What’s missing & what is it used for?

[Bob LambParticipant @boblamb44747]

I inherited this from a friend's father who was keen on horology. There are obviously some bits missing from the front and the back as there are some threaded holes, marks and location studs. There are three lots of marks where some attachment/s were screwed onto the front. The back also has some marks which I assume were for fixing the main plate in some way?

It is presumably for dividing something but it seems a bit big for watch repairing.

The left hand knurled knob in the first photo rotates the inner circle which is marked from zero to 180 degrees in both directions. The small pin on the right seems to lock the inner circle to the outer circle when the vernier is on zero. The larger top right knob rotates the blank outer circle together with the vernier scale on it. The bottom right knurled knob locks the outer circle to the outer frame. I think the threaded hole in the "north east" corner is supposed to have another knurled knob which would be able to lock the inner to the outer circles at any angle which can be measured on the vernier scale. The long straight edge is 7 ¼ " long. That's as far as I have got. It is well made but I cannot see a maker's mark anywhere

Does this device have a name and what is it used for? It would be good to know. Thanks in advance – I am sure someone here will come up with the answer.

Bob

[Bob LambParticipant @boblamb44747]

[Michael GilliganParticipant @michaelgilligan61133]

It's only a guess, Bob … but it looks to me like the two groups of four holes, below centre, probably secured a spirit level; which would make the device a clinometer.

MichaelG.

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Edit: something like this in general concept [but much nicer]

https://prospectors.com.au/collections/tools-forestry-clinometers/products/sola-clinometer-13cm

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… Maybe more like this:

http://www.warrenknight.com/clinometers/wk-23-1990-propeller-protractor/

Edited By Michael Gilligan on 06/04/2018 17:05:49

[John HaineParticipant @johnhaine32865]

As a guess, if it came from a horologist, whilst it may have another original application it may well have been adapted as a jig to mark out wheels for crossing-out.

[Roderick JenkinsParticipant @roderickjenkins93242]

I think it has name – Goniometer. I was thinking mayby X-ray diffraction but it looks like Michael's second link has it.

Rod

Edited By Roderick Jenkins on 06/04/2018 20:07:24

[Bob LambParticipant @boblamb44747]

Most impressed Michael – thank you. I didn't know such things existed let alone that I would actually own one! I made the stupid assumption that because he was interested in watches it had to be something to do with horology. Now my eyes have been opened I remember that, amongst many other things, he worked with radar in the aviation industry and that he was always keen to make use of anything that might be being discarded so it may be a relic from those days. Maybe that is why it doesn't have the level and the bit that goes in the bottom left hand corner. It is so nicely made I suspect he may have thought he must be able to use it SOMEWHERE. Mind you – he also worked on the hydrogen bomb tests at Bikini Atoll so maybe I should check it with a geiger counter………………………

He taught me that if you ever see anything on a market stall that you don't know what it is, looks well made and is cheap – buy it and find out later! How many of us buy or keep things that may just come in handy sometime?

Thanks again, especially to Michael – All I need to do now is find a propellor to measure.

Bob

[Bob MurrayParticipant @bobmurray]

It's also used for rigging an airplane; making all the floppy bits move the same amount at the same time, so the airplane flies reasonably straight and level. It can be used to check relative angles as well as absolute angles. I wouldn't be without mine.

Bob

Edited By Bob Murray on 06/04/2018 21:33:18

[Bob LambParticipant @boblamb44747]

Thanks to Michael I googled propellor protractor and found a U tube video on how to use it. Chances are I won't be using it. The Aircraft Tool Supply Company also still appears to sell them at 5 cents under 1700 dollars! I said it seemed to be well made but didn't realise it was that well made.

This one is missing two bubbles and a handle so does anyone want a bargain at say 1000 dollars?…… I thought not.

Bob

[Michael GilliganParticipant @michaelgilligan61133]

[Ian S CParticipant @iansc]

50 years ago I might have taken you up on buying it, not now though. We could have used it on prop overhauls.

Ian S C

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