Unusual Go-No Go Tool?

[Graham MeekParticipant @grahammeek88282]

Posted by Michael Gilligan on 23/08/2021 22:07:39:

This one's for you, Gray

[ click ^^^ for larger image ]

.

MichaelG.

Hi Michael,

Having done my fair share of engraving whilst working in the Oncology Workshop, I know how easy it is to make a mistake, at least it was worth a shot.

One question, When the instrument is in the "Go" position, or Zero, do the two contacts, contact? Or is there still a gap? (Two questions really I suppose).

Regards

Gray,

Edited By Graham Meek on 24/08/2021 10:40:28

[Michael GilliganParticipant @michaelgilligan61133]

A somewhat belated ‘fact check’ …

The ‘square’ is approximately 10.3 x 10.6mm, with rounded corners

The hole is about 2.25mm diameter, and not quite central in the width of the strip

The clip [previously assumed to be a viewfinder] is bent and twisted from flat strips of brass/bronze.

Presumably fit-for-purpose … but not ‘precision’

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Graham Meek on 24/08/2021 10:35:47:

Posted by Michael Gilligan on 23/08/2021 22:07:39:

One question, When the instrument is in the "Go" position, or Zero, do the two contacts, contact? Or is there still a gap? (Two questions really I suppose).

.

I’m a little confused by the GO – NOT GO arrangement of this device

You will see that the line above the scale window is discontinuous … which suggests three states !

In answer to your question : There is still a small gap [a few thou’] when the scale is reading zero

[ and, just for info, the thread disengages about one turn beyond the 300 mark ]

MichaelG.

[Jon LawesParticipant @jonlawes51698]

The part that confuses me is that Go/ no-go gauges are usually fixed. The idea of an adjustable go/no-go gauge kind of defeats the point….

 

Unless of course the difference between whatever is Go and Not Go is fixed and moves with the adjustment. In what capacity, I have no idea.

The scaling I would assume is down to the inverse square law.

Edited By Jon Lawes on 24/08/2021 13:40:01

[Graham MeekParticipant @grahammeek88282]

Hi Michael,

I noted the gap in that line. It reminded me of the Zero line on a micrometer barrel at first, but then why the gap. As there is no room on the adjuster for a second scale I ruled that out.

What does not settle with me and why I asked the question.

If this tool was for testing spark strength then the "Go" condition would pass a fairly weak spark. Whereas the "Not Go" would be failing one hell of a spark. So the scale to me does not make sense for that application.

It may well be that the sweet spot for setting what ever this tool was setting is in the 0-50 range, there being more graduations, the rest of the scale being arbitrary.

We had settings on the Varian Linear accelerators that were in the preferred range, although these settings were well within the upper and lower accepted values, and in many cases not in the middle.

Regards

Gray,

[SteviegtrParticipant @steviegtr]

Posted by Graham Meek on 24/08/2021 16:37:16:

Hi Michael,

I noted the gap in that line. It reminded me of the Zero line on a micrometer barrel at first, but then why the gap. As there is no room on the adjuster for a second scale I ruled that out.

What does not settle with me and why I asked the question.

If this tool was for testing spark strength then the "Go" condition would pass a fairly weak spark. Whereas the "Not Go" would be failing one hell of a spark. So the scale to me does not make sense for that application.

It may well be that the sweet spot for setting what ever this tool was setting is in the 0-50 range, there being more graduations, the rest of the scale being arbitrary.

We had settings on the Varian Linear accelerators that were in the preferred range, although these settings were well within the upper and lower accepted values, and in many cases not in the middle.

Regards

Gray,

Yes of course Gray. You are right the wording would be opposite, if for a spark. Doh.

Steve.

[Michael GilliganParticipant @michaelgilligan61133]

Fun isn’t it …

the more we think about this, to more obscure its purpose becomes !

MichaelG.

[Jon LawesParticipant @jonlawes51698]

Just scraping the barrel for clues, Martin says it was in the bottom of a crate of tooling. Where did it come from? Do we have any hints there?

[Martin King 2Participant @martinking2]

Hi Jon,

no help I am afraid, it was discovered under the flap of a cardboard crate about to go in the bin!

just a box of mixed tools and stuff.

Martin

[SillyOldDufferModerator @sillyoldduffer]

Posted by Graham Meek on 24/08/2021 16:37:16:

…

If this tool was for testing spark strength then the "Go" condition would pass a fairly weak spark. Whereas the "Not Go" would be failing one hell of a spark.

…

In which case maybe it detects over-voltage? I wonder if it was used on a process that incidently but usefully generated static electricity, such as unrolling paper for a high-speed printer. A mild static charge would be useful for attracting ink, but too much static would collect dirt, consume excessive ink, and blur the image.

Might explain why one contact is square. It's rested on an edge while the peephole side is tilted to touch a hot test point. If it sparks the machine is generating too much charge, and a resistor would be adjusted to bleed off electrons. The amount of charge generated by friction depends much on the weather, so the machine might have needed frequent adjustment. Electronics made this easy to automate after about 1975, so the gauge may have had a short working life.

Is 'Micrograph' print-trade jargon? Small writing, specks of ink, rather than the 'magnified picture of a small object' definition we're familiar with.

Dave

[Graham MeekParticipant @grahammeek88282]

I did think that the test was for a weak spark, rather than a really powerful one.

While working at Rank-Xerox, their copiers had a power supply to deal with attracting ink onto the paper. With special electrodes with numerous spikes on to distribute this to the paper.

High speed printers which I have also worked on, (made in Germany and used mainly in the car industry, paper speed was around a metre/s, if my memory serves me correct), used a similar set-up and what was called in house a Corotron assembly.

Maybe as Dave suggests, this tool pre-dates the Xerox as regards a printing process.

On a separate theme, I did wonder if it had anything to with Marconi or Tesla, and the early spark generated communication. Not necessarily for the spark used, but for setting any air based capacitors in the circuit.

Regards

Gray,

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