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Old 10th Dec 2017, 10:42 pm   #1
Sinewave
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Default Avometer cases

I really wasn't sure which area to place this in, but as it involves some home work, I'll try here.

Over the years, some people tend to lose cases for Avometers, so when aquiring some meters, I've got so many with no cases. I think I've 6 or so with no case.

So I was thinking of making a wooden case with some foam inners to store them in.

Now this will be rather simple in design really. Some form of wooden sides with perhaps spruce ply bottom and hinged top perhaps.

But I was also wondering if anyone here has ever made one, what suggestions, ideas or designs might you be willing to share?

Thanks.
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Old 11th Dec 2017, 2:43 pm   #2
pmmunro
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Default Re: Avometer cases

This has long been a problem, ever since a source of genuine original parts dried up. The problem is that high pressures and temperatures are needed together with a machined steel mould.

Some suggestions for a solution are:

As high grade 3D print, probably professionally done. This might be viable if someone was willing to co- ordinate orders to make up a suitable batch quantity.

Contract manufacture of phenolic resin cases from a manufacturer who still has the capability, probably in India. The problems are the same as above but on a larger scale.

Make a transparent acrylic case (Perspex) and turn the meter into a display piece.


PMM
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Old 11th Dec 2017, 3:00 pm   #3
Argus25
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Default Re: Avometer cases

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Originally Posted by pmmunro View Post
Contract manufacture of phenolic resin cases from a manufacturer who still has the capability, probably in India.
That is a very good suggestion. One place in India that definitely has the setup is Lucas-TVS. They still make electro-mechanical voltage regulators (clones of Lucas's originals) with the same type of phenolic resin.
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Old 11th Dec 2017, 3:24 pm   #4
M0FYA Andy
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Default Re: Avometer cases

Are we talking here about the bakelite case of the instrument itself, or the leather carrying case which provides additional protection? I'm not sure how the former gets lost, unless the instrument is dropped and the case smashed.
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Old 11th Dec 2017, 4:26 pm   #5
Sinewave
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Default Re: Avometer cases

I was actually talking about the storage/carrying case.
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Old 11th Dec 2017, 7:30 pm   #6
The Philpott
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Default Re: Avometer cases

On the original boxes (of which there are a few variations) the hinges are typically under a fair amount of stress, being too small for the stress of abuse, ie the lid hanging open at 'maximum' which tries to pull the screws out. On my 48A set the hinges had cracked and i started from scratch with a piano type stainless hinge, although i had to drill the holes myself. (it was ex marconi scrap) On a Model 8 box which i had dismantled and reassembled with woodglue in all the appropriate places, i used salvaged restraining straps from a flatpack furniture kit (the safety straps that allegedly save your small child from pulling a bookcase onto himself) and set them so the lid would just about go over-centre without straining the hinges. Once i had 'jabbed' the straps to stay inside the box a few times rather than folding outwards and getting trapped in the lid, they folded inside every time. Both these solutions worked well.

Maybe other considerations if making boxes from scratch-
-Best to leave enough room for the avo to be lifted out by it's strap.
-A separate compartment for (all the) test leads and probes... and possibly one for spare batteries...you might want to remove the batteries and keep them in a separate compartment anyway, to avoid the 'green plague' attacking your battery compartment..
-Enough headroom for the meter to fit in whilst the (later type) terminals are fully unscrewed?
-I have never fully trusted the original catches, although i have never had one come open by accident. More secure catches..? Stainless over-centre ones are available.
- Wood (just like leather) can hold a lot of moisture and a tough modern varnish for the box would be ideal.

I think there is room to improve on the original design.
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Old 11th Dec 2017, 9:29 pm   #7
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Default Re: Avometer cases

Every now and then you find an AVO auction listing with home-made wooden cases, as you've undoubtedly seen. I always find these interesting in themselves.

I'd go down the home-made route as well as it's more fun but what I was looking at ages ago was one of those small aluminium flight cases sold for DJ's headphones/mics etc. They're 23x23x17 cm (AVO 7 is around 20x18x12) and around £10 to 12 a pop on the same site as all the AVO's.

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Old 11th Dec 2017, 10:11 pm   #8
The Philpott
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Default Re: Avometer cases

Repurposing other containers does sometimes comes up trumps-

For the (universal) Avominor a Dove Men Care tin from the Christmas aisle of Asda gives a modicum of dust/shower protection (the latches close well, and if you get one that doesn't it's just a matter of bending the wire slightly.) Mine is lined with jiffy bag material and there is a little room for leads down the side.

They are £6 now with shower gel and anti-perspirant included, but expect some to be sold off after crimbo for less- that's what usually happens.
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Old 12th Dec 2017, 10:10 pm   #9
pmmunro
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Default Re: Avometer cases

Sinewave,

Sorry I misunderstood what you are looking for. I assumed that it was the phenolic moulded case, which is often broken, that you were looking for.

Avometers were not supplied with carrying cases unless ordered separately, with the exception of the Admiralty Pattern 47A and 48A. The 47A case was for a meter only; the 48A cases also had space for accessories, shunts and current transformers. Presumably some ex RN people liked the idea because a commercial version, known as "Industrial Test Sets" were offered in the 1950s and 1960s. See attachment.

I have made a speculative, fictional version of the 47A case for an Air Ministry Model 'D'. I painted it AM grey and marked it as a replica, just in case anyone thought it might be a genuine article. It only takes modest woodworking skills to make a case like this if you use half-lapped joints rather than the much more ambitious comb-jointing.

Both 47A and 48A meters appear from time to time on eBay and if you don't have one then you do of course need one for your collection. You could then use the wooden box as a pattern.

To return to the leather and other "soft" cases, these also appear occasionally on eBay and there are two military versions which can sometimes be bought in as-new condition. The more common one is a hard leather (or synthetic leather) type in black. The other is the olive-green drab soft case which was standard issue with military panclimatic Models 8 and 9 (Test Set No 1).

To my mind, the "Every Ready" style of leather case is much to be preferred to the leather box style because the meter seldom has to be removed from the case.

Meters which have been kept in cases generally seem to have survived better than unprotected ones.

PMM
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Old 12th Dec 2017, 10:37 pm   #10
mark_in_manc
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Default Re: Avometer cases

Quote:
Originally Posted by The Philpott View Post
For the (universal) Avominor a Dove Men Care tin from the Christmas aisle of Asda gives a modicum of dust/shower protection
That's fantastic! I can just imaging getting a tin of smellies for Christmas, putting my best 'how thoughtful, I'm so pleased' face on, opening it and being genuinely happy!

And it offers protection in the shower. When working live on one of those electric hot-water-on-demand things, presumably
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