Drill bit sizes

A question recently arose on a classic car group to which I subscribe, and as it has an engineering relevance, I wonder if anyone on here could help. It regards the use of the phrase Morse 61-58. Whilst a number of contributors were aware of the "Morse taper", as this was specifically referencing a carburettor gap setting usually given in thousandths of an inch and often using a drill as a measuring aid, it was suggested that Morse may be related to the numbering system used for drills.

Does anyone have any knowledge of this?

Thanks

Peter

About half way down this thread **LINK** there is a page from the first edition of Machinery's Handbook which refers to the differences between the size of the same number bit from the Standard Tool Co. (whose bits were based on Stubb's Iron Wire Gauge, and included half sizes) and the "Manufacturer's Standard" used by the Morse Twist Drill & Machine Co. and Brown & Sharpe. Perhaps the reference to Morse is to ensure that the "Manufacturer's Standard" and not the Standard Tool Co. drill was used?

Brian

A good find, Brian ... and your logic seems very sound, to me.

MichaelG.

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For the sake of meticulous attention to detail [O.K. perhaps gratuitous pedandtry] I must mention that the apostrophe in the original is correctly placed.

For the sake of similar meticulous attention, I feel it necessary to note that there are more than one apostrophe in the original!!

Hmmm... since there is a number of 'em, should that be "...there are more than one apostrophes..."?

As you are talking about one apostrophe (even though there are, or could be, others) it surely should read "...there is more than one apostrophe..."?

May I observe that an apostrophe looks remarkably like a pinhead....

.

Yes you may ... 'though I would probably disagree.

Punctuation is my downfall, although I normally trip up on semicolons. Whilst on the subject of punctuation as opposed to drill numbers, what is the Model Engineer style guide's position on Oxford commas? (You'll never know how much effort it took to avoid a greengrocer's apostrophe at the end of that sentence).

Brian

EDIT:  Back on the subject of drill numbers, whilst we can see a logical explanation for number drills being derived from wire gauge, is there a similar rationale for letter drills, or are their sizes completely arbitrary?

B

Edited By Brian G on 11/05/2018 21:42:44

Sorry for starting all this nonsense, Brian

... My point was serious, but probably not worth making.

The original mentioned "the manufacturers' standard" because the standard was common to more than one manufacturer.

MichaelG.

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I may regret reviving this, Brian ... but I have just come across an excellent example where an Oxford comma would disambiguate a statement [which is, in this instance, a book subtitle].

Title: The World of Leonardo da Vinci

Subtitle: Man of Science, Engineer and Dreamer of Flight

That subtitle would be clarified by the insertion of the Oxford comma, thus:

Subtitle: Man of Science, Engineer, and Dreamer of Flight

.

My personal style-guide is that [used properly] they can help convey the writer's intention.

MichaelG.

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Note: Someone will probably now assert that the list was only intended to contain two 'roles' rather than the three that I have forced upon it.