No:199 fuze

[BMG50]

Got a nice No:199 IV fuze dated RL4/37 but also dated RL1/38 on the same ring, why the two dates?
Unfortunately the fuze is missing the nose cone but not sure what type should be fitted. Is it a Bakelite one or an aluminium one. The rest of the fuze is missing the spring and pin. Looking at the diagram how the fuze worksvto set off the delay fuze looks quite simple. Why did they change to clockwork and what did they change when they used this fuze for the 3inch mortar smoke the No390. Is there any other information about this fuze and what to look out for.

 

[AMMOTECHXT]

Date and manufacturer of the empty store and date and place of filling of the store. The number 178 is the filled lot number.

 

[Alpini]

http://www.bocn.co.uk/vbforum/threads/90964-Questions-regarding-No-199-Fuzes

Maybe this old thread will answer the question about the material of the cap.

//Edit: sorry just see it wasn't the cap material but the body material described in the drawing

 

[BMG50]

When was the Bakelite cap introduced.

 

[Darkman]

All the nose caps I have seen on mk IV fuzes dated 1937, 38, 39 and 40 were aluminium. (You used to often see WW2 Blitz relic nose caps and blown up brass rings on eBay - a prized find for young boys). I imagine that early in WW2 aluminium became a more precious commodity and alternative materials such as Bakelite became acceptable to use. Also probably cheaper to produce than aluminium, particularly for private firms manufacturing fuzes for a fixed contract price. Here in Australia we continued to manufacture 199 powder fuzes throughout WW2 and used imported British clockwork fuzes where necessary. I note that fuzes made in Australian Govt munitions factories (eg MF) continued to use aluminium caps, whereas privately made fuzes (eg D&H - Duly & Hansford) used Bakelite, which suggests a cost saving.

Powder time fuzes were satisfactory for plane altitudes in the 1930s and early WW2. But as technology developed and higher altitudes could be achieved, powder fuze burning time (and hence burst accuracy) was inconsistent at these higher altitudes due to atmospheric conditions. Clockwork mechanical fuzes had to be adopted for high altitude use. These had been around since the later 1930s (Britain copied the German Thiel movement I believe), but were obviously much more expensive to produce. The clockwork fuzes could also achieve higher altitudes by a longer running time, compared to about 30sec max (?) of the powder fuzes. There are numerous posts on powder vs clockwork if you want to search.

On a 390 fuze you can see the use of a longer tube where the detonator pellet is contained. I have no real idea why, I’ll leave that to others with more expertise.

Graeme

 

[Darkman]

I think that as the war progressed it became obvious production wise that Bakelite nose caps were quicker, easier and cheaper to make than aluminium. With Bakelite there is minimal finishing required after casting, but aluminium required milling, turning, boring and thread cutting - quite time and labour intensive.

Here are a couple of original early war exploded and recovered Mk IV fuze remnants that I have. Possibly from the Blitz, as I obtained these from the UK many years ago.
First one made by Ferranti Ltd in 11/39 and filled by Royal Labs in 4/40. Second one also made by Ferranti in 6/40 and filled by Vickers Armstrong in 8/40.

Also you can obtain replica resin nose caps from Nathan S on Quickfire Auctions for a very reasonable price. The new batch may not be on there yet, but won't be long. These look good and fit well.

Graeme

 

[BMG50]

Nathan is going to do a batch for the 199, i did see some original Bakelite ones on Ebay but they were for the 221 fuze that had a larger thread. Anyone know the thread size for the 199 nose cone. I know someone who can cast me a nose cone in aluminium if need be, but i will look out on eBay first to see if i can find one if anyone has a spare.
Another thing i did notice on 199 fuzes on some is the time rings are painted red was there a reason why?

 

[Darkman]

I've not seen the time rings painted red on a 199?

 

[ron3350]

The powder time ring grooves are often red coated as a protection? on some new unfilled fuzes. Never seen the outside rings painted red.

 

[Andysarmoury]

I have only seen a red painted ring on a 221B Fuze

 

[BMG50]

Must be a 221 ring i saw.

 

[Dronic69]

I have a few No 199 IV caps if interested - one potential may be already taken.
Cheers
Drew

 

[BMG50]

Hi Drew shame you didn't ask me earlier, just bought one but do need a nose cone for a 199.

 

[BMG50]

Anyone know the thread size of the nose cone that screws on the top.

 

[Alpini]

I did not find "official" meassurements when I made my cap's. My meassurement was 21.5 mm x 18 t.p.i. I don't think it's a standardised thread like BSW, BSF, etc. With 18 tpi there are not much standardised threads.

//edit: I am not familar with the inch fractions (that's devils work ) so I may be completely wrong: 27/32" = 21.431 mm would be the nearest value to my meassure diameter. I just remeassured a No.199 and got 21.45 mm which is still a little bit to large for 27/32". So I guess they used a decimal inch size for thread diameter. Or is it possible they used a metric diameter - not really?

//2nd edit: I meassured the diameter of the cylindrical shaft of the fuze were the rings are put on and it's pretty exactly 30 mm diametrer, the small top screw has a thread diameter of 12.5 mm. Is it just coincidence?

 

[BMG50]

Thats what i clocked it out as 21.5 x 18 tpi, it would be nice to fine such a die or tap. Wondered if the thread was screw cut.

 

[Alpini]

Think with such an exotic size it's almost impossible to find one. But..., you won't get around a lathe to make such a cap so why not turn the thread on the lathe. It's aluminium and will cut very easily. Or do you want to enter mass production? If so, you can make you own tap that's 1-2 hours of work if you have a small milling machine. Without you could improvise with a angle grinder and a file.

Here are pictures of two of such taps I made for the same purpose. Not sure if it is of interest but I could post some pictures of a very similar project under "restoration" for which I made the taps.

The '199 caps I made were some older sheet metal type. The fuzes I restored still had minor rusty remains of these caps. I don't know why but in all the years I have seen only one picture of an original fuze with sheet metal caps. It was this old thread: http://www.bocn.co.uk/vbforum/threa...g-No-199-Fuzes?p=255584&viewfull=1#post255584

 

[BMG50]

I think in the long run i will get a tap made up and screw cut the size on a lathe. Its interesting why they didn't keep to a standard thread size especially for war work. I would be interested to see pictures of a similar project.

 

[Alpini]

I would be interested to see pictures of a similar project.

started a thread here: http://www.bocn.co.uk/vbforum/threads/103430-Fuze-cap-reproduction?p=316964#post316964

 

[Falcon]

I made a cone for a No. 199 Fuze back in 2009. There is some information on the thread types here:

http://www.bocn.co.uk/vbforum/threads/28785-Thread-types-on-No-199-Fuze