Is this complex protractor-like tool for machinists or another trade?

Cannonmn · Sep 18, 2017

A visitor to another forum posted this photo with no other info, then disappeared. Wanted ID. Now, so do I. Looks like you set and lock an angle on the scale and the straight edge of triangular piece takes that angle. Anybody seen another one of these? Sry, no dimensions avl. Maybe the fact that it is only marked up to 75 degrees will help reveal the original purpose.

stephen thomas · Sep 18, 2017

I was using my Durometers yesterday.
So to me it looks like an early, very heavy duty, durometer type gage. Or other tension type gage.

Depending whether it is currently locked, or what happens when it is locked/unlocked, the scale would read backwards for that purpose, though, maybe?

Going by the apparent scale direction, maybe it is just a simple quick depth type gage for a specific product, task, or industry. I don't think it is for tire treads, but maybe something like that.

smt

9100 · Sep 18, 2017

A similar device is used for evaluating fabric on airplanes. You press it against the fabric and the depth it penetrates indicates the strength. That would explain why 0 is at the top of the scale, no penetration. I don't think it is for aircraft but some other application. the scale is not in degrees. Note that it is not quite linear.

Bill

Cannonmn · Sep 18, 2017

Thanks, my first guess on the other forum was also that it was some kind of penetrometer, but nothing remotely similar showed up when I googled the term. But now I agree, and the built-in handle tends to support that theory.

DDoug · Sep 18, 2017

9100 said:
A similar device is used for evaluating fabric on airplanes. You press it against the fabric and the depth it penetrates indicates the strength. That would explain why 0 is at the top of the scale, no penetration. I don't think it is for aircraft but some other application. the scale is not in degrees. Note that it is not quite linear.

Bill

That don't look like the punch testers I have seen....
airplane fabric tester - Google Search

Not even close, especially in the "working end".

michiganbuck · Sep 18, 2017

where or what angle does the point go when set at zero?

lionelt · Sep 18, 2017

maybe a welding guage?

Marty Feldman · Sep 18, 2017

michiganbuck's question, above, is pertinant.
It might help to have some dimensions and another view or two.
Helpful too, and perhaps most helpful of all, would be a series of measurements, linear and angular, of exactly what on the instrument changes when the pointer is set at each of the marks.

Why have we assumed that the scale is in degrees, or that it is angles that are being measured? What I see could be a depth gauge of some sort, perhaps task-specific, as stephen thomas speculates.
Exactly which surface is "the straight edge of the triangular piece" of the OP?
Are there any clues as to what those 4 transverse holes were meant for? They were put there for a purpose.

-Marty-

litlerob1 · Sep 18, 2017

Marty Feldman said:
michiganbuck's question, above, is pertinant.
It might help to have some dimensions and another view or two.
Helpful too, and perhaps most helpful of all, would be a series of measurements, linear and angular, of exactly what on the instrument changes when the pointer is set at each of the marks.

Why have we assumed that the scale is in degrees, or that it is angles that are being measured? What I see could be a depth gauge of some sort, perhaps task-specific, as stephen thomas speculates.
Exactly which surface is "the straight edge of the triangular piece" of the OP?
Are there any clues as to what those 4 transverse holes were meant for? They were put there for a purpose.

-Marty-

The build looks a decent quality, but the scale itself looks like a 4 year old did them especially between the 65 and 70. I'm sure it's because of the picture angle, but the center of the theoretical Compass does not look the same for each unit. So I agree with the above post, is it angularity? Can you put a real protractor up against it and verify the angles?

michiganbuck · Sep 18, 2017

Perhaps a machine set gauge.. A drill pointer or the like..but I have seen many drill pointers and never saw that gauge.

Being special likely it should have a patent number, a part number or manufactures mark or symbol .. with not it may be home made.

Benta · Sep 18, 2017

It's home-made. Whatever it's for is anybody's guess.

Cannonmn · Sep 18, 2017

Good thoughts; for any seeking dimensions and other views, as mentioned in OP, the owner dropped only this one photo with no other info, then disappeared, unfortunately.

EPAIII · Sep 18, 2017

Another possibility is it may be for measuring the width of a gap or groove. The wider the opening, the deeper the "V" shape will penetrate into it.

As for those four holes, they are probably for screws or pins that hold the mechanism in place, either on the back side or in an interior pocket.

It would be helpful to see some photos from the back and bottom sides.

Cannonmn said:
A visitor to another forum posted this photo with no other info, then disappeared. Wanted ID. Now, so do I. Looks like you set and lock an angle on the scale and the straight edge of triangular piece takes that angle. Anybody seen another one of these? Sry, no dimensions avl. Maybe the fact that it is only marked up to 75 degrees will help reveal the original purpose.

eKretz · Sep 19, 2017

No idea on the purpose of the device, but it sure looks homemade to me.

Georgineer · Sep 19, 2017

A ruler laid across the 0 line passes the centre of the big hole, which suggests a pivot. Interestingly, that hole has been plugged and re-drilled on a different centre. The same ruler laid across the 75 line passes through nowhere-in-particular.

Enlarging the view shows that all four holes are occupied, presumably by screws which hold parts of the mechanism to the back. What a pity that we can't see the other side of it! The shadows indicate that it is sitting flat on the surface; if so anything on the back is either flush or recessed.

The 'tongue' moves in a recess (or it may be a slot - I can't make it out from the picture) which can just be seen on the lower edge. The two holes at bottom left may hold a corner backing piece in place. The left side of the tongue is very irregular and looks flaked at the edge. Was it hardened and then broken? Inexpert sharpening is a possibility I suppose, but seems less likely.

The vertical slot and wingnut suggests a depth setting, possibly clamping the angle at the same time. If it was a simple angular clamp I would expect to see a curved axial slot rather than a straight vertical one.

The job it was intended for was important enough, and repeated often enough, to justify a significant investment of time and materials in making this tool. Its style is very typical of late 19th century tools I have encountered. If it was a penetrometer I would expect to see some way of applying and controlling the penetrating force.

I am flummoxed!

George

michiganbuck · Sep 19, 2017

Does the gauge point travel horizontal or into the assembly? The thumb lock suggests into. How far does the gauge point move to make zero?...Perhaps the same as the thumb lock travel..Does the gauge point have any wear land?
Odd the thumb lock is up top, and the indicator point and gauge point are down..
looks like about 6" x 3"?

But yes the OP only has a photo not the device..

DMF_TomB · Sep 19, 2017

if it had a level vial i would say for a printing press setting a doctor blade that wipes excess ink.
.
possible you dont have all of it. some parts removed

Marty Feldman · Sep 19, 2017

michiganbuck said:
But yes the OP only has a photo not the device...

Having nothing more than the one photograph is the crux of the matter. We are all just shooting in the dark.

-Marty-

Georgineer · Sep 19, 2017

Marty Feldman said:
... We are all just shooting in the dark.

-Marty-

That's what makes it so interesting. If we knew the answer we'd just look and then move on!

George

tdmidget · Sep 19, 2017

I measure the angle of the surface at the bottom of the Photo to the damaged/maybe repaired edge of the pointer at 79 degrees. It could be as simple as a cam inside to move the indicator arm and measure angles. Seems unnecessarily complicated for that.

Is this complex protractor-like tool for machinists or another trade?

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