British fuze thread sizes??

[tigbrand]

Can anyone give me the thread size and type for the following grub screws on these fuzes please.
No80 Mk6 nose locking grub screw.
No 82 Mk3 nose locking grub screw, three grub screws in 2" thread area, these are equidistant.
No 88 Mk? This fuze has no stamps so nicked off the production line, has hole for safety pin.
Any help appreciated. Cheers Tig.

 

[2pounder]

if you have the item the thread is in measure the hole inside dia and then you need to find out the thread pitch then you can look up the size, so long as it's not a 'bastard' size, in thread tables. I suspect you may have figured that out. Less than easy to do unless you have a good set of calipers and or vernier caliper gauge, the pitch you really need an imperial set of thread gauges or if you have a supply of small coarse threaded bolts to try. I think for ease of production of parts the screws could well be common to other fuzes, might be worth trying some from others. Hopefully someone here knows or has access to the items and can let you havethe details required. Good luck.

 

[tigbrand]

Hi Clive, thanks for the reply and hope your well. I have bigger metric thread gauges, but not imperial, and even with glasses cant see in the holes! Was hoping someone may have a diagram with details on. I have a local fastener supplier who has a lot of Whitworth,Bsf ,Ba etc. It seems as you say that oddball sizes are common in British ammo.
Thanks Tony

 

[Alpini]

Hello,

it's not exactly what you are looking for but at least Hamilton's "Shrapnel Shell Manufacture" has some info about the set screw threads of the cap of a Vickers exported fuze for Russia. As it has the same design as the No.80 it may be possible that the set screw size is the same for No.80, etc.

It seems that the screw doesn't fit into any British standard. The tolerance given for the screw diameter is between 0.155 and 0.159 inch. The middle between both values is 0.157 inch. If I divide 4 mm / 25,4 mm it's 0.1574 inches. So my conclusion - I think the screw had 4 mm diameter with a 24 tpi thread. It was common practise for all 1st WW german fuzes to have metrical diameters and imperial pitches but I never thought this could have been the case for british fuzes. That's really strange - can anyone help me to understand why such "mixtures" were used in the UK too?

//Edit: I have such a Russian Vickers fuze and can confirm slightly less than 4 mm diameter / 25 tpi for the set screw. The set-screws of my No.80's won't screw out but the hole looks like the same diameter as on the russian type.

 

[tigbrand]

Thank you very Much Alpini, I think you are correct in that the fuze shown is very similar to the No80. The top cap matches the profile perfectly. Unfortunately odd sizes are common in British ordnance.
I have had trouble before with some older items using 55 degree pitch Whitworth threads, the diameter does not match any of the standard Whitworth sizes when it comes to Tpi. I looked last night using the figures you gave and nothing matched in BSF,BA or UNF. I am unlikely to find any spare grub screws in relic fuzes as they are impossible to get out without damage.I have friend who is good with model engineering so may see what he can do.
On a different subject I recently looked at the Cesim site on which you have made many posts and it is very good indeed, perhaps there could be a link from Bocn to it?
Thanks Tig.

 

[Alpini]

It's not me, I am not active there due to language trouble. And I would wonder if someone is there with my nickname as Alpini is plural in Italian language.

 

[TimG]

Alpini,

You may well have answered your on question - who designed the No. 80? However, it should be borne in mind that The Royal Laboratories, Woolwich were not constrained by thread standards and would specify whatever diameter and thread pitch they saw fit.

TimG

p.s. see here - http://www.bocn.co.uk/vbforum/attachment.php?attachmentid=164884&d=1605965372

p.p.s - 0.156 = 5/32"

 

[2pounder]

I think early British bicycles had non std threads and some motor bikes did as well. Certainly gun makers used their own sizes and gas fittings are different in some cases.

 

[TimG]

Actually no -

Bicycles and motor cycles - BSC - British Standard Cycle (although BSA apparently broke ranks and had a couple of thread permutations of their own)

Gas - BSP - British Standard Pipe.

However, gun makers - yes and if the threads on an Enfield rifle are anything to go by, they were in a world of their own.

TimG

 

[tigbrand]

Lucky were not going to talk about hydraulic thread and fitting types, that's another nightmare. Thanks for the input everyone and sorry for the confusion Alpini! I have a plan, I am going to find some wooden dowel and screw it in to form a thread, when removed it will leave an impression which i can measure hopefully. I believe that all three fuzes seem to have very similar thread type/size, that would make it easier to make replica screws.