Thanks Winky, yes I'd already appreciated that although the point of a centre drill is ground to the usual angle of 118 degrees the cone angle is much less at 60 degrees to match that of a live or a dead centre. I guess I now need to grind a short stubby jobbers drill up to 120 degrees and try it out myself.
There are so many things that a closer look and a little thought will solve, yet it takes a video like yours to wake me up to the bleeding obvious!!! Cheers and thanks again Winky.
Thanks for another great and thoughtful video! That's what I love about your channel. You put a lot of thought into your work and your videos. Then, when I watch, I get to think too. I always learn something. I think it was Stefan Gotteswinter who pointed out that the only part of the center drill that's at the correct angle for spotting is the very tip. Just be sure to use a big enough center drill so the tip is bigger than the web at the tip of the drill you plan to use next. For those asking how many spotting drills you need, look again at the diagram in this video. The spotting drill (or center drill tip) makes a tapered hole larger than the tip of the next drill. It doesn't need to match a specific size, so you don't need a whole set. If you really want to plan ahead, you can use the spotting operation to create a chamfer or countersink, then drill the hole.
I learned something from this video . I have always used a centre drill. Really enjoy your program and appreciate your very tidy and well kept shop. Aaron from Canada
At last an American TH-camr discovered spot drills! Lol Good show Winky, this will help reduce my shouting at the screen, & will help many people achieve better results.
I still like the center drill for visibility in the drill press but find that it's more accurate if I drill shallow. However, I'll never go back to a center drill in the lathe. I'm guessing the visibility aspect is why center drills are more popular.
@@WinkysWorkshop There ought to be a combo. A drill like a centre drill but ground with the 118° angle. The tip of the drill would go in bang on centre and then the sides of the tit on the end would keep the drill centred while the main cutting faces get to work.
@@WinkysWorkshop I have seen recently on YT 'boring' drills that have a lump on the tip to go down a pilot hole before the drilling portion starts to cut - I suspect they were 'counterbore' drills / end mills as they had flat cutting ends - I THINK.
@@WinkysWorkshop Get your bigger drill & drill the tip of it a diameter to match the length of the chisel point and then fix into it a half inch length of smaller twist drill. I don't know why they just scale up twist drills rather than keeping the chisel point as small as possible.
If you use a large center drill and only the 118 degree tip of it, it will function the same as a spotting drill. Learned that from Stefan Gotteswinter
I was looking for this comment, this is something an old school machinist told me. I keep a 118 degree CD in my box and thats all i really use because its short and does the same thing
When I was younger I watched an older machinist do center drilling. He would use a center drill the same diameter as he was going to drill and center drill deep enough to reach the OD of the center drill. When he switched to the regular bit the OD of the hole centered and held the bit true as it started drilling. I am only a hobbyist shavings maker, but I still use his technique I learned from many years ago.
You might try the spotting drill... get a 1/4" and use it for every size drill. It works great and doesn't cost much at all. There is a link in the description. $8 buck I think.
Winky, you always have excellent videos and awesome information. I have noticed that nearly every time I see someone drilling a hole in the end of something, it always wobbles! Now I know why. I will have to get me some of them spotting drills. I guess they are available on most tool supply sites. Thank you Sir!!!
Well explained Winky, the only time centre drills figured in my apprenticeship was for either prepping to turn between centres or for a live centre. Doesn't stop me using them incorrectly most of the time lol. Centre drills are actually fine if used correctly, ie do not go deep enough to get onto the 60 deg cone, this way you have an on centre pilot hole to follow which should be about 1/3 the diameter of the drill. Try it. Cheers, Jon
Yes you are right and I probably should have brought that up in the video. Thanks. I like center drills for hitting a mark. On the lathe for drilling no.
Thanks Mark I always like your ideas. I have been using both lately, One of the things i did a few weeks ago is to take one of my broken center drills and re grind the tip using my Drill doctor and made a spot drill out of it. When the weather warms up a little more I will get back in the shop and just play around with both. I did order a couple of the Bangood Cobalt spotting drills but they are 3/8" diameter so i have not used them much yet.
Mine is 1/4" and carbide. I suspect is will last for ever unless I drop it. I still like the center drill for visibility in the drill press but find that it's more accurate if I drill shallow. However, I'll never go back to a center drill in the lathe. I'm guessing the visibility aspect is why center drills are more popular.
The center drill is still important. like the center drill in the drill press if I need to hit a mark. The visibility is better. I have learned that if you only go as deep as the tip of the center drill it works better.
Drilling holes invokes passion in men. Their are thousands of opinions of best practices. But i am game to try most any of them that helps me get a better hole. Spotting drill will get ordered promptly for home and work thank you Mark on target as always.
@@WinkysWorkshop Spotting drills last a long time because they are not used anywhere near as much as a centre drill or standard jobber drills. A shallow lead for the later drill is not a lot of work for the spotting drill. A centre drill is used far deeper unless you try to just use it on the end. So even if one seems expensive then over time it is not.
Thanks Winky, I had to learn this the hard way when I should have researched "Center" Vs "Spotting" Drill first. That's how I found this video. Now I know why I've consistently been disappointed in my Center Drill results! After seeing your video I'm convinced more than ever that besides the points you made, ..the Center Drill has no place in Drill Press operations. I've been using them for that following center punch operations. EEEK! 🥵 Wakodahatchee Chris
Your welcome. There is one thing I failed to mention in this video. The very tip of a center drill is the same as a spotting drill. I occasionally use a center drill for small holes. Its easier to see the mark. If you get a spotting drill I would suggest getting an 1/8" carbide. It's very ridged and will last forever plus its easier to see you center punch mark.
If the drill starts wobbling, I have always used the back end of a tool holder, or if in a hurry or feeling slack, the mounted tool, to apply a slight pressure to the side of the drill near the point to take out the wobble. Slowly feed the drill while also slowly removing the side pressure and you will find it will find the center perfectly.
You bet, the only think I don't like about the spotting drill is that is is harder to see a mark. I'll probably use the center drill in the drill press
You know I need to go out to the shop tomorrow and look more closely at centering drills. What about using a Large centering drill bit in the tailstock. Those large ones would be quite rigid. But then only use the very tip of the centering bit to make the small mark, divot, or whatever you call it. Then don't go beyond that very starter point with the center drill. This may just work because they seem to have the 118 degree grind on them. Will check tomorrow on a large one. Thank you for pointing out this issue.
I could be wrong but I'm not certain I agree with this video: My philosophy is that a correctly sized center drill should be used in a lathe and a spotting drill is for the milling machine. Here is my reasoning: if you watch the center drill when it first contacts the rotating work piece (in a lathe) you will see that rather than allowing the center of the cut to be defined by the XY location of the lathe chuck (lathe chuck XY location often has small concentrically errors.. especially on older lathes), instead the center drill "finds" the center of rotation. Do a center drill operation with the tail stock loose and you will see the center drill "snap" to the center of rotation. I don't know how it does this, but I suspect center drills were designed to "find" the center of rotation and, in this way, take up small errors and not allow the error-prone tail stock to dictate the exact center of rotation. OK so a good spot drill will be made from very rigid solid solid-carbide and is intended instead to make a spot that stays on the center of a rotating tool rather than the on the center of a rotating work-piece. TOM
Interesting theory although so far I have not noticed this. It is a little more like a regular drill in that it has a web between the flutes but it is very thin. What I like about this spotting drill is that you can jump to a much larger size drill. At least with a small center drill you have to drill the first hole with a small drill. I used the spotting drill today and went right to a 5/16" and it worked perfectly... saved a lot of time too.
Hello Winky, I'd like to add a few other reasons, it could be the tail stock is misaligned due to cutting tappers or maybe there is some foreign material between the tail stock and the ways, also it could be wear, maybe the end of the round bar has a pip due to incorrect center height, as an exercise try drilling a piece of round stock and watch carefully what happens when the drill makes contact with the round bar, if you see the drill kick to one side and then the drill starts to wobble, then do some tests about the tail stock alignment or foreign material between the ways and the tailstock guides. Hope you don't mind me throwing in my two nickels worth. :)) Thanks for your suggestions very helpful indeed! Cheers ...
I have a few of them but they are all 118* I ordered one and will try it out. When I make my tool paths I’ll have to figure out how deep to make the spot.
It's kind of easy to go too deep but once you get used to it, its not a problem. The 118 will work fine as long as it's not a stubby drill. The spotting drills have a very narrow web between the flutes.
Your reasoning makes good sense to me, my drills often wobble as they initially enter a deep, centre drilled hole. As a self taught hobby machinist I've always used centre drills to start holes on the lathe, never heard of 'spotting drills before seeing your video. So, I've just searched online for 'spotting drills' (here in NZ) - BUT, they all have a 90 degree point, not 120 degrees. So, now I'm confused!! Can anyone help? After seeing pictures of spotting drills online, I realised that I already have one (with a 90 degree tip)! I've been using it by hand to deburr small holes. I'm off to the workshop to try it out.... Regards Paul in NZ
That's strange you can't get it in 180. Something I learned about the center drill is that the very tip is 120 degrees. If you use a larger one and drill shallow it will work the same as a spotting drill.
Good point but did you know that center drills commonly have a 120° angle on the small tip? If you just poke in with the very tip you get the same effect. (As long as the very first mark is truly on center)
Good tip! - I realized this a short time ago and it works. The only negative is a very small spot to hit and you need to use a small drill first. I just drilled several holes with a spotting drill in the drill press and went straight to a 5/16 and it worked great. It saved a lot of time too.
Both very valid points. If you use just the tip it works but limits the hole size. I find using them this way for small stuff and dedicated spot drills for larger is a good combo.
I agree with this absolutly. Once you start using spotting drills the only time you will pick up a center drill again is to make a hole for a lathe center.
That was interesting thank you. Speaking as a retired engineer with 50 years service in high quality Machine Tool manufacture, I'd never heard of a spotting drill before and I must have drilled many thousands of holes without any problems after using a centre drill first. The theory of how your spotting drill works sounds ok, but I'm assuming that an accurately positioned hole is the object of the exercise? My question is how do you stop the spotting drill from wandering from it's position when starting to drill? Surely a short and stiff Centre Drill is much less likely too?
A good spotting drill is split point so its basically the same as a center drill. I use carbide so it is super ridged. Something I failed to mention is that the very tip of the center drill is the correct angle, its the larger part of the center drill that is not. In the past I've had problems with drill staying on center following a center drill but I was also drilling deep.
The way it was explained to me was to use all three types of drills. A center drill is ground to cut right from the tip, and is used on a lathe like a center punch would be in a drill press, to mark a spot for the spotting drill to start. The spotting drill is then used to make a deep enough spot that the non-cutting center tip portion of the dimensional drill has some relief from the surface and the ground cutting edges then remove the material. Of course, the center drill is used alone to make a specially sized hole for the lathe turning center, a different operation.
I guess a conclusion would be that center drills are only for drilling holes using centers on the lathe? I know a purpose spotting drill has few flutes making it much stiffer than a normal bit but it brings up the topic of how successful would you be grinding your own 120 degree end on regular drill bits for use as spotting drills? Of all the thousands of drill bits of all kinds that I have collected over the past six decades I only have a handful if that of spotting drills and hesitate somewhat (as much as a guy can when buying tools!) in acquiring a full range set of spotting drills if I can make my own. I recognize the problem though and have often watched the drill take off out of round from a center hole shallow or deep. It is a forlorn hope that it will straighten itself as you step up to larger bits I can tell you. Good video. Happy New Year.
Excellent demonstration. I have been using spotting drills for ages but, here in the UK, they are not so easy to find as centre drills. Also, often, I will just use a centre drill because it is handy ... I'm a bit lazy I suppose, must try harder 😉.
I agree... it should have been deeper in the chuck. Also I have seen better spotting drills. There is no need for much in the say of flutes and this drill has long flutes.
Perfect. Just the kind of tip I was looking for. Now that I bought a few sets of center drills... But let me ask you this. What if I am not using them on a lathe but with a drill gun or drill press? What if I need a 3/16" hole? Could I use the center drill that has the biggest diameter of 3/16" and drill a 3/16" hole? So the center drill would start with the smaller tip on a center punch dimple, and just follow with the 3/16" diameter part of the drill.
One thing i failed to point out was that a center drill has the correct angle at the very tip. You can use it as a spotting drill but ideally the drill needs to be no more than the diameter of the tip of the center drill. I still use the center drill occasionally because it has better visibility. That is, if you are trying to hit a mark made by a center punch you can see the tip of the center drill. The biggest issues arise when you use the upper part is a center drill to guide a drill.
The cutting angle difference is clear to see. But how about a short cutting drill from a holesaw, if you choice in up in the drill chuck as far as it will go that works very well.
Spot drills are designed to only go as deep as the tip or cutting edge. The web between the flutes is very thin and there is no side relief. If you go very deep the bit will bind and brake.
I think the reason a lot of people used a center drill is they see the TH-cam makers use center drills and think they are supposed to also. I always start with a smaller drill bit and work my way up.
There is one flaw in the depiction. A drill doesn't come to a point, it comes up to the chisel edge which is flat. Not saying that the use of the spotting drill doesn't get the job done though. I think center drills work fine if the hole is not much larger than the chisel point of the drill used (outside hole, of the inner one). That way there is very little side to side force due to imperfectly ground cutting edges. If you go bigger one drill cutting edge will always contact first causing uneven forces. Also even if you use a larger center drill, the second smaller diameter hole guides the chisel toward the center due to unbalanced forces and taking less force to follow the existing hole. So it may not be centered perfect right as it touches, but with good pressure should center up. It would be interesting to do some tests though. I suspect that starting the hole too gently will allow it to be out of center. I have been able to hold less than .005in position with center drills for all of my machining career, so never found it to be a big problem, but is worth switching as the argument is logical.
This is true, I should have shown that flat on the tip of the drill. The spotting drill has a very small web between the flutes so it is minimized. This makes the center drill very slightly better but the difference is very slight. Some spotting drills have a split point which is an extra grind on the flute and makes it just as good as the center drill but with a larger spot to hit. To drill accurately with a center drill you really need to use it like the spot drill, very shallow but, this also necessitates following with a smaller drill. Stepping up the center drill diameter is an option but it requires a lot more pressure than the spotting drill.
I've seen the stubby drills but never owned one. If you buy a spotting drill that what it will be called. The spotting drill is different from a standard drill at the tip the web at the point is very small.
Potentially just 1 spotting drill could be enough. You choose how far to spot drill into the surface. Even a large spotting drill can be gently used to make a dimple small enough for a narrow follow-up drill. So find your largest diameter drill, measure the web and buy a spotting drill say 1.5 times the web thickness. If you have holes to drill that are very close to surface features that protrude away from the surface to be drilled, then you might need a second narrower spotting drill.
I have a 1/4" and 3/16". The 1/4 will do anything I need but its easier to hit a mark in the drill press with a smaller drill. In fact I sometimes use the tip of a center drill in the drill press. If you don't go deep and use a small drill to follow it does well.
I haven’t really used spotting drills, but a center punch, before drilling, and I have to admit I had to look up its tip angle - surprisingly it is between 60° and 90°. From the photos of transfer punches the same appears to be true. So, it is interesting to see the difference it makes on a lathe, which is not usually observed on a drill press. Maybe it cones down to rigidity and stick out differences between these machines... but I haven’t heard chatter on drill press yet the punched center does prevent the drill from wandering. Could you please make a comparison video of this using the same bits is your advanced drill-press?
You can buy centre punches with a 120° angles for drilling. They are best used by using a small angled punch to position the centre (you can see better what you are doing) then open it out with the large angled punch.
The spotting drill are different. Aside from being shot they has a very thin web between the flute at the time. They also have no relief on the sides. If you drill deep they will bind and break. They are design to go no deeper than the cutting edges.
There are quite a few things that are shown by the "experts" that are just plain wrong. They were taught to use them by some other old "expert" and so it must be the correct way to do it. I have never seen a center drill used on a cnc mill or lathe. For obvious reasons. It is the wrong tool. Spotting drills are great! The smaller sizes of center drills break very easily on a lathe because, wait for it. . . . a drill wants to do anything but cut on center point. So that fragile little nub sticking out snaps right off. Great video Winky, you may have started a revolution, LOL.
What I've wondered since I don't have any spoting drills is couldn't you make a spoting drill by just cutting down a regular drill just past the shank then just put a 120 degree grind on the tip it'll be a Lil shorter but not really any shorter for the size then a center drill ???
I'm sure you could make a spot drill although they are fairly cheap. I recommend a solid carbide maybe 3/16". Spot drill usually have a very small web in the middle so they won't walk around. You can also use the very tip of a center drill the same as a spotting drill although its a bit small. One other thing, on a standard drill the web gets much larger toward the shank so they are not ideal. Really not so good as a regular drill.
@@WinkysWorkshop yeah I found some 5 piece sets at pretty reasonable prices HSS/ 8 percent cobalt last time I had looked around everything I found was super expensive for what they are I get carbides expensive but I was seeing 5 piece hss/cobalt for like 450 a set thanks for the video and explanation 👍👍👍
@@Rolingmetal I agree with that although I think the stock market is even worse. I never shop at walmart for the same reason. Amazon has a great business model but like the market its about who does the most with the least.
I have always had a bit of bad holes using standard twist drills. If you examine a hole from a twist drill it sometimes looks like a cutaway of a rotary engine. I am not sure why the triangle shape but it happens. Especially in thin material.
@@t.d.mich.7064 have not tried a brad point in thin sheetmetal but will give it a shot. I use step bits the most in sheetmetal except for when i need the twist drill for taping holes.
Yes it does. It averages out in deeper holes where the sides of the hole can guide the bit. You see the same pattern with the spotting drill but it seen to work better anyway. Most drilled holes will also be slightly over size.
Yeah, but like everything, there's the right way to do something, and the lazy way. I've already got a frequently used centre drill in my one spare tailstock chuck, and it's just sitting there on my lathe table, so I'm going to just grab that rather than digging out a spotting drill and swapping it out. :) It's like using a flat bladed screwdriver to open paint tins. We all know it's not the right way to do it, but it's convenient, so we don't think about it.
@@BatByke I usually need a centre for support way before I start thinking about drilling/boring out the middle of something, so by the time a spot drill would be the right tool to use it's already too late to use it. On those rare occasions when I didn't need a centre in the work first, the centre drills already right there in my smaller chuck. It still works about 80% as well as a spot drill....... and I'm lazy. :D
A couple things that are either incorrect, misunderstood, or misrepresented. 1. You're first attempt, with the center drill, was too deep. (more later) 2. Your drawing is correct, but you apply it incorrectly. The depiction on the left should be used for HSS and Cobalt, while the right would be for Carbide. This is referring to the spotting angle (greater for carbide and less for HSS/Cobalt). 3. Your spotting diameter should be ~30% < final drill diameter. This is why I say your first attempt was doomed to fail, regardless of any other particular point. Other than these points, I think it was a decent video and it seems others have learned a thing or two. ;)
I might not understand correctly. The first example was doomed to fail because second angle on the spotting drill is meant for a lathe center not for spotting. Did you mean that the TIP diameter of the center drill needed to be 30%? If so, I would agree with that. Also why would the spotting drill angles be different for HSS vs carbide? The angle of the spotting drill needs to be the same of slightly greater than the bit that follows. Your 30% diameter rule sounds about right but the angles compared to the drill that follows is critical. This is a good website: www.harveyperformance.com/in-the-loupe/choosing-spot-drill/#:~:text=Ideally%2C%20the%20center%20of%20a,to%20140%C2%B0%20and%20larger.
If this is true...that having the lip of the drill contact first instead of the center web is bad and can make it wobble or hurt the edge or whatever...how do people explain pilot holes and stepping up in sizes? Either one is fine. Center drills have been working to start holes for a over a hundred years or whatever. And no they are not strictly for lathe centers only. The actual name of them is a combination center drill and countersink. The countersink part is the part meant for lathe centers. The center drill part is the little tip with a regular drill angle. If you need a hole to be really accurate, you need to bore it either way.
You are right about the tip of the center drill. I need to redo this video and include this. If you go to deep and use the upper portion of the center drill the bit tends to wander. As for the edge of the bit hitting first when stepping up in drill sizes. It will wander! The difference is, the existing hold aligns the bit. The hole will almost be larger at the entrance of the hold until the bit settles into the existing pilot hole. You could say the same about a hole drilled with a center drill too deep but there is a brief period time when the bit is only touching the outer edges and has no centering force. www.harveyperformance.com/in-the-loupe/choosing-spot-drill/
You just turned on my light. I have center drills. I have your standard and those made specifically for live/dead centers. I also have spotting drills. For some reason I never use them. I will now!!
You sound just like me. I thing outwardly the center drill seems like it would be better but after looking at the science you start to see why the spotting drill is better.
The center drill is for drilling stock to run on a center in the lathe. Technically it can be used as a spotting drill if you only dill with the very tip. If you go too deep where the upper part of the center drill is cutting a countersink the angle is wrong and there's a change the cutting edges will pull the bit of center.
Ha... that up to you. I like the center drill in the drill press if I need to hit a mark. The visibility is better. I have learned that if you only go as deep as the tip of the center drill it works better.
Why don't you just drill with the drill part of the combination drill countersink to a shallow depth , it is ground to 118 degrees like your drill bit is. It should follow like the spotting bit at 120 degrees.
Good point and I should have mentioned that. The only negative is a very small start unless you use a larger center drill. Something else I have notice is that the tip of a center drill is sharpened weird. No spiral. It's kind of like a lathe tool without back rake (or very little). The spotting drill is much sharper and requires almost no pressure. It seems like the larger center drills require a lot of pressure. It might not matter but I'd much rather use the spotting drill.
Now just tell me how you really pick a spotting drill since it seems there are a lot of variation. Even if you pick 120 degree do you need a whole set in imperial and decimal sizes and do you match the size to the drill size you want in the end. Always used center drill I guess the wrong way. www.travers.com/spotting-drills/c/297807/#
Great question and I should have covered this better. One drill works for everything. I use 1/4" although 3/16" might be better if you are trying to hit a mark. The smaller drill doesn't obstruct the mark as much. I have a 3/16 and 1/4 but use the 1/4" more because it carbide and sharp. The maximum depth is the drill diameter. In other words the pilot hole can't have straight sides. Don't go too deep.
Doesn't the small point on a centre drill have a 60 degree angle too ? If so, then every 118 degree drill is going to make contact with the sharp edge of the hole created by the centre drill, no matter how small a hole you dug.
@@mikeparfitt8897 yeah I kinda thought of that after the fact too.. but in my limited experience once the center drill self centers by that tendency to want to ride towards the middle the regular drill at least has a starting point that tends to follow.. seriously I never knew there was a thing called a spotting drill.
I've been frustrated with center drills in the lathe. They are usable but it seems like every time you need a concentric hole you see the drill wobbling as it goes in. Starting with a very small bit help. I still use the center drill in the drill press because of better visibly its easier to hit a mark.
It was slight. Nevertheless using a center drill like I did it prone to problems. I did fail to mention that the very tip of a center drill can be used as a spotting drill. It's sharpened to 120 degrees and works well when followed by a 118 degree. The only problem is that unless you use a fairly large center drill it makes a very small starting hole.
"a center drill is actually for a lathe center" "a spotting drill is when you want to locate a hole accurately and follow up with a larger drill" Do I get an A?
Almost never use spot drills. Especially on CNC equipment. Use the right tools and you won't need to spot drill. Split point drills negate the need for spotting or center drilling. YMMV.
Yes a good option. I don't know a lot about them but you need one for each size right? Spotting drill may not be the best option but better than a center drill.
@@WinkysWorkshop Buy split point drills as you need them. You won't regret having them. A good source for reasonably priced GOOD drills is McMaster Carr.
@@WinkysWorkshop it is easy to split them yourself with a bit of careful grinding, or you can get a jig to do it. I would get a diamond wheel though, as you really need a sharp wheel edge to do it well.
Happy Belated New Year Mark & Family. You explained this very well - it's kind of common sense isn't it. I have a box of old drills that have many uses. They're good for practice grinding with, so I've ground my own spot drills. Only need a couple of sizes but I'd like to get better a tempering them. Stay safe and well :)
Thanks Anthony! Obviously the short drill bit is stiff and will stay put a little better but a spotting drill is made much differently. Spot drills are designed to only go as deep as the tip or cutting edge. The web between the flutes is very thin and there is no side relief. If you go very deep the bit will bind and brake. Regular drill have a wider web and the web gets even wider as it progresses. If you re-sharpen a broken drill you will probably see it.
@@WinkysWorkshop That's what I've been playing around with when grinding the old bits. For me, seeing & doing something is how I learn more than just reading about it. I haven't tried on a blank yet though. ATB :)
Great demonstration of a very interesting concept. Never heard of a spotting drill before this. I guess I'll have to pick some up.
You really only need one. 3/16' or 1/4" .. So far I love these drills.
Thanks Winky, yes I'd already appreciated that although the point of a centre drill is ground to the usual angle of 118 degrees the cone angle is much less at 60 degrees to match that of a live or a dead centre. I guess I now need to grind a short stubby jobbers drill up to 120 degrees and try it out myself.
There are so many things that a closer look and a little thought will solve, yet it takes a video like yours to wake me up to the bleeding obvious!!! Cheers and thanks again Winky.
I agree with you (no point in repeating your comments). I looked at the video and wondered why I had not seen the obvious....
Well... haha.. I read an article on the internet so don't feel too bad.
Gday Mark, well you have convinced me there, I best order a couple of spot drills, thanks for taking the time to explain this, cheers Matty
Absolutely, thanks for watching
Not just saying not to, but explaining it! Nicely done!
@@dans_Learning_Curve - Thanks and yes, I agree. It's much better to support what you say.
Thanks for another great and thoughtful video! That's what I love about your channel. You put a lot of thought into your work and your videos. Then, when I watch, I get to think too. I always learn something. I think it was Stefan Gotteswinter who pointed out that the only part of the center drill that's at the correct angle for spotting is the very tip. Just be sure to use a big enough center drill so the tip is bigger than the web at the tip of the drill you plan to use next. For those asking how many spotting drills you need, look again at the diagram in this video. The spotting drill (or center drill tip) makes a tapered hole larger than the tip of the next drill. It doesn't need to match a specific size, so you don't need a whole set. If you really want to plan ahead, you can use the spotting operation to create a chamfer or countersink, then drill the hole.
Excellent points. And a 3/16" or 1/4" will do everything you want.
Thanks!
I learned something from this video . I have always used a centre drill. Really enjoy your program and appreciate your very tidy and well kept shop. Aaron from Canada
Great to hear!
I worked in a machine shop for 40 years and I never knew this little trick. Thanks
No problem!
At last an American TH-camr discovered spot drills! Lol Good show Winky, this will help reduce my shouting at the screen, & will help many people achieve better results.
Funny! Thanks!
@@WinkysWorkshop sorry Winky, you can tell I'm English
@@davemason6273 English is good
Makes sense to me winky, definitely gonna try a spotting bit. Great info.
Glad it was helpful!
Thanks Mark, you convinced me
Today was the last time I used a center drill as a "starter".
All the best for 2021 from The Netherlands!
Ron
I still like the center drill for visibility in the drill press but find that it's more accurate if I drill shallow. However, I'll never go back to a center drill in the lathe. I'm guessing the visibility aspect is why center drills are more popular.
@@WinkysWorkshop There ought to be a combo. A drill like a centre drill but ground with the 118° angle. The tip of the drill would go in bang on centre and then the sides of the tit on the end would keep the drill centred while the main cutting faces get to work.
@@millomweb - I love this idea!
@@WinkysWorkshop I have seen recently on YT 'boring' drills that have a lump on the tip to go down a pilot hole before the drilling portion starts to cut - I suspect they were 'counterbore' drills / end mills as they had flat cutting ends - I THINK.
@@WinkysWorkshop Get your bigger drill & drill the tip of it a diameter to match the length of the chisel point and then fix into it a half inch length of smaller twist drill.
I don't know why they just scale up twist drills rather than keeping the chisel point as small as possible.
Thanks Mark, as pure coincidence I noticed the wandering drill bit this weekend and thought "something is not right"... So thanks for this!
Glad to help
If you use a large center drill and only the 118 degree tip of it, it will function the same as a spotting drill. Learned that from Stefan Gotteswinter
I agree.
I was looking for this comment, this is something an old school machinist told me. I keep a 118 degree CD in my box and thats all i really use because its short and does the same thing
When I was younger I watched an older machinist do center drilling. He would use a center drill the same diameter as he was going to drill and center drill deep enough to reach the OD of the center drill. When he switched to the regular bit the OD of the hole centered and held the bit true as it started drilling. I am only a hobbyist shavings maker, but I still use his technique I learned from many years ago.
You might try the spotting drill... get a 1/4" and use it for every size drill. It works great and doesn't cost much at all. There is a link in the description. $8 buck I think.
Winky, you always have excellent videos and awesome information. I have noticed that nearly every time I see someone drilling a hole in the end of something, it always wobbles! Now I know why. I will have to get me some of them spotting drills. I guess they are available on most tool supply sites. Thank you Sir!!!
Amazon has them very cheap! amzn.to/3bl5tO6
I'm new to mill/lathe work. Trying to absorb the best knowledge. Think this might be something I store for later. Thanks for the post.
Glad to help
Hi Winky. Wonderfully clear demonstration. Even I understood it! Thanks. BobUK.
Glad it was helpful!
Well explained Winky, the only time centre drills figured in my apprenticeship was for either prepping to turn between centres or for a live centre. Doesn't stop me using them incorrectly most of the time lol. Centre drills are actually fine if used correctly, ie do not go deep enough to get onto the 60 deg cone, this way you have an on centre pilot hole to follow which should be about 1/3 the diameter of the drill. Try it. Cheers, Jon
Yes you are right and I probably should have brought that up in the video. Thanks. I like center drills for hitting a mark. On the lathe for drilling no.
Can't argue with that demonstration!
It seems to work well
Thanks Mark I always like your ideas. I have been using both lately, One of the things i did a few weeks ago is to take one of my broken center drills and re grind the tip using my Drill doctor and made a spot drill out of it. When the weather warms up a little more I will get back in the shop and just play around with both. I did order a couple of the Bangood Cobalt spotting drills but they are 3/8" diameter so i have not used them much yet.
Mine is 1/4" and carbide. I suspect is will last for ever unless I drop it. I still like the center drill for visibility in the drill press but find that it's more accurate if I drill shallow. However, I'll never go back to a center drill in the lathe. I'm guessing the visibility aspect is why center drills are more popular.
The Drill Doctor is a great tool for the home shop. There is a bit of a learning curve but with a little practice you can't beat them for the price.
Now I always thought you used a center drill to spot because of its rigidity.
I'm 62 and still learning! Thanks
That's great! Me too, I'm 65
Great video. Explaining why one is better than the other is key to learning something new. Thanks.
The center drill is still important. like the center drill in the drill press if I need to hit a mark. The visibility is better. I have learned that if you only go as deep as the tip of the center drill it works better.
Drilling holes invokes passion in men. Their are thousands of opinions of best practices. But i am game to try most any of them that helps me get a better hole.
Spotting drill will get ordered promptly for home and work thank you Mark on target as always.
I don't thick it fits every situation but it des way better in the lathe
I put a link in the description. They are cheap
I checked out the link and am going to get a few.
THANK YOU!
@@countrycraftsman5110 - Cool Amazon has a bunch of them, get one that is short.
@@WinkysWorkshop Spotting drills last a long time because they are not used anywhere near as much as a centre drill or standard jobber drills. A shallow lead for the later drill is not a lot of work for the spotting drill. A centre drill is used far deeper unless you try to just use it on the end. So even if one seems expensive then over time it is not.
Thanks for the explanation. Have a great day!!
You're welcome!
This sure makes a lot of sense to me. Actually I had never thought much about it but now I will! Thank you
The only drawback is visibility in a drill press. Like trying to hit a mark
The necessary information and useful video. Thank you.
Glad it was helpful!
Thanks Winky, I had to learn this the hard way when I should have researched "Center" Vs "Spotting" Drill first. That's how I found this video. Now I know why I've consistently been disappointed in my Center Drill results! After seeing your video I'm convinced more than ever that besides the points you made, ..the Center Drill has no place in Drill Press operations. I've been using them for that following center punch operations. EEEK! 🥵
Wakodahatchee Chris
Your welcome. There is one thing I failed to mention in this video. The very tip of a center drill is the same as a spotting drill. I occasionally use a center drill for small holes. Its easier to see the mark. If you get a spotting drill I would suggest getting an 1/8" carbide. It's very ridged and will last forever plus its easier to see you center punch mark.
If the drill starts wobbling, I have always used the back end of a tool holder, or if in a hurry or feeling slack, the mounted tool, to apply a slight pressure to the side of the drill near the point to take out the wobble. Slowly feed the drill while also slowly removing the side pressure and you will find it will find the center perfectly.
I have done the same but never need to do this with the spotting dill, it hits center every time.
I believe you have got a good tip the Winky, thanks.
You bet, the only think I don't like about the spotting drill is that is is harder to see a mark. I'll probably use the center drill in the drill press
Good to know why was always told in college that a center drill is for centers and spotting drill for drilling
Hmmm not sure
You know I need to go out to the shop tomorrow and look more closely at centering drills. What about using a Large centering drill bit in the tailstock. Those large ones would be quite rigid. But then only use the very tip of the centering bit to make the small mark, divot, or whatever you call it. Then don't go beyond that very starter point with the center drill. This may just work because they seem to have the 118 degree grind on them. Will check tomorrow on a large one. Thank you for pointing out this issue.
I like the idea and I think you are right, the tip is more blunt.
Makes a lot of sense. Thanks Winko
You're welcome Mattewo
I could be wrong but I'm not certain I agree with this video:
My philosophy is that a correctly sized center drill should be used in a lathe and a spotting drill is for the milling machine.
Here is my reasoning: if you watch the center drill when it first contacts the rotating work piece (in a lathe) you will see that rather than allowing the center of the cut to be defined by the XY location of the lathe chuck (lathe chuck XY location often has small concentrically errors.. especially on older lathes), instead the center drill "finds" the center of rotation. Do a center drill operation with the tail stock loose and you will see the center drill "snap" to the center of rotation. I don't know how it does this, but I suspect center drills were designed to "find" the center of rotation and, in this way, take up small errors and not allow the error-prone tail stock to dictate the exact center of rotation.
OK so a good spot drill will be made from very rigid solid solid-carbide and is intended instead to make a spot that stays on the center of a rotating tool rather than the on the center of a rotating work-piece. TOM
Interesting theory although so far I have not noticed this. It is a little more like a regular drill in that it has a web between the flutes but it is very thin. What I like about this spotting drill is that you can jump to a much larger size drill. At least with a small center drill you have to drill the first hole with a small drill. I used the spotting drill today and went right to a 5/16" and it worked perfectly... saved a lot of time too.
Hello Winky, I'd like to add a few other reasons, it could be the tail stock is misaligned due to cutting tappers or maybe there is some foreign material between the tail stock and the ways, also it could be wear, maybe the end of the round bar has a pip due to incorrect center height, as an exercise try drilling a piece of round stock and watch carefully what happens when the drill makes contact with the round bar, if you see the drill kick to one side and then the drill starts to wobble, then do some tests about the tail stock alignment or foreign material between the ways and the tailstock guides. Hope you don't mind me throwing in my two nickels worth. :)) Thanks for your suggestions very helpful indeed! Cheers ...
Thanks, and all good points.
I have a few of them but they are all 118* I ordered one and will try it out. When I make my tool paths I’ll have to figure out how deep to make the spot.
It's kind of easy to go too deep but once you get used to it, its not a problem. The 118 will work fine as long as it's not a stubby drill. The spotting drills have a very narrow web between the flutes.
Your reasoning makes good sense to me, my drills often wobble as they initially enter a deep, centre drilled hole.
As a self taught hobby machinist I've always used centre drills to start holes on the lathe, never heard of 'spotting drills before seeing your video.
So, I've just searched online for 'spotting drills' (here in NZ) - BUT, they all have a 90 degree point, not 120 degrees.
So, now I'm confused!! Can anyone help?
After seeing pictures of spotting drills online, I realised that I already have one (with a 90 degree tip)! I've been using it by hand to deburr small holes. I'm off to the workshop to try it out....
Regards Paul in NZ
That's strange you can't get it in 180. Something I learned about the center drill is that the very tip is 120 degrees. If you use a larger one and drill shallow it will work the same as a spotting drill.
Good point but did you know that center drills commonly have a 120° angle on the small tip? If you just poke in with the very tip you get the same effect. (As long as the very first mark is truly on center)
Good tip! - I realized this a short time ago and it works. The only negative is a very small spot to hit and you need to use a small drill first. I just drilled several holes with a spotting drill in the drill press and went straight to a 5/16 and it worked great. It saved a lot of time too.
Both very valid points. If you use just the tip it works but limits the hole size. I find using them this way for small stuff and dedicated spot drills for larger is a good combo.
I agree with this absolutly. Once you start using spotting drills the only time you will pick up a center drill again is to make a hole for a lathe center.
Yep, I agree
It is very useful information. I've been struggling with the same problem. Super useful information. Thank you for sharing...
Glad it was helpful! I had a lot of problems until I started using the spotting drill too
That was interesting thank you. Speaking as a retired engineer with 50 years service in high quality Machine Tool manufacture, I'd never heard of a spotting drill before and I must have drilled many thousands of holes without any problems after using a centre drill first. The theory of how your spotting drill works sounds ok, but I'm assuming that an accurately positioned hole is the object of the exercise? My question is how do you stop the spotting drill from wandering from it's position when starting to drill? Surely a short and stiff Centre Drill is much less likely too?
A good spotting drill is split point so its basically the same as a center drill. I use carbide so it is super ridged. Something I failed to mention is that the very tip of the center drill is the correct angle, its the larger part of the center drill that is not. In the past I've had problems with drill staying on center following a center drill but I was also drilling deep.
The way it was explained to me was to use all three types of drills. A center drill is ground to cut right from the tip, and is used on a lathe like a center punch would be in a drill press, to mark a spot for the spotting drill to start. The spotting drill is then used to make a deep enough spot that the non-cutting center tip portion of the dimensional drill has some relief from the surface and the ground cutting edges then remove the material.
Of course, the center drill is used alone to make a specially sized hole for the lathe turning center, a different operation.
Thats a lot of bit changing but I agree that the spot drill is not good for some things.
I guess a conclusion would be that center drills are only for drilling holes using centers on the lathe? I know a purpose spotting drill has few flutes making it much stiffer than a normal bit but it brings up the topic of how successful would you be grinding your own 120 degree end on regular drill bits for use as spotting drills? Of all the thousands of drill bits of all kinds that I have collected over the past six decades I only have a handful if that of spotting drills and hesitate somewhat (as much as a guy can when buying tools!) in acquiring a full range set of spotting drills if I can make my own. I recognize the problem though and have often watched the drill take off out of round from a center hole shallow or deep. It is a forlorn hope that it will straighten itself as you step up to larger bits I can tell you. Good video. Happy New Year.
Thanks... also spotting drills have a very thin web. A standard twist drill is thick.
Good info Winkster, thanks for sharing,
Cheers
Sure thing Rickster 😃
Excellent demonstration. I have been using spotting drills for ages but, here in the UK, they are not so easy to find as centre drills. Also, often, I will just use a centre drill because it is handy ... I'm a bit lazy I suppose, must try harder 😉.
Thanks for the comment.
I use them to. But cut a a part from it. So only the spiral is out of the chuck.
LIKE YOUR VIDEOS
I agree... it should have been deeper in the chuck. Also I have seen better spotting drills. There is no need for much in the say of flutes and this drill has long flutes.
Thanks again for sharing!!!!
Ευχαριστούμε πολύ!!
Your welcome!
Perfect. Just the kind of tip I was looking for. Now that I bought a few sets of center drills... But let me ask you this. What if I am not using them on a lathe but with a drill gun or drill press? What if I need a 3/16" hole? Could I use the center drill that has the biggest diameter of 3/16" and drill a 3/16" hole? So the center drill would start with the smaller tip on a center punch dimple, and just follow with the 3/16" diameter part of the drill.
One thing i failed to point out was that a center drill has the correct angle at the very tip. You can use it as a spotting drill but ideally the drill needs to be no more than the diameter of the tip of the center drill. I still use the center drill occasionally because it has better visibility. That is, if you are trying to hit a mark made by a center punch you can see the tip of the center drill. The biggest issues arise when you use the upper part is a center drill to guide a drill.
yep I you made sense there. Just ordered a set! Plus will double as a stubby bit when needed?
Don't go very deep with the spotting drill. They have no side relief and will bund in the hole and snap off.
Beautifully explained
Thanks Wayne!
Very useful I will do the same as this.Thanks Sir
Your welcome
Very informative. Thanks for doing this video.
My pleasure! Thanks for watching
Very very useful. Thanks. I just ordered some spot drills. Now, it begs the question: Are there 138 (or 140deg) spotters made to work with 135 drills?
Thanks, I'm sure there is.
The cutting angle difference is clear to see.
But how about a short cutting drill from a holesaw, if you choice in up in the drill chuck as far as it will go that works very well.
Spot drills are designed to only go as deep as the tip or cutting edge. The web between the flutes is very thin and there is no side relief. If you go very deep the bit will bind and brake.
Interesting demonstration.
Thanks
I think the reason a lot of people used a center drill is they see the TH-cam makers use center drills and think they are supposed to also. I always start with a smaller drill bit and work my way up.
Haha... maybe
There is one flaw in the depiction. A drill doesn't come to a point, it comes up to the chisel edge which is flat. Not saying that the use of the spotting drill doesn't get the job done though.
I think center drills work fine if the hole is not much larger than the chisel point of the drill used (outside hole, of the inner one). That way there is very little side to side force due to imperfectly ground cutting edges. If you go bigger one drill cutting edge will always contact first causing uneven forces. Also even if you use a larger center drill, the second smaller diameter hole guides the chisel toward the center due to unbalanced forces and taking less force to follow the existing hole. So it may not be centered perfect right as it touches, but with good pressure should center up.
It would be interesting to do some tests though. I suspect that starting the hole too gently will allow it to be out of center. I have been able to hold less than .005in position with center drills for all of my machining career, so never found it to be a big problem, but is worth switching as the argument is logical.
This is true, I should have shown that flat on the tip of the drill. The spotting drill has a very small web between the flutes so it is minimized. This makes the center drill very slightly better but the difference is very slight. Some spotting drills have a split point which is an extra grind on the flute and makes it just as good as the center drill but with a larger spot to hit. To drill accurately with a center drill you really need to use it like the spot drill, very shallow but, this also necessitates following with a smaller drill. Stepping up the center drill diameter is an option but it requires a lot more pressure than the spotting drill.
Will the spotting drill be marked special? How would I know it’s a spotting drill and not stub length drill bits?
I've seen the stubby drills but never owned one. If you buy a spotting drill that what it will be called. The spotting drill is different from a standard drill at the tip the web at the point is very small.
Also... I put a link in the description. Good price.
So how many sizes of spotting drills should one have.
A 2" one should do most people. For smaller sizes spots, just don't drill so deep ;)
@@millomweb I was referring to diameter. I see you only have one size
Potentially just 1 spotting drill could be enough. You choose how far to spot drill into the surface. Even a large spotting drill can be gently used to make a dimple small enough for a narrow follow-up drill. So find your largest diameter drill, measure the web and buy a spotting drill say 1.5 times the web thickness. If you have holes to drill that are very close to surface features that protrude away from the surface to be drilled, then you might need a second narrower spotting drill.
It would depend on the size hole you need to drill afterward. It should have very short flutes and overall length for rigidity.
I have a 1/4" and 3/16". The 1/4 will do anything I need but its easier to hit a mark in the drill press with a smaller drill. In fact I sometimes use the tip of a center drill in the drill press. If you don't go deep and use a small drill to follow it does well.
I haven’t really used spotting drills, but a center punch, before drilling, and I have to admit I had to look up its tip angle - surprisingly it is between 60° and 90°. From the photos of transfer punches the same appears to be true. So, it is interesting to see the difference it makes on a lathe, which is not usually observed on a drill press. Maybe it cones down to rigidity and stick out differences between these machines... but I haven’t heard chatter on drill press yet the punched center does prevent the drill from wandering. Could you please make a comparison video of this using the same bits is your advanced drill-press?
You can buy centre punches with a 120° angles for drilling. They are best used by using a small angled punch to position the centre (you can see better what you are doing) then open it out with the large angled punch.
Yeah I do that too.
I may do that. I also have more problem on the lathe.
For ease and accuracy could a center drill front edge be cut like a spotting drill. Smaller start but multipurpose is nice.
Yes, most center drills are sharpened at the correct angle (at the very tip) for a 118 degree bit. I left this important fact out of the video.
So a drill bit sharpened to 120° would be considered a spotting drill bit then?
The spotting drill are different. Aside from being shot they has a very thin web between the flute at the time. They also have no relief on the sides. If you drill deep they will bind and break. They are design to go no deeper than the cutting edges.
THANK YOU, EVERY DAY IS A SCHOOL DAY. REGARDS RICHARD.
Same here
There are quite a few things that are shown by the "experts" that are just plain wrong. They were taught to use them by some other old "expert" and so it must be the correct way to do it. I have never seen a center drill used on a cnc mill or lathe. For obvious reasons. It is the wrong tool.
Spotting drills are great! The smaller sizes of center drills break very easily on a lathe because, wait for it. . . . a drill wants to do anything but cut on center point. So that fragile little nub sticking out snaps right off.
Great video Winky, you may have started a revolution, LOL.
Haha... Thanks!
What I've wondered since I don't have any spoting drills is couldn't you make a spoting drill by just cutting down a regular drill just past the shank then just put a 120 degree grind on the tip it'll be a Lil shorter but not really any shorter for the size then a center drill ???
I'm sure you could make a spot drill although they are fairly cheap. I recommend a solid carbide maybe 3/16". Spot drill usually have a very small web in the middle so they won't walk around. You can also use the very tip of a center drill the same as a spotting drill although its a bit small. One other thing, on a standard drill the web gets much larger toward the shank so they are not ideal. Really not so good as a regular drill.
@@WinkysWorkshop yeah I found some 5 piece sets at pretty reasonable prices HSS/ 8 percent cobalt last time I had looked around everything I found was super expensive for what they are I get carbides expensive but I was seeing 5 piece hss/cobalt for like 450 a set thanks for the video and explanation 👍👍👍
@@umahunter Not paying that kind of money... I think I paid $22 for my 1/4 carbide but they seem to have gone up in price.
@@WinkysWorkshop yea I found a 5 piece hss/cobalt at all industrial tool supply 1/8-1/2 for 34 bucks free shipping on ebay
Thanks for explanation sir!!
Always welcome
That makes cense. Too bad most spotting drill on Ebay seem to have a 90 degree grind angle.
Amazon has some good ones. I bought carbide. If I remember right it was less than $20
@@WinkysWorkshop I don't use Amazon on principle, they embody what is wrong with this world i.m.h.o.
@@Rolingmetal I agree with that although I think the stock market is even worse. I never shop at walmart for the same reason. Amazon has a great business model but like the market its about who does the most with the least.
Awesome thank you!
Your welcome, thanks for watching.
Good point Winky! Pun intended. LOL
HA.. Thanks
I'm sure glad you pointed that out Mike.
Dale in Canada
Good tip Winky
Glad it was helpful!
Pretty obvious from the drawing, after you see it. Thanks for pointing this out!
You're welcome!
I have always had a bit of bad holes using standard twist drills. If you examine a hole from a twist drill it sometimes looks like a cutaway of a rotary engine. I am not sure why the triangle shape but it happens. Especially in thin material.
You need to use a "Brad point" drill for sheet and thinner metal.
@@t.d.mich.7064 have not tried a brad point in thin sheetmetal but will give it a shot. I use step bits the most in sheetmetal except for when i need the twist drill for taping holes.
@@countrycraftsman5110 puts all doubled up piece of cloth over the hole then drill, will be a round hole
@@ke6bnl i will try that.
I wonder how the cloth effects the hole.
Yes it does. It averages out in deeper holes where the sides of the hole can guide the bit. You see the same pattern with the spotting drill but it seen to work better anyway. Most drilled holes will also be slightly over size.
Yeah, but like everything, there's the right way to do something, and the lazy way. I've already got a frequently used centre drill in my one spare tailstock chuck, and it's just sitting there on my lathe table, so I'm going to just grab that rather than digging out a spotting drill and swapping it out. :)
It's like using a flat bladed screwdriver to open paint tins. We all know it's not the right way to do it, but it's convenient, so we don't think about it.
Good point
Why not have the best of both worlds, and just replace the center drill in that chuck with a spotting drill?
@@BatByke I usually need a centre for support way before I start thinking about drilling/boring out the middle of something, so by the time a spot drill would be the right tool to use it's already too late to use it. On those rare occasions when I didn't need a centre in the work first, the centre drills already right there in my smaller chuck. It still works about 80% as well as a spot drill....... and I'm lazy. :D
A couple things that are either incorrect, misunderstood, or misrepresented.
1. You're first attempt, with the center drill, was too deep. (more later)
2. Your drawing is correct, but you apply it incorrectly. The depiction on the left should be used for HSS and Cobalt, while the right would be for Carbide. This is referring to the spotting angle (greater for carbide and less for HSS/Cobalt).
3. Your spotting diameter should be ~30% < final drill diameter. This is why I say your first attempt was doomed to fail, regardless of any other particular point.
Other than these points, I think it was a decent video and it seems others have learned a thing or two. ;)
I might not understand correctly. The first example was doomed to fail because second angle on the spotting drill is meant for a lathe center not for spotting. Did you mean that the TIP diameter of the center drill needed to be 30%? If so, I would agree with that. Also why would the spotting drill angles be different for HSS vs carbide? The angle of the spotting drill needs to be the same of slightly greater than the bit that follows. Your 30% diameter rule sounds about right but the angles compared to the drill that follows is critical. This is a good website: www.harveyperformance.com/in-the-loupe/choosing-spot-drill/#:~:text=Ideally%2C%20the%20center%20of%20a,to%20140%C2%B0%20and%20larger.
If this is true...that having the lip of the drill contact first instead of the center web is bad and can make it wobble or hurt the edge or whatever...how do people explain pilot holes and stepping up in sizes?
Either one is fine. Center drills have been working to start holes for a over a hundred years or whatever. And no they are not strictly for lathe centers only. The actual name of them is a combination center drill and countersink. The countersink part is the part meant for lathe centers. The center drill part is the little tip with a regular drill angle.
If you need a hole to be really accurate, you need to bore it either way.
You are right about the tip of the center drill. I need to redo this video and include this. If you go to deep and use the upper portion of the center drill the bit tends to wander. As for the edge of the bit hitting first when stepping up in drill sizes. It will wander! The difference is, the existing hold aligns the bit. The hole will almost be larger at the entrance of the hold until the bit settles into the existing pilot hole. You could say the same about a hole drilled with a center drill too deep but there is a brief period time when the bit is only touching the outer edges and has no centering force. www.harveyperformance.com/in-the-loupe/choosing-spot-drill/
You just turned on my light.
I have center drills. I have your standard and those made specifically for live/dead centers.
I also have spotting drills. For some reason I never use them. I will now!!
You sound just like me. I thing outwardly the center drill seems like it would be better but after looking at the science you start to see why the spotting drill is better.
Another good video
I appreciate that
Mr. Mark, I bet a box of register marks and a paper stretcher you’re right 😄
Dude... you need to get out quick...printing is consuming you! Ha Funny
Thank you
Thanks for watching!
Could anyone tell me the effect a centre drill has?
The center drill is for drilling stock to run on a center in the lathe. Technically it can be used as a spotting drill if you only dill with the very tip. If you go too deep where the upper part of the center drill is cutting a countersink the angle is wrong and there's a change the cutting edges will pull the bit of center.
I have drills, bought as spotting drills, that are ground to 90 degrees included angle
Yes you can get them in many angles.
So we should throw away our center drills? :)
Ha... that up to you. I like the center drill in the drill press if I need to hit a mark. The visibility is better. I have learned that if you only go as deep as the tip of the center drill it works better.
You speakum truth.
Ha... Thanks!
Why don't you just drill with the drill part of the combination drill countersink to a shallow depth , it is ground to 118 degrees like your drill bit is. It should follow like the spotting bit at 120 degrees.
Good point and I should have mentioned that. The only negative is a very small start unless you use a larger center drill. Something else I have notice is that the tip of a center drill is sharpened weird. No spiral. It's kind of like a lathe tool without back rake (or very little). The spotting drill is much sharper and requires almost no pressure. It seems like the larger center drills require a lot of pressure. It might not matter but I'd much rather use the spotting drill.
@@WinkysWorkshop yes, spotting drill sounds like the better idea.....best wishes, Paul
Now just tell me how you really pick a spotting drill since it seems there are a lot of variation. Even if you pick 120 degree do you need a whole set in imperial and decimal sizes and do you match the size to the drill size you want in the end. Always used center drill I guess the wrong way. www.travers.com/spotting-drills/c/297807/#
Great question and I should have covered this better. One drill works for everything. I use 1/4" although 3/16" might be better if you are trying to hit a mark. The smaller drill doesn't obstruct the mark as much. I have a 3/16 and 1/4 but use the 1/4" more because it carbide and sharp. The maximum depth is the drill diameter. In other words the pilot hole can't have straight sides. Don't go too deep.
What if you "spot" with a center drill? just don't push it deep.. cause I'm lazy and cheep!
Doesn't the small point on a centre drill have a 60 degree angle too ? If so, then every 118 degree drill is going to make contact with the sharp edge of the hole created by the centre drill, no matter how small a hole you dug.
@@mikeparfitt8897 yeah I kinda thought of that after the fact too.. but in my limited experience once the center drill self centers by that tendency to want to ride towards the middle the regular drill at least has a starting point that tends to follow.. seriously I never knew there was a thing called a spotting drill.
I do that in the drill press.
Its hard to say but the tip is more blunt.
I knew they were out there but recently learned what they were for. I think a center drill works well if you go shallow and follow with a small drill.
I love my 140° spotting drill.
Thats almost flat?
@@WinkysWorkshop 180 would be flat but 140 means that my 135 bits will center properly
@@ninthm00n From what I have read 120 is ideal for a standard 118 degree drill bit. But yes, 180 is flat but 140 isn't far from it
You can't lose with a spotting drill, the next drill will always go to center. You can hear a huge difference in the video.
I've been frustrated with center drills in the lathe. They are usable but it seems like every time you need a concentric hole you see the drill wobbling as it goes in. Starting with a very small bit help. I still use the center drill in the drill press because of better visibly its easier to hit a mark.
I didn't see the wobble.
It was slight. Nevertheless using a center drill like I did it prone to problems. I did fail to mention that the very tip of a center drill can be used as a spotting drill. It's sharpened to 120 degrees and works well when followed by a 118 degree. The only problem is that unless you use a fairly large center drill it makes a very small starting hole.
Never understood this confusion. Center drills are specifically for lathe centers. Not centering for a follow-on drill. Period.
So true. I remember machinist at work using center drills to start holes.
"a center drill is actually for a lathe center"
"a spotting drill is when you want to locate a hole accurately and follow up with a larger drill"
Do I get an A?
You got an A. Ha... You can use the very tip of a center drill for spotting however. It's sharpened to the correct angle.
Any practical practical information about "DIN 333-B" center drill? Anyone?
Looks interesting although I'm not sure of the purpose. www.fanar.pl/en/produkty/drilling-tools/spotting-drills/for-centre-holes/din-333-b-hss-en/
Almost never use spot drills. Especially on CNC equipment. Use the right tools and you won't need to spot drill. Split point drills negate the need for spotting or center drilling. YMMV.
Yes a good option. I don't know a lot about them but you need one for each size right? Spotting drill may not be the best option but better than a center drill.
@@WinkysWorkshop Buy split point drills as you need them. You won't regret having them. A good source for reasonably priced GOOD drills is McMaster Carr.
@@terrymoorecnc2500 - It would certainly be a plus when you have 50 holes to drill.
@@WinkysWorkshop it is easy to split them yourself with a bit of careful grinding, or you can get a jig to do it. I would get a diamond wheel though, as you really need a sharp wheel edge to do it well.
Yep, drives me mad when people use centre drills.
Or calipers as scribes. Destroyed in two seconds .
It's amazing how many use them. They do work but not as well
Happy Belated New Year Mark & Family. You explained this very well - it's kind of common sense isn't it. I have a box of old drills that have many uses. They're good for practice grinding with, so I've ground my own spot drills. Only need a couple of sizes but I'd like to get better a tempering them. Stay safe and well :)
Thanks Anthony! Obviously the short drill bit is stiff and will stay put a little better but a spotting drill is made much differently. Spot drills are designed to only go as deep as the tip or cutting edge. The web between the flutes is very thin and there is no side relief. If you go very deep the bit will bind and brake. Regular drill have a wider web and the web gets even wider as it progresses. If you re-sharpen a broken drill you will probably see it.
@@WinkysWorkshop That's what I've been playing around with when grinding the old bits. For me, seeing & doing something is how I learn more than just reading about it. I haven't tried on a blank yet though. ATB :)
If a person doesn't know tat already...shouldn't b aloud to turn on the lathe...only my opinion
It happens a lot. Ha
!!!.
Thanks
By the eye you're "spot" on. Good demo!
Haha... thanks John