Vertical Mill Tutorial 4 : Basic Milling Operations

hello Internet my name is Quinn and this is bloody axe this is mill skills series of quick videos on getting started with your vertical mill this is episode 4 basic milling let's dive in probably the most foundational thing that you need to know about milling is Direction there are two milling directions conventional milling and climb milling and I'm sure you've heard these terms but it can be a little bit difficult to understand what they mean so I'm going to illustrate it with this setup right here so I have here a comically oversized milling cutter and standing in for the stock is this material here which you may not be familiar with this is a carbohydrate foam product the ore is typically found in forests and the smelting process is very low temperature it's actually room temperature pretty interesting it's difficult to work with for the life of me I can't seem to find the right settings on the welder and the dust from this will actually kill you very slowly so be careful when working with this stuff okay so imagine we're deep in this exaggerated cut here the milling cutter is always going to be spinning this way but the material is being pushed by the table and it could be getting pushed this way or this way if the material is moving this way that's conventional milling if the material is moving this way that's climb milling remembering which is which is easy climb milling is the intuitive one and conventional milling is the other one so if this material is moving this way and the cutters spinning like this you can see that the cutter is actually wanting to climb its way up the hill of this cut that's exactly why it's called climb milling but what's interesting is these two different operations have very different cutting properties in conventional milling you can see as I approach the curve of the previous cut this tooth here it starts out on a very gentle slope and progressively eases its way into the material you can see how that would happen here and so the tooth actually starts out rubbing and then eventually as it keeps getting pushed into this slope it starts to become a cut now over here on the climb milling side when this tooth impacts the material you can see it's basically at a right angle to the material and so it's going to dig right in immediately start cutting there's no easing into the material it's biting right in and starting a chip immediately so because of that better cutting action climb milling actually produces better chips and also results in a better surface finish conventional milling meanwhile because the cutter starts out rubbing the the cut doesn't start very well and so you get a worse surface finish and you also get more wear on the cutter so given all that climb milling sounds like the way to go right but all you ever hear is it climb milling bad conventional milling good right that's what everybody says and it's basically true and for one main reason and that's rigidity because of this climbing action that the cutter is doing and climb milling the power of the mill is actually working against its own rigidity it's using its own power to push the cutter off track so there's a tremendous demand on rigidity one climb milling whereas conventional milling because the cutter starts out with very low tool pressure and then as it digs in it tends to pull itself into the material the rigidity demands of conventional milling are much much lower and if you get aggressive with climb milling cuts you can actually feel that climbing or that pulling on the table and you know you'll know that feeling if you've you know come from a DIY or a woodworking background and you've used a handheld router you know that when you use it in one direction it howls like a wounded banshee and when you use it in the climb milling direction it attempts to murder you and that's how you know which is which so on high-performance mills like modern CNC machines climb milling is actually preferable and the books will actually tell you to prefer climb milling but the conventional wisdom says climb milling is bad because well most of us have older manual machines that don't have as much rigidity and for those machines conventional milling is much better but we can get the best of both worlds if we do most of our milling conventional and then when you need a really good surface finish you can do a light finishing pass climb milling to get the best possible finish so much talking let's make some chips right after a little more talking so I'm going to do a conventional milling pass and then a climb milling pass and remember that the cutter is spinning this way and milling cutters always spin the same direction they spend clockwise when you're looking down on them that's how I remember it and so you'll see that if the material is moving this way cutters spinning this way that's going to be a conventional mill and then if the cutter is spinning of course the same direction and the material moves this way that's going to be a climb mill here's the kind of finish you can expect from conventional milling it's smooth to the touch but under the macro lens you can kind of see these vertical ribs that are caused by the start of that chip formation being a little funky and here's the finish from climb milling all the same settings on the machine and you can see that the finish is much nicer you can still see the tool box just barely but mostly what you now see is just the horizontal grain in the aluminum so assuming you have an average less than superhumanly rigid mill the way I like to remember which is better is that conventional milling the cutter is fighting the direction of the material feed whereas in climb milling it's following the direction of the material feed so you want to be a fighter not a follower and I find that you Nimonic useful because it's easy enough to visualize climb milling versus conventional in two dimensions on the bench but here in the heat of battle setup on the mill it can be a little harder to wrap your brain around which direction the material is moving relative to the teeth so imagine the cutter always moving in slow motion like this and you can see that if I move the material this way you can see that that material is following the teeth it's going with the teeth so following that's climb milling the material is moving this way you can see that it's resisting the direction of the cutting teeth it's it's fighting the cutter so be a fighter not a follower we're gonna talk about face milling first which is generally the first operation that you're gonna do on a given part and it's also the most common operation that you're likely to do on the vertical mill and its most basic level face milling is how we make things flat and that's kind of a super power of the vertical mill that makes things flat so you might take something like this here which is a rough bandsaw cut it's very typical of what you're going to start with because you're gonna rough cut your stock to the very approximate dimensions of the part you're gonna be making and after face milling you get a nice smooth machined surface like this guy so face milling turns this into this face milling on the vertical mill is analogous to the facing cut that you start with on the lathe it's the first operation that you're going to do it gives you your first reference surface and then typically how on the lathe you would then turn the outer diameter of the stock to some major diameter that's going to be the basis for adding your features to the part on the mill we're going to face this first surface and then we're going to typically square up the stock by face milling all of the sides to get it to the rough outer dimension of our part upon which we can then add features so here's a selection of milling cutters that you can use for face milling so over here we've got your basic end mills and these come in a few different flavors which we'll discuss here in a moment and then in the center here we've got a couple of examples of shell mills which are like great big and Mel's except they have a hollow Center in them sometimes filled with jelly and then over here we've got a fly cutter and then also a great option our face mills these are typically gonna be set up for carbide inserts and those are a great option for larger machines for smaller home and hobbyist benchtop machines I tend to prefer the high speed steel options so I like the shell mills and for a larger surfaces the fly cutter let's take a closer look at the geometry of the humble end mill it's the most common tool that you're going to be face milling with but these guys are marvels of engineering and they are called end mills and they have cutting edges on the end so you might think that they cut on the end of the end mill but in fact that's actually not really how these guys work so let's say I've got this guy set up in the mill and I dial in some depth of cut and then I start moving this guy across you can see how it's not really the bottom of the mill that's doing any cutting it's actually really this front edge of the bottom of the flute that's doing this cut the cutting this corner here and this edge so depending on how deep your depth of cut is if you're doing a 50 thousand let's talk about the most visually obvious difference between different end mills that you're going to find first is the color sometimes there's silver sometimes they're yellow sometimes they're purple striped or whatever and they have different numbers of flutes so the most common you're probably going to encounter are two flute and four flute so what's all the differences here well the color is generally some sort of coating now in this case this yellow color on these guys comes from the titanium nitride coating that they have which is a very common kind of entry-level coating for high-speed steel mills and basically it just increases the hardness of the mill now you'll also find other coatings to increase lubricity or you know increase wear resistance or lots of other valuable properties and you know these coatings come in many many flavours and they're about 80% science and 20% marketing but compare that to this silver coloured mill here this is sometimes referred to as bright finish which is marketing speak for cheap and this has no coating on it at all this is just raw high speed steel and frankly not very good high speed steel at that this is a low-budget end mill that you'll find on Amazon and yeah this guy is gonna wear out and get dull much much quicker than these guys now let's talk about flute count again the most common choices you're going to encounter are two and for flute and this is certainly sufficient options for the home a hobbyist machine shop there's no hard and fast rules about when to use 2 or 4 flute mills but there are some general guidelines that you can go by each has strengths in different situations the two flute mill gives you much more clearance between the flutes and this is great for materials that tend to make stringy chips or materials that are gummy or soft and need more time to get out of the way before that next flute comes around during the cut and because of that extra chip clearance the two flute mill is much less likely to clog up with material so this makes two flute mills a great choice for things like aluminum brass copper and so on - flute mills are also a good choice when you need to do plunging into material straight down this is not something that I like to do but if you need to two flutes are a better choice for that now you can get so-called Center cutting mills in both flavors - for and and other flute counts but regardless of that the two flute is always still going to be a better choice now the for flute mill on the other hand has its own advantages the first is that because there are more cutting teeth and engaged with the material at any given time it's going to move material faster but one thing to be aware of is you don't ever want more than two teeth engaged with your material at a time so be thinking about that as your flute count goes up on your mills the other thing these extra flutes do is add rigidity so a for flute mill is a great choice for tougher materials like steel you're going to be able to take deeper cuts because the mill itself will be more rigid thanks to these extra flutes and for materials where your rpm is lower more flutes is helpful because it allows you to get the same amount of work done with lower rpm because you've got more teeth and doing cutting on each lap around we'll start with this - flute mill because it's the easiest to understand but the basic features are the same on on all end mills so you've got your spiral flutes here on the outside and similar to a drill they do serve to evacuate chips but unlike a drill they actually evacuate chips outward not upward and very much unlike a drill they are also cutting edges now on the end here is where things get really interesting so you've got two more cutting edges here you can see on this particular mill the cutting edges along the bottom meet at a point in the center and that's because this is a center cutting end mill we'll talk about that a little bit later but at the business end here these points here on the end or where all the action happens and you can see there's these little scallops cut out of the end and then you can see there's an angle here and an angle here and an angle here these are all relief angles to understand the nml it helps to look at a basic lathe turning tools so this is a single point tool this point right here is doing the cutting and then there's angles here and here and here and the tool itself sits at an angle like this so there's all these angles and these are all relief clearance and rake angles and they all serve basically the same purpose which is to make sure that this point right here is touching the work and nothing else is and then there's also of course the rake angle which helps to do the actual cutting but primarily it's just all about making sure that only the part of the tool that you want doing the work is touching the work so you can think of the corners of the end mill as little tiny single point lathe tools this point right here is what's doing most of the heavy lifting and then this little scoop cut out here right behind the point this is the rake angle and so this is what's creating the right angle at that point for the cutting action for the material so you know if you recall from grinding lathe tools you want like I say a 10 degree top break on your lathe tool for steel that's what this little scoop right here is doing same thing now here on the end we've got a clearance angle behind this point right here and then frequently you'll find a second surface behind that at a different angle so there will be a primary and a secondary clearance angle and that's because clearance angles are always a trade-off between support and clearance you want the clearance angles behind any cutting edge to be as shallow as possible because that gives the cutting edge more support you want to support you want material behind that cutting edge but the the less the angle is the less clearance you have you want as much clearance as you can so there's always a tension there between those two goals so one of the ways that we get around that is by having multiple clearance angles so high performance Mills really you know expensive mills might even have you know three different surfaces behind every cutting edge to give as much of a sweet spot between support and clearance as possible for comparison here is a more expensive for flute mill and you can see this is not a center cutting and amel the flutes don't meet at a web in the center but you can clearly see we've got multiple clearance angles here behind the edges and there's our rake angle there again behind the cutting point very clearly visible and if you look closely here on the side flutes you can again see your cutting edge and a clearance angle there so anything the cuts has clearance angles oh but that's not all you remember the lathe tool had clearances in all three dimensions around that point well again every single cutting surface and cutting point on an end mill has clearance angles around it in all three dimensions so another area that shows up here is on the bottom and you might think that these two bottom cutting edges are flat because in Mills make flat surfaces but in fact there is an angle here they they dish into the center in fact this is called the dish angle and it's a little hard to see but maybe this will help you see that this block that I'm holding is machined flat you can see the bottom cutting edge is there don't touch it all the way across only the corners of the mill are touching that surface that's the dish angle and this works very much in the same way that a lathe can cut a perfect cylinder because it's a single point cutting tool the points of this end mill are doing the cutting and so as this guy spins it's creating kind of a halo of single point cutting tools effectively and so as this guy moves across the work it's like a whole bunch of little single point cutting tools spinning and they are creating a flat surface and then these inner areas here or just trying to stay out of the way if these guys if you tried to make them flat they'd end up gouging and touching the surface and the surface wouldn't end up flat so this little dish angle here is subtle a little bit of magic now we've really just scratched the surface here on end mill geometry you know there are land angles and helix angles and chip breakers and gash angles and there's so much more that goes into and Mel's especially high-performance ones but here's a little taste of some of the other geometry that you might see especially in the home shop and that's a roughing end mill the roughing end mill has the the side flutes broken up like so and all that does is lower the tool pressure of the whole cutting edge as a whole and this allows you to take much deeper depths of cut and move more material in a hurry okay let's do some actual face milling using all the tools that I described earlier so this is your basic half inch end mill and I'm feeding the material right to left because that back edge of that end mill is technically going to be conventional milling if I do it this way and for feeds and speeds I will refer you to the speeds and feeds video in my lathe skills series because I covered milling in there as well and so at the end of this pass I use the rapids to come back so that I can again feed in the same direction for the next pass so that that far edge is technically conventional milling now the truth is that this isn't actually that important if you're not taking a very deep cut because you know you're only talking now this is a 25 on I got 20,000 gauged there it's fine if you want to mill back the other way so if you've ever wondered though technically why you're not supposed to mail back and forth this is why and here's the end result of this style of milling so you can see the tool marks there you can tell it was done in multiple passes but if your mill is set up right then it'll still feel smooth to the touch and if I run the needle over that there's a little bit of a catch like there's a few tenths there between two of the passes but otherwise it's all smooth but you will get better results if you can use a milling cutter that's larger than the face that you're milling so here we are with the 2-inch shell mill or if you have one of those big carbide insert face mills those are a great option and with these guys it doesn't matter at all which direction you mill in because there's cutting happening on the front or the back of the cutter and you're always going to get a nicer result here because while you can still see tool marks they're very uniform and it's a very nice smooth surface and lastly here's the fly cutter and a fly cutter is a great way to sort of cheat it acts as a virtual face mill that's much larger than your mill would normally have the rigidity or the power to support because it is a single point cutter but it is not fast so you won't be in a hurry with this guy but it does make absolutely the best finish and you will also find out how good the trim is on your head because the larger the cutting radius of your cutter is the more of a dished effect you'll get if your trim isn't perfect and the second most common type of milling is side milling and I would teach you that right now but I already taught you that when you weren't looking so here's that footage again the only thing you need to be aware of here is if there is a lot more cutting edge engage with the material so it's asking more rigidity of the cutter and so you may want to dial down your depth of cut and your RPM a little bit I promised at the top of the show that I'd talk to you about the dark horse of milling operations plunging and I lied I'm not going to talk about it I'm going to show it to you and a lot again I'm going to talk about it too so these are both Center cutting animals which in principle can be used for plunging I still think it's not the greatest idea to do that within mills and you should avoid it when possible but an example of some places where you might need to do it or if you're trying to get a flat bottom hole or if you're doing slot cutting is another common application and if you need to plunge directly into material you really want to use a - flute and mail if at all possible and these guys are going to have a pretty good Center cutting action similar to a drill now there are also Center cutting mills of other types for example this is a for flute Center cutting mill but you can see what's happening here it's kind of a compromise they've got two of the flutes meeting in the center and then the other two flutes are just kind of trying to stay out of the way and so while you can plunge with these guys it's you know it's gonna work okay these outer flutes here are not going to be having a great day and the the edges in here aren't super robust because they're you know trying to meet in a web while staying out of the way of the other two flutes and you know it's it's a compromise but it turns out to be pretty rare that you actually need to plunge directly into material instead what you can do almost every time is drill out the bulk of the material with a drill and of course that will leave you with 118 degrees cone and the bottom of your hole is for a normal drill and then you can come back in here with this animal and finish it out to final dimension and then flatten out the bottom of the hole and that way the end mill isn't doing very much work it's just the outer edges of the flutes that are cutting and then if you drill to say 20,000 I'll depth then you're only having to plunge a little bit with the center cutting action but the real truth of the matter is that it's very rare that you actually need a flat bottom hole it's almost always easier to just leave a little extra thickness in the material in your design and drill a hole with a drill and just accept the fact that the bottom of the hole that nobody will ever see has a little bit of a cone in it and you can you know still accommodate your alignment pin or whatever else is going in that hole but in machining the devil is always in the details if you genuinely do need a flat bottom hole then this trick within a center cutting end mill won't actually even work because remember there's a dish angle on the end of this and it's slight it's only a few degrees but technically if you plunge down into your material you're gonna end up with a little bit of a cone in the bottom so if you do genuinely need a precisely flat bottom hole your best bets are going to be the boring bar on the lathe or a boring head in the mill and remember you can learn a lot about whether your Melling technique and your speeds and feeds are right by looking at your chips so for regular like face milling type operations you want to see these kind of comma-shaped chips like this guy here and one side milling you're looking for these icicles like this guy here the big thing to watch out for is powdery dusty looking chips if you see that it means your tool is doing more rubbing than it is cutting and that's really bad for the tool so now figure out what's going on with your feeds and speeds your tool pressure might be too low tool might be dull something like that so look out for those commas and those icicles and you know when you're done store these with your fingernail clippings as is tradition what does does nobody else do that you

Channel: Blondihacks

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Rating: 4.9466667 out of 5

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: 5V0s6fLyRH0

Length: 23min 2sec (1382 seconds)

Published: Sat Oct 12 2019