[Newbie] Help Identify And Explain This Surface Gauge

[Tim at AST]

Hi,

I got this surface gauge at a shop in my town (Alexandria, Egypt). I just took a photo and labelled it. I've left out the top part of the photo.

It is second hand, clearly, and been used a lot.
I understand the following parts (please correct me if wrong):
a) fine tune adjust
b) main adjust

But I don't understand these parts
1) The screw (c) allows the entire arm to be removed or to swing down through slot (d) up to 90 deg.
Why would this be useful since the main adjust (b) already does this.

2) the pins e1 and e2 extend upwards. I thought they were supposed to extend downwards underneath the piece to hang onto the edge the surface plate. Underneath there are non-threaded cavities of the size of the pins, but the pins don't easily move down (could be stuck with rust?) and there is no evidence of banging on top of the pins that would indicate they were sometimes pressed down into these cavities.
So why the pins, and why the cavities?

3) the gauge is very heavy. I thought that they needed to be light so you could move them along a surface to scratch a line.

So is this a regular surface gauge or an unusual one?

There is no stamp or writing on the gauge. The shop sells a lot of ex-Soviet machinery tools (from the 1960's). There are no USA products here.

Could anyone explain the bits I don't understand?

Thanks,

Tim

 

[Ed ke6bnl]

no expert, the pin can be pushed down run the gauge along a straight edge, there is on mine a pointed probe the rides up and down that is use to scribe a part while move across the surface plate onto a work piece usually with layout dye.

 

[rgray]

C is the pivot bolt. The part pivoting on it should be spring loaded so there is always down pressure on bolt A for fine adjust. B is tension on the rod or course adjust. E1 & E2 should slide in their holes. They are guides to use on the edge of a surface plate. They can be used to scribe a taper on a horizontal surface. The edge of the surface plate is straight the guides follow that straight path and your scribe also....setting the part at the angle gives the taper....general angle to sine plate set up for something technical.

Most scribing I do is on a vertical surface. The most use I get from a surface gauge is with indicators attached for measuring squareness and flatness/parallelism...the weight is an advantage to not have the gauge tip over.

 

[12bolts]

You got it pretty much correct
a) is for fine adjustments
b) is for coarse adjustments
c) is an assembly screw and the pivot for the rocker which sits in slot (d) and will have a spring beneath it.
e1 & e2) extend upwards so the gauge can be used on a flat surface, or be pushed down (easily) to enable the gauge to be run along an edge. They often use a small piece of spring wire in a groove to provide some friction but still enable them to be moved with thumb pressure. They are most likely stuck with gunk/corrosion, a good soaking in penetrating oil will probably fix that. Dont bang on them!
The gauges are heavy because they are usually made from cast iron for stability and self lubricating properties.
It is just a regular surface gauge.
Many surface gauges are made by hand as part of a machinists career and may be unmarked or signed with the makers name/initials and nothing more.
Do you have the scribe and associated clamp for the post?

Cheers Phil

 

[12bolts]

The most use I get from a surface gauge is as a paperweight...the weight helps there too

The most use I get from a surface gauge is with indicators attached for measuring squareness and flatness/parallelism...

Cheers Phil

 

[janvanruth]

i had one for some time without knowing what it was
it came with some tooling i bought
found out just recently what it is used for

i use it with a dti on the surplace plate to check for flatness of parts i scraped
as the dti only has a travel of 0,01 mm the fine adjustement is needed