Are standard “M4” nuts & bolts normally fine or course pitch?

[SillyOldDufferModerator @sillyoldduffer]

Posted by Simon Williams 3 on 13/01/2022 22:40:46:

I read that mnemonics are the more effective the more outrageous they are.

Thus SOHCAHTOA, becomes instantly rememberable as "Sock it to her" especially to those of an age and disposition to remember Rowan and Martin's Laugh In

Rgds to all

Simon

You bet your sweet bippy!

I thought Rowan and Martin's Laugh In was excellent even though a percentage of jokes were unintelligible American references. The parody news bulletins from Downtown Burbank were probably funnier in California than Nempnett Thrubwell. But the joke works throughout the English speaking world when an attractive young woman is drenched in water after saying "It may be rice wine to you, but it's Saki to me."

I wonder if 'Laugh In' stands up today? At about the same time I thoroughly enjoyed 'The Man From Uncle', but the years have been very unkind to that – lost it's sparkle completely.

Dave

[Nigel Graham 2Participant @nigelgraham2]

To the original question…..

Yes, normally the standard Metric fixings are in the Coarse range. If you need M-Fine you'd have to seek them out especially.

However….

There are Metric Coarse range threads with alternative pitches so you may have been caught by this:

M3.5 X 0.6mm (Tapping drill 2.9mm)

M4 X 0.7mm (3.3mm)

M4 X 0.75 mm (3.25) Not a "preferred" thread, it seems.

M4.5 X 0.9mm (3.75)
'

Those Tracy charts (quoted above) give all the standard M_ Coarse and Fine series by diameter, pitch and tapping-drill; and the tapping-drills recommended for all threads (BS, UN, BA, ISO), in readily-available mm diameters. The foot-note says these give around 65% full thread depth – the user to determine by experiment if a particular application needs an alternative depth.

Some of the less-common M-Coarse, and M-Fine, taps need tapping drills to 0.05mm – I assume reasonably easy to buy.

I have not used number drills for years and don't recall using my letter-drills set!

'

Usually I avoid buying fasteners from the DIY supermarkets in favour of the building-trades chains, on the premise that they are supplying the trade so a bit more careful about quality – and often cheaper.

'

I like those other mnemoics but stick to the "Trigonometrical Volcano" because a) SOHCAHTOA is the only acronym among them, and b) one of my other interests is Geology!

I would if I really have to, calculate tapping sizes but always endeavour avoid turning on the computer, navigating the wretched "cookie" traps, ferreting through the offered web-sites and so on, just to read a common, standard diameter established years afore The Home Computer.

When I use t'Net for more arcane information (rarely), I would probably print the tables for future reference.

Instead I have a reasonable library of reference-books for both the hobby and the trade; and two pairs of each of sets of look-up tables. They are the Zeus book, and the poster-size, double-sided Tracy Tools charts giving dimesion conversions and all the tapping sizes I'll need. One copy of each in the workshop plus a cheap, basic calculator (used in a protective freezer-bag); t'others plus scientific calculator near the computer for CAD reference.

Surprising invention, printed information, you know. I gather the principle goes back centuries, like that of Matrices but without their abstruse abstraction; but offering simple, rapid, direct reference not needing electricity and not going all unsupported on a Californian whim…. I wonder if it will catch on?

[John Smith 47Participant @johnsmith47]

Posted by Thor 🇳🇴 on 13/01/2022 06:42:03:

Hi John,

Harold Hall has a very good page on tapping drill sizes, and he gives various depths. You can get data for both Metric, BA and ME threads. I use about 75% for softer materials and somewhat less for harder materials.

Thor

Harold Hall's page looks like a very useful resource. I have bookmarked that. Thanks!

Re the "Zeus book", is this thing published by Roebuck, what you all mean?
It looks like different versions exist… Which one is best?

e.g. This one by RGDTools.

"RDGTOOLS ZEUS CHART 2008 LATEST REVISION"
**LINK**
https://www.amazon.co.uk/RDGTOOLS-ZEUS-CHART-LATEST-REVISION/dp/B00S9SVESM/

Or this one…
**LINK**
https://www.amazon.co.uk/workshop-decimal-equivalents-details-clearance/dp/B00C77BX46/
(Looks similar but seems that it is not from RGDTools)

Or this one
**LINK**
https://www.amazon.co.uk/Precision-Reference-Drawing-Toolroom-Workshop/dp/0999275011/ref=monarch_sidesheet

(But surely that can't be the correct image??)

Fwiw, wherever possible I always use metric.

J

[Martin ConnellyParticipant @martinconnelly55370]

It's the yellow and black one in the first image that is being referred to. I have two, the latest has some CNC codes instead of logs and antilogs. Neither of them has the addition of Roebuck on the front of them, the name of Buck and Hickman's own brand tooling. One is copyright 1980 and the other is copyright 1995. The information in them doesn't go out of date but clearly the use of logs is considered obsolete since people have calculators as stand alone equipment, on mobile phones or pads, or on some DRO units or shop based computers. I think I need to see what is in the latest books to see if a new one is in order, a birthday of Christmas present maybe.

Martin C

PS Just had a look on line for the latest version and I have to say there are some people looking to make a lot of money from selling these at a very inflated price. If you look to buy one make sure it's not overpriced, compare it to other suppliers. As a guide the current prices from RDG and RUBIX, the people who are now the name for Buck and Hickman, should be used as a guide to a reasonable price.

Edited By Martin Connelly on 14/01/2022 21:25:02

[Dave SParticipant @daves59043]

Six Old Horses

Cold And Hungry

Tan is the other one… (I'm sure there is a proper one for this)

Metric tap drills I use M number – pitch, then pick the closest I have available, being mindful of too small hole -> more likely to snap a tap, too large hole -> more likely to strip when tightened .

Dave

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