Mini Lathe Operations #2: Drilling

hi it's Frank who's from mini live.com this is number two in our series of basic machining operations on the mini lathe this one will be about drilling well I thought it would be interesting to start out with an actual demonstration of drilling on the lathe and I think the thing that's interesting about it particularly if you haven't seen it before is that unlike most other drilling operations in a lathe the work terms and the drill bit remains stationary in just about any other type of drilling situation the work remains stationary and the drill bit turns significant advantage of drilling on the lathe is it tends to make the drill bit self centering so you're more likely to get a hole that runs right down the midline of the word anytime you are going to drill into the end of a workpiece it's good practice to always face the workpiece that'll give you a smooth surface that's even and square to the work whereas a rough surface might snag the tip of the drill bit and the drill bit being a little bit limber could be pushed off to one side after facing the workpiece the next step is to drill a short starter hole with a so called center drill or Center drill and countersink and these typically are double ended drills that are short and stiff and they are used to start the hole so that it's exactly where you want it if you start the hole with a twist drill there's a possibility that the drill will flex a little bit and not be exactly on center this is a typical set of five centered drills and I've included a penny here for scale and for those of you who may be interested in such things this is a so-called lead penny made in 1943 when copper was a very valuable resource for World War two they made a lot of pennies that had little no copper and this happens to be one so just thought I'd throw that in for entertainment value because I found it in the drawer over here but these this is a number five and number four a number three number two and this one happens to have a broken end on one end and then a number one now they also these are typically sold in sets like this but you can buy them individually in packs of five or ten or whatever or one and you can also get bigger ones if you have a big lathe you can also get smaller ones for specialty work and they look similar to the number one but it has a very fine point on it as you can hopefully see this is an import one that has a an unusually long tip on it and the only problem with that is if your drill chuck is a little bit off-center and as a result the tip will break off like has happened on this one so if you have a choice try to get one that don't have these real long tips on them to avoid that problem now as far as which which size drill to used for a particular job you want to choose one where the diameter is just a little bit larger or about equal to the diameter of the hole that you're going to be drilling but if it's smaller it won't matter too much as long as it's not real small but you want it to make a big enough hole to give your drill bit a good start as the whole idea now let's say I want to drill a quarter inch diameter hole in this piece of steel stock I have in the chuck here so I'm going to select this number three Center drill and we'll drill our starter hole with that when you put your center drill in the chuck as you're tightening it down before you tighten it real tight give it a twist like this then if there's any grit or chips or anything either on the jaws of a chuck or on the drill bit they will tend to get wiped off and end up in the spaces between the jaws rather than underneath the jaws so that will not only give you a tighter hold on the center drill but it will also avoid the possibility of having a chip under there that might cause it to you know be skewed to one side or the other and once it's in place you can tighten it down with your Chuck key and a lot of times I like to use two holes when I try it a bit for that reason I try to keep two holes accessible but in this case I have the Chuck twist a little bit more towards the bottom than I would like usually there's enough room you can have the carriage out here somewhere but you want to keep it well away from the chuck and the rotating work if you can do that drilling operations are one place that cutting fluid is particularly important so I'd like to put a few drops of cutting fluid on the tip of the drill bit and maybe on the surface of the work as well and that will help the chips to flow smoothly away from the cut especially with aluminum the chips have a tendency to weld themselves to the tip of the drill bit and cutting fluid will help quite a lot and I use a typically a brand called tap magic or tap magic aluminum if I'm working with aluminum but there are other good brands as well and some people use wd-40 work with aluminum and seem to get good results with that now I got this tap magic in quart bottles quite a few years ago a quart is quite a lot of this stuff you only use a few drops at a time and this is probably at least a 10 or 15 year supply even for me I guess but for the average home shop just the four ounce can is all you really need and that'll probably last you a year or two at least so but in any case this is the tap magic aluminum and I use that only for aluminum and this other variety here is just called tap magic cutting fluid I use this plain tap magic for just about any material and the fact they list on here a whole slew of materials that it's recommended for and I think even aluminum may appear on a even aluminum appears on here so you can use this with aluminum as well but I've always had good luck with the aluminum specific stuff so I stick with that I've got my tail stock lock down I've got my my drill bit up close here who will start up the lathe and start drilling our hole now that we're done with the center drill we'll remove that from the Chuck and now we'll get our I'm going to use a quarter inch diameter drill bit to drill our hole this is our quarter inch drill bit and it's about mid size in terms of length and diameter in the sets but you've probably all seen the common sets of twenty nine drill bits that range from a sixteenth of an inch up to a half inch in increments of a 64th and I usually so frequently have several sets of that type but these are what we call jobber length drills and they're the most common ones that you'd find you know Home Depot or Lowe's or any place other than a specialty machinist supplier but in the world of machinists there are other drill bit choices and you can buy sets like these that are called screw machine drills and it's the same typical set of 29 sizes but the difference is they're very short and stubby and these can be a great thing to have particularly if you have one of the shorter lathes if you don't need to drill a real deep hole you have these short stubby drills that tend to not flex as much but they also don't take up as much of the space between the tailstock and the headstock so they may enable you to get a job done where your ordinary job or drill would be too long to fit on your lathe the only thing about the short screw machine drills is they're typically going to be more expensive than you're not going to find the cheap sets like you'd get at Harbor Freight but you'd probably pay you know sixty to eighty dollars for a set of 29 of the screw machine drills but I just looked them up on Amazon and you can find some good sets on there and typical suppliers like Shara's or MSC would have them as well well let's suppose that our project plan calls for drilling this quarter inch diameter hole 3/4 of an inch deep so first I want to make sure that my scale on the tailstock Ram is set to the zero position so I'll just withdraw that until it's reading zero and then we want to bring the tip of the drill bit right up until it starts to touch the work now there's a little bit of an ambiguity you know where does the drill tip end or where do you measure the depth to the point or the place at which it starts to be full diameter I don't know the answer to that it really depends on the specs of the project you're working on so I typically bring it up so that it's the cone of the drill bit tip is just started down into the hole left by the center drill then I'll lock my tail stock in place I want to put some cutting fluid here on the drill bit itself and far enough up so that it's lubricated up to the length that I'm going to drill the hole which in this case will be three quarters of an inch now as far as the rotational speed to use that's something you'll have to judge by experience but the general rule is smaller diameter drill bits you want to use a faster speed larger diameter drill bits you want to use a slower speed and harder materials you want to use a slower speed so within those parameters you have to do some experimentation and I'm guessing that this is about seven maybe eight hundred rpm here maybe a little fast will try to drop it down to around six hundred to try that and I'm watching my calibrations on the RAM and after you get in a ways the chips are going to start to back up behind the drill bit and you need to back the drill out to let those chips clear so you can do that by turning the hand wheel and coming again and what's also probably happening typically happens is that the heat of drilling the friction causes the oil on the tip of the drill to get burned away or just evaporate or go away somewhere but anyway you need to add more oil from time to time if you're drilling a hole that's very deep at all now we're coming up on the three quarter inch mark all right so that's it so it's fairly typical to have to withdraw the drill bit once or twice or three times you know the deeper the hole the more you have to do that but every time you've gone in about two to three diameters it's good to draw the drill bit out to clear the chips otherwise the chips are going to jam up in here you'll start to overheat you may burn up your drill if it gets real bad but at the least there's a chance that you're gonna start to get a hole that is no longer the desired size because it's going to have all these chips built up on it so be sure to clear your chips out and while you have the drill bit withdrawn you can take a brush and clear it off but be careful because the drill bit often will be very hot from friction if you're not careful if you touch that you could get a bad burn so if we take a close look at our hole looks pretty clean clean entry hole and the part of it that I can see you know looks smooth looks like the drill did a good job cutting in there and not just grinding the material away but one thing that's always desirable to do and I pretty much always do it is to use some sort of a countersink on the drilled hole just to clean off any burrs that might be there and it also helps with if you have a shaft that's gonna go in there it will the taper will help the shaft to go in more easily well if you've been reading about many ladies for very long on the internet you've probably heard about Jose Rodriguez he was one of the early users of the mini laser early adopters way back before I got mine in 1999 he was one of the few people back then had a website about the mini leh and I learned this trick from him on one of his videos is this is just a countersink mounted in a file handle and you can use that to put a little chamfer on the end of your work so you just run the lathe very slowly and bring that countersink up in there put a little pressure on it and that will clean up any burrs that may be on your hole sometimes when you're drilling it it will feel like the drill bits not making progress and a reason that can happen is if you don't have the tailstock locked down securely it will actually slide backwards or ken's drift backwards as you apply force on the drill bit the tailstock will actually move away so if you are having trouble making progress you might want to check that and just make sure that the tailstock is in fact tight and not sliding or slipping now in this case of course we only went in about 3/4 of an inch but frequently you know you have need to drill a hole all the way through your work and basically the process is the same the important thing of course is you have to continually withdraw the drill bit and clear those chips out now if you're going in with a relatively deep hole like that which might be 10 or more times the diameter of the drill bit you can unlock your tailstock and just without using the hand wheel just pull the whole tailstock back to clear your chips and bring it back in until it makes contact and lock it down and that can save you a lot of time on a deep hole cranking the drill bit in and out just to clear the chips I did want to mention also that in the terminology of machining a deep hole is typically regarded as any hole that's deeper than about three Dyanne three times the diameter so this hole that we drilled is 3/4 we've got a 1/4 inch drill bit so we're getting on the verge of a deep hole if I went into a one-inch hole one inch deep that would be considered a quote unquote deep hole and of course that's when chip clearance becomes important and using lubricant becomes very important because friction is a much bigger factor well now that we've covered some of the fundamentals of drilling on the mini lathe I wanted to step back and talk about a few variations of different mini lays that are available on the market and if you've looked at them at all you're probably well aware that one of the key factors is the bed length and they're all seven inch swings so when you here for example of a 7 by 16 inch lathe which is what this is it means the largest diameter that you can rotate over the bed is 7 inches and the 16 inches refers approximately to the length of the bed that is from the headstock to the tailstock now the mini lay is actually are sold in four different lengths and the longest is the 7 by 16 which is approximately 16 inches from the headstock to the tailstock the next size is the 7 by 14 and I've made some 2-inch marks here along the bed to make this a little bit more evident and so if you have a 7 by 14 your bed would end here and then if you had a 7 by 12 your bed would end here so one of the things you can quickly see from this is if you have a relatively long drill bit in the tailstock chuck the amount of room that you have left to work is shorter depending on the bed obviously now the next size down from the 7 by 12 is called the 7 by 10 which would take us to here and our 1/2 inch drill bit now is too long to fit in that space but the lathe that is referred to as a 7 by 10 is sold by Harbor Freight and I've actually owned 2 of those over the years and if you measure it you'll find that it is actually only a 7 by 8 so the bed length on the 7 by so-called 7 by 10 actually ends here and you can see there's no way you're going to get that 1/2 inch drill bit in there so if you if you've already bought your lathe that's sort of a done deal but if you're still in the process of making a decision about which lathe to buy keep that in mind because it can have an effect on your ability to do certain jobs now the 7 by 10 or 7 by 8 is what it really is it's not a bad little lathe but it is quite short and so if you're planning to work on relatively large pieces of work longer than 2 or 3 or 4 inches then you want to you probably are going to be wanting a longer lays like a 7 by 12 or longer but if you're working on model ships or something and all of the work that you do that's very small the 7 by 10 may do that without any problems for you so but if you ever plan to use a long drill bit keep that in mind and as we saw earlier you can mitigate that a little bit by going to the so called screw machine drills which give you the same diameters but in a shorter length but there you can only drill you know whatever depth that will give you well now that we've covered that I wanted to mention a couple of other differences you'll find across the different mini lathes this one has what is called a lever locking tailstock so this lever back here he just clamped that down and it draws a plate up underneath the ways and clamps the tail stock in place these are found on a few varieties of lays but many of the lays don't have this adjustment they just have a nut and a bolt here in order to move the tail stock you have to take a wrench and loosen the nut slide it and then take your wrench and tighten the nut so that's fine it works great and you get used to it but this is a lot more convenient and certainly if you have the opportunity to get the lever locking that's a nice feature to have one other thing about the tailstock it's the way it's designed it's kind of top-heavy it's very top-heavy really it has a tendency to want to tip over that's annoying at first but eventually you learn to grasp it down low when you want to move it so if you hold it down here and slide it down near the base and keep a little downward pressure on it you can avoid most of that tendency for it to tip let's take a look at the Chuck and how its held in place now if you already have a mini lathe you no doubt know that to remove the Chuck you lock your tail stock down and then just turn the tail stock hand wheel in the direction that retracts the RAM and once the RAM is even with the front of the tail stock casting if you continue to turn it it will force the tooling whatever it is in this case the drill drill chuck will be forced out what happens is when this when the tailstock Ram retracts the arbor that holds the chuck is forced back against the tip of the lead screw and as that ram goes back in here the lead screw eventually forces the tapered arbor out in order to replace that you have to bring the tail stock Ram out beyond the zero mark here you want to make sure your tail stocks lock down so it doesn't move and what I like to do is just get the truck in position here loosely and with the jaws withdrawn all the way just take a whack with my palm of my hand and that force is enough to seat it firmly inside the RAM there's quite a lot of force imposed on this taper which is all that's holding the drill chuck in place so if it's if this taper isn't locked up tightly the torque on the drill bit can actually cause the taper to break loose not broken in any sense that it's ruined but just loses its grip let's say and then the chuck will start to rotate inside the spindle and you want to avoid that because that can actually cause you know some scouring or gouging of both surfaces if goes on too long and you get heating in there so in order to avoid that anytime you put the chuck in place you want to take a rag that's fairly clean you can take your hand if it it's not covered with chips but you want to make sure that there are no chips adhering or grit or anything no foreign matter adhering to this tapered area the same thing inside here you get little tools that will fit in here to clean it out but you can use your finger or put a little piece of rag on your finger and run it in there but the idea is you don't want any oil or grease or any foreign material chips or whatever getting in between those two paper surfaces it won't lock up properly another fact is that if you if you had a piece of a foreign particle of some sort in here it could actually cause this to be skewed a little bit so that your drill bit is no longer exactly in line with the headstock we've seen that the mini lathes will drill a 1/2 inch diameter hole and steel without too much trouble let's try this 5/8 inch diameter drill bit and see how it does break up the chips when you've completed the drilling operation or if you start to get a lot of chips built up or a lot of shards of metal you want to stop the lathe and clear those out of the way so they don't get dragged up in there and cause trouble and you definitely don't want to grab them with your fingers particularly with a harder metal like steel these shards can have extremely sharp edges on them razor sharp and will slice your finger in a minute if they get snagged on something so always use needle nose pliers to withdraw them well that wasn't too bad it's strained a little bit but it got the job done let's try now with a 3/4 inch diameter drill bit it's not liking that it jarred the Chuck loose quickly onlays and other machine tools drill chucks are held in place just by a taper and under normal circumstances the taper holds very tightly but it is possible as we just saw to create a situation where it can't hold under the forces involved but we did we were doing sort of an extreme cut for a small lathe like this this would be a convenient time to demonstrate how to seat the taper I like to just sharply wrap the end of the taper to Arbor on a tabletop and that will drive the other end of the arbor up into the Chuck and seat it that's all it takes and that should create a very tight bond now it's important of course that you don't have any dirt or oil or particles on either surface of the taper it won't lock up properly so I think we've pretty well demonstrated that the largest practical hole that I can drill with a drill bit at least in steel is five eighths of an inch so if we need a larger diameter hole than five eighths inch at least in Steel we'll have to resort to boring and that will be the topic of another video but I'll just give you a quick demo here so here's our little board work piece and we'll go into a lot more detail on that in subsequent boring video not that this one was boring well having now done some drilling demonstrations let's consider the various types of drills that you can get this is a fairly standard set this one is from Harbor Freight it's probably eight or ten years old so they may not sell this exact set anymore but in any case this is a fairly typical set of inch size drills running from one sixteenth of an inch up to one half inch diameter in increments of a 64th so these are very handy to have many of the projects you may come across or machines that you may work on may have metric parts in them and require metric size holes so you'll probably need some metric drills the sets of metric drills are not quite as easy to find as inch size drills you can find good sets of them but they're often quite expensive you know in the range of you know eighty two hundred dollars and up but this particular set I got from grizzly and it goes from one millimeter to six millimeters and it's in increments of a tenth of a millimeter so it's a pretty good little set I've been happy with it so far now one set of metric drills I did find at Harbor Freight that actually is very handy for small holes is this thirty piece mini drill set and it runs from 1/2 millimeter up to three millimeters so these are inexpensive and very useful for small holes now in addition to metric and inch size drills a very common set of drills used by machinists they are these so called number drills and these are standard size they range from number one is the largest which is I believe just a little under a quarter of an inch down to a number 60 which is a pretty small drill but these are great for filling in all the gaps between the in size drills and they're also specified frequently you know as the proper size drill for a you know tapping operation or whatever so it's very useful to get one of these sets now another type of set that's pretty handy this would be a good set to get starting out if you can find one and you like the price in the deal but what's good about this is you have a complete set of the standard inch size drills that from 1/16 up to a half inch by sixteenths then you have a set of number drills from 1 to 60 and then over here you have what are called the letter drills and these are useful because they fill in a lot of the gaps that you don't find in the in size drills but they run up to sizes that are larger than the number size drills some of these in fact are duplicates of standard in size drill I believe in an a size for example I think is the same as a quarter inch drill so you do get some duplication there of course we've already talked about the short so called screw machine drill bits and the benefits for them on the short mini lathes and blast these little tiny number drills these extend the range of our number drill set from 61 down to 80 so these range in size from a number 61 at the large end which is thirty nine thousandths down to number 80 at the small end which is 13 and a half thousands very tiny little drills but I found uses for them over the years another thing I find very useful is a chart like this and I don't know where I got this one but you can if you search on google for drill size charts and especially search under images you'll find the whole slew of different formats of charts but I like this particular format because it lists all the drills number drills inch drills metric drills letter drills in sequence strictly by size so it starts with the smallest that number 80 and goes on up the advantage of a chart like this if you know you need a hole of a particular size maybe you have an odd piece of machinery that you're trying to fit something to you can look on this chart and find the the nearest size to it let's say it's a let's say it's a five-point form a meter but you don't have a 5.4 millimeter drill well you could see that a number four drill is just a little bit smaller the number three drill is just a little bit larger so it gives you the ability to find the closest drill to the one you really need now as far as the quality of the drills it's safe to say that american-made drills are still generally superior to the inexpensive imports that you'll find but it's been my experience that the import drills from China in particular have gotten steadily better over the years now this set I got I don't know maybe ten or twelve years ago and I've labeled the box wobbly drills because I found that a number of the drill bits in here are not concentric when you put put them in the chuck you can visibly see that they're they're skewed and hence the name so I say these and the larger sized ones work fine it's the smaller ones that are not very good so you may have to search around to find some that are decent but in general the ones I've been getting from Harbor Freight in the last few years have been fine for a hobbyist type work but if you have unlimited funds you know where as your finances permit you may want to invest in some american-made drill bits as well which generally hold up better and are dimensionally accurate and just all around better quality for the most part we've looked at the large size holes that can be drilled on a mini mill and as a closing gesture I thought we'd look at something small so I've got a little piece of brass 1/8 inch diameter stock and I've turned it down a little bit and I have my number zero Center drill in place and I'm just going to put a tiny dot of a hole in the center there that's all we need to start the hole okay I've got a number 70 drill bit in place and you can see I've put a drop of cutting oil on there hanging off of there but because it's such a small diameter we'll use it Peck thrilling if you want to call it that Hey and they managed to do it without breaking the drill bit that's not too bad one thing that surprised me is that this truck that I got from LMS little machine shop comm was able to grip this tiny little drill bit so that's a number 70 drill bit and it's 23,000 syn diameter well there's our tiny little hole not too bad for cheaply huh wow that wasn't much of a challenge let's cut off this piece and go for something smaller well first we'll bring our center drill up here and make a little starter hole getting a little wobble there forgot to use cutting fluid that brass cuts pretty well without it just to give you a sense of the scale here this is a number sixty drill bit that's the smallest size in our set of number drills a drill bit that we're using came from this little set here and these are truly tiny little micro drills used I think primarily for drilling tiny holes in electronic circuit boards and maybe for other scientific and engineering purposes that the particular drill bit we're using here looks like it's 20,000th in diameter oK we've looked at drilling small holes drilling large holes and many other aspects of drilling on the mini lathe one thing we we didn't get time to do was get to drilling sprayer holes but we'll look at that another day after I get some more squared drill bits anyway I hope you enjoyed this video and thanks for tuning in so we'll see you next time

Channel: Frank Hoose

Views: 85,674

Keywords: lathe, mini lathe, mini-lathe.com, frank hoose, drilling, machining, tailstock

Id: QSKG3e3ndQU

Length: 35min 15sec (2115 seconds)

Published: Fri Jan 05 2018

Reddit Comments

[u/Tarehjerne]

I take it you are the real Frank

I really appreciate your videos, especially when I started with this. Have you seen anyone make a through coolant setup for their tailstock? I have tried, I DIY-ed some sealed ER collets to put in but it wasn't as straight forward as I had hoped since you basically need to drill through your entire tail stock assembly which I didn't want to risk.

You were under the knife right? did it all go well?

Stay safe and healthy