarter twenty your standard uh your standard threading um this is a great tap wrench for a quarter twenty but it’s way too freaking big for uh a 632 like this if you put this in here and i’m not even sure you can get it in there but you might be able to sometimes the tap sets come yeah it’s not quite at any rate a big tap wrench on a small tap is a recipe for disaster which is why the first thing i’m going to tell you about tapping 101 is this tap wrench right here the star at tap wrench and one of the reasons people don’t like tapping is it’s hard to get a good feel this may end up needing to go later in the video but i’m going to shoot it now anyway one of the reasons people don’t like tapping is because you’re using a small tap like 440 here and you’ve got it chucked into a big tap wrench and you can’t quite feel the steel resisting you and you go tap tap tap into your motorcycle tank and it crook it cracks freaking disaster when you get one of these tap wrenches and it snaps and they love to snap because it’s super brittle steel remember because it’s made for cutting threads out of steel uh you get a piece of this lodged into something and you can’t get it back out

again you can but it’s a real pain in the ass uh and so in order to obtain feel from my tabs i use this little small starrett sterit tap wrench look at how beautiful this thing is it’s just it’s life-changing and you go and you’ll see i’m going to tap later on you’ll see how nice a feel i get for how to how to use that tap but i think i’m getting ahead of myself i think some of this i’m going to actually shoot in line as i go but i’m kind of excited to talk about taps because again i love it most people are afraid of it i’d like less people to be afraid of it so let’s go here are the basic complements of taps that i’ve always had in my shop since the early 90s uh and they have served me really well i’m a believer that you don’t need to go buy the full tap set you should buy the taps that you need as you need them you’ll be buying higher quality taps because a lot of the times the ones you buy in the big kits aren’t that great and again you don’t need all the sizes 256 is even arguable for most people that’s a very small screw most chops could get away with 440 as their smallest screw but here’s what we have 256 that means a size two screw with 56 threads per inch 440 size 4 screw 40 threads per inch again first number’s the size of screw second number is the threads per inch 632 832 1024 1032 excuse me and then quarter 20. quarter 20 is the bread and butter if you only had one tap this would be it um so i think where to start is for me to drill a hole and tap it in front of you so you can see what the hell i’m talking about so to drill this hole i’m i’ve got some really nice extruded one-inch acrylic i am going to make a couple slices on my table saw and maybe even flame polish this so you can see the tap happening as i’m going it’s really instructive i’m using this acrylic educationally which means i’d like to be able to see through it and i can tap down like this but i’m also going to just smooth out this side so i did a table saw cut with my triple kerf uh with my zero kerf triple chip blade i got a nice cut i did a quick wet sand on uh 320 grit sandpaper i have a nice smooth surface and you’ll see i’m gonna do a flame polish on this it’s gonna be right pretty bet you didn’t know how efficiently a flame could polish the edge of acrylic but yes it does it’s not a perfect job but it’s not a perfect piece just kind of showing you a proof of concept great all right so again if you’re looking at the tap and you’re doing an elevation drawing where you see these little zigzags the drill bit describes the inside of the drill of the zigzags for a quarter twenty tap the correct drill bit size is a number seven now you know you’ll never forget so we’re going to drill a number seven hole right here and then we’re going to tap it i’m about to drill acrylic and normally if you’re drilling acrylic you actually want to use a different drill bit for acrylic that’s actually a whole other video talking about acrylic drilling and stuff like that for the purposes of this video i’m doing a quick drill with a normal drill bit which works just fine um drilling acrylic works much better if you use a cooling fluid and the only cooling fluid you need is water so i’m going to use some water while i’m drilling this and you’ll get to see if you if the drill bit gets too hot it’s going to start to melt the acrylic and then all hell breaks loose you don’t want that yeah i know you don’t like to use water around the pieces of steel in your shop but it’s totally fine too as long as you wipe it off a little wd-40 works great too now we’re going to tap this piece of extruded acrylic with a quarter twenty tap uh oh first problem is my super sensitive sweet tap wrench does not fit the quarter twenty luckily sterrit makes more than one size we’ll use a slightly bigger one here oh look at that i can’t tell you how good a well-made piece of machinist equipment feels um first rule of tapping this is the title of a chapter of my book use more cooling fluid use

tap fluid i love this stuff rapid tap um jamie used to have this stuff in his shop called molly b molly b molly b and it was called that because it had molybdenum in it and it had the best ad copy it was like from the 50s it had the best ad copy on the bot on the on the can it said molly b the finest machining assistant yet devised by nature and the skill of man the use of molybdenum allows and quote ever-present cushion of lubricity right that was ad copy okay so i’m going to use a little rapid tap tapping fluid here this just helps my cuts happen put a little bit in the side of the tap and we’re just going to start tapping and again as the as the blades of the tap start cutting they start creating little bits of swarf which the spiral point will send out a head of the tab and you should start to see those kind of start to form is that starting yet yeah okay cool now again even though this is a spiral point i’ve had them break on me when i’ve over over taxed them so you can’t put too much tapping fluid on it it’s really it’s like you shouldn’t be working too hard to tap but i do about a full a half rotation and then a quarterback and a half and then a quarterback and then a half and then a quarterback and you just get into this rhythm so that anytime you encounter real resistance you’re stopping coming back it’s also allowing the tool to cool a little just peeling up material you are carving through molecules and atoms and that carving creates friction and that friction creates heat and the heat’s what can screw up your hole now you’ve seen me use drills for taps like this and i certainly do for shallower material for a one inch hole i’m always going to do it by hand you wanna you don’t want to overheat your uh overheat the threaded hole that you’re making again just more tap fluid is even better there we go that is our tapped hole and here you can see the bits of swarf that were cut right so that’s little bits of acrylic peeled out of the sides if you look into this thing you’ll see i’ve cut threads in there and you’ll see further when i take a quarter twenty bolt it threads really nicely oh look at that isn’t that glorious that is just beautiful okay that’s the easy one i know you’re all comfortable with the quarter twenty what you’re freaking out about is the 440 and i totally get that we’ll do a 440 but we’re going to do it in aluminum because we’re going to have this one have stakes if i uh if i did the 440 in this stuff you’d be able to see it but it’s acrylic it’s the stakes are low um let’s do it out of a chunk chunky chunk of aluminum and then you’ll see how i attack that i’ve got here a piece of thick wall square aluminum tube so i’m going to drill a 440 hole right through there now i told you that i had memorized that a quarter 20 tap drill was number seven i’ve also memorized that the 440 tap drill is a 42. somehow the number 440 and 42 they sit nicely in my brain together so i’ve never forgotten that 42 is not only the answer to life the universe and everything it’s the tap drill for a 440 tap i’m setting all my tap drills up in the drill press which is just the way to guarantee that they’re perfectly vertical know that i don’t always do that if i’m doing a quick and dirty build i’ll do everything with a hand drill and some of it’s not going to be on point but in the aggregate over a day-long build if i’m tapping 30 holes doing with a hand drill as opposed to constantly doing it at the drill press is going to save me sometimes well more than an hour of time so i’m happy to give up the drill press but for the straight and narrow you want to use the drill press you want all your taps to be aimed in the direction that you intend you’ll notice that i took several passes to drill that hole in aluminum and the rules for aluminum follow just like the ones for acrylic you don’t want your bit to get too hot and you don’t want to start gathering up aluminum what will happen is when the steel gets too hot it can actually gall which means it can uh mechanically

bond with the aluminum that it’s drilling out and then all of a sudden you’ve got this irregularly shaped bit that’s hot and caked with aluminum and all of a sudden it’s making your hole not only bigger but not round yeah so for exacting work like making a hole that you’re going to tap you’re going to want to just go gently and again some cooling fluid i don’t really need it for a hole like this on this setup but it can’t hurt so i’ve got a 440 tap here the first thing i’m going to do is i’m going to tap it wrong i’m going to put this in here and i’m going to aim to snap this tap and you’re going to see how little force it actually takes so i’m just going in just going in okay so now i’ve tapped that hole that’s gone pretty good i can actually already feel that it’s a little bit loose because i allowed i this wasn’t a spiral point and i didn’t allow it to push the material and i didn’t go back so i kind of got a little bit of a loose hole watch this that’s all that it takes that was a piece of hardened steel and in fact the fact of its hardness is what made it so easy to break now in this instance it just turns out that because the hole is a little looser it’s actually not that difficult for me to untwist that tap out of the hole i’m here to tell you that a hardened tap inside a hole is its whole entire own nightmare and there are things called tap extractors i’ve i’m sure there are some people for whom they are useful i have two sets here i have never made tap extractors work ever at all um the way i had one mission critical tap break on a part that i literally could not rebuild and i went in with a hardened steel point and i shattered the tap uh and shattered the point but i was able to then kind of mostly pick the pieces of the tap out of the hole that was the one time in my whole life full of tons of broken taps in my past that i was able to rescue a hole the fact is you just don’t want that tap to break otherwise things are really difficult so let’s redrill another hole and i’ll go really gently it’s a beautiful spire point tap once again a liberal application of a bead of tapping oil and i’m coming up to it now here’s something interesting is that i’m tapping but actually look how far off of a vertical i can be watch this i’m going to try and tap this off the vertical here we go so you see i’m about like six or eight degrees off off the vertical axis and low i’m still being able to tap this hole and you can see how much the tap is moving around that’s all the reason it’s moving around is because it can and the reason it can is because i’m drilling off center and the tap is moving a bit and all that movement means that when the screw goes in there later it’s got room to move and room to move isn’t great it means it’s going to rattle around it’s going to make its hole even wider but like when i first started tapping i didn’t think you i didn’t know that you could tap off center even a long deep hole you can tap off center so what’s the answer yeah see that i’ve tapped that and you can clearly see that it’s canted a little bit like this to camera left and then oh yeah look at that in this in the y direction it’s even worse um so what is the solution i’m glad you asked this it’s a key part of every young machinist’s uh early tool making this is a tapping guide block this is a chunk of steel that a machinist on bicentennial man gave me and said it’s time for you to make your own tapping block and all this is is a chunk of steel with holes in it that fit most of these sizes of taps and by fit i mean specifically it fits the barrel of the tap okay one last thing when you’re removing a small tap from a hole you can see i’ve still got some material to pull out here you can see how much this moves if you’re like torquing the tap wrench again you’re carving material out so at this point if i have a real precise hole and the threading wants to remain sacrosanct i’ll take off the tap wrench and i’ll undo the tap by hand and this allows me again a finer control of keeping the tap from carving a new home so here is this smallest hole fits the barrel

that’s the fat part of this tap and guides it so that it can’t go off the vertical axis so let’s tap one and i’ll show you exactly how it works so i’ve got a little bit of tapping oil on my 440 tap i’m going to feed it into my tapping guide block so it sticks out the bottom there it is now i’m going to line up there we go the point of my tap with the hole that i’m tapping now now i’m holding all this in orientation my tap is in the hole i want the tapping block is making sure it is perfectly vertical on the x and y axis and now because i’ve got a spiral point in here i can actually just turn but again tapping is all about feeling how much resistance you’re getting so i might even recommend if you really wanted to get to know this is like buy some buy an old tap set on craigslist and tap some of these as practice until one breaks it’s really really good to break one on purpose so you feel how much force and each one’s a little different but holy hell man it’s less than you think it’s really good to train yourself on that yeah look under here you can see it’s coming through and i’m drilling i am tapping a perfectly vertical hole in this material there we go now that is an excellent and successful tap so the other nice thing about a tapping guide block is remember how i said sometimes i pull off the tap wrench to undo the tap with my fingers because i’m using the guide block i can actually pull the tap out just like this just give it a little spin there we go and it’s out here is the hole that i drilled off center and you’ll see i’ll put the thing in there and you’ll see how much see that that’s just that’s not pretty not only is it not pretty it’s mechanically problematic like if you wanted to drill a hole through this and attach it to this well you’d have a vertical hole through this but not a vertical tap that’s going to cause you real problems later this is why you want to make sure everything’s on the straight up and down and now i’ll put it in the nice hole that i just tapped oh and the difference is like this one rattles when i get this one in a little bit it doesn’t rattle at all it’s really tight it’s just a little bit of movement not nearly as much as there is here and that is a beautiful mechanical connection there’s two processes which felt like magic the first time i did them one was welding two pieces of steel together and realizing that they were now permanently affixed like forever until some outside force acted upon them that felt really amazing the other was this tapping a perfectly straight hole on both the x and y axis and mechanically connecting two things that joined it the right way at the right place and time feels magical feels like you’re making a real thing because you are okay i know i’m forgetting ah i would be remiss if i didn’t talk to you about bottom tapping now we’re going to talk about the other main kind of tap which is a bottom tap and that’s what you’d use for a blind hole and i’m going to show you what all that is now remember how i said that a tap works its way into the hole with its taper so again you can see the very tapered point of this and then the fact that the thread cutting aspect is also tapered to allow the tap to guide itself into the hole but let’s tap this hole and then we’ll talk about what’s wrong with it once we’ve tapped it where am i at nope not quite there so now you can see one issue that’s happening is the swarf that cut from my thread cutting is gathering up at the bottom of this hole and again when you have extra material going where it can’t escape from it could be problematic so i’m going to pull this out i’m not quite done tapping this hole but i’m going to pull this out so i can remove some of that stuff okay go ahead another pass of it so this hole is called a blind hole because you can only see it from one side of the material and this happens a lot mechanically you have a part you can’t drill all the way through or you can’t get to both sides for tapping that is a fairly common occurrence okay so i think i’m

yeah i think i’m mostly at the bottom there and if we pull this tap back out you’ll see the issue that i’m talking about right the tap has a taper and the taper’s in the hole so the threads don’t go to the bottom of the hole but they need to if this is going to be a mechanically sound hole you don’t want to put one of these in it and when it reaches the bottom of its threads what do you do you just force it if you did this whole thing would crack that’s no good that’s why you need a bottom tap and that’s the next thing we’re going to play with so this is a bottom tap and it’s actually been cut really nicely so this tap as you can see how much different it looks it’s missing this whole taper which means it can carry the threads much farther down and you can’t just start with the bottom tap you have to start with a normal tap and then you have to finish the hole with the bottom tap this is a multi-step process because i got to keep clearing the material out and you will want to as well especially when you’re working with metal it’s going to be a lot less forgiving so you’re just going to want to do this in several passes the nice thing about a bottom tap is they honestly don’t come up very often for me but when they do if i don’t have one you can take a normal tap that you’ve got and grind it it’s totally sufficient to do that and i’ve done that many many times okay so i’m just going to carry these threads down a little bit farther i’ll feel them stopping that’s a good sound there we go i’m showing you this with the big quarter 20 tap but all these rules apply to all the sizes so now you can see that i have a much more mechanically sound hole because my bolt can go pretty much to the bottom of that hole and that my friends is a bottom tab so now i’m going to make a tapping guide block like this but i’m going to do it out of clear acrylic which is actually honestly i think a slightly better material and you can find this stuff sometimes in the scrap pile at tap plastics or a plastic supplier or you can buy chunks of this off of ebay or even amazon it’s a great time to be a maker because you can buy chunks of what would be expensive material that is off cuts from factory work this one inch acrylic it’s extruded which means it doesn’t have the same melty problems that normal cast acrylic has and i wait this is cast and cast acrylic doesn’t have the same thermal problems that extruded acrylic does and i really like working with it because it gives you some nice finished edges and also for demonstration purposes what you can see in it it’s fabulous so let’s make a tapping block out of some 1 inch acrylic whenever you’re cutting stuff on a table saw it’s always good to make sure that the surface you’re holding up against is smooth of debris because one little knobby knob over here can throw your piece way out of square so get your hands in there make sure it’s clean uh it’ll probably be about that thick i’ll go right through there yeah there we go all right so i’m going to smooth up the sides of this block i’m going to use some 320 grit sandpaper and i’m going to wet sand it and what the wetness does is it allows the material you are sanding off to not gum up the sandpaper itself it allows it to move a little bit it just gives us a really nice smooth surface your table saw table is a fantastically flat surface and large flat surfaces are super useful for setting up and clamping and gluing and stuff this table saw gets used a lot for this kind of thing okay uh before i get to the actual making of my tapping guide block um i think it’s worth talking about why we have different thread counts depending um and for me uh the number 10 size taps are the ones in which i am always making a delineation as to whether to use the 1024 and the 1032 this is a 1024 you can see it’s got those heavier threads and that’s a 10 32 it’s much finer that just means 24 threads per inch 32 threads per inch

which one would i use in a given situation if i was tapping a piece of steel like this i’d use the 1032 it gives me fine granular control the closer threads allow me to do a wider turn to tighten it and that’s a nice amount of mechanical advantage i get on that with the coarser threads uh the the the graph for tightening is much sharper it’s a sharper hockey stick with soft material the opposite is the case i wouldn’t want to use a 1032 tap in acrylic because if i’m putting a mechanical load on those threads and when you’re putting a screw in there and tightening it it’s friction torqued against every single thread that it’s touching so you’re putting that mechanical load on acrylic it’s going to fail on you so in acrylic and softer materials like delrin i use the heavier taps for the harder materials than this like aluminum and steel i use the finer taps within mechanical engineering there’s entire fields of study about this that really don’t ever fall within the purview of making shit at home but it’s worth it to know it here’s what we got two four seven taps and i’ve got a piece of acrylic i’ve put a piece of masking tape on the top as a guide so i can kind of map out where i want these holes to go and i think i’m going to line them up on one side these are just guide holes so their actual position doesn’t really isn’t super mission critical like they can be slightly mis spaced if need be in fact for this quarter 20 i’m going to go a little bit farther so that is one two three four five six seven one two three four i tend to circle where i’m going to be drilling because on the drill press this just makes it really easier that i’m drilling in the circle okay so this one is 0.14 and i bet this is the same 0.14 yeah i think this is the same two 0.14 and this is bigger so first three holes are all the same i’m going to want to go with a 0.454 that’s the one 0.144 i don’t want it too big but i want it slightly oversized so if i measure this i get point one four four and this is point one four oh an extra fourth out it’s the difference of a piece of paper which is about four thousandths of an inch or the thickness of your hair yeah pretty much okay so that’s the 144 that is the number 27 now we move up and that’s a 165 and this is nope that’s bigger okay so i want one six six i want something slightly bigger than that six nine did you see that you see how that grabbed it that’s one of the particular things about regular drills that’s rough on acrylic is that this drill has these flutes and at the bottom it’s cut at an angle and that cutting angle is moving around and it’s pulling itself into the work which means the moment it breaks through the bottom it yanks down and then pulls the material up and that can cause stuff to shatter it’s not something i’m super concerned about with this acrylic because i’m familiar with it but it can really ruin your day otherwise so it’s a good idea to clamp stuff down that’s why it’s happening okay next row so now this is 0.19.196 if this seems tedious it’s totally tedious i’ve made lots of these things and they always are kind of a slow and plodding build but at the end of it when you end up with a thing that you built that makes your life easier those are some of the loveliest tools to

have floating around your shop i’ve had that tapping guide since 1998 1999 1999 bicentennial man that’s where i got that one okay here we go i’m almost all the way through here but i want to show you a little technique if you want to stop that kind of grabbing like when i break through the bottom of this this is going to want to go up like that and that’s when it could shatter all sorts of bad stuff could happen so what you want perhaps is a what you want perhaps is a bit of a frangible piece of acrylic to go underneath it and you’ll see this breaks through but because there’s another piece of acrylic underneath it it doesn’t automatically drag everything to the top and that’s how you eliminate that problem barrel of this is exactly 0.254 so i want to go slightly oversized to a quarter bit quarter inch bit yeah we’ll go with 257 an f drill here lovely all right let’s try out our tapping block shall we i’m going to use a 256 tap 2 56 4 40 6 32 8 32 10 24 10 32 quarter 20 1 2 3 four five six seven just to complete this build we’re gonna use the tapping block but first we’re gonna label it with an engraver engraver always good to do a little test piece in a piece of material you don’t care about this piece and i’ll work on top of it yeah that’s it that’s what i wanted just like that all right here we go yeah a little grease pencil little grease pencil inside the engraving i think this might make it stand out quite nicely or it could just be a total wash hard to say let’s see here obviously you can laser cut these labels you can do it however you want ladies and germs i think that’s a respectable tool addition to my shop that savage tap block right we drilled a hole in order to use this here we go this is a 256 there is the 256 guide hold you can see it holds it really nicely with almost zero chatter it’s only about four thou over i’m lining it up with my hole here oh right do a little tap magic going on and here we go ladies and gents now i’m just holding that nice oh nice might have gone with a slightly oversized drill bit on this one because it’s uh it’s going quite nicely there we are so let’s just test that out with the 256 screw machine bolt and there you have it look at that absolutely perfect

and like i said for a couple of hours work this is a tool that will live in your shop and work with you for the rest of your life and those are like i’ve said already my favorite tools oh i almost forgot you might have been wondering this whole time how do i look up which drill bit goes with which tap and the answer is there’s a chart and it’s in your pocket pal it’s online but my recommendation is to find a guide like this a handy little guide that shows you all the tap sizes and the drills that go in them their decimal equivalents etc etc this is an invaluable thing to have in a shop lots of people have them as posters up on the wall you can find them online you can print them out you can make your own you can laminate them but you should have a hard copy frankly that definitely makes things go faster thank you so much for watching that entire video your viewing helps us keep the lights on well it’s one of the ways one of the other ways is through selling our merch and you guys have been so fabulous about suggesting great merch ideas when i say something strange or funny and you suggested in the comments that we put it on a sticker or we put it on a t-shirt well we are following your advice and if you follow the links below you can buy some of our merch so that we can make some more videos thank you guys for watching

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