A Double Dial Dial Caliper?..... Just cool looking

rivett608 · Jan 12, 2013

Normally I buy really old tools for my collection but every now and then I buy something a little modern. This was just too cool looking not to own.... one thing about collecting for over 35 years is you know what you have never seen before. So when I saw these I felt I had to buy them just to take a good look at them...... and when opened the box I just jumped with excitement! I think they are German and from the early 20th century..... but that is only a guess. Does anyone know anything about what D. R. P. A. means? I'm guessing it is the maker.

What is cool is these have a dial for metric, hence "meter" and a dial for inches hence "London" meaning English measure....... Notice there are two separate rack gears and since the gears are different diameters one is set deeper than the other so both dials line up with each other....... the inch dial also has fractions buy 16ths on it's outer scale.

To me this sort of reminds on the eyes of M.I.T.'s Kismet......

Also being a new year it's time to Thank Don again for giving us a forum where we can share such things as this.... THANK YOU DON...... and I just noticed this my 5,400th post!

gbent · Jan 12, 2013

Rivett,
Could you explain that inch dial a little more? Given the size of the drive gear, is there a two speed unit in there to give the choice of either 1/128 or 1/1,000 on the same dial and pointer?

rivett608 · Jan 12, 2013

I would think it is a single speed dial...... the gear train would move it one revolution in one inch.... any difference would just be the way the dial is graduated... right???? I have had a few glasses of wine so I might be mixed up on this.....

Atomkinder · Jan 12, 2013

This is VERY cool! Congratulations on your find. I'm going to be keeping an eye out for another for the rest of my life, now.

Atomkinder · Jan 12, 2013

gbent said:
Rivett,
Could you explain that inch dial a little more? Given the size of the drive gear, is there a two speed unit in there to give the choice of either 1/128 or 1/1,000 on the same dial and pointer?

Looks to me as if there are simply two sets of graduations, like MPH and KMH on the same speedometer.

Edit: although with the inch side it seems to be divided into .01" increments and 1/128 increments, obviously with the 1/128 being a more accurate scale.

pan60 · Jan 12, 2013

Very cool looking for sure!

number 2 · Jan 12, 2013

Whats the idea behind the inside legs ? Are they ment to measure an OD of a face groove or something similar ?

Heavey Metal · Jan 12, 2013

I think each mark is 1/100th on the inner dial and 1/16 on the outer

one rotation being 1''

gbent said:
Rivett,
Could you explain that inch dial a little more? Given the size of the drive gear, is there a two speed unit in there to give the choice of either 1/128 or 1/1,000 on the same dial and pointer?

gbent · Jan 12, 2013

Atomkinder said:
Looks to me as if there are simply two sets of graduations, like MPH and KMH on the same speedometer.

Edit: although with the inch side it seems to be divided into .01" increments and 1/128 increments, obviously with the 1/128 being a more accurate scale.

I think you are right. The decimal divisions don't represent .001 inches, they represent .01 inches, One revolution per inch rather than the later standard on 10 revolutions per inch. I simply didn't think of that with the metric dial having more normal graduations.

Leigh B · Jan 12, 2013

I ever though about being a hand tool collector. Way cool calipers. I'm gonna start now. You've got competition now.

Frank R · Jan 12, 2013

Okay, I'll venture a guess... the D and R stand for Deutsche Republik... which would make it during the cold war.

rivett608 · Jan 12, 2013

The answer to what D. R. P. A. is may be solved....... it may mean a patent was applied for? This was sent to me by a friend who is into clocks....

"The trademark is from Junghans. By 1913 they were claiming to be the world's largest clock manufacturer. This trademark was introduced in 1890
The "DRP" refers to a German patent, and is usually followed by a patent number. Here it's probably "DRPa," the "a" an abbreviation for "angemeldet," meaning "applied for." In short, Junghans was claiming they'd applied for a patent (on something).

The then German patent office had stated that such a marking was not to be used. Reference must be made only to what had actually been granted.

However the "DRPa" marking does show up not infrequently, and from different manufacturers, so evidently they weren't all that impressed."

Also the spiky inside legs are typical of some European calipers....

And for those that his makes them want to start collecting I say GREAT..... but be warned.... this is the first one I have seen in over 35 years of collecting this stuff!!!!!!.... now how many more will be found????

Markusfu · Jan 12, 2013

Rivett- very cool calipers

thanks for sharing
Markus

adammil1 · Jan 13, 2013

That is cool do you think that is ivory in the dials? If so once upon a time was ivory cheaper and more common probably before we had killed most of the animals producing it or would this really have been a very expensive tool back then?

L Vanice · Jan 13, 2013

adammil1 said:
That is cool do you think that is ivory in the dials? If so once upon a time was ivory cheaper and more common probably before we had killed most of the animals producing it or would this really have been a very expensive tool back then?

The dials were likely made the same way watch and small clock dials were made circa 1900. Sheet copper was fired with white glass enamel, then the markings were applied in black and the dial fired again.

But you are correct that, before the invention of Nylon or other suitable plastic materials, drafting scales and small folding rules were sometimes made of ivory. Cheaper ones were made of boxwood. Enameled copper dials were almost always used on watches, though. Some old watches had all-metal dials. I never saw an ivory dial on a watch.

Larry

stephen thomas · Jan 13, 2013

That is one of the coolest old tools I've ever seen!
Almost looks like what a "steampunk" designer for a movie producer would dream up in modern times, for a movie set in the 19-teens. Something Captain Nemo would have had on board...

dials could be celluloid, or if they are actually from the 30's, maybe even something a little better.

Adam- I have read early accounts of when europeans first started to explore Africa, that tusks more or less littered the place in certain areas at that time. Eons of dead elephants, and only sporadic or minor use of the by products in carvings and such. It actually took a century or two before they started to have to "expedite" the production rate from current walking stocks....

smt

JST · Jan 13, 2013

On the closeup of the dials you can clearly see what appears to be the pointer drive gears. Inch side appears roughly 0.3 inch diameter, the other is credible for about 3mm, or 10mm/rev.

Dial faces appear to be some solid material, if you look closely at the inside edge where the space for the pointer shaft is. They do not appear to be enameled, there is a suggestion of translucency to them

rivett608 · Jan 13, 2013

The dials are a celluloid type material...... one of the PM reader is visiting right now and we are having loads of fun!!!!!! He says hi to everyone!

Asquith · Jan 13, 2013

I believe that DRPa = Deutsches Reich Patent angemeldet (angemeldet = pending).

They were being imported to the UK by 1907.

There were also single dial versions (mm or inch).

rivett608 · Jan 13, 2013

Asquith.... Wow, Great.... do you have any catalog picture of either the singles or doubles?

A Double Dial Dial Caliper?..... Just cool looking

Diamond

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