Unusual Go-No Go Tool?

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Having [or so I thought] successfully re-formed the strip slightly, to make the ‘sight’ work properly; it now appears that I have actually deformed it from the shape required for it to function as a pair of electrical contacts for some [as yet unidentified] component under test.

I probed it with the multimeter and discovered that:

• There is no electrical continuity between the two sides
• The square frame is connected to the internal insert
• The ‘peep-hole’ strip is connected to the spring strip which contacts the pointed brass rod
• The Brass ring has no electrical connection with any of these parts

There is surface corrosion on the brass rod, but I am sure that it would be in good electrical contact if it was clean.

So … the moral of the story to date is :

Don’t assume that because it looks like something you know, that’s what it actually is !

MichaelG.

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P.S. __ I remain utterly bewildered by the use of the word MICROGRAPHS, and have no idea what the thing tests … but it’s keeping me amused

Does either of the 2 fingers or jaws move . I was thinking a part missing that when the bottom was screwed up it closed the jaws. Giving an exact size for an object. If under or say oversize. The marker line would show not go.

Steve.

How about a Disappearing Filament Pyrometer?

The peephole and square holder takes a plug-in battery, filament, on/off switch and lens module. Does turning the base knob vary a resistance inside the handle? If so, the temperature of the filament could be altered to determine if furnace is close to correct operating temperature.

I agree 'Micrographs' defies logic!

Dave

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Sorry but No, Steve … no movement except for them being springy … But they are each electrically connected to one of the contacts inside.

All that the screw does is move the pointed brass rod [and the indicator line], so changing the size of the ‘spark gap’

The gadget appears to have no other electrical connection with the outside world … so could it perhaps be that the thing being tested is a source of energy [hopefully not a radioactive source]

Keep the ideas coming, please …

MichaelG.

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No, Dave … it just moves the pointed brass rod and the indicator line

Here, for convenience, is a crop from the photo that I posted before:

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MichaelG.

Hi Michael,

Is the the staining on the brass point similar to the powder from an arc strike?

The reason I ask is that this unit clearly clips onto something with the square portion, and the hole in the other contact rest on another exposed contact area. Both these parts appear to be insulated from each other.

In the view finder there appears to be a small "hair pin" electrode just beneath the clip.

My reasoning is the brass point is wound in until the current jumps the gap, viewed through the view finder. The position of the red line shows if the device is set correctly.

The problem is I don't know what would warrant such a tool in the electrical field. It might well be something to do with power generation. Or possibly capacitor storage capacity.

Regards

Gray,

Many thanks for the input, Gray

Yes, the staining does have that general appearance …

I am hoping to take some detail photos later today.

MichaelG.

As promised :

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MichaelG.

Michael,

If the grubby window part will clean up it will transform the item visually!

Just wondering if there are is any small melted pitting on the inside which would support the arc idea? ie sparks?

Martin (who had no idea that this thread would run on so!) Excellent detailed work.

Martin

BTW is that a helix on the parallel brass part of the point?

Martin

If you don't like silly stories then don't read this.

It's 1854, 15 years after Charles Goodyear invented ebonite. The coalition forces are fighting Russia in the Crimea. We're in the T&SD dept of the War Office. Great Grandad Q is briefing Grandpa Bond:

"This machine can be taken apart and concealed in a mere cabin trunk. To use it you charge up these Leyden jars by rubbing your amber cane across the silk. Once charged you need to be certain that the voltage is accurately calibrated. Place the micrograph controller around the print area and clip the hole upon the stylus tip in it's retracted position. If you only see a spark when the indictator is in the GO position then it's ready. If not then you may have to discharge the jar to the needed level.
Once adjusted place one of the thin wafers of ivory into the print area and lower the stylus to the writing position. Wind the clockwork spring that controls the on-off contact, set it spinning, switch on and you can now use the pantograph to trace your message in micrography."

pgk

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It’s a scuff mark from the ‘wiper’ contact … pitch matches the screw thread.

MichaelG.

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I need to investigate this very carefully … not sure how fragile that plastic might be.

As you can see; the heavy marks are on the area where the plastic sleeve is contacting the ebonite body.

It will be tricky to look at the interior surface of the ‘window’ areas, but I’ll give it a go.

MichaelG.

It is almost certainly a breakdown voltage tester. A lower voltage version of this:

www.lasertools.co.uk/Product/5655/Adjustable-Spark-Tester

But I can't figure out what it was connected to or the scale units.

Robert G8RPI

Thinking some more I came to magneto tester, possibly on the primary circuit. I then found this webpage:
https://www.themagnetoguys.co.uk/test-equipment
see the wooden handled spark gap abut 1/3 down the page.

My only other thought was testing the early medical type shock machines. That might explain the odd measurement units.

Robert G8RPI.

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Thanks, Robert

… I think revelation might eventually come if we can ever find any reference to MICROGRAPHS as a unit of measurement.

I know what micrographs are ; and to date, I have failed to find any other use of the word.

MichaelG.

I tried to dive in deeper to the use of the word Micrograph, and even the earliest use of the term says they are to do with Photographs taken through a microscope or by similar techniques. But in the earliest editions of Merriam Webster it also lists this version which I was unaware of:

"an instrument for measuring minute movements by magnifying and recording photographically the corresponding vibrations of a diaphragm moving in unison with the original object"

That’s further away from the standard definition than I have ever seen, Jon

… you may be onto something [‘though I’m not exactly sure what]

MichaelG.
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A good working definition for modern usage is that a micrograph is a representation of a microscopical view.

We then have a sub-set called photomicrographs, where the medium is photographic.

… and on this page, Jon’s new-found definition gets top-billing : **LINK**

https://medicine.en-academic.com/32911/micrograph

I need to find some details of these instruments

MichaelG.

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and … as if by magic: Nineteen pages from 1911

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2124883/

 I  now need some coffee !

Edited By Michael Gilligan on 23/08/2021 07:42:51

Another Link for you

https://www.mayoclinic.org/tests-procedures/mohs-surgery/about/pac-20385222