The Physics Of Grippers

[MetalAndy]

Hi,

I'm new here and i'd wondering about how grippers are rated in Lbs. Here's why I ask. I discovered this site a few weeks ago and then just this week my friend bought a Heavy Grip that says 250 on the handle. His first one and the first one i've ever tried. So on thier website I read that it was 250 In-Lbs, and that got me to thinking. I imagine that that would mean at 1 inch from the virtual "Hinge" there is 250 LBS of force. So at, say the middle of the handle, the force would be less. I would have to get myself one of these before I could figure out the details (im planning to soon). I should be right about this. However, are all grippers measured in this way? In in-lbs I mean. And is this force measured when the handles touch each other? I have read on here that there are variations in the force of most grippers that are the same model. So I guess the advertised force would in theory be the mean of quite a large sample of the same model grippers.

So what does everyone think. Im new to this whole grip and wrist training thing. But it sounds fun.

Edit: So what kind of K constant do you think these springs have, just from you're experiance. Linear (Force increases linearly), Some sort of upward curve (exponential or one other type... gets hard mostly at the end), or logararithmic (gets strong fast then says the same-ish.)

Edited February 15, 2007 by MetalAndy

[Hubgeezer]

There are roughly 280,000 posts on this board. Approximately 10,000 of them discuss some aspect of your observations and questions. It is probably unlikely that someone who has invested hundreds of hours sifting through the board will take the time to synthesize the issue down to a few sentences. I don't say this to criticize your comments, just to explain that there may not be many people who have the expertise and are that generous with their talent or their time.

With that in mind, any information you get will be gravy.

I will go first. Heavy Grips are the most unreliable of the types of grippers, and the numbers have virtually no correlation with the ratings they place on them as far as poundage ratings go.

[mobsterone]

PDA, site sponser, sell a book with many of the answers.

[rying]

I'm not an expert and haven't done or studied the research, but here's my basic observations:

Most gripper ratings aren't in in-lbs. I believe the Ironmind gripper ratings are based on the force required to close the gripper if the force is applied to the center of the handle. The Beefbuilder ratings (at least on the Weightlifters warehouse website) are based on force applied near the end of the handle (?). So the IM #2 rated at 195 lbs is the same as a BBM rated at 155 (I think?), but both are harder (on average) than a HG 250. I didn't know the HG's were rated in in-lbs, but that would explain the numbers. But the grippers can vary so much that the numbers are a rough estimate at best!

Probably the best approximation for most grippers is linear (F = -kx), but grippers vary alot. So some will have an easy sweep but a hard finish, and vice versa. Keep in mind that the torsion springs are operating beyond their intended range in the design of grippers. I'm not sure how well torsion springs obey Hooke's law, or at what range they fail to do so, but I'm sure someone out there has done the testing...

The design used in an Ivanko Supergripper will be much closer to perfectly linear and more consistent than the torsion springs. And while similar, it definately has a different "feel".

Hope this helps.

[mbcx6pmw]

I would have thought the k should stay fairly constant. Experience suggests this may not be the case, you may hear people refer to the spring 'stacking' in the close, though there could be biomechanical issues as well. I think someone showed a force vs. displacement plot a while ago, you may be able to find it if you search around.

[mobsterone]

Bill Morrison of HG has said on record that the numbers he has given to his grippers do not indicate in any way the strength required to close them. At best they indicate that a 300 is harder than a 200.

There are so many variables that the easiest way to know the strength of a gripper is by wire size and so that's how they are listed in the FAQ section.

Finally an understanding of the physics doesn't make you a better athlete. Blood, sweat and tears do. Chalk up and go at it.

[ObsceneJester]

Bill Morrison of HG has said on record that the numbers he has given to his grippers do not indicate in any way the strength required to close them. At best they indicate that a 300 is harder than a 200.

There are so many variables that the easiest way to know the strength of a gripper is by wire size and so that's how they are listed in the FAQ section.

Finally an understanding of the physics doesn't make you a better athlete. Blood, sweat and tears do. Chalk up and go at it.

Uh oh you know you messed up when Steve has to come in here and explain things..

[AP]

Bill Morrison of HG has said on record that the numbers he has given to his grippers do not indicate in any way the strength required to close them. At best they indicate that a 300 is harder than a 200.

There are so many variables that the easiest way to know the strength of a gripper is by wire size and so that's how they are listed in the FAQ section.

Finally an understanding of the physics doesn't make you a better athlete. Blood, sweat and tears do. Chalk up and go at it.

Uh oh you know you messed up when Steve has to come in here and explain things..

You're only in trouble if you don't listen.

[Jedd Johnson]

I do not think that the number ratings given to the IronMind grippers were obtained by using any means other than someone squeezing them and estimating them. Similar to what Bill Morrison is quoted to have said about his grippers.

With that said, there are some members that are calibrating their grippers using devices. The names that come to mind are Dave Morton (dave), Greg Amidon (gamidon) Ben Edwards (bencrush) and John Eaton.

[Trevor111]

And don't the numbers come from the tip tp tip closing of the grippers? NOT from teh spring load strength. i believe the idea is that if you were to put a gripper onto a zeroed scale and then put plates on it till it closed a, 200lb rate gripper should touch handles with 200lbs on the handles opposing. This begs the question of the variability of the grippers and what the tendancy of each is, this is of no concern in reality, you just need to realize that a little research on how your gripper rates to other grippers of its' type will tell you it's strength or weakness. Grippers DO ned more strength or weight to close them the CLOSER you get to the spring. I do not know the physical curve for this force rate.

[mobsterone]

Read the CoC book for Randalls take, speak to Warren Tetting for his (posts here by GB members who did so on that subject) and read PDA's conclusion - he spent an absolute fortune and the book exceeds 60 pages (I think) and eventually gave up. Not one is in agreement with any other and most long term GB members who looked at it agreed there are too many variables - esp as the way we use torsion spring grippers differs to usual use. This is also why the instructions on the MM grippers manufacture were very specific - anal even.

So as no one has a clear understanding, from both those that use and those that make them, and knowing hasn't made Warren, Randall or Bill Morrison CoC's (Robert Baraban close his 3 before he started making grippers) my comment about blood, sweat, tears and chalk is esp valid.

Remind yourselves, on a daily basis if need be, that effort and some knowledge of how to shut them is what will make you strong. I own no ground down grippers, mine are kept in a box, no gaffer tape, no secret weapon and so on. Look at many of those who are even better than me - as good etc as I might be - few if any have any of these accessories. The Holles are fine examples.

When spring / handle width (so-called 'spread) varies, as does hand size, handle thickness and spring depth into the handle. When if the spring touches the handle, when quality control and depth of knurling differ, when setting varies, wire size differs, when aged, Four score and seven years ago I am the MAN because I swear and I want everyone to know how manly I am by using profanity.ing torched (yes some take the right piss) and seasoning with feet all effect the gripper knowing the physics of an ideally set, ideally spread, ideally seasoned etc etc gripper and it's spring will not help you one iota.

All this is here, on the GB, for you to read. Most have. The best grip guys work harder than those who are not so good.