Taking the Mystery out of the Threading Dial

in my last video thread cutting on the way part 4 I touched up on the subject of the three cut with a threading dial and what did what it is and what it's used for well since my my heart Inge didn't doesn't have a threading dial I borrowed this one from my dad's atlas and attempted to explain how it worked but I don't know about you but theory kind of bores me and I think it does you you guys too because I'm sure I noticed some some ice fogging over and some thousand-yard stairs even over the Internet so I thought I'd uh revisit this subject and put the threading dial back on my dad's laid where it belongs and give you a little practical demonstration of how it works I know it's it's easy to look up on a chart and say and figure out which of these marks you have to engage on for whatever threaded thread you're cutting but I find it easy to remember how remember things like that if I know the why behind it so let me let me attempt to demonstrate the why behind the threading dial and what you know the mystery of what Mark you can engage on and what marks you can't all right if you notice that when we move the carriage this threading dial rotates okay well what it's doing is it's it's telling us where our carriage is relative to the to the lead screw and the reason it's doing ed is so we can know exactly where to engage our half nuts so the threading tool will always go back in the same position on the thread we're cutting I'm gonna have to worry about cutting a thread halfway between or some some ridiculous thing like that and ruining our thread so let me let me give a little demo on how this works if we line up with the number one okay line number one mark up with with the indicator mark on the dial and we'll put a little mark on this piece of masking tape I have stuck on my dad's lathe here alright now if we if we rotate or if we move the carriage down so the dial rotates half 1/2 of half way around to the to put another mark okay this was one and this is two we measure those two marks you can see they're one inch apart alright so the distance between numbered marks is one inch some dials have two numbered marks like this one some dowels have four and in fact a lot of them have four all right in this case since we only have two if we go all the way around put another mark you can see the total distance we travel is two edges for one revolution of the dial if it had four numbered marks that this would be four inches okay one or volution of the dial be four inches the important thing is to see that numbered marks on the dial the distance between numbered marks is one inch and why is that important well if we're cutting an even number of threads or an odd number of threads any pitch whether it's a 20 or a 13 or a 12 as long as it's a hole numbered as long as the threads have a hole number on them you're not fractional threads we can engage her half nut or a dial any on any one inch increment or any number dial or any unnumbered dial if we want to do it that way I prefer to stick with with the number dials it's easy to keep track of now on even number of threads we have a little bit of an option okay even number of threads are divisible by two the 12 pitch for instance divided by 2 we get 6 so we can do the same thing on our dowel here we can we can engage halfway between the numbered lines on one of these unnumbered ones here and it will still work now work fine ok so I give us a lot more opportunities to engage our dau we don't have to wait around for the right number to come up so an even number of threads you can engage on any numbered division or any number division if we're cutting an odd number of threads you can't do that cuz ID numbers are not divisible by two thirteen threads per inch can't divide it by two and get a whole number you can cut you can divide it by two but you'll get six and a half all right so that means if we engage on a division between the numbered lines we're going to put a thread right on top of the thread we cut the first time and totally ruin it okay then there's always the the odd or the fractional number of threads some pipe threads for instance like one inch one inch pipe thread is 11 and a half threads per inch well we can't we can't engage on a one inch increment for a for an 11 1/2 pitch thread because you can't engage on a hat if we if we do we'll put a thread right on top of our old one 11 and 1/2 it's not a whole number so we have to go we can only get engage a 11 and a half threat every 2 inches ok 2 times 11 and a half is 23 ok so that's that's a pain pain in the butt to machine a 1/2 pitch threat because you can only engage your thread dial every full revolution so it's a lot of waiting around alright so I have a set up here to to demonstrate the right and wrong way to use a thread dial I have the the one-inch 12 thread that we cut in the last video mounted in the Chuck and I'm getting ready to make a nut to fit this thread so I have an internal threading tool made up on a boring bar and I've got this thing pointed or I got it lined up with the thread just so you can see what happens when you engage on the wrong the line on the thread down right I also got my little paper trick to back wet paper tricks so you can see what's going on a little easier so let's turn this thing on and see what happens see the thread now going around and now we're cutting an even number of threads that means I can engage the half nut on any numbered or any unnumbered mark on the dial let's try the two here let this thing go over to get over the thread then I'm going to shut the spindle off and let it close to a stop leaving the half not engaged okay now if we back our tool out until it goes in starts cutting in or going into the thread you can see it's perfectly aligned with the thread all right all right let's try it again that was that was on the - let's try engaging it on an unnumbered Division remember I said it even you can do it on any number or another is that we do we're doing my camera one hand so let's shut the spindle off but it goes to a stop okay now you can see that the thread the cutting tool goes right into the thread perfectly lined gray just like before all right now here's what happens if you do it wrong let's go back out here start it up let's say we engage we miss our mark by a little bit like the ball here okay let's engage a little bit heading for the thread we'll see what happens shut the spindle off we have to engage now look at how the tool lines up with the thread okay we're in big trouble okay what we've got is we cut a thread right on top of the original thread we cut that would ruin your day okay so don't do that all right hope you hopefully you picked up a few pointers with this and hopefully you understand the concept behind the thread dial that's all I have for the moment

Channel: Toms Techniques

Views: 173,778

Keywords: treading dial, half nut, half nuts, machining, machinist, processes, techniques, how to, turning, milling, lathe, mill, threading, thread cutting, South Bend, Logan, Clausing, Delta, Sheldon, Atlas, Bridgeport, Starrett, Lufkin, Mitutoyo, instructional, tutorial, educational, metal, metalworking, shop, machinery, tubalcain, millwork, facing, drilling, grinding, grinder, Harrison, Hardinge, lathe section

Id: jbRcs_Hhtuw

Length: 8min 32sec (512 seconds)

Published: Sun Sep 08 2013