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Barr & Stroud CF41

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Optics Apprentice
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    Posted: March/28/2020 at 03:49
Now I got these from a collector who could not service or repair them and his previous tech had passed on some time ago, so he was selling off his collection. Because of the work needed I got two of these.
One, has both prisms separated (see previous post on prism cementing), the other pair needs to have the Canada Balsam replaced as it has gone cloudy on both sets of prisms.

The pair I am working on at the moment are those with the separated prisms. I had hoped to have re-cemented both sets by now, but my strap wrench broke trying to get the second turret off. They are a real bugger to get loose, it does not help that you have to hold them upside down, to stop the bloody prisms jamming in the filter mechanism and breaking or chipping; I am waiting for new ones to arrive. Going to the local hardware store is not an option at the moment, so I am only able to work on one half of these at the moment.

When I got these the ocular finger knurling was caked with green verdigris, to the extent that it was quite polished and shiny, a bit like very dark green jade in fact. Looked pretty but it couldn't be allowed to remain.
Removing this corrosion was long, fiddly and time consuming. It involved wearing my surgeons eyeglasses, a bright light and steel dental picks. Restoring the knurling one row at a time until the verdigris had all gone. Of course the paint has all gone as well, So I have removed the remainder, leaving the bare brass for repainting.

In the photos you can see some of the work done, unfortunately I did not think to take photos of the green gunk before removing it. It was strangely satisfying to do so and possibly would have made a good ASMR video.

Here you can see the state of the drying valves before and after cleaning. I have removed the ocular to do the tear down, clean, paint and re-lube work.


I removed the brass ports and covers completely and removed the corrosion and polished them. I did not polish the piping on the inside of the turret as that would have been pointless and besides they had a nice patina on them.


Before state and after.

The brass diopter adjustment sleeve. Cleaned, stripped of all paint and oil, ready to be resprayed and the graduations painted. I shall not prime these as the graduations are quite shallow and might not show up for painting. I have re-engraved them, to make them a bit more defined as they had worn a bit over the years.

I am waiting for my new snapmaker 2-350 to arrive and I am wondering if the laser unit on that could have been used to remove the verdigris and paint layer. Bit of a delay as it comes from China. I have a wicked laser ARCTIC model that I might try and use to test the theory. It can set things on fire and stuff, so it might do the job. I used to use it for setting up DLOS shots over distance in Afghanistan.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DPI Quote  Post ReplyReply Direct Link To This Post Posted: April/22/2020 at 08:28
GOOD NEWS!

The strap wrench just turned up, so I can continue with these.

Managed to get the second turret off, and took out the separated prism, that's been cleaned and new balsam applied, now waiting to cure.

Now taking the rest of the turret and ocular apart.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote DPI Quote  Post ReplyReply Direct Link To This Post Posted: June/01/2020 at 05:06
An interesting and unusual item.

These are pair of Watch keeper B&S CF41s. The interesting item is the spray shields that extend from the objective housings.

The barrels also have been modified in service to have a tarred canvas covering instead of the normal 'crackle' finish. To give a better grip I would imagine.

images of RN officers and sailors using these abound on the internet.

Finding a pair in good condition, prisms still cemented, with the spray shields in good working condition is very rare. The in service mod, makes up for the missing 'Crows feet'







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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dogger Quote  Post ReplyReply Direct Link To This Post Posted: June/01/2020 at 06:17
Interesting mechanism on the shields.
God save the Empire!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DPI Quote  Post ReplyReply Direct Link To This Post Posted: June/01/2020 at 06:22
It is, flexible steel banding, of course this is why there are not many around any more, they rust like crazy.

I am going have to address the slight spotting of rust on these and then oil them. But at the moment they work exactly as designed and no problems opening or closing them, quite smooth.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Alp1 Quote  Post ReplyReply Direct Link To This Post Posted: June/01/2020 at 08:22
Steel? Mine are tin-plated copper. No rust, the tin wears over time though, revealing the copper underneath.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DPI Quote  Post ReplyReply Direct Link To This Post Posted: June/01/2020 at 08:55
These appear to be steel, some I have seen rusted completely through. I shall have a closer look, but I have seen so many variations on a theme with wartime binoculars that its difficult to make any hard and fast statements about their construction materials.

Its all down to the availability of materials at the time. Copper would have been at a premium for electrical wiring as the UK has copper deposits but no serious copper mines it would have had to been imported.

Copper stockpiling was aimed for 500,000 tons for 1941, by 1942, we had only 69,000 tons of that, well short of the intent.

So it is possible that different materials were used as situations changed.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DPI Quote  Post ReplyReply Direct Link To This Post Posted: June/01/2020 at 12:38
Alp1

You are correct. I have just taken a look under a magnifying glass and removed a rust spot and it is copper underneath.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Alp1 Quote  Post ReplyReply Direct Link To This Post Posted: June/01/2020 at 13:17
Ah! Yep, Thought So
I thought so! 
Cheers mate!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gumball Quote  Post ReplyReply Direct Link To This Post Posted: August/13/2020 at 13:27
Nice find !!
I have a CF42 (with the collapsible shields)  
Very nice glasses, and I love the filters

Enjoy !!
Leitz beh 7x50 U-boat
Leitz beh 7x50
Leitz 10x50 "WA"
Zeiss 10x50 (1917)
Zeiss 18x50 (1923)
Zeiss 7x50 "U-boat"
Zeiss 7x50 "Gas Mask"
Zeiss 7x50 "Smooth Ocular"
Zeiss 8x60
Barr & Stroud CF42


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Have You Driven A Ford Lately?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tahqua Quote  Post ReplyReply Direct Link To This Post Posted: August/15/2020 at 13:17
Hey Gumball, I love the Tyrell 004. One of my favorites of all time. 
Doug
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gumball Quote  Post ReplyReply Direct Link To This Post Posted: August/15/2020 at 19:20
Actually, that is #002.  Cevert won US GP at in that car.  Both Francois and Jackie drove that car.
Now owned and driven by John Delane.
Leitz beh 7x50 U-boat
Leitz beh 7x50
Leitz 10x50 "WA"
Zeiss 10x50 (1917)
Zeiss 18x50 (1923)
Zeiss 7x50 "U-boat"
Zeiss 7x50 "Gas Mask"
Zeiss 7x50 "Smooth Ocular"
Zeiss 8x60
Barr & Stroud CF42


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