Try **LINK**

Other retailers do supply

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

Thank you, Andyf. Very comprehensive.

Regards, Bear..

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

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

I thought you would never notice!!

Harold

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

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of some of the oddball special purpose short series, plating allowances, washer sizes et al too although horribly out of date by now at least they give you some idea.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

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

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

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

Hi John

Miserable foggy day here – no motivation to do anything so I got to browse a few "Threads" ( no pun intended) and came across your advice :-

"The ultimate book is Guide to World Screw threads."

Now I may just put that on my list for Santa – It sounds like an excellent cure for insomnia!

Cheers

Norman

Clive;

My wage is as a scientist/R&D engineer.

I think you are confusing "understanding numbers" and metric/imperial. Not a lot of people "see" numbers, especially in this age of computers and cash registers that tell what change to give (for those of us still carrying cash!)

Another JohnS

Edited By John Alexander Stewart on 19/12/2012 18:50:50