Terminator, I admit it, you were right

[Guest StrongerthanArne]

My latest testing. Subjects: One 286 ip IM #2 and two SOS grippers. One rated at 302 ip and the other at 338 ip. 10 reps on the 302 equals about 10 reps on the 338. But 10 reps on the 338 (and 302) equals about 5 reps with the 286. Obviously these data speak for themselves.  Basically, I admit that I trusted PDA's ip numbers far too much. Interestingly I closed the 286 ip #2 all the way and then opened it up a couple of mm and closed it again and repeated the process with the 338. The 286 felt harder every time. The class III SOS grippers are much more in line with the 396 and 410 IM #3's I had access to. I wanted, however, more than anything else a gripper intermediate in strength between the 286 #2 and my 396 #3 for doing strap holds. What I got was a 302 and a 338 that are both much easier to close than the #2.

[Guest Jeff Roark]

M.S.,

Where does it feel harder? I don't understand all this really. HaHaHa be afraid of what you don't understand and ridicule the heck out of it!!! No I'm kidding. Do you think that this IP rating thing is measuring static ip, (closure) and not dynamic the work it takes to get to the point of contact? Being logical you would think that there would be a big difference between a 286 and a 338.

[terminator]

StrongerthanArne, thanks for admitting it.  I had seen a lot of information that convinced me, as did others, plus an engineering background.  I know we have a lot of intelligent people on the board who are hard to convince once they have an idea in their mind.  Real world (hand test) always wins in the end, it is after all a hand gripper.  I never believe when someone tells me something is easier by a number, when my hand tells me everytime it's harder (or vice versa).  The numbers seem to mean less than #3, #4 etc., as 3 and 4 are only ranges.  As simple and elegant as these grippers are, there is a lot of hidden science.

[Guest StrongerthanArne]

The 338 feels easier all along the ride than the 286 and I have closed both very very slowly to see where the resistens of the mighty 338 would kick in. Arne who basically never have been able to close his 286 cold with his weaker left hand, slammed the 338 shut first attempt without warm up. There is something very strange going on with these IP numbers, I have to admit.

[Guest StrongerthanArne]

In my first posting I meant that I trusted the IP numbers to much when it comes to reflect degree of difficulty. The 399 ip SOS felt very similar to my 396 #3 but was just a fraction easier to close (they are so close I can't really complain at all). The 437 SOS is definitely harder than both my 396 #3 and Arne's 410 #3. Nothing strange here. Likewise the 359 SOS is easier to close than the 399 SOS. Like David Horne, I must say that both I and another #3 closer at my gym both liked the feeling of the SOS more than that om the IM's. Pitty about that weak 338 (and 302). I still want a gripper intermediate between my #3 and the 286 #2.

[Bill Piche]

Hello....is my mike on.....I said this before...

I say it's dynamic versus static friction coming into play.  And, the force curves on top of that.  

That is force per inch of deflection is what is varying.  Probably due to the spring itself and more importantly how tight it was wound.

And, getting tired is skewing the final STATIC IP with it shut.  AND, it is measured CENTER of the handle.

Just some of my thoughts.

[Guest StrongerthanArne]

Obviously, what everyone would like to have is a numbering system that reflects difficulty as closely as possible. Do we need to know the closing IP if it does not tell us that much about how difficult it is to close a gripper?

[gaster]

Is the handle length different between the brands?  I know John worked very hard on this to make it equal though.

   

As we all know, force X length = torque.  Maybe the PDA grippers have a different handle length, or maybe as Wannagrip stated it has to do with how the spring has been wound.  

I've noticed that some grippers have springs that have sort of a kink in them in a place or two, (especially at the transition of where the wire goes from straight coming out of the handle to the curved and wound part), but other springs have smooth continuous curves.  Maybe that makes a difference somehow.  Is it possible the closing torque would measure the same, but the effective handle length would be different as to make it feel easier or harder?  Maybe I'm just nuts and need to go back to work.  ha ha

[Guest StrongerthanArne]

As Dr. of Handlelengthmania I can assure you that the handle lengths on the 286 IM and 302 +338 SOS were almost identical (differed less than one mm).