how does a pipe wrench and a vise grip work?

My advice for you is to obtain one of each and play around with it.

It would have the most value if you can figure it out yourselves.

You can then read the other posts or search the web to confirm or reject your thoughts.

Hi Karen

I am going to give you more advice of how to go about it.

You already have enough knowledge to solve your questions.

You must start with your notes or handbook and say a vice grip.

look at each component and see what you know about it.

start with the screw at the back. Jot down the data.

Why not a hex head?

Then take the next part. look up links, levers, springs, rivets etc.

start playing with the parts - close the grip and turn the screw - what happens?

Then play with the funny thing in the handle. see what it does and why.

-

do the same with the wrench

I KNOW YOU CAN!

At the end you can post your findings for CR4 to evaluate and score it for you.

Exactly,

You may conduct a 'brain-storming' secession among your peers or juniors.

Show each component say: movable jaw, focus on each feature say: welded face and keep asking at least (as told by TPM experts) 5 times 'why'.

Record it and see it turns to a great reverse engineered analysis.

This is very good advice. Spending some time really thinking about the function of each part of these tools would be much more valuable than having people here explain them. The pipe wrench tightens more securely on the pipe the harder you turn it. Why is that? The Vise Grips suddenly get a little easier to squeeze just before they lock. Why is that? Use both tools for various tasks and see how they work. Have fun.

For the vise grip. The way it multiplies the force is quite easy to see. The handle moves through a much greater distance than the jaws do. This is the same way pulleys multiply the load which can be lifted. Lets take the equation work=force * distance. If we say that the work done is equal and the distance is increased then the force needed decreases.

The way it locks is the hinge mechanism. When the handle reaches a certain point the hinge lies at 180 degrees. In other words it is like a flip phone which has been opened up. Once it goes past 180 degrees the spring attached to the jaws pulls the handle in. Haven't really explained it all that well.

And the unlocking mechanism simply pushes the hinge back to less than 180 degrees.

If you take a look it really is a very good and simple design.

The welded jaw on a pipe wrench is on the movable side and can be completely remove from wrench for replacement if worn. The stationary side is pin in to the handle for replacement.

The spring is to hold the jaws open.

Teeth are designed engage the over the crown of the pipe. As force is applied to the handle the movable jaw pivots closing the gap between the jaws. The more force applied the tighter it closes.

Vice grip works on fulcrum compounding force. Center of fulcrum is a pin and levers. Properly adjusted when clamping forces levers to bind. Release lever is just another fulcrum lever forcing it out of the bind.

Here's another approach. Both the tools are actually compound tools. Start by figuring out each basic fundamental tool comprised by each of the pipe wrench (which is not a fundamental tool in and of itself) and the vice-grip pliers (...likewise). You are now on the way to an analysis. As you figure out how and in what order each fundamental tool component of the compound tool comes into play, you have now broken the analysis task into manageable portions. Examining/studying those smaller tool actions and forces comprised by the larger, compound tool (the pliers and/or the wrench) you will find it easier to discern the choice of material used to fabricate the tools and how they were made, and what purpose each tool component, and material selection in the manufacture, serves. Part of that analysis of components of the whole tool, can also consist in trying to understand what would be the result if a different material and component properties had been used.

I was once told that dismantling and re-assembly was easier than the original invention. All you have to do is figure out how someone else's invention works.

These tools employ principles that are universal to many designs, so take the time and figure it out. Buy the tools and take them apart. Experiment with them, and you will become a better employee to some one because you now have hands on experience.

The principle used in the vise grips is the same principle used to lock down retractable landing gear on some aircraft, so it is well worth the study.

"I was once told that dismantling and re-assembly was easier than the original invention. All you have to do is figure out how someone else's invention works."

And that's what separates an excellent mechanic from a lackadaisical wrench-turner!

Regards

Or a creative engineer from average.

Should we ask them to investigate a mechanism which will prevent the vice grip from closing in the presence of a nut?

Ouch!

(Oh, wrong nut!)

I thought vice grips were designed to remove the corners from nuts!

You mention "design critique" and also analysis, which are not necessarily synonymous. Are we considering any tools or some specific makes of tools? The mention of design critique is suggestive of testing (more so than analysis) of a particular example of the tools--possibly to state its deficiencies or how its design might have been improved. Analysis could be more fundamental, and apply to particular tool's design or the design of the whole class of similar tools. For example, your evaluation could be from a comparative standpoint, pointing out disadvantages and advantages between, say, two or more makes of wrenches or pliers. In other words, you need to come up with ways to organize your results in a meaningful way for presentation to the class or instructor. You may consider this a critique of effective ways to approach analysis and/or critique tasks to be documented for presentation.

Being married to a Filipina and having been brought up as a good old American Yankee, I'm noticing how our different cultures shape our thought processes. The strength of the Old American system is exemplified by the excellent answers to the posted question. Using the socratic method and trying and proving things, looking for the essential principles at work in a system, are or were the core of American engineering innovation and know-how. Having never had vise grips or pipe wrenches explained to me, I had conjured in my mind pretty much the same answers listed here in a few seconds. Like: a vise grip uses the principle of the lever and the principle of wedging and the pipe wrench uses the principle of a squashing rhombus, with sharp bitey teeth and levering and wedging to grab a pipe in one direction and release in the other.

I noticed with my wife and step kids and several other geniuses of copying by watching (in the Philipino community), an incredible adeptness at mimicking, copying, and memorizing, with almost a complete aversion to, and allergic reaction against analytical, observational, cause and effect logic, and an inability to use the socratic method of asking oneself questions and considering alternatives,...this interestingly contrasted for instance by an older Philipino woman, who was very good at exactly this kind of thoughtful cause and effect logic, she had been a civil engineer specializing in plumbing in Philippines.

Anyway I'm guessing that the one teaching the course in Philippines recognizes the need to develop, analytical, cause and effect logic through examination of the objects in question and playing around with them, which is the mental environment for developing a good engineering mind. Especially in a culture that seems to view learning and memorization as almost synonymous.

I mean only to stress the differences in cultural environment.

Geoff

A most astute observation. Interestingly--and strangely so some might say--Filipinos, male and female alike, are a highly preferred human labor resource, at all levels, around the world, including the U.S. And, from a Philippines national perspective, there's virtue in not being of too-naturally-analytic bent. Social skill will carry almost anyone a lot further...up the money tree, that is.