14mm spanner

As JS indicated spanners are made to use with nuts that they fit.

Today I had need of a 29mm AF spanner to remove a two stage thermostat from a car radiator . Because of its restricted access and attached wires, It had to be an open ended spanner which is a size I've never needed before.

Although I dont like doing it was able to enlarge an existing 94AF spanner so it fitted a 29mm hex!

I've had the spanner for at least 40 years and definitely not used it in the last 25. (I still have another 15/16" AF anyway).

I have a few other spanners that have end marked in fractions and 'decimals' of an inch but I wonder if any fitters or mechanics ever used the decimal inch markings.

Ian P

I've an old toolbox full of spanners and sockets that I rescued from scrap cars. I have absolutely no qualms about modifying them for special jobs. If that means chopping them down to fit or bending them to clear an obstruction, then so be it.

This was a tired 30mm socket with worn 1/2" drive hole. I bored the hole to accomodate a Torx socket, and welded on a piece of strap to make a spanner for my cambelt adjusters. I could have bought the cranked spanner to do the job, but this tool took about 10minutes to make and saved about £40.

There was a mention of a 25/32 in spanner,this was known as united States standard,the US like the UK used a larger nut size pre WW2 for their standard coarse thread series. e.g. 5/16 dia had a 19/32 hex,7/16 dia had a 25/32 hex and 9/16 had a 31/32 hex. In my set of Ring spanners now over 50 years old there is a 25/32 size only used in recent years when I found that some old US made stationary engines used these large hex nuts ,for example the most well known open crank engines, Amanco .on the 2 1/4 hp version the nuts and lock nuts on the 7/16 main bearings studs are 25/32 hex, of course only found on good very original engines,very many in their 100 odd year life have had a lot of nuts replaced with Whitworth nuts which fit with no problems,

10mm hex head bolts were 17m af but the americans used 15mm af. when it became time to formulate the ISO for hexagon head bolts and screws there was much toing and froing and earnest representations. The eventual result being a compromise at 16mm. So now we need three sizes of spanner. Long live standardisation!

When I was teaching motorcycle engineering in the 1970s I was told by someone at Suzuki GB (but it might have been Honda or Kawasaki) that the number 13 is regarded as unlucky in Japan. (It is in the UK by some.) As a result their designs tended to use 14mm heads on 10mm where strength was important, and 12mm where it was not so critical (but only on bolt heads, not nuts).

You may also find 14mm on the nuts connecting the top of a swivelling vice to the bottom, for example. So your new tool might come in handy again.

As to spanners from one standard fitting heads from another, 5/16 AF = 8mm, and (would you believe it ...) 5/8AF = 16mm (not 15, honest). Then 3/4 AF = 19mm and 15/16 AF = 24mm. Also 18mm = a Whitworth size but I'm not going out to the garage in the fog to check which exactly.

The symbol = above means 'Jolly nearly, certainly within the tolerances of nuts and bolts and spanners, and generally within 2 or three thou'. I can't find the approximately equals symbol on my keyboard.

And Stahlwille spanners are noticeably thinner in the heads and in the shanks than most other makes. The amount of spring does not depend on the quality of the steel, but this does effect how much bend will spring all the way back.

Regards, Tim

Different manufcaturers will use A/F sizes to suit. On the Renault 5, most 8mm threads had 13mm A/F nuts. In one location, the studs securing the twin choke carburettor, used 12mm A/F because of the restricted space.

Washer faced hardware often uses smaller A/F sizes. M8 calls for a 10mm A/F spanner, M6 an 8mm A/F spanner, sometimes M10 is 15mm A/F, sometimes 14mm.

Often having the nut with a different size A/F from the head, is an advantage, allowing a 10mm spanner to be used on the head and a 13mm on the nut. That way you don't need two sets of spanners!

The hexagon is only the means of applying torque to apply clamp load via the screw thread.

There is at least one brand of Japanese fuel injection pump that uses fixings with 5 sided heads. Presumably ensuring that only their agents, with trained staff can work on them. (In the same way that Bosch used an odd three sided fitting on each end of the governor pivot shaft of the EPVE fuel injection pump). Guess where was the only place that you could buy a suitable socket ?

But with some complicated devices, it is just as well that they cannot be accessed by the untrained; saving them the money that they would have spent buying a replacement for the one that they have just ruined.

(Being a retired mechanical engineer, I am wary of applying a voltage to check resistances on a pcb, for fear of reverse polarising some solid state device)

Howard

Perhaps an odd mix of sizes in this German set? No 12mm or 16mm.

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