All Clamps ARE the Same

Of course you are right!

All wooden clamps are made with the same four basic pieces:

A stopped screw, or end spindle, shown in yellow, with its handle down,A through screw, or middle spindle, shown in red, with its handle up,
A stopped jaw, shown in blue, and
A through jaw, shown in green.

Stopped Screw

A stopped screw, or end spindle, has three parts:

a stub that fits into the pit of the stopped jaw
a long shaft with threads that goes through the threaded hole in the through jaw, and
a handle, usually fairly cylindrical.

The stopped screw belongs in the end hole, not the middle hole, but you'll see a lot of stopped screws in the middle hole. The problem is that the handle on a stopped screw doesn't have a shoulder to press against the stopped jaw, like a through screw, so there's lots of wear.

For a clamp user, the lengths of the two screws should be about the same, and roughly equal to the length of the jaws. There's a limit to how small a handle can be, so the proportions do change as the size of the screw changes. Of course, the shafts have to mate with the holes, the threads should not bind, and there should be useful threads everywhere along the shaft.

For a collector, the question is, "Does this stopped screw belong with all the other pieces?" To answer that, you have to have a Field Guide.

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Through Screw

A through screw, or middle spindle, has three parts:

a handle, usually shaped to fit the hand, with a shoulder to press against the stopped jaw,
a short section without threads that passes through the smooth hole in the stopped jaw, and
a long shaft with threads that goes through the threaded hole in the through jaw.

Depending on the maker, the tip of the screw may be cut flat, or rounded into an acorn-like shape, or tapered.

The through screw belongs in the hole in the middle of the jaw, not the hole at the end, but you'll see a lot of through screws out of place. The problem is that the tip on a through screw doesn't fit into the pit in stopped jaw, like a stopped screw, so the threads have to be taken off. The damage looks ugly.

For a clamp user, the lengths of the two screws should be about the same, and roughly equal to the length of the jaws. There's a limit to how small a handle can be, so the proportions do change as the size of the screw changes. Of course, the shaft have to mate with the holes, the threads should not bind, and there should be useful threads everywhere along the shaft.

For a collector, the question is, "Does this through screw belong with all the other pieces?" To answer that, you have to have a Field Guide.

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Stopped Jaw

A stopped jaw is distinguished by having two smooth bore holes, one of which stops before it goes all the way through, and thus forms a pit to hold the tip of the stopped screw.

The places on a stopped jaw are conventionally called:

the inside face, which touches the item to be clamped,
the outside face, the opposite face,
the back, which is the squarish end,
the nose, the opposite end, usually rectangular,
the angle (guess where that name came from),
the right side, which is to the right when you look at the back with the outside face on top (the sketch above shows the right side full on), and
the left side, the opposite side.

For a clamp user, the depth of the pit of the stopped jaw should match the size of the stub of the stopped screw. Also, the un-threaded part of the through screw should match the distance between inside and outside faces of the stopped jaw. The jaws can't be fully closed if the handle is too far from the first threads on the through screw.

The maker often put a mark on the back, along with identification of the model; owners put their marks almost anywhere.

Different makers had different ways to decorate the jaws, usually by chamfering some of the edges. What kinds of chamfers, and which edges were chamfered, can be used to identify a maker, even in the absence of a mark by the maker. The Field Guide has more details.

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Through Jaw

A through jaw can be distinguished by having two threaded holes, both of which go all the way through.

The places on a through jaw have the same conventional names:

the inside face, which touches the item to be clamped,
the outside face, the opposite face,
the back, which is the squarish end,
the nose, the opposite end, usually rectangular,
the angle (guess where that name came from),
the right side, which is to the right when you look at the back with the outside face on the bottom (the sketch above shows the right side full on), and
the left side, the opposite side.

For a clamp user, the main questions are about the threads on the through jaw mating well with the threads on the screws.

The maker sometimes put a mark on the back, along with identification of the model; owners put their marks almost anywhere.

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