Screw thread handbook

My 1977 copy of Bradley's handbook 'Screw Threads and Twist Drills' is falling to bits and is probably out of date with regard to metric threads.

Is there an up to date similar handbook?

Try **LINK**

Other retailers do supply

The Zeus handbook is pretty good. That said, I usually refer to my inherited 1941 Machinery's handbook, because it's much easier to find, and nothing regarding screw threads or drill sizes seems to have changed much.

If I can't find either, I usually try Maryland Metrics for threads and tap drill sizes.

Andy

"If I can't find either, I usually try Maryland Metrics for threads and tap drill sizes"

Thank you, Andyf. Very comprehensive.

Regards, Bear..

Bear, bhere's an even better German website, but I don't have it bookmarked. Maybe someone else knows the one I mean.

Apologies for dragging this into the cyber world, Merlin. I appreciate that you probably want a book you can keep in the workshop.

Andy

If you want to download and print tapping/clearance sizes the **LINK** is a good site - print page logo top right or page.

Good bit of software called Threadpal has a trial version

May I suggest Merlin that you consider The Metalworkers Data Book, Workshop Practice Series number 42. Over 200 pages of data and only £5.12 from Amazon with free deliver in the UK

See here Also here

Harold

Advertising again Harold

I thought you would never notice!!

Harold

Hi Everyone, Some good METRIC info. here. **LINK**

Regards, Bear..

Hi,

For just about any data you are likely to need (and some you will not) download 'Model Engineers Utilities' from here. Install it on your PC and never need a 'Handbook' again. And it's free. unlike books from Amazon!

Best regards,

Terry

The ultimate book is Guide to World Screw threads.

Not cheap but then quality never is.

Edited By John Stevenson on 14/12/2012 22:49:04

Sorry John Guide to World Screw Threads may be the ultimate book but its still not comprehensive, I've hit a few that weren't in there. Newnes Engineers Manual and Caxtons Engineering Workshop Data fill in some of the gaps. Especially with handy dandy listings of some of the oddball special purpose short series, plating allowances, washer sizes et al too although horribly out of date by now at least they give you some idea. (Nice to discover that that box of high quality but way out of spec bolts I found were actually made to size for thick chrome plate!)

Not a handbook but really helpful when a "Can you fix this?" job comes out all obscure is the listing of of a wide range of threads in ascending size order originally due to Andy Pugh and extended / reformatted by other workers. The original is at :- **LINK** Two other sources are **LINK** and **LINK** . The last is probably nicest formatted version.  I now use an Excel format version but I don't know where that came from.

Clive

Edited By Clive Foster on 15/12/2012 00:04:21

Clive, I dare say none of the lists are comprehensive.

That first link of yours is missing 24 and 25 BA

This is the reasonably comprehensive German list I mentioned earlier on. It displays a lot of boxes saying "Web page can't be found" but that seems to be because adverts have gone missing. 24 and 25 BA are listed, though.

Andy

Agreed John comprehensive is indeed probably an impossible dream. Especially if you consider the OEM specials used by, for example, instrument makers (Hi Mr Starrett), carburettor companies et al. So we are stuck with multiple sources. Short series listings where a few threads have been pretty much agreed on by industry for specific applications can be a great help as knowing what its for cuts through the "which form is it / nearly the same metric or imperial" confusion which can be a major pain. Most specials seem to be itsy bitsy tiny or / and very short which doesn't play well with 58 year old eyes.

I do wonder what some of the standards committees were smoking and drinking at decision time tho'. BA threads no 20 and below vary in diameter by around a couple or three thou and pitch increments are around 3 to 5 tenths of a thou! Leaving aside the practical difficulty of separating t'other from which when identifying a replacement and whether or not producing threading tooling to the necessary precision was actually industrially realistic at the time the standards were defined you have to ask just what difference such small variations make in engineering terms. Probably yet another demonstration of the ease with which complete disconnection from reality occurs when using the all too often obnoxious metric system. So easy to drop another decimal place without thinking it through. Seamless progression through many orders of magnitude can be great when doing science but, cumbersome though they are, fractions have something going for them when interpreting engineering.

Clive

Most Imperial precision engineering is done in the decimal system not fractions which are too crude, one only has to browse ME or MEW to see that. Are you saying that decimal places do not get misplaced in the Imperial system?

The only time we used fractions in my engineering days was for large fabrications or for carpentry. If you wish to see the ridiculous you only have to look at some American engineering drawings where there is often no limit to the number of decimal p[laces and one gets dimensions with 6 decimal places when fractions have been converted willy nilly.

Regards

T

I have just had a look at the above quoted German list, which is the DIN standard document, and the Maryland Metrics document. The latter appears to be a copy of the former. And I thought the common camera tripod mounting thread was 1/4 Whit! I am told it is 1/4 UNC.

No list of threads can be comprehensive. In the last ten years I have used the British Standard Microscope thread, a Whitworth thread, and I have no idea where I got the details from. In addition it was common practice in some companies in Britain at least to use their own threads. These were usually Whitworth form but with the wrong number of theads for their diameter. Three offenders come to mind, BSA (the bolts that held the sprocket onto the rear wheel on some of their motorcycles, AJS (pre1931) on engine parts and Bristol Engines on their big radial engines.

JA

Terryd

Decimals get misplaced or taken to excessive extremes whatever the system. Problem with metric is that its seamless nature and limited unit set make it very easy to follow a logical path from sensible to just plain silly. With imperial there are plenty of potential "hang on a sec" break points and different ways of setting up the problem making it easier to see when the line is being crossed. Inappropriate units is always a good indicator that someone has crossed the line or is trying to pull the wool.

Good point about engineering being in decimals but this not so much intrinsic as due to the fact that most of the time clearances or fits are what matters. If you need a ten thou clearance on diameter between shaft and hole then obviously you must work in thous (decimals) as this is an appropriate unit for clearance but for fundamental engineering it (usually) matters not a jot whether the shaft is 0.500" and the hole 0.510" or the shaft 0.490" and the hole 0.500". Fact is no one would be surprised if the whole kit and caboodle would engineer to work just fine with a 3/8 or 5/8 shaft. Of course if you see a call out of 0.5118" you know there is a metric conversion from 13 mm going on but when you see things like 0.5256" its fairly obvious that its time to check the maths and drawings. 13.35 mm is just as potentially silly but it doesn't stand out as much.

My wage slavery was as a scientist / R&D engineer and I saw plenty of occasions when people (including me) went seriously awry due to following the numbers and loosing track of what they meant. Once had to teach half the attendees of one meeting imperial and fractions from scratch to blast them out of a rut of vastly excessive performance expectation due to chasing the metric numbers. (Self protection as I was gonna have to build something to demonstrate what was decided upon! ± 10 nm range-finding at 10 km, get real guys!!).

Clive