Several years ago I was at a garage sale in Pennsylvania with some friends and ran across this pair of inside calipers. They were covered with rust and nothing much moved...but I figured for 50 cents I couldn't go too far wrong. After much cleaning I finally got them where everything worked and they were reasonably presentable.
The overall length is about 13 1/2 inches. As you can tell from the pictures, they will open 180 degrees, which as far as I can tell is a totally useless feature. The lever just below the small fine adjustment knob unlocks the leg so that it can move in towards the other leg. I speculate that this would be useful if you need to measure inside a cylinder that had a lip that would not let you withdraw them without changing the main adjustment.
These appear to be very well made, although perhaps overly complicated. Even after all the cleaning everything is tight, i.e. no sloppiness, even the moveable leg is nice and snug.
Have any of you run across any others like these or know anything about who may have made them? There are no marks of any kind.
Mike
