Sorry, I should probably have explained how they work. It's quite a neat design. Their power comes from the extremely short "forward" lever arm. Here's a comparison pic with some large channellocks:
The ratio of the red to the blue lever arm gives the "force multiplier" of the pliers. On the traditional pliers, the distance from the tip of the jaws to the fulcrum is 75 mm. From the fulcrum to a point close to the end of the handle, it's 250 mm. If you apply, say 10lb of force to that point on the handle, the tips of the jaws will experience
10lb * (250/75) = 33.3 lb
of force. Now for the Knipex ones, we get
10lb * (200/13) = 153.8 lb (4.6 times more)
That's what makes the Knipex ones so unique. The whole jaw is pushed up by that much larger force because the forward distance is so small.
I used two hands for the studs and I'm sure I developed at least 50lb of force on the handle. That means the jaws were clamped shut by a 770 lb force!!! That allowed the flat face to grip a smooth fastener.
Actually, when you play with the things and put your finger in them, it takes almost no force on the handle for it to start hurting
bchee, you're right. When fully closed, there is a small angle between the jaws. I think that's there on purpose. It takes up the slack of the whole mechanism when you apply some force. Kind of like pre-tensioning it. When you clamp down on something, they do seem parallel.
I've also used them on dirty brass AC fittings (elbows with square corners). The load was distributed so evenly that they hardly disturbed the grease and dirt on the fitting... From other times I've used them, I know that they work a bunch better than the "vise-grips plus wrench" approach, as well.
chammyman, the lack of teeth is what makes them so attractive to me. You don't have to worry about tearing stuff up.
Stuey, I have to check out the channellocks you mentioned. Do they work on the same principle?
Finally, thanks for the "thanks for the review"s. I like reading reviews here a lot, myself.
I hope this post helps. Otherwise, fire away