German 7.7cm Driving band restoration project...

[starshell]

Hello,

Having decided to attempt to reband this nice German 7.7cm, I thought I'd keep a log of how it goes for those members who might be interested.
It's another one of those projects I've never undertaken before so may fall flat on its face....
Sadly, some of the original driving band had crumbled over time, and so I removed what was left to reveal a clean band recess.

The idea is to pour molten Pewter into a preformed cavity/mould made from Plaster of Paris, and to allow the molten metal to form a complete unbroken 'ring' within the shell driving band recess. Pewter seemed to be a good compromise; it has a low melting point, is cheap, and the colour when solid is not too dissimilar to Zinc Alloy.

The pictures show the shell before the project. Further pictures show the shell base encased with PoP. A strip of 5mm thick floor lino was wrapped around the shell, covering the driving band recess, with the lower edge of the lino laying about a millimetre or two below the recess. This will allow a small margin for error when it comes to profiling the band at the lower edge. Better to have more material than less.
After the plaster had cured, the Lino strips were removed leaving an opening all around the shell into which the pewter will be poured. Fortunately, Plaster of Paris has a very low shrink rate, so no cracks have formed in the mould. The plaster recess around the shell is perfectly uniform at the lower edge of the shell driving band recess, and the plaster recess is larger to allow for a larger 'new' Driving band to be moulded. This can then be profiled to the correct size.
The pewter I'll use will be broken old English Pewter tankards.

The next stage is the melting and pouring of the pewter into the plaster recess.....Watch this space!
Cheers!

 

[starshell]

Good morning,

Just a quick update from my previous post....

I am now at the stage where the molten Pewter has been poured, and the plaster mould removed after cooling. The mould was pre-warmed before pouring.
The band was moulded oversized to have enough material to 'turn' down to the correct size. My only concern is that there are no bubble cavities, and that the wife doesn't return home from work before I have cleaned the molten Pewter spattered kitchen table.....
So far, the 'band' has not suffered from any hairline cracks during cooling, and seems very firmly seated into the band recess on the shell.
The next and final stage is the profiling of the band....

Cheers!

 

[starshell]

Good afternoon,

Following on from my last posts, the final stage of the driving band project is now complete, with these images showing the end result. Fortunately no blow holes or cavities appeared during turning on the lathe, and the band has been turned to original specification. I'm pleased as punch it's worked out, I certainly had my doubts!
I'm hoping as time goes by it will dull to a nice 'Grey' patina.

Will repaint the shell in due course an post pics for those interested.

Many thanks to all members (you know who you are!) who provided info, especially technical diagrams of band dimensions, it is much appreciated and made this possible.

Enjoy the pics.
cheers!

 

[Andysarmoury]

Well done that looks great.
Cheers
Andy

 

[starshell]

Many thanks Andy, appreciate your comments.

 

[DICKAREN]

Great job Dylan. Look forward to seeing the finished shell.
Richard

 

[tnor_fr]

Very nice result, the technique is accessible, well done!
The passage to the lathe is more difficult because of the diameter.
I'll think about it, thank you!

 

[starshell]

Many thanks to all for your kind comments.

Dickaren: Many thanks Richard, researching colour schemes & stencils for this one at present, so watch this space. Cheers!

tnor-fr: Many thanks! Yes, the casting technique is relatively straightforward, but finding a lathe with a large enough chuck is the challenge. Also, to stop the shell oscillating when on the lathe a plug had to be made for the fuze socket to centre the shell properly. If you have a shell needing a new band I say give it a go. The beauty of a project like this is you can always remove the band and start again if it goes wrong, the shell is still unaffected. Good luck!