WHAT IS IT ?

[Speedy Builder5Participant @speedybuilder5]

Anyone have someone studying mathematics at university or works at NASA ??

[not done it yetParticipant @notdoneityet]

I’ve made one but only about to look at it. Wife’s birthday deliveries, phone calls etc have got in the way. Now lunch, so it may be later this afternoon, as I have a couple of workshop jobs to get done first

[not done it yetParticipant @notdoneityet]

It is clear that there is two windows on a missing over-layer (one for each of the two sets of 1-9) which is fixed to, and rotates with, the inner ring of 1-20. Presumably these windows would show the relevance of the inner number and middle/outer circles of fractions.

I wondered if it was something to do with cobbling? Although sections up to 20 are shown, only shoe/boot sizes up to 14 are used? Possibly one circle would be for the ‘fold-over’ for uppers being sewn to the soles?

Possibly cutting timbers for over-lapping fence-work?

The sewing industry for cutting allowances?

Cheese making, or some other recipe?

Apart from those guesses, I’m lost!

Observations

What is clear is that the outer bit is fixed/stationary (all numbers read upright/flat viewed from one side).

The two arrows are there to indicate the direction to turn the windows (along with the centre 0-30 selector).

The dial is set agaianst the metal bar (reads correct way at that point).

Anyone else any clue?

[Ian ParkinParticipant @ianparkin39383]

My BIL had a look and suggested imperial weights going down to drams which is why some of the fractions have + 2 (say)after them that figure is drams

[Mike HurleyParticipant @mikehurley60381]

Posted by Speedy Builder5 on 24/03/2021 10:53:22:

Anyone have someone studying mathematics at university or works at NASA ??

Yes, my great-niece is studying mathematics at Oxford (obvious doesn't get her brain genes from my side of the family!) and I sent her a copy of the picture and some suggestions from the thread. Even though she's not into 'engineering' I thought a more logical, un-biased clinical examination may bear fruit. She apparently even passed it onto a ' group ' at Oxford who do very hard sums. Even they couldn't make head or tail of it – sorry.

Regards to all.

[Howard LewisParticipant @howardlewis46836]

It is a device intended to start Engineers scratching their heads!

Howard

[old martParticipant @oldmart]

I keep checking on the progress of this thread, but no answer yet, fingers crossed.

[Nigel Graham 2Participant @nigelgraham2]

Ooh, two of 'em now….

Though it seems probably not photographic I have asked a friend who has been a keen amateur photographer for many years, and is well clued-up on antique cameras and techniques, if he's seen anything like it or might recognise the sums.

Or maybe in the building-trade, his work – he told there used to be all manner of manual calculators in that area, and one he still uses for estimating heating radiator sizes is more comprehensive, accurate and convenient to use on site, than the spread-sheet versions he's encountered!. (The spread-sheets are arithmetically precise but tend to omit smaller details that can still be significant.)

[Charles DunhamParticipant @charlesdunham36570]

Hi folks! I am not an engineer but I do have the aforementioned unknown device in my possession. In my yearly scouring of the internet to find answers, I came across this page and you guys are clearly way smarter than myself!

As far as I know, my Dad got the calculator when 40+ years ago he bought a spinning pedestal mounted cabinet with many drawers of all shapes and sizes on all four sides. The cabinet was said to have come from a really old mom and pop hardware store (Alabama USA) and the device was in one of the drawers. The cabinet is full of all types of old nuts and bolts and just a wild assortment of things. Some of the items are clearly old and some are much more modern so I wouldn't say for sure that the items in the cabinet are related to the device.

The dimensions are ~5.125" X 5.125" X .375". The body of the device is wooden and the dials look like tarnished brass to me. I have posted a video to my YouTube channel https://youtu.be/hV0QzhUW7_0

It's so cool to see how many places this item has been since I shared the original picture back in 2012 with a British coworker of mine while we were working in Africa. Since then, it has been all over the place and even in the top ten unsolved items on reddit a couple of years ago under the guise "The Fraction Calculator of doom". (https://new.reddit.com/r/whatisthisthing/comments/bg853q/whats_this_thing_with_one_million_subscribers_its/).

Thanks for the help and please let me know if I can answer any questions! Y'all seem like a group capable of figuring this thing out!

[noel shelleyParticipant @noelshelley55608]

Hi Charles, I was responsible for posting it here, having had it sent to me by a school friend. Thanks for the dimensions and the story. Surely someone must know what it's purpose is ? Best wishes Noel.

[Neil WyattModerator @neilwyatt]

I've been scratching my head looking at this for a while.

These are just observations.

The outer dial goes from 0 to 19.

Many but not all numbers are accompanied by fractions.

For 4 fractions 1/4, 2/8 and 3/12 all are equivalent to 4/16

For 8 the fractions 1/2, 4,8, 3/6 and 6/12 are equivalent to 8/16

For 10 5/8 = 10/16

For 12 3/4, 6/8/ 9/12 are equivalent to 12/16

This suggests 4/5 + 12 may therefore be equivalent to 12/6 (or 3/4).

All the fractions with an addition next to them give a result that is slightly too large. e.g. 7/12 > 9/16

The outer arrows indicate movement i8na negative direction.

Against 9, is it possible that 7/12 + 1 means 7/12 'plus' one step of the dial in a negative direction?

[Ady1Participant @ady1]

Its an Imperial to Mayan(Base 20) measurement convertor

They must have used it to build pyramids and stuff

[BazyleParticipant @bazyle]

I like your observation that the large numbers refer to 16th. But I'm lost from your line "This suggests…."
Against 10 we have "…2/3+2 5/8" so your explanation shows there is a sepearation aftetr the 2.
In a way all the plain fractions could be read as "x/16 +0" sort of implying the "+ something" is significant.
Although there are 19 spaces the 19th is not marked so perhaps insignificant. However there are 20 lines so I think that is more significant. Each line has little holes in it as if one could pin prick through to mark on a map or drawing as si sometimes done with protractors. The 20 divisions mean 18 degrees for the lines. Is this linked to the numbers only going to 18.
The big holes match the lines at 20, but the inner ring has 30 holes. Could this have something to do with minutes of arc?

[Charles DunhamParticipant @charlesdunham36570]

Those dots that look like holes are small tacks holding the plastic face plate to the wooden frame. There are no holes anywhere that a pin could go through..

[HOWARDTParticipant @howardt]

Like many I keep coming back to this to see if it has been solved.
We know a date 1908.

Do we have a country, UK or USA.?
Can we recognise the numbers in relation to something around at that time which is not relevant now, or has changed significantly.

I have no idea at present but will keep digging.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Charles Dunham on 27/06/2021 16:45:38:

Those dots that look like holes are small tacks holding the plastic face plate to the wooden frame. There are no holes anywhere that a pin could go through..

.

That’s useful to know, Charles

… or would be, if I had any idea !

MichaelG.

[Jon LawesParticipant @jonlawes51698]

It reminds me of the Lufkin thread size circular calculators, if thats not too grand name for them (they are much simpler than this).

[Nigel Graham 2Participant @nigelgraham2]

A possibility. There were still some odd threads around in the early-1900s, perhaps more in horology than other branches of engineering.

Another suggestion I have… clutching at straws, or dropped stitches. Something textile?. Setting pattern- (e.g. lace-) weaving looms or special knitting-machines, maybe?

No good. Short of someone coming on here and saying, "Oh, my Grandad used one of them every day for [ … ] " , we may have to start asking specialist trades or museums selected by intelligent guess, if they recognise it.

You never know, there may even be modern electronic ISO-Metric equivalents in use as we type!

[Ches Green UKParticipant @chesgreenuk]

As was posted earlier, there is a much higher resolution image of the device here … https://www.reddit.com/r/whatisthisthing/comments/bo4dhp/does_anyone_know_what_this_was_used_for/

Ches

[Julian MorrisParticipant @julianmorris86763]

This is fascinating. I have pondered it and realise that as it stands it does not calculate anything as there is no pointer and so there appears to be a significant piece missing such as an outer dial with possibly a window to set or read off the stamped numbers in the inner dial. The wire may act as a click stop for the outer dial. The dial may or may not behave been connected to a machine or manually set.

Yes I'm pretty sure there's at least one part missing that physically links and gives meaning to the relationship between the dials and the outer figures.

There doesn't seem to be any screw holes in the wooden box that indicate it was fixed to a machine.

Just speculating, like everyone else.

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