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climber511

Redneck Gripper Calibrator

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http://gripperhell.blogspot.com/

http://www.software-henritzi.net/Articles/...ationDevice.pdf

At the BBB2 contest Dave Morton was telling me about the gripper calibrator he and Greg had come up with. It sounded like just exactly what has been needed for a very long time in our sport so I was excited when Greg sent me his article and pictures. I welded one up ASAP (mine mounts in my power rack) and ran all my grippers thru it along with the few I have borrowed at the moment. My numbers came out very close to theirs and were also very close to my personal impressions of the relative strengths. It will test grippers of all common sizes and models except for those with the huge handles diameters.

It’s very simple in construction so it will be easy for people to make and will allow a consistent method of measurement. I used plates weighed on a certified scale and included the spread of each gripper I did. I thought this might explain the different “feel” between grippers somewhat. If you make one and send the results to Greg – he will build a database of all grippers tested – it should be interesting.

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I may have to make myself one of those.

- Aaron

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This is really cool. :cool I would think this to be repeatable and fairy accurate.

I didn't understand this part:

Here a GM is loaded and a block of wood is used as a spreader. The goal is to not allow the strap to contact the fixed leg of the gripper and throw off the calibration. The picture on the left shows the loading pin loaded with 155 pounds. The picture on the right is when the gripper just closed with 150 pounds on it. In the picture the gripper looks close to the metal rod on the left, but it is not touching it.

Are the numbers just backwards? The gripper closed at 155 and not at 150 right? Just making sure I didn't miss something about how this works.

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This is really cool. :cool I would think this to be repeatable and fairy accurate.

I didn't understand this part:

Here a GM is loaded and a block of wood is used as a spreader. The goal is to not allow the strap to contact the fixed leg of the gripper and throw off the calibration. The picture on the left shows the loading pin loaded with 155 pounds. The picture on the right is when the gripper just closed with 150 pounds on it. In the picture the gripper looks close to the metal rod on the left, but it is not touching it.

Are the numbers just backwards? The gripper closed at 155 and not at 150 right? Just making sure I didn't miss something about how this works.

Good find Matt.

I proof read it and overlooked that part. :trout

150# is the correct value when its closed, see the table at the end of the article.

The 155# should be somehow lower (maybe 135# or so).

Greg can give the exact value (which is not important at all, but its <150# of course).

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Good find Matt.

I proof read it and overlooked that part. :trout

150# is the correct value when its closed, see the table at the end of the article.

The 155# should be somehow lower (maybe 135# or so).

Greg can give the exact value (which is not important at all, but its <150# of course).

This thing is really cool, Franky. I may have to make one and send Greg my results. I have a friend who could whip this up in no time. It's interesting to me to see that the both BBSMs tested very close to the CoC3.

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Good find Matt.

I proof read it and overlooked that part. :trout

150# is the correct value when its closed, see the table at the end of the article.

The 155# should be somehow lower (maybe 135# or so).

Greg can give the exact value (which is not important at all, but its <150# of course).

This thing is really cool, Franky. I may have to make one and send Greg my results. I have a friend who could whip this up in no time. It's interesting to me to see that the both BBSMs tested very close to the CoC3.

The 155 is a typo, it should say 125.

One of the BBSM measured 132.5 which put it in the middle of the #2 and the #3. The other is actually a BBSM+ this is a new gripper from Tetting where he buries the spring. He stamps them with a P on one handle to indicate it is harder than a SM. This particular one is not seasoned at all so I will use it and then see how it drops off in difficulty.

There are several grippers that the first close was on the calibrator, we will track the changes as they are seasoned. It should be very interesting. Perhaps I can stomp the crap out of one and see what that does :trout:tongue Its a joke so don't get all pissed. HAHAHAHA

Thanks Franky for proofreading and hosting the document.

Greg

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Something that surprised me was how much harder 5# on a gripper is to close. Even 2 1/2# can easily be felt.

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How do you guys think this compares to the work PDA did? They seemed to have big problems getting numbers that accurately reflected the toughness of the gripper.

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How do you guys think this compares to the work PDA did? They seemed to have big problems getting numbers that accurately reflected the toughness of the gripper.

Scott,

So far everything I have seen puts grippers that are close in "feel" close in poundage. Chris mentioned that 2.5 or 5 pounds is a lot in how a gripper feels. This is very true. I think the sweep would have to be measured to show how the gripper goes from 2" open to 1.5" and so on to closed to show how the griper would feel in a TNS or credit card set. For MM sets I would think these numbers are really accurate.

I would like to see the mash monster grippers calibrate!!! Any chance of making that possible? It would be real cool to know which of your own grippers is close to a particular MM gripper. hmmm

Edited by gamidon

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I'll go out on a limb and say I bet that ain't gonna happen

:inno:whistel:whistel:inno

Edited by dubthewonderscot

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I just went out in the garage and dug out PDA's Torsion Spring Grippers report that John sent me long ago. I just gave it a quick read and the short version is this - at least in my non engineer pea brain. The total force measurement numbers we get will be different than Johns because we measure at the end of the handles and he didn't - also John is an engineer and used very high quality testing procudures compared to ours with fine increments. The gross force measurements will not accurately reflect the complete force draw curve unless we take the time to actually measure and chart each gripper at very small increments like PDA did and Greg suggested. This set of measurements indicates better the "feel" of one gripper versus another one. As Greg points out - this doesn't seem to matter nearly as much when using a MM set as when a no set or CC set is used. Does this testing mean that if you can close one gripper of say 150# that you can close all grippers of that same resistance - probably not - but it sure gives us a much better and easier to use method than handing them back and forth and saying - "how hard do you think this one is?" I believe that at a practical level and at an availibility level - this will be a giant step forward for us all. At most contests I've been to - often grippers seem "out of order" compared to what the so called expected ratings were but in reality, were correct. Those people who have spent years closing hundreds of grippers - like Dave and Heath and seveal in Europe etc - develop a very good feel for how grippers rank. But everyone in the world can't practically send them each and every gripper we would like calibrated - but everyone can use this device and get very close without a lot of trouble or money spent. It's super simple to make and easy to use - give it a try!

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Pretty neat. Does "nonCoC" mean it doesn't have the stamped handles?

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Pretty neat. Does "nonCoC" mean it doesn't have the stamped handles?

The engraving around the rings is not there. So it is a double stamped gripper without the engraving. Hope that makes sense.

Greg

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Chris mentioned that we measure at the end of the handle. There is a VERY good reason for this, wait till you have to lift the 200 pounds for a #4 and try and gently set it on a gripper. Well if you were using the center of the handle the amount of wieght would be a hell of a lot more. In fact take a look at this chart it should look familier

Trainer 100

#1 140

#2 195

#3 280

#4 365

These are the IM ratings, if you assume they are measured in the center of the handle then the same figures when measured at the end of the handle would be:

Trainer 59.5

#1 83.3

#2 116

#3 166.5

#4 217

These numbers are VERY close to what we are measuring.

Take a look at Tom Black's site for the calculations of these measurements:

Tom Black's Site

We also created a formula to rank grippers in 3.x scale so you would have a griper that by its closing weight is a 3.56 (just an example) As we get more grippers calibrated and the results we can fine tune the numbers to be very accurate. This was removed from the document because we did not feel we had enough of a statistical sample to go forward with the ratings as of yet. Oh and you could end up with a gripper that is a 3.464763879238762364587632652341 HAHAHAHAHAHAHAHAHA I know how people find that crap hilarious when people squeeze a gripper and give some insanely precise value to it. Ours we cut off at two digits, for obvious reasons...

Greg

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Trainer 59.5

#1 83.3

#2 116

#3 166.5

#4 217

These numbers are VERY close to what we are measuring.

Why aren't these the numbers to use as the basis for the comparison ratios? Is it because Tom's math can calculate the weight at the exact end of the gripper and your method adds weight to the last inch of the gripper handle?

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Trainer 59.5

#1 83.3

#2 116

#3 166.5

#4 217

These numbers are VERY close to what we are measuring.

Why aren't these the numbers to use as the basis for the comparison ratios? Is it because Tom's math can calculate the weight at the exact end of the gripper and your method adds weight to the last inch of the gripper handle?

The reason is the initial IM ratings may not be so accurate, they are aweful "round" numbers if you ask me. I have not measured a #3 that comes close to 166.5 pounds. 6.5 pounds is a lot of difference from the 160 we measured on 2 brand new #3s right out of the package. When we season them they will likely fall back some. If I used 166 most #3 (or all I have ever touched) will be rated as less than 2.9

So it would be much better to get a true range of #3s out there and see what we feel the baseline 3.0 gripper should be.

Great question!

Greg

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good stuff guys, and PDA made it seem so damn complicated and undoable.. hahaha

nice work

~Steve

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Great stuff! Thanks for all your work!

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Chris mentioned that we measure at the end of the handle. There is a VERY good reason for this, wait till you have to lift the 200 pounds for a #4 and try and gently set it on a gripper. Well if you were using the center of the handle the amount of wieght would be a hell of a lot more. In fact take a look at this chart it should look familier

Trainer 100

#1 140

#2 195

#3 280

#4 365

These are the IM ratings, if you assume they are measured in the center of the handle then the same figures when measured at the end of the handle would be:

Trainer 59.5

#1 83.3

#2 116

#3 166.5

#4 217

These numbers are VERY close to what we are measuring.

Take a look at Tom Black's site for the calculations of these measurements:

Tom Black's Site

We also created a formula to rank grippers in 3.x scale so you would have a griper that by its closing weight is a 3.56 (just an example) As we get more grippers calibrated and the results we can fine tune the numbers to be very accurate. This was removed from the document because we did not feel we had enough of a statistical sample to go forward with the ratings as of yet. Oh and you could end up with a gripper that is a 3.464763879238762364587632652341 HAHAHAHAHAHAHAHAHA I know how people find that crap hilarious when people squeeze a gripper and give some insanely precise value to it. Ours we cut off at two digits, for obvious reasons...

Greg

End of the handle is almost exactly 60% of the IronMind rating... 365 = 219. :rock

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Probably splitting hairs but would it make sense to calibrate the plates used? Cumulatively it might make a difference.

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Great work!!

Thanks for putting in the time to calibrate all those grippers. Nice simple idea to calibrate. Takes the human subjectiveness out of the old real redneck way to calibrate grippers.

I think you guys are doing this, but it would be cool to see a graph dipicting the spread to close (at 1/2" increments) as a function of poundage. I know this would take a lot of time but would be cool to see.

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Hope you ordered the new tweeners so we can see where they fall.

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