Imperial measurements

[osgii]

Guys,

I don't really know if this concern must be under the "technical" category, as it is more a general matter. Please move my thread if needed.

I ordered several times nuts and bolts from Namrick (which are very helpful). Unfortunately, the received parts are not always the same dimensions than my measurements.

Within a few days, i'll have a big order to do and I want to be sure about what i'm ordering, so that's why i'm asking for some help.

I made a little technical drawing to help you understand my measurements.
Unfortunately for me, my digital caliper only displays decimal inches, and not fractions (which seems to be more commonly used...).



If I understand correctly, my thread size is 0.18. If I do a conversion, the closest fraction is 3/16. But there is no such dimension on Namrick's online shop, so what size should I pick then? The closest is 1/4, but it's 0.08 inches away from my measurements... Is there a trick, or a rule, like "always take the closest upmost"?

I have exactly the same problem for nylocs and nuts.

If someone can point out what i'm doing wrong, it will be really appreciated and helpful.

[1954Etype]

3/16 threads are available. I buy all my fasteners from Charnwood Fasteners Ltd - good guys and they know their stuff. Www.charnwoodfasteners.co.uk.

[Tony]

You can say that again?

[1954Etype]

Deleted duplicate post Tony! (saw Barry today, he still regrets selling you his car!)

[Tony]

Oh no , now my post makes no sense. How is Barry doing, has he started any new projects. The car is still getting compliments from other jag owners.

[1954Etype]

He's fine. Just finjshed an XK150 drophead but, as I warned him, completely different drive to the E!

[christopher storey]

A few observations .

1.The head size is irrelevant except for choosing the spanner to fit

2.Measuring inches even to 2 places of decimals is not sufficiently accurate to identify a fastening because as you have noted the sizes were vulgar fractions and not decimal, so 3/16 is 0.1875

3. First identify the type of thread . The common ones on Jaguar are UNF , with some UNC where they go into alloy , and a very few Whitworth . In the small sizes e.g. trim fastening with very fine threads ( the armrests are a case in point I think ) you may find BA ( British Association ) threads or BSF which were in essence a finer version of Whitworth. The easiest way to identify threads is to buy a thread gauge which gives you ( for metric threads) the pitch in millimetres e.g. 0.7 means a thread every 0.7mm , and for imperial gives you thread per inch e.g. UNF 1/2 X 2 -20 is a half inch thread diameter, 2 inches long with 20 threads per inch - a similar size UNC bolt would only have, from memory, 13 threads per inch and would be designated UNC 1/2 X 2 - 13

[abowie]

..and 4 the bolt length is measured from under the head to the tip so doesn't include the thickness of the head.

If you haven't already this is worth a read too..

https://dl.dropboxusercontent.com/u/849 ... teners.pdf

[rfs1957]

It's worth reminding those that are new to bolt identification that you rarely find the theoretical dimensions in real life - OD's are always undersize on used bolts - and that BA threads don't "do" either TPI or a simple metric pitch, which is confusing when you can't find a "comb" in either the Imperial or the Metric series that will fit your bolt.

These people have the Moore + Wright combs I have always used, the 806 series does all the Imperial TPI stuff, and the 801 the Metric - between them I've never needed anything else.

http://www.toolfastdirect.co.uk/acatalo ... ages_.html



Sorting out bolt identification like this doesn't require elaborate reference works, I would stand by my "kids' stuff" as suggested earlier, since it fits in your palm or top-pocket or on top of the lathe :

http://www.ebay.co.uk/itm/Zeus-Precisio ... 2c5f74591c

I use these pages as A4's on a 10-leaved / 20-sided flip-display on the 2-post-lift column so that they are immediately to hand, in a fixed position, and can survive greasy-fingers.



Inch - Metric conversions here :

https://www.dropbox.com/s/q2juuackzi2r9 ... lents.docx

and - REALLY USEFUL - when confronted with unfamiliar bolts, Spanner Conversion Tables here :

https://www.dropbox.com/s/8aqreq3nttjj9 ... Sizes.xlsx

[abowie]

and - REALLY USEFUL - when confronted with unfamiliar bolts, Spanner Conversion Tables here :

https://www.dropbox.com/s/8aqreq3nttjj9 ... Sizes.xlsx

Nice one Centurion! This is a very useful thing, and explains why the 1/4 Whitworth heads on the top of SU float chambers won't fit anything else I have in my arsenal.

[frogeater]

Deleted duplicate post Tony! (saw Barry today, he still regrets selling you his car!)

Does he mean, because of his son (who break the car when he use it)? :)

[38E]

The most likely reason you cannot find 3/16" bolts is because bolts and screws smaller than 1/4" nominal diameter are usually referred to by a number. (12, 10, 8, 6 and so on.)

So a bolt that is 3/16" diameter over the threads, such as the one you show would be called a #10. Then you need to specify the threads per inch (or tpi) which could be 32 or 24. So the bolt would either be called a hex head 10-32 x 1/2" or 10-24 x 1/2".

Another complication is that a 3/16" screw on an E-Type could possibly be a BA size.

So also I'd recommend the Zeus booklet already mentioned and a set of thread gauges.

[osgii]

Thank's to you all for the answers guys!