Re: Dodge caravan Metric Tools?

Tegger  <tegger@[EMAIL PROTECTED]
> wrote:
>> The DIN (Deutsches Institut für Normung) EIS standards and the JIS
>> share a lot BUT there are more than a few gotchas in the mix.
>> Depending on the thread pitch itself the root diameters and thread
>> wall angles may be different. In practical use it means that you may
>> have a M-8 bolt in JIS and an M-8 hole in DIN and they will not go
>> together. Things like head bolts on German autos and bottom end parts
>> are a couple of the OOPs areas I have run into.
>
>I had NO idea, so thanks.
>
>We have two Japanese cars, and Japanese is all I've ever owned (with the 
>exception of one Dodge Coronet).
>
>Any Metric fasteners I've ever bought have come from all sorts of places,

>from the auto dealer to auto parts jobbers to the corner hardware store. 
>I've never encountered any sort of problems with the fit of any bolt in
any 
>hole. Nor have I ever been asked which standard of Metric fastener I 
>require.

Some of the thread profiles are the same, and the ones that aren't
are mostly close enough.  

For most things, there's not a big deal, but if you have bolts that need
to be torqued precisely, it's a huge deal.  This makes it a big deal for
the aircraft industry.

It's also a big deal on very small parts where the torque to seat them
and the torque to strip them are sometimes already very close.  I
encountered
that issue with M1.5 screw on the Studer (German) tape machines.

>I have a Metric tap and die set. The labeling does not specify the
standard 
>to which the tools conform.
>
>I'm thinking either most fasteners must be made to a single standard 
>(DIN?), or the standards are so similar you'd need to find yourself in 
>unusual situations to see any difference.

Yes, this is what makes it so insidious.  Everything is mostly fine until
you find yourself in an unusual situation.

It't not QUITE as bad as Whitworth threads... a 1/4-20 Whitworth bolt will

fit into a 1/4-20NC nut but the 1/4-20NC bolt won't fit into a 1/4-20
Whitworth
nut.  Or is it the other way around?  Legions of folks ruined MG engine
blocks
this way.
--scott
-- 
"C'est un Nagra.  C'est suisse, et tres, tres precis."