On Sharpening Twist Drills

[Ropetangler]

There is this thread http://www.model-engineer.co.uk/forums/postings.asp?th=95436 on the English 'Model Engineer' website that makes for interesting reading on drill sharpening. There are quite a few pages and I have not read them all, but on the first page, the moderator recounts his earlier career working for a company making piano movements. They drilled thousands of holes a day into wood, and the positioning was often to within a half thou, and hole sizes would be to within tenths of thous. No commercial drills would drill to size from the packet, so they would be graded, and remachined and resharpened to size. When they were installed, test pieces would be done and it might still take some hours of tuning before the machine was passed by the inspector for work. Some of these drills would then go on to drill over 30,000 holes before they were changed out. Well worth the read if the weather is as drizzly as it is here:rolleyes:
Rob.

[Ueee]

Hmmmm......
So there workshop must have been very well climate controlled to get that sort of accuracy in timber. I'm amazed there is no immediate outcry in that thread, as a .0005" pin gauge could easily be pushed into a hole that was .001" small in timber.
Just the fact that the timber is not a consistent medium means that 10 holes drilled in the same piece but 10 different places and grain directions means you will get 10 different sized holes, no matter how good the drill.
If the timber was ebony and ivory (but more likely the timber for the hammers etc, not sure what they use there) then better tolerances could be achieved but i still don't think they could be that good.

Ew

[PDW]

There is this thread http://www.model-engineer.co.uk/forums/postings.asp?th=95436 on the English 'Model Engineer' website that makes for interesting reading on drill sharpening. There are quite a few pages and I have not read them all, but on the first page, the moderator recounts his earlier career working for a company making piano movements. They drilled thousands of holes a day into wood, and the positioning was often to within a half thou, and hole sizes would be to within tenths of thous. No commercial drills would drill to size from the packet, so they would be graded, and remachined and resharpened to size. When they were installed, test pieces would be done and it might still take some hours of tuning before the machine was passed by the inspector for work. Some of these drills would then go on to drill over 30,000 holes before they were changed out. Well worth the read if the weather is as drizzly as it is here:rolleyes:
Rob.

Tenths of thousands of a foot, maybe.

In short, I don't believe it. Someone is dreaming, as Ewan says, not in a material as subject to movement as any wood out there, not outside of a climate controlled environment.

PDW

[ventureoverland]

The tolerances are somewhat irrelevant in my mind, although I do agree with the comments already made in this regard. The important thing to consider is that the drills needed a labour of love applying before they were considered accurate enough and thereafter they would last a long while.


Thx
Jon

[Grahame Collins]

Maybe you have been reading the April 1st edition of the Magazine or someones having a lend of someone.:D

The 1/2 thou reference on timber and then the 1/10 thou hole tolerance on a piano hole sizing.
Last time I looked,the piano was a musical instrument not a scientific one.:?

Overall I think many metal workers are duped into thinking they must have a drill doctor when in truth the application for the majority of drilled holes is for a bolt clearance or tapped holes.
I do concede, however, there are some applications for precisely sharpened drills for drilling accurate holes.

Maybe its just me thinking the that the old well regarded hand skills are fast disappearing.

Grahame

[.RC.]

Does anyone keep in mind that when you are sharpening drills, all you are doing is grinding a clearance angle onto the drill... The actual cutting angle is fixed by the helix angle of the groove..



Last time I looked,the piano was a musical instrument not a scientific one.:?


I will say, but...... If the goal is to produce pure clean sound tones that are fully repeatable.. It may amaze people to what extent some go to to get the best results. Or maybe to what extent you have to go..

Look at the price of some extreme high quality electronic audio equipment...

[Ropetangler]

Maybe you have been reading the April 1st edition of the Magazine or someones having a lend of someone.:D

The 1/2 thou reference on timber and then the 1/10 thou hole tolerance on a piano hole sizing.
Last time I looked,the piano was a musical instrument not a scientific one.:?

Overall I think many metal workers are duped into thinking they must have a drill doctor when in truth the application for the majority of drilled holes is for a bolt clearance or tapped holes.
I do concede, however, there are some applications for precisely sharpened drills for drilling accurate holes.

Maybe its just me thinking the that the old well regarded hand skills are fast disappearing.

Grahame

To be honest, I would have expressed much the same views everyone has expressed here myself, but if I am right, prety well every time John Stevenson has popped up on some metalwork forum, he sounded like he knew his stuff, and was generally held in high regard. I can only suggest that you all read the link posted for yourselves. I know nothing about the making of pianos, but I have no reason to think him untruthful when he described the procedures at his old workplace. I just reported the link, because I found it interesting and somewhat against the prevailing wisdom on these matters, but that company made the movements for many of the top names such as Steinway, Kemble, Kimble Bechstein, Baldin and Bosendorfer, so they must have been doing something right. JS goes on to mention that "any moving part on an action ran on pins 0.0505" in diameter, a standard reached in the late 18th century but unfortunately a size no drills exist for. In the early days of the 20th century they made drills by filings tool steel wire down, hammering and filing into a spade bit then hardening. In my day we bought HSS drill blanks in exact size then hand ground these into spade drills". Go ahead and read it all, there is plenty of thought provoking stuff there.

I realise that it would be easy to push a gauge pin 1/2 a thou bigger than the hole in wood into that hole, but that is also the case with a micrometer set a thou smaller than the true diameter of a shaft, being easily pushed over that shaft. It is repetition and lots of practice that make a machinist able to measure with his tools and instruments to high standards of accuracy, or in other words to develop the feel in his hands to get it right. That inspector did nothing but check and sign off on machine adjustments for quality control, so he would be capable of making these judgements with all the years of experience, the same with a piano tuner really, - he could possibly give an adjusting screw a 90 degree turn, and chances are that most of us wouldn't be able to tell the difference, but another piano tuner or a concert pianist would have no trouble detecting it.
Rob.

[PDW]

To be honest, I would have expressed much the same views everyone has expressed here myself, but if I am right, prety well every time John Stevenson has popped up on some metalwork forum, he sounded like he knew his stuff, and was generally held in high regard. I can only suggest that you all read the link posted for yourselves. I know nothing about the making of pianos, but I have no reason to think him untruthful when he described the procedures at his old workplace. I just reported the link, because I found it interesting and somewhat against the prevailing wisdom on these matters, but that company made the movements for many of the top names such as Steinway, Kemble, Kimble Bechstein, Baldin and Bosendorfer, so they must have been doing something right. JS goes on to mention that "any moving part on an action ran on pins 0.0505" in diameter, a standard reached in the late 18th century but unfortunately a size no drills exist for. In the early days of the 20th century they made drills by filings tool steel wire down, hammering and filing into a spade bit then hardening. In my day we bought HSS drill blanks in exact size then hand ground these into spade drills". Go ahead and read it all, there is plenty of thought provoking stuff there.

I realise that it would be easy to push a gauge pin 1/2 a thou bigger than the hole in wood into that hole, but that is also the case with a micrometer set a thou smaller than the true diameter of a shaft, being easily pushed over that shaft. It is repetition and lots of practice that make a machinist able to measure with his tools and instruments to high standards of accuracy, or in other words to develop the feel in his hands to get it right. That inspector did nothing but check and sign off on machine adjustments for quality control, so he would be capable of making these judgements with all the years of experience, the same with a piano tuner really, - he could possibly give an adjusting screw a 90 degree turn, and chances are that most of us wouldn't be able to tell the difference, but another piano tuner or a concert pianist would have no trouble detecting it.
Rob.

I used to argue at times with John Stevenson on r.c.m 20 years ago. I agree he's a smart man and very knowledgeable in his field, but that doesn't mean he's always right. Like Rich King on PM, sometimes he has the tendency to think that because he does things in a particular way, that's the best and only way, simply because that's how he & his father before him have done it, and it works. Not what I regard as meeting any scientific methodology.

Now WRT small holes in wood, the 2 things that cannot be avoided are temperature fluctuations and humidity fluctuations. We all know what happens to holes in metal with temperature changes. Wood is no better and has the very large compounding factor of humidity as well. Even very dense woods like iron bark and blue gum move. I've been working with blue gum cut and air dried in a shed for over 8 years now; the cross cuts just look polished off the saw due to the density. It still moves when you get down to measurements with vernier calipers and micrometers.

So *maybe* you can drill a hole using a drill made to tolerances of tenths of a thousand of an inch, and *maybe* that hole will be on size to a similar tolerance level at the moment that the drill clears the work.

Anyone want to bet what size the hole will be, say, 3 months later, when the item may well be in a completely different country? Say, a shift from the north of England to Singapore?

PDW

[eskimo]

Look at the price of some extreme high quality electronic audio equipment...

and the best are still using valves I believe

[simonl]

and the best are still using valves I believe

While beauty is in the eye of the beholder, so too with sound to peoples ears. You will never when an argument with valve amp audiophiles that mosfets (or whatever) are better because they like valves!

I would almost go out on a limb and say that of these people, 1% may be able to spot the sound difference while the other 99% are just hanging onto the past, similar to what we do when we admire fine old machine tools.

Persoanlly I can't tell the difference.

Enjoying the thread on drilling holes in timber though! :D

[Oldneweng]

and the best are still using valves I believe

Not the best. Like those people who believe that music played from vinyl records is better than from digital media, there are some people who prefer the sound of valve equipment. It is my understanding that it is simply a matter of personal taste.

Dean

[Pete F]

If accuracy of the order claimed was required, you wouldn't be drilling it, not as a final operation, and definitely not with a twist drill, irrespective of the material (and I agree strongly with the above regarding wood). Twist drills only came in to use IIRC at the beginning of the 20th century, prior to that other drill designs were used, some of which remain a more accurate way to bore a hole, albeit with other disadvantages. The point being if they are claiming no twist drills existed of that size in the 18th century, I'd suggest that's about the only piece of fact there; since NO twist drills existed at that time.

[PDW]

If accuracy of the order claimed was required, you wouldn't be drilling it, not as a final operation, and definitely not with a twist drill, irrespective of the material (and I agree strongly with the above regarding wood). Twist drills only came in to use IIRC at the beginning of the 20th century

No I'm pretty sure it was earlier than that - 1860 to 1880 era I think.

But your point is still valid. There were no spiral drills before that, and the design was under patent when first brought out, so other manufacturers still had straight flute drills.

PDW

[RayG]

No I'm pretty sure it was earlier than that - 1860 to 1880 era I think.

But your point is still valid. There were no spiral drills before that, and the design was under patent when first brought out, so other manufacturers still had straight flute drills.

PDW

Spiral pattern augers go back way further than that, but, to stay on topic, I'd think that augers with straight sided flutes would drill a more accurate hole in wood than twist drills.

Ray

[Pete F]

Spiral pattern augers go back way further than that, but, to stay on topic, I'd think that augers with straight sided flutes would drill a more accurate hole in wood than twist drills.

Ray

So, how many 1.3 mm augers have you come across? :wink:

As I mentioned, there were other drill designs before the modern twist drill, and some of them are much more accurate, though rarely seen these days, however claims were being made that are difficult to justify on a number of fronts. Ewan mentioned wood movement (and I fully agree), I mentioned that if they're claiming that accuracy from twist drills, they didn't exist before 1860ish, at best. No disrespect to the OP, just pointing out where things don't add up.

[PDW]

Amazing what you can find on Google...

http://www.whalingmuseum.org/explore/library/finding-aids/mss116

This matches my memory which was telling me it was the Morse Company sometime around 1860. I think I might have read it in Charles Porters 'Engineering Reminiscences' or 'English & American Tool Builders'.

Sad thing is, it'd be over 20 years since I read either of those books. I used to buy a lot off of Lindsay Books back then.

PDW

[Oldneweng]

While beauty is in the eye of the beholder, so too with sound to peoples ears. You will never when an argument with valve amp audiophiles that mosfets (or whatever) are better because they like valves!

I would almost go out on a limb and say that of these people, 1% may be able to spot the sound difference while the other 99% are just hanging onto the past, similar to what we do when we admire fine old machine tools.

Persoanlly I can't tell the difference.

Enjoying the thread on drilling holes in timber though! :D

You beat me on that one Simon.

I am a member of an Audio Forum based in the US. There are people on that forum that claim they can pick the difference, not just between different speaker cables, which is an argument that has been ongoing for years, but that they can pick the difference when using different extension cords to connect the audio system to power. You do have to remember that they are using 110v so that would make a difference compared to our power supply effects. I am not joking about this.

Dean

[RayG]

So, how many 1.3 mm augers have you come across? :wink:

As I mentioned, there were other drill designs before the modern twist drill, and some of them are much more accurate, though rarely seen these days, however claims were being made that are difficult to justify on a number of fronts. Ewan mentioned wood movement (and I fully agree), I mentioned that if they're claiming that accuracy from twist drills, they didn't exist before 1860ish, at best. No disrespect to the OP, just pointing out where things don't add up.

Not quite sure exactly what you are saying.. it's a bit disjointed.

The article linked to by Rob was about a guy who worked making tooling for making pianos... I've no doubt he did work for some company drilling holes in wood for pianos, and he believes the accuracy he claims, it's a bit of a stretch to then claim that some unknown piano maker doesn't know about wood movement.. I'd prefer to think it's more likely he was just exaggerating the accuracy for the purposes of impressing his fan club. A mix of myth and anecdote intended to highlight the importance of accurately ground twist drills in a production environment. No surprise there.

Storm in a teacup.

Ray

[sossity]

You beat me on that one Simon.

I am a member of an Audio Forum based in the US. There are people on that forum that claim they can pick the difference, not just between different speaker cables, which is an argument that has been ongoing for years, but that they can pick the difference when using different extension cords to connect the audio system to power. You do have to remember that they are using 110v so that would make a difference compared to our power supply effects. I am not joking about this.

Dean

Last time I looked (which is quite a few years ago I must admit), they used to insist on oxygen free copper in their cable, and could tell the difference depending on which way round the speaker wire was connected (what end was connected to the amplifier)
In the old days, the audiophiles used to love listening to radio 3 on the BBC (classical music). Especially live concerts, because they had the impression there was no processing involved, and so this was the purest source they could have. I used to work in the BBC and when CD's first came along, the audiophiles used to phone in complaining that the CD's were giving them headaches and they could hear all the quantisation noise, and could we stop using them. What they didn't know was that for the last year before CD's, we had been distributing radio 3 over NICAM, which was a lossy system, unlike CD's which are lossless. No-one complained about NICAM because they never knew it was there. Still, what can we say, if you read this forum we mostly seem to buy machines so we can make/repair machines. There's nowt stranger than folks, as they say.

[Pete F]

Not quite sure exactly what you are saying.. it's a bit disjointed.


"any moving part on an action ran on pins 0.0505" in diameter, a standard reached in the late 18th century but unfortunately a size no drills exist for. In the early days of the 20th century they made drills by filings tool steel wire down, hammering and filing into a spade bit then hardening. In my day we bought HSS drill blanks in exact size then hand ground these into spade drills"

Sorry my post was "disjointed" Ray. I've highlighted the appropriate section I was referring to. 0.0505" is roughly 1.3 mm (1.2827 mm in fact for those paid-up members of the pedantic club). Again, there were other types of drills available prior to the invention of twist drills, some of which were alluded to in John Stevenson's posts. However I'd be surprised if I were to learn "micro-augers" featured amongst them.

I have enormous respect for John Stevenson, have learnt a lot through his writings, and have "spoken" with him many times via email, so I'm reluctant to doubt what he claims. However by the same token I have every reason to doubt the accuracy being claimed, in addition to why there would be any good reason to aim for that degree of accuracy in the first place. While the wood may well be of a specific moisture level while being worked, as soon as it leaves the workshop that will change, therefore so will the hole size. Furthermore, if accuracy of that order was indeed demanded, why spend hours (as claimed) setting up machines to drill holes that accurately, when they could be reamed to precisely that size as a second op. The whole story makes no sense, at least as it appears, on a number of grounds.

However I don't think Rob's intention was to dispute the integrity of the posters, and the thread was an interesting one in regard those drill sharpening jigs. I have one and never was happy with it. I found it clumsy to set up, not at all accurate, and painfully slow. Good luck to the gentleman who modified it to supposedly perform better. Having said that, I prefer modified drill points myself, as suggested by JS, as they drill a lot more accurately and with less pressure. If anyone is interested I'd suggest looking up multi-faceted drill sharpening; essentially just sharpening them as you would an end mill. Reading through the whole thread it was a shame to see it disintegrate to the point where the original poster decided to quite the whole forum in frustration. But then again, I can empathise with him!

[Oldneweng]

Last time I looked (which is quite a few years ago I must admit), they used to insist on oxygen free copper in their cable, and could tell the difference depending on which way round the speaker wire was connected (what end was connected to the amplifier)
In the old days, the audiophiles used to love listening to radio 3 on the BBC (classical music). Especially live concerts, because they had the impression there was no processing involved, and so this was the purest source they could have. I used to work in the BBC and when CD's first came along, the audiophiles used to phone in complaining that the CD's were giving them headaches and they could hear all the quantisation noise, and could we stop using them. What they didn't know was that for the last year before CD's, we had been distributing radio 3 over NICAM, which was a lossy system, unlike CD's which are lossless. No-one complained about NICAM because they never knew it was there. Still, what can we say, if you read this forum we mostly seem to buy machines so we can make/repair machines. There's nowt stranger than folks, as they say.

Which end is connected? That is a new one. I try to use Oxygen Free Copper (OFC), but I believe this is more related to longevity than sound (corrosion free). I have a pretty good audio system, but I don't think I can pick the difference with this stuff. I have an audio system to enjoy it, not to pick holes in it.

I would like to see the results of a test set up to prove/disprove this sensitivity to sound. Personally, I think that if you have hearing that sensitive, you are unlikely to enjoy the music as you will always be picking fault.

Dean

[Ueee]

Its dead easy to pick the difference between a CD on a transistor system and a record over a valve system. Just listen for the noise between tracks.....(and sometimes during the tracks):D
Some music, for me particularly jazz, just sounds better off a record, but lets face it, i don't really get the time to sit down and just listen to music any more! Once it becomes a background sound i couldn't care less what its played from.

Ew

[thorens]

Its dead easy to pick the difference between a CD on a transistor system and a record over a valve system. Just listen for the noise between tracks.....(and sometimes during the tracks):D
Some music, for me particularly jazz, just sounds better off a record, but lets face it, i don't really get the time to sit down and just listen to music any more! Once it becomes a background sound i couldn't care less what its played from.

Ew

Ew , I didn't know you are an audio man as well and love records :)

Peter

[Ropetangler]

I note that most think that the need for drilling holes to such accuracy levels in wood is a waste of time and effort because of the effects of shrinkage and expansion due to changes in water content of the timber. This was also my initial thought, but then I thought of the hole size and how that size was most likely arrived at. With a pin or axle size of 0.0505" itself initially surprising to me for material specification in the 1700's, the hole may have been around 0.0520 say for a sliding fit, and I imagine that this size was arrived at from hard won experience, with that experience saying that any smaller and there would be issues from time to time when drier conditions caused wood shrinkage and a tightening of tolerances, and making it bigger just made for a looser keyboard say, so that size was made the default size for production purposes. Not having knowledge of the timbers used and their properties, I can't comment on the likely variation of hole size due to changes in humidity, but I can say that with Tasmanian Celery Top, the shrinkage is very low, low enough that window frames can be made with unseasoned timber, and there would be a low likelihood of problems as they seasoned over time. One source gives the change in dimension as 0.19% for every 1% change in moisture content, from 3% to the point of fibre saturation.http://www.woodsolutions.com.au/Wood-Species/celery-top-pine This works out for about a 0.001" change in size for a 10% change in moisture content at these sizes if they had used Celery Top, but like I said I do not know the timber qualities of the material they used in the critical parts of the piano movement. Taking into account the use of a low movement species of timber, and a pin size of only 0.0505", I am not that surprised that a tight spec could be called for, and at some point a change in size of only 0.0005" could make the difference between a small but significant number of problems, and virtually no issues at all. Over to you blokes,
Rob.:)

[Oldneweng]

Its dead easy to pick the difference between a CD on a transistor system and a record over a valve system. Just listen for the noise between tracks.....(and sometimes during the tracks):D

I can honestly say I have never heard music fro a valve system except for guitar played thru an amp. What about music ripped from a record and recorded as wave and then converted to MP3 and played on a transistor system? I can certainly tell the difference easily. I silence the gap between tracks as well. Some of my records have no damage. I have some that have only been played a couple of times. If there is to much noise during the track I don't bother with the recording.


Some music, for me particularly jazz, just sounds better off a record, but lets face it, i don't really get the time to sit down and just listen to music any more! Once it becomes a background sound i couldn't care less what its played from.


I do sit down just to listen to music occasionally. I don't have a turntable set up to run off my audio system and in fact it does not have a magnetic preamp to allow it. I only set up the turntable to rip music. I agree about the background sound up to a point. If a radio transmission has static, I get away from it as soon as I can. My ears and me cannot deal with it. I was listening to music today in the shed. I have a cheap audio system (pretend surround - get real people) I used my tablet to provide the music for the first time. As background music, I thought it was quite acceptable. If I was sitting down, concentrating on it? I spent $1700 on a pair of speakers last year. Worth every cent. Fabulous.

Dean