Thread: Defender Imperial or Metric?

Originally Posted by Zeros

Honorary PhD required 🙂

To be a fitter-machinist first class with Advanced Machining Certificate plus a number of other post trade certificates takes longer to get than a Ph.D (or Dott. Phil. if one went to the other university). Add in twenty years importing and selling machine shop supplies with a major emphasis on rare, obsolete, hard to find, and "no longer available" taps and dies. I could have banged on about the more obscure systems like BA, Admiralty Fine, Bottle Closure, and the plethora of Metric systems, erc, etc.

Originally Posted by bee utey

The Puma 90 I worked on last month still had imperial tailshaft nuts and bolts as they were never updated.

Yes the 3/8 UNF nuts on the prop shafts are one item that has never been updated.

Originally Posted by Kidbeen

The bolt heads appeared to be rather soft. Is that due to the effect on the steel of heating and cooling all the time? .

A LOT of bolt heads used on a Land Rover are made of cheese, you often get ONE careful go using a 6 point socket at undoing it before the head strips round.

Originally Posted by Bigbjorn

To be a fitter-machinist first class with Advanced Machining Certificate plus a number of other post trade certificates takes longer to get than a Ph.D (or Dott. Phil. if one went to the other university). Add in twenty years importing and selling machine shop supplies with a major emphasis on rare, obsolete, hard to find, and "no longer available" taps and dies. I could have banged on about the more obscure systems like BA, Admiralty Fine, Bottle Closure, and the plethora of Metric systems, erc, etc.

Roger that. Honorary Post-Doc too! Cheers Bigbjorn, keep it coming!

...One of the reasons I like being on AULRO is that I learn huge amounts from people with knowledge in fields other than my own...particularly mechanical engineering!

Fine threaded fastener are imperial. UNF. Coarse threads are metric. There are some exceptions but that is pretty much it.

Originally Posted by Bigbjorn

To be a fitter-machinist first class with Advanced Machining Certificate plus a number of other post trade certificates takes longer to get than a Ph.D (or Dott. Phil. if one went to the other university). Add in twenty years importing and selling machine shop supplies with a major emphasis on rare, obsolete, hard to find, and "no longer available" taps and dies. I could have banged on about the more obscure systems like BA, Admiralty Fine, Bottle Closure, and the plethora of Metric systems, erc, etc.

I used to have (likely still do have if I looked, still have the toolbox I had back then) sets of BA tube spanners, open enders etc.... Installing/maintaining British electrical instrumentation and protection systems etc...

Originally Posted by tact

I used to have (likely still do have if I looked, still have the toolbox I had back then) sets of BA tube spanners, open enders etc.... Installing/maintaining British electrical instrumentation and protection systems etc...

Little tiny spanners for little tiny nuts and screws. The biggest, 0BA is roughly equivalent to 1/4" BSF and they go down to 22BA which has a major diameter of 0.0146". A 47.5 degree thread form originally from Switzerland and known then as the Thury thread. The British Association adopted it in 1884 for use on small fasteners mostly in electrical and instrument applications. Dimensions and pitch of BA make more sense if metric measure is used. Now obsolete and I don't know if any manufacturer still uses it. Repairers and restorers still have a place for BA tools. The taps and dies get disproportionately more expensive as the sizes get smaller.

Originally Posted by DazzaTD5

A LOT of bolt heads used on a Land Rover are made of cheese, you often get ONE careful go using a 6 point socket at undoing it before the head strips round.

Thanks for that. I laid the blame on myself for rounding the heads. Thought they must have gone soft from the constant heating and cooling.