Which set of Drills for my first Lathe?

In article , Scrim writes

First point, I can guarantee you will need drill bits in 0.1 mm steps, for all sorts of reasons. The most obvious is that tapping sizes (whether for metric or imperial threads) mostly do not coincide with 0.5 mm steps. If you need to ream holes, you must first drill 0.1 - 0.3 mm undersize depending on size (and you probably will need to ream holes, for several reasons). Buying a set is so much cheaper, per size, that it would be a false economy to start buying individual sizes across the range (but see point 3).

Second, don't buy carbide drill bits until you need them for drilling exceptionally difficult material; they are much less robust than HS ones.

Third, do you really need to get a 6.0 - 10.0 mm set straight away? Only you can say what type of work you will be doing, but you may get by for now with a 1.0 - 6.0 mm set and a couple of larger bits as needed.

Fourth, I doubt you need worry too much about exotic types or geometries. This set:

should suit your needs for some time; if you find with more experience that you need something more sophisticated, you will by then have the knowledge to decide what that is. In some ways you may even be better to start with a cheaper imported set:

and get a better one when you have acquired the skills to justify it.

I did this, and still use the cheaper set for less critical work after

20+ years, having had to replace only a couple of worn out or broken ones. I have several better sets with various machines for more critical work.

David

You are likely to need the 0.1mm increments as tapping sizes are not in

0.5mm or larger steps, so you can either get a set of say 0.5mm increments and add the common tapping drill sizes such as 3.3mm, 4.2mm etc depending on what threads you are likely to be cutting.

Or buy a cheaper set of 1-6mm in 0.1mm increments and as these need replacing buy Dormers and a few larger sizes.

The A002 Dormers are quite good and what I tend to buy, I also have stub drills in the common sizes from their A022 range, I get them from J&L usually when they have a promotion on but also have a look at Greenwood tools as they often discount Dormer sets.

(use the virtual catalogue)

Jason

Register with J&L Industrial's website. You get special offers that sometimes make these things affordable. I've now a 1 - 10 mm set of Hertel drills in 0.1mm steps and some dormer via being patient on the right offer. The Dormer are excellent, but not sure a reamer is a replacement for a poor drill (or vice versa)!!

I did pay £30 for a set of chinese drills 6 - 10mm in 0.1mm steps and I didn't like them and replaced them with the Hertel (on a deep discount from J&L).

Thanks for the help folks. I think I'm going to skip getting a cheap set, but who are the best drill manufacturers and which ranges should I be looking at? I tend to work with mild steel, aluminium, brass, copper, PTFE and acrylic.

I don't know how competent you are at using a lathe, but as you say this is your first lathe you will need some time practicing with it. I learnt the hard way, don't make your initial mistakes with expensive tooling. get a cheap set of drills, say 1-10 mm in 0.5mm steps (I've found the cobalt coated sets in metal boxes with the Powerfix label that turn up from time to time in Lidl and Aldi stores for as little as £3.99 to be accurate enough for a lot of jobs like making jigs etc). Use these initially, later when you start accurate work get a good expensive set but still use the cheap ones for "roughing out" eg cutting smaller pilot holes thus reducing wear on your good drill which will then be used to cut it to full size. By the way always start with a centre drill.

Alan

I've used a lathe and pillar drill at school (long time ago) and done plenty of hand drilling of all sorts since. I think I know how to use a drill.

Scrim

and done

Alan Dawes advice was very true, no matter how experienced you are. After 45 years as machinist I always have different quality tools for precise and not so precise drilling. Sharpening very small drills is no fun:mad:Most clearance holes don't need high precision so a .5mm steps set would be adequate. Don't know how it is in your parts but here (Canada) you can buy taps metric/Imperial with matching drill. When you drill in a lathe(were the job rotate and the drill doesn't)the drill has less of a tendancy to wander but there is less feeling of the cut with a regular tail-stock wheel. So it require more cares than usind a drill press specially with small drill and deep holes.

What?? There is absolutely no reason why that should be so, unless you have a lousy drill press & don't clamp your work.

Regards, Tony

Have never seen a lousy machine tool but have met lousy "machinists" on occasion,off course they didn't last long on the job! When the job rotate around the drill(propely sharpened!)the path of least resistance is the exact center. When using a drill press there is no self-correcting tendancy and deep holes with a poorly sharpened drill,wrong feeding or cutting speed become impossible. I have drilled

1/4" holes 12" deep on occasion and found out it was a lot easier in the lathe than drill press. This is the kind of drill press I am talking about!

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That simply isn't true - sorry. If you were a gnat sitting at the end of that drill mounted in the drill press, it would seem to you that the work was rotating, not the drill. The relative movement of the work and the drill are identical in both cases.

Drilling deep holes with poorly sharpened drills is a problem regardless of how you try to drill them.

There is absolutely no difference between rotating the work and rotating the cutting tool (or rotating both at the same time, for that matter). If you are seeing a difference, then it is down to how you set up the job, or the relative accuracy of the machines you are using, and nothing whatsoever to do with whether you choose to rotate the work or rotate the drill.

Regards, Tony

But the question is not do you know how to use a drill, it's do you know how to use a lathe. And apparently you don't, or at least not well.

Try some reasonable-but-cheap ones first, say a reasonable HSS set with

0.5mm spacing up to 13mm. Buy a couple of HSSE/HSS-Co ones, and some carbide ones.

You will learn the feel of things, how to avoid breakages, how to drill fast without overheating the bit, how to get good drill life, when and how to use HSSE carbide, and so on, without buying an expensive set which is perhaps not what you need.

'Course if you are extremely rich go ahead and buy all six different Dormer sets, and we'll all envy you them, but think what a waste it is your having them as you don't know how to use them.

Generally, I agree with the comments below.

-- Peter Fairbrother

Yes - if the centers are perfectly inline. However if they aren't inline then there *is* a difference.

No. We have had this conversation before, and it's kinda hard to explain, but I'll try;

Suppose a drill with a single cutting edge 1" in diameter which is 1/2" offline. If the piece is still and the drill rotates then the edge cuts steadily at pi inches per revolution, whether the drill is offline or not.

However if the work is rotating and the drill is still, at one point in a turn the edge is cutting metal at a rate of 2 x pi inches per revolution, and at another point it is not cutting at all, because it is still.

Hope this makes it clearer.

The idea that the frames of reference are identical (except maybe for centripetal force) is only true, geometrically speaking, when the center of rotation in inline with the center of the desired hole. Move 'em aside, and the frames are *different*.

-- Peter Fairbrother

As I said, if you set the job up correctly there is no difference. If you set up the machine and/or the work and#/or the drill off center, then all bets are off - in both cases.

Regards, Tony

Another thing about drilling in the lathe tailstock is using speed to get better concentricity, especially at the beginnjing of a hole.

Your tailstock is not central, no matter how good your adjustment and lathe are it's always a bit out.

You could use a single point cutter like a boring bar, which tends to cut a hole centered on the lathe axis (though it doesn't actually do this perfectly if the initial hole is off center, which it always is, contrary to many people's belief), but that's a hassle, and sometimes speed helps and is easier especially with knob-adjust.

There are three effects I know of going on here, and maybe more.

First, it means that one flute will be doing more of the cutting. One flute always cuts more, but when the plunge-per-rev is less this effect is magnified. You get a bit of the single cutter effect.

Second, the energy required to wobble the drill (just the wobble, ignoring cutting forces) depends on the square of the speed, as is the force the work is exerting on the drill to make it wobble - the drill is more likely to stay where it is if it's moving fast.

Third, the centering effect mentioned in my last post, which a lot of people think doesn't exist, but it does.

The first and second effects do occur in pillar drills, but they doesn't cause centering in the same way. The third effect don't occur in pillar drills at all.

See? While you may know how to use drills in a pillar drill, you do still have things to learn about using drills in a lathe - and practice with cheap stuff is the best way.

I'll shut up now.

-- Peter Fairbrother

Yes - but if the work is rotating then you can use the difference in cutting speed to pull an offcenter drill back to the axis of rotation of the work. Gun barrel makers do that a lot, as do watch and clock makers.

If the work isn't rotating then there is no axis to pull the drill to, you are reliant only on the stiffness of the drill, and once it goes off the desired line there is little or nothing to pull it back.

-- Peter

The tailstock of my 1965-vintage lathe was abused as an anvil horn by trade school students. The dealer gave me another spindle but the fit isn't perfect, so the point of a chucked drill bit droops. If I start a hole without centerdrilling the point almost immediately snaps to center and runs visibly true, showing almost no wobble. The same bit is likely to walk and drill off center on the mill. I know what you are saying but something differs between the two cases.

jsw

Hope I've answered that, if you didn't understand anything please say. It's a bit of a crusade of mine, if I can convince one person per year then someday the frame-of-reference fallacy may cease to exist ...

"Setting the job up correctly", while a laudable ideal, is just that - an ideal, and unobtainable in practice.

It'll always go off-center.

However if being off-center means it tends to go back on-center, then we can have a center-following action ... and the center is the axis of revolution of the work, which in a lathe is *exactly* the axis we want ... :)

-- Peter Fairbrother

I guess I could always drive my drill press table with that spare 5hp motor I've got and lock the spindle :-)

Mark Rand RTFM

Now that would be a sight to behold :)

Regards, Tony