Vickers S/20 fuze body reproduction

[Alpini]

It's more a partly reproduction than a restoration thread but I hope it is still interesting for the members interested in mechanical engineering

Some time ago I asked some questions about the following unknown british fuze in the following thread:

http://www.bocn.co.uk/vbforum/threads/94762-unknown-british-(export-)-fuze

After getting some very useful informations there (thanks again to all involved) I decided to give it a try in making a complete reproduction of the fuze body.

First of all: The photos of the finished project:

O=Original Part, R=Reproduction

 

[Alpini]

And now pictures of the major machining steps. Please exuse some of them may be unusual machining operations - I have absolutely no apprentise in metalworking and doing this as a hobbyist only. Most of my machines are aged two or three times older than myself and I am not equipped with every existing professional equipment so I had to improvise at some steps.

All started with a 40 mm Aluminium round bar (AlMgSi0.5). After some machining steps the shape to hold the time rings and the fuze cap thread was finished:

Now turning the grooves used for gluing the washer under the lower time ring

Finished the grooves / meassuring fuze cap thread pitch

finished the outside angular shape of the fuze body which receives the graduation in a later step

 

[Alpini]

First machining of the lower part after reversing the work piece and fixing it in a collet chuck

Finished the shape for fuze thread

After cutting the fuze thread

Rough cutting the cavity for the fuze's internal parts

 

[Alpini]

after cutting both the inside threads (the small part had to fit with an original part "detonator holder")

Now moving from the lathe to the milling machine and boring the hole for the ignition of the upper time ring with an end mill

Milling the hole which catched the flame from the lower time ring in a position relative to the later graduation. That's why I already marked the position of the later graduation with a pen.

boring a hole which connects the lower time ring with the detonator

 

[Alpini]

milling two half round slots which prevents the rotation of the upper time ring by inserting two small round brass pieces

Now I moved the rotary table to the engraving machine and adjusted the angle of the rotary table with the dial indicator so that the surface which has to be engraved is in perfect 90° angle to the engraving spindle. After that finding the center (highest point) with the dial indicator as a reference point for engraving the graduations. This point is the later center for the lines and also for the digits.

The annoying engraving work in progress (don't do this drunken or tired). I use a printed Excel sheet with calculated degrees for every single engraved element and the number engraved elements was 103.

back on the milling machine - machining the two key holes of the gaine (pictures of other machining steps of the gaine are missing - sorry)

 

[Alpini]

Start machining a safety shutter from a brass bar (thanks @TimG for the photo of such a safety shutter)

machining centering holes with a carbide drill

milling the external shape with the help of the rotary table

finished external shape and holes

 

[Alpini]

cutting of two safety shutters (one as a spare)

cutting a slot into the safety shutter which is later holding the safety shutter spring

finished both safety shutters

 

[Alpini]

boring holes which hold the pins for the safety shutter

That's it Such a fuze must have been very expensive because I needed more than a complete weekend to finish. So I guess the production at the Vickers-Armstrong factory was a little bit more efficient.

Finally to prevent the reproduced parts being seen as original parts I engraved a similar small stamp on every reproduced part and the manufacturing date on the base:

Hope you will like it and I am open the critics as well (if you find failures for example). I am aware that it has some small failures compared to an original.

Regards, Alpini

//Edit: sorry for dividing it into so many posts but it was only possible to insert 4 images "inline" in one post.

 

[TimG]

Excellent work, I'm most impressed with the time graduations.

TimG

 

[hangarman]

Most impressed with the whole thing !
Thanks for sharing.
Cheers
Gary

 

[highlandotter]

Very professional job. If you are in as good condition as you tools, you have no worries re age!

 

[starshell]

Superb piece of engineering! The graduations are excellent, such precision. I love stuff like this. Just wish I had the skill to produce stuff to this level.
Well done Alpini!

 

[Alpini]

Thank you all..

@Starshell: it's no magic with an engraving machine. With a CNC machine it would be 2 hours programming time and 1 minute production time but as I have a manual pantograph engraving the scale takes one hour for calculating a Excel sheet and 1-2 hours manual engraving time with the "eyes full open". It's very annoying when a failure happens during engraving because there isn't a "undo" key and it would destroy many hours of work.

The original scales where mostly rolled on the work piece with a negative ring made of hardened tool steel in special devices. If needed such negative rings sometimes had exchangeable parts which were for example used for lot-numbers, dates, factory codes, etc.

On very early time fuzes I have seen also scales where the numbers were hand-stamped with only the lines rolled on. Very old zinc fuzes had sometimes casted numbers. Since CNC machines exist the latest modern fuzes can also have engraved scales.

@highlandotter: I don't think I'll reach an age like the machines But also the machines have their traces from 60 years usage - I am just at the moment trying to recondition the lathe as it is worn very much.

 

[25thapril]

Fantastic work you should be very proud of the result !!!