Tweak of the Drills and Drilling FAQ

Following discussions about updating John Schmitt's and Clive Elsmore's FAQ so it ties in with the recent faq sections on different types of drills, I have done a tweaked version. Much is the same, but with some new sections on tile and metal drilling and a couple of extra paragraphs elswhere.

The original can be found here:

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proposed new version here:

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as usual please.

If you have any additional info to expand the metal drilling section, then fire away!

Reply to
John Rumm
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Looks good from here.

1 typo alert: In the Stirring section "sow" should be "slow". Spell checkers are handy but less than perfect. I recieved a flyer from a friend informing me that he would be "mowing house".

What about:

Drilling sheet metal into a block of scrap wood (MDF ideal) will result in a cleaner exit hole and less chance of the metal "climbing" up the flutes of the drill immediately after breakthrough.

There are also, for those of you intending to do a lot of metal drilling, coated drills. Normally this is Titanium Aluminium Nitride (TiAlN). This is a golden colour, but beware, some of the super-cheap ones are simply flash-plated gold, or even painted gold. The coating is applied by vapour deposition and is hard, tough and has a low coefficient of friction. High speed steel drills do not drill aluminium gracefully, as that metal tends to weld itself to the drill bit, resulting in poor swarf clearance and a badly toleranced hole, either oversize, out-of-round or both. The use of paraffin or white spirit helps to an extent for aluminium. With TiAlN the low coefficient of friction eliminates this, and most metals can be drilled without coolant/lubricant. On top of this, faster cutting speeds can be employed and the tool life is about 10 times that of HSS. Obviously the price is higher, but industry seems to find it cost-effective, including less interruption for changing the bit. I (JS) went to a building exhibition some years ago and one of the stands was demonstrating these bits. The sales man had a pillar drill and on a cycle time of about once a second drilled through a 10" file until it resembled Swiss cheese. Very impressive!

Cut and paste at will.

John Schmitt

Reply to
John Schmitt

Some just jarred, some are additions.

After "stud finder". Wiring regulations specify that cables run close to the surface of plasterboard should be vertical or horizontal, from switches or sockets, however, in practice this may vary. (I'm not sure of the exact regulations, but maybe just a sentance along these lines) "loud and also", I'd lose the also.

Perhaps after "heating and cracking", "One way of drilling holes in glass is to add abrasive to this liquid, and use a simple rod or tube as a drill" "quite large diameter (150mm) sizes" I'd lose diameter. "One some" = "On some". "vital component." Add "If unlucky, broken wrists can be the result, due to the very high torque". "sow fixed" = "slow fixed" "keep it in the chuck" = "tie it securely to the mains flex next to the plug" "7Kg" = "7Kg force for a 10mm bit" "do the work.", add "For smaller bits, reduce this greatly, for a 2mm bit, under a kilo may be appropriate".

After "rather than the sheds", "Sharp drillbits will need significantly less power and effort to drill with, this is especially important with cordless drills as it will prolong battery life. One useful document on those who want to try sharpening drills can be found on "

Reply to
Ian Stirling

I'd leave out the rod, mention that suitable carborundum powder (typically

60 grit) is available from lapidary suppliers. Also copper is used for the tube, because it is soft and tends to pick up the abrasive particles, so that cutting rate is maximised. A pumping action is also important as the abrasive tends to ooze back up the hole.

If you are left-handed check that if there is button to lock the trigger down it does not engage under your finger in normal use.

This is exactly what happened to me. It was only by luck that I got my hand off a 750w drill when it caught. The drill carried on until it jerked the plug out of the wall. The drill was an excellent shot; the plug caught me in the crown jewels. :-#

John Schmitt

Reply to
John Schmitt

Apparently the same "copper and grit" technique is also commonly used for various deep cut glass engraving techniques according to my (glass engraver) FIL. A small lathe is used to spin copper wheels of various types and profiles, and the glase os offered up to them while a mixture of grit and oil is applied with a finger to the rotating wheel.

Ouch!

I bet there was for a very brief moment a slightly smug expression on your face that said "ha! got away with it that time!). ;-)

Reply to
John Rumm

Great as usual. Additions - drills stands? And the use of Cobalt drill bits for stainless steel.

Dave

Reply to
david lang

OK, Will add a section on drill stands to the end of the metal drilling bit since that seems to be where it fits best.

As to cobalt, how about a new section after coated drills:

"Cobalt Drills

Another variation on the metal drilling theme. Cobalt drills are hard! They are designed to drill very hard materials like stainless steel. The only common DIY application that you are likely to find for these is drilling out the remains of other broken drill bits!"

Sound OK? Anything else to add?

Reply to
John Rumm

Will they really drill through HSS, though?

Reply to
Chris Bacon

More like "That was close, Phewoooooooooooh!"

John Schmitt

Reply to
John Schmitt

However, as I just found myself, after sharpening a poorly performing drillbit - even the sharpest drills don't work very well backwards...

Reply to
Ian Stirling

Been there, done that, got the t-shirt.

John Schmitt

Reply to
John Schmitt

Neither do chain-saws!

Reply to
Bob Martin

Yes :-)

Having been at the blunt end of drills used in the aerospace industry for many years, cobalt drills are only one step above a standard HHS twist drill. They can be blunted with some stainless steels though.

The next step up is called a C 1150. This has short flutes and a longer shank than normal.

After this comes a D 200 twist drill. Looks quite a lot like a HSS twist drill, so you have to look at the packet it comes in. Quite a good drill to have for stainless.

As an aside, I had to drill some steel that the Italians had supplied for a modification to an aircraft wing. It was so hard, that the 2.5 mm pilot drill I was using would last just 3 holes before refusing to drill any further. I spent more time walking to the grindstone than drilling holes :-(

The Italian rep passed this job one day and observed that a fellow worker had turned the colour of the paint on these panels a light brown colour (it is normally yellow).

Italian 'Your drill is blunt.'

Brit. 'No! Your metal is too hard.'

Italian. 'Yees, we should take the designer round the corner and keel him.'

:-)

You are quite right about lots of pressure and a slow rotational speed when drilling hard metals. If you let up on the pressure, you end up polishing the metal. By the way, put the pressure on and _then_ start to drill. When you decide to stop drilling, keep the speed up and _quickly_ remove the twist drill.

When drilling pure aluminium, there can be a build up of swarf that sticks to the drill cutting edge. A fast rotation speed can reduce this risk, if used with a slow feed rate.

When drilling thin sheet, no matter what you do, you will end up with a triangular hole if you do not have something quite solid under the metal. Whatever this is, it must be quite solid. I would imagine something like MDF to be OK.

The use of subsequently larger drill, to avoid this, does not work if the twist drill you are drilling with has nothing to hold it on its path at half break through point. (This is the point when the drill decides to make a triangular hole.)

Finally, in my experience, comes the solid tungsten carbide drill. Now this is a beast. It will drill and cut into an easy out, or also known as an extractor tool for a broken stud/bolt. (quite hard steel in its own right). I would imagine that it could cut into any of the above drills, if you could keep it on centre.

Finally, there is a diamond drill, but I have had no experience of these.

HTH

Dave

Reply to
Dave

Thanks for that! (I knew that metal drilling was going to end up being a FAQ in its own right almost).

If you have no objections I shall plagiarise that with due haste!

Reply to
John Rumm

Dave

Reply to
Dave

You have been assimilated (and tabulated)... how does it feel?

New version uploaded...

Reply to
John Rumm

No different.

It must be the alcohol ;-)

Dave

Reply to
Dave

But where are all these frequently asked questions frequently asked?

The only thread on drilling in here in the last few years has been the FAQs.

Reply to
Michael Mcneil

We're a helpful lot here; not only do we answer actually, infrequently and frequently asked questions, but we also give answers to questions that people didn't realise they needed to ask.

Seriously, the term "FAQ" these days is generic like hoover. It refers to any authoritative body of information on some topic. Maybe I should start writing it with lower case like hoover. Almost everyone I know pronounces it phack (rhymes with whack), hence "a faq" rather than "an F. A. Q."

Phil The uk.d-i-y FAQ is at

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Google uk.d-i-y archive is at
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NOSPAM from address to email me

Reply to
Phil Addison

A mention of cone-cutters and step drills for drilling largish holes in thin sheet metal? I use an excellent 4-12mm step drill for making holes for switches and such like in aluminium panels. Give a good clean round hole, especially if you make the last cut from the other side, and very little danger of grabbing.

Reply to
dcbwhaley

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