How To Align Your Lathe

hello internet my name is Quinton and this is blondie axe do you want your lathe to cut straight if so you got to get the bed straight and you gotta get the tailstock aligned we're gonna do both right now so the other day I'm working on this part that needs to be 500000 I am attorney metal and I'm a couple tenths off pretty happy with that to keep myself on us to measure the tailstock hand it's about half an hour and then I measure the Chuck end and it's almost a full Thau under so I'm turning about a thousand I have taper here over about four inches that's no good so I'm going to show you how to take taper out of your parts but when do you need to do this kind of setup well anytime you get a new machine of course you need to go through this exercise or any time you move the machine you're gonna need to do this as well and in my case you know this machine's been sitting here happily cutting straight for many years but you know things in the environment change concrete settles steel benches can shift cast iron in the machine itself can settle so something you know has changed in the environment it doesn't take much for the machine to start cutting tapers there are two basic things that can introduce taper into the part from the machine itself the first is twist in the bed and the second is misalignment of the tailstock from the spindle now of course the alignment of the tailstock depends on the flatness of the bed so we have to check the flatness of the bed first here's a little arts and crafts project to demonstrate how twist in the ways creates taper so here's our stock here and here's our little tool post here and watch what happens when I twist one end of the ways so pay attention to the distance between the tool and the stock right there now when I twist one end here you can see that the distance between the tool and the stock changes so if the near side of the tail stock is tilted down the tool gets further away from the stock and so that end of the stock is going to be larger and the machine is going to turn a taper or a cone if you like and here's another view on that so you can see now this is obviously very exaggerated we're talking about you know microscopic amounts of twist here on the real machine but how do we measure twist in something like this it turns out to be really hard to do be because the bed here the ways is the reference on the machine so if this thing isn't straight we have no reference to compare anything else on the machine to luckily we have one handy Universal reference for all of this stuff the earth machinists often talk about leveling your lathe and how important that is it's actually not true a lathe doesn't have to be level any Navy machinist I'll tell you they bolt lathes to the decks of ships and they work just fine however what we're doing is we're using level as a proxy for measuring twists in the bed so what we do is we measure level down here and we measure level up here and if this guy is kind of here and this guy is kind of here that's going to show up as different level positions and then that you can see is gonna tell us if there's twists in the bed now of course we're talking about microscopic amounts of twists here so how do we measure that now I happen to know my machine is level already but I'm gonna give you a crash course in this just so you can see how it's done now we're talking properly level not like woodworker level like properly machinist level so how do we measure that it's okay I can make those jokes my best friend is a woodworker this is a typical machinist level well it works very similar in principle to the basic carpenter or DIY level but of course it has some very important differences the first is cost these things are not cheap they are of extremely high precision instruments you can however find them on ebay that's where I got this guy but be careful make sure that you know it's in good condition especially check the bottom surface if there's no damage or wear anything on there and you know buyer beware but you can save a lot of money buying these guys on eBay it's like an important difference of course is precision these tick marks here are 5 thousandths of an inch per foot or 0.5 millimeters per meter so that's the sensitivity give or take of this guy and so it's extremely sensitive and the other important feature of these guys is that they are self-proving you can adjust one end of it and then the bottoms of them of course our precision ground and they have a V in them to minimize contact surface for increased precision and to that end you want to try and minimize how much you handle these guys because the temperature of your hands can actually warm it up and change the readings step one is to calibrate it so we with a clean and dry surface plate get everything clean now because we know the surface plate is a perfect plane in principle there will be some orientation on it that is level wherever you place it might not be level depends how the bench is sitting and how the stone is sitting on the bench and so on but there will be some rotation of this thing that is perfectly level so just rotate this guide until you find that point and then what we do is we take something that's a precision straightedge something heavy so it won't move give it a little extra mass here behind it like so and then we rotate the level 180 degrees and it should have the same reading and if it doesn't then adjust the thumbscrews here up and down a little bit until it reads the same in both orientations and you might have to change the position on the plate as you go but as soon as you get it to a position where it reads the same in both directions then it is self proved and calibrated then what we want to do is place the level on the far end of our ways and to do that the ways of course have to be completely clean and dry you need to matching flat spots on your ways on some machines this is easy on others it's a little tricky this is what's often called a prismatic ways where there's multiple trapezoidal sections at different heights but there are two flat spots here that are at the same height and in the same plane and ostensibly so we need to be able to put our level on these guys but of course the prismatic sections are in the way so we can put some sort of precision blocks on the flat spots now these have to be precision blocks ideally you want to use gauge blocks for this because those are precision ground and extremely precise I'm using these 1 2 3 blocks here that I've checked and I know that they're good these are quality 1 2 3 blocks but obviously if these two blocks aren't exactly the same height then this whole exercise is moot so be very careful which blocks you use and then we just place our level on here and we look at our reading right there and we do the same thing down here and what you want is the same reading at both ends so we need to twist this end of the ways slightly to get those two bubbles to be in the same position and so if you've got a large machine with feet on it then those feet are going to be adjustable and that's how you do this on a small bench top machine like this we achieve twist adjustment by putting shims under the front or back of the cast iron feet that are down there now all that fancy measuring just gets us in the ballpark yes machinists have very small ballparks what is this a ballpark for ants but the truth is always in the cut so to really get the Machine dialed in you need to make a test bar to make this test bar I'm using a piece of one-inch steel and you want generally to use the thickest bar that will fit through your spindle board to make it easier to work with but you want it to be as thick as possible so that it will support its own weight with a large overhang as we will see here so I'm going to face the end of that off and then we're going to put a Center in it with a number two Center drill and take care to make this Center as clean and nice as possible make sure there's no chatter in it and then we're going to pull this bar out to about there so this is six inches of extension which is good for a bench top lathe and then we bring the tail stock in and square up the tool post and then we're just going to do a light cleanup pass on this thing just like ten thousand something like that is enough just so that we have a concentric surface there and then I'm going to come in here with a grooving tool and I'm gonna make a little trench at one end about half an inch from the end and that end is going to form basically a journal so I'm cutting that little trench in there at each end and again leaving about a half inch at the far end and then we turn down the middle between those journals so we're making a barbell shape and the center diameter is about thirty or forty thousand the ends and the smaller you make that Center area the more tries you'll get for the adjustments that we're gonna make but if you make it too small you're gonna lose rigidity so thirty or forty thousand to make sure our turning tool is really nice and sharp so I'm honing it by hand you have to get a very very good finish on the operations that we're about to do here and then we pull the tailstock out and then we start turning and I know what you're saying this is madness you can't possibly turn stock with that much overhang this is way way beyond the recommended limit of two to three times the diameter of the stock but you see we have to do this without tail support because if the tail stock is in place that's establishing the access of the part but we need to measure how the tool travels across the ways relative to the spindle and so that's why we do this without tail support and the reason that we made that barbell shape is because we only want to be doing cutting at the very ends and that minimizes buildup of heat in the part which would change the dimension and also minimize us to aware between cutting one journal and the other so that the cutting conditions at each end of this bar are as similar as possible that's really important and the way we get away with this much overhang is that we're cutting very very very light passes like mm at the max and you may still encounter some chatter and if you get chatter even with a tooth out cut then your your test bar is a little bit too long so as I say with a one inch bar about six inches of overhanging we can get away with and do a tooth out cut with no chatter so now what we do is a series of mm and we're using the power feed for the cutting at the ends but then we're just hand cranking in between to speed up the process and you need to get to a point where you get a full clean up pass at both ends in this setup and that took it can be a little hard to tell with such a shallow cut if you're actually cleaning up the entire surface so just put some sharpie marker on there and now you can tell if after your pass there's no sharpie marker left and you know it was a full cleanup and once you get to the point where you've got a full cleanup pass at both ends then now we know we're measuring the true straightness of the ways from here on out and we can start taking measurements so now I measure the far end and I take this measurement repeatedly until I get the same reading three times and I'm using a tense micrometer here because ultimate precision is very important here so I make a note of that measurement and then I do the same thing at the near end and now we can see where we're at and I'm just using the last digits on the micrometer here so I've got two point seven at one end and 2.0 at the other so the Chuck end is 7/10 larger so again referencing our toothpick model that means that the tool is too close to the work at the tailstock end so I want to tilt the back of the tailstock end of the ways up a little bit so I start by unbolting it from the bench and then I come in on the back and I pry it up off the bench and I slide a shim under there so it's quite hard to know what size shim to use so just start with something round I'm starting with a ten thousand here and that you're gonna need an assortment of precision shim stock so you can either dismantle an old feeler gauge or you can buy packs of assorted shim stock which I'll include in the description below and don't push that shim all the way under the foot or you'll never get it out again and now you can bolt the machine back down to the bench and we can take another test cut and see where we're at and once again we do clean up passes until we're cutting cleanly on both ends so after that first attempt we're one point one at this end actually at one point zero after double-checking that and we're point four at the other end so we're actually now 6/10 larger at the tailstock end so this tells us two things first that we went in the correct direction the tailstock end got bigger but we actually went too far by about a hundred percent so that was a ten thousand and I actually went back and forth a couple of times I went to a five thousand you know experimented with one and three thousands and did a few iterations that I will spare you here but this is the process so after a few iterations of that I managed to get twenty point five at both ends this actually surprised me I didn't quite believe it but here is the measurement twenty and 5/10 at both ends so both ends are the same size within my ability to measure a tenth on the micrometer that I have over a distance of four or five inches so very happy with that now we need to align the tailstock the quickest way to do this is with something called a tail stock alignment bar and it's a very high precision ground bar that you put between centers and you just put an indicator on each end and you adjust your tail stock until the indicators read the same now these bars cost money and you may not have one and they're very specialty item that isn't worth owning unless you you're tailstock a lot so I'm going to show you the old-school method so we bring the tailstock back in and if you need to deepen your recess this is a good time to do that so it gave myself another thirty thousand do is pull this bar out a little bit and part it off because the next step needs to be done turning between centers so we have to put a Center in the far end now hey what you do in there Quinn while you're parting it off so close to that Journal we need room for the lathe dog to turn this between centers no wait no stop what no oh Yahtzee I guess luckily I just installed the new Toni OS so I can just command C that to undo it cuz boy it sure would be annoying if I had to make that part again just for this video yep that sure would be annoying but luckily I didn't have to do that anyway go ahead and set up for turning between centers here so we put a lathe drive pin in there which this is a some that I made for this lathe and then we put our big Center in there and then the tailstock centre and I'm using a high-pressure grease here you'll note that I've put in a dead centre there because I don't want to use a live Center and introduce more variables for this process so going old-school with the grease in the dead center and I also put some counter weights on the drive dog and there just to make it run as smoothly as possible so now we do the same process that we did for the previous test bar and make sure that we're getting cleanup cuts before we go any further all the way across both journals and you'll notice some run out in the recessed center of the bar because of course that Center was turned inside the Chuck and now we're turning between centers on a different center but that doesn't matter because we're recutting the journal areas and once we've got a full cleanup then we know the journals are concentric with our centers and once again we take measurements of both ends and again I'm triple checking each measurement so to start with we've got twenty point four at one end and we've got twenty point nine at the other so we are half a thousand with tail support in place so then we set up a indicator on the quill and ideally you would do this with a tense indicator I don't have one they're very expensive so I've got a half thio indicator and this is good enough for the shenanigans that go on in my shop the lateral position of the tail stock adjusted with these bolts in the base that work against each other so you loosened one and tighten the other so since our tail stock end was half ass out to big we want to move the tail stock backwards about half that distance because we're measuring diameters so we want to move it a quarter of a thousand two of the lines on my budget half our indicator so after that first move we've got 18.9 at this tail stock end and 19.9 at the check-in so we moved it the wrong direction because our half thou problem turned into a one think about that toothpick model when you're doing this it can sometimes still be unintuitive a little bit so yeah and we just do it again and go the other way but the good thing is we saw an expected result it moved the diameter amount that we expected so that we know that our setup here is correct we just got to do it the other way and it may take more fooling around on each of these moves than you expect because everything here is in tension the screws are tight against each other and as you start to loosen things you can get spring effects that kind of things start to relax so the indicator may move in unexpected ways when you first start making each move so sometimes you have to mess with these screws back and forth a couple of times but the important thing is to believe the indicator and keep going until the indicator reading is what you want it to be for your next test so that got us to 16 at the tailstock end in fifteen point eight at the Chuck end so we're two-tenths large on the tail stock now so a couple more iterations and I got two fourteen point four at the tail stock end and fourteen point four oh let's call that four eight at the Chuck end so fourteen point four eight and fourteen point four so we're eight hundred thousandths large at the Chuck end over about six inches I'm very happy with that you can drive yourself crazy chasing hundredths so we're gonna live with that and you can keep this bar for future use next time you have to adjust your tail stock but the real proof is in the production so then I went back to making that part I was trying to make when this all started and again I took three measurements and all three measurements are dead nuts on 14 and nine-tenths so now I can no longer do detect any taper within the resolution of my tools so very happy with that result I hope this helps you align your lathe thank you very much for watching and we'll see you next time you

Channel: Blondihacks

Views: 390,493

Keywords: blondihacks, machining, machinist, abom79, this old tony, vintage machinery, steam, electronics, making, maker, hacking, hacker, lathe, mill, woodworking, workshop, shop, model engineering, engineer, engineering, live steam, machine shop, metal lathe, vertical mill, metalworking, metal shop, jewlery making, diy, home improvement, resin casting, how to, do it yourself, do it yourself (hobby), ASMR, mini mill, mini lathe

Id: H0MwCyWeP7I

Length: 18min 13sec (1093 seconds)

Published: Sat Dec 21 2019