whitworth question

[river1]

any whitworth experts in the house?

i have a bolt that is the same diameter as an American 1/2 in bolt, but it has 12 threads per inch where the American is 13 threads per inch.
is it possible i have a whitworth?
if so where can someone in the staes find one?
are they available in stronger strengths like grade 8?

thanks in advance

later jim

[enjenjo]

Whitworth threads are squared off, kind of like an Acme thread. I would guess you have a metric bolt, 13mm by 1.5mm

[river1]

i thought about metric but couldn't get a match at three different stores, including mark's nuts and bolt where all they sell are nuts and bolts. there is another bolt store here in the valley, i'll go look there tommorow.

thanks frank

later jim

[chimp koose]

take a thread gage and check the included angle of the threads . Whitworth threads have a 55 degree angle as opposed to the 60 degree found on american national , unified national and metric threads. I was told by an old machinist that these were made so that the germans could not salvage hardware off british equipment during the war.

[Carnut]

Wiki has some info on British Standard Whitworth.

http://en.wikipedia.org/wiki/British_Standard_Whitworth

[C9]

A difference in thread angle as noted, but I found I could use American bolts in many areas on my 1956 BSA Alloy Clipper (6 days trials bike).

Whitworth wrenches are marked differently than American wrenches.

They used bolt shaft size instead of hex size.
A wrench that looked like a 3/4" American size-wise would be marked 1/2" etc.

You may be able to find Whitworth bolts and nuts at a supply house that caters to restoring British bikes and cars.


Any chance the bolt is "home-made?"
Sometimes home machinists will make oddly threaded stuff.

I do once in a while.

Just got finished with a screw on aluminum gas cap that has 2.040 x 11 threads.

And a spare cap to carry along....

[wayne petty]

i have a 1/2" -12 tap in my tool box....   i never looked close at the thread angle...  but i have picked it up too many times to use......

i seem to recall getting it from washington hardware in los angeles... it was a  surplus store with hundreds of tons of WWII surplus...  i almost cryed when the old man passed away and they started hauling it out the door into scrap bins..   i was reminded and visited cal aero supply in paramont ca... they still have some of the great old nuts and bolts.. but only a fraction of what washington hardware had.. i spent days there.. just wondering around looking in bolt bins.. i don't think i ever saw everything..

somewhere in a box.. i have a general tools catalog... it lists dozens of special sized taps and dies..   with some really creative thread counts... including the 1/2"-12.... they don't list the uses... or history....

as for there being bolts stronger than grade 8... yes.. in some sizes...  there are grade 9... i saw them a few days ago at mcmaster carr...  

http://www.mcmaster.com/#grade-9-steel-bolts/=49s9e2

there are also aircraft bolts..  but those are a little harder to select by size.. they are sometimes only listed by part number.. prevents someone from using the wrong bolt in the wrong app...


one more funny...   the owner of one of the engine rebuilders worked in the car pool during the WWII...   somebody took apart to rebuild an engine in a Spanish built truck...  they threw all the nuts and bolts in a bucket to wash them...    problem..   the fasteners on that truck were not standard sized... each bolt only fit one nut..   he described taking almost a month to put it all back together..


http://www.britishfasteners.com/mm5/merchant.mvc?Screen=PROD&Product_Code=1595&Store_Code=BTF&Category_Code=40

this shows the thread angles and a little history of bsw threads

http://www.ides.com/articles/design/2006/beall_10.asp

[kb426]

I have a set of Whitworth end wrenches left over from my British bike days. No spare bolts and no memory of what there was.