Guest Rog Posted August 29, 2001 Share Posted August 29, 2001 Some of us have tested our grippers using various methods including weights and now the PDA calibration method. I believe there are inconsistencies between the results generated by these different methods that should be explained. Those who've done their own testing as well as PDAs have data to compare. Gorilla and 1stCOC posted data some time ago based on their testing that to me just doesn't square with the PDA results. For example, while I haven't had my #3 tested by PDA, the 175lbs I tested it at according to the above post, implies about a 520 in-lb rating. That's unlikely,given the data we've seen from PDA. Why the difference ? Until I understand that better, I see no reason to believe more strongly in the PDA method. Quote Link to comment Share on other sites More sharing options...
Bearcat 74 Posted August 29, 2001 Share Posted August 29, 2001 I may be wrong, but 175 * 2.375 = 415.625. Strongman's #3 is 181lbs and 429inlbs. To get 520inlbs you have to hit 219lbs. I may be wrong, if I am someone please correct me. I've also done the scales test, and it was awful. I got a different reading almost everytime. If the handle is in a different position, the poundage is different. I think PDA's machine holds it in the same place with probably 10 readings, then an average. To me, this is a lot more reliable. Just MHO. (Edited by Bearcat 74 at 5:42 pm on Aug. 29, 2001) Quote Link to comment Share on other sites More sharing options...
Bill Piche Posted August 29, 2001 Share Posted August 29, 2001 Yeah, bathroom scales rank right up there as a viable method when compared to how PDA thought this out and is executing the measurements. Sheesh. Quote Link to comment Share on other sites More sharing options...
RogerSteffens Posted August 30, 2001 Share Posted August 30, 2001 I don't mean to start a lengthy thread on this. But the 175 was determined using plates. It was also not at the center of the gripper, but at 1/2" from the bottom, which corresponds to about 220 at the center. But I'm not asking anyone to agree with individual numbers, just to recognize there are differences that haven't been explained if you look at just the few, more reasonable methods like the weight approach and the PDA device. Both apparently reasonable, but different results. By the way, Bill, sarcasm also doesn't explain the differences. (Edited by RogerSteffens at 7:45 pm on Aug. 29, 2001) Quote Link to comment Share on other sites More sharing options...
Tom Black Posted August 30, 2001 Share Posted August 30, 2001 Roger, Could you explain the math you used to arrive at your “520 in-lb rating” and your 220 number? The number you report, 175-pounds at ½” from the bottom would correspond to a smaller number if you placed the weights right on the end, which would be still in line with the PDA numbers. This is because of the extra leverage acquired when placing the weights on the end. Also, I think the center of the gripper measurement was something that everyone agreed accurately modeled the gripper closure torque. The 2.375” is the length from the center of the spring to the end of the handle divided by two. The center of the spring is the pivot point of the lever arm (the handle combined with the spring post) in standard torque equations, but I’m sure John S. could explain this better. I believe Gorilla hands used a plate loading method with results similar to PDA’s, at least within the standard deviation already found with the #3 grippers (which I calculate to be 47 inch-pounds). The standand deviation of grippers alone can account for different results since we already know the grippers vary. Perhaps now would be a good time for someone to try another accurate method and test the same gripper already tested by PDA. Quote Link to comment Share on other sites More sharing options...
RogerSteffens Posted August 30, 2001 Share Posted August 30, 2001 Tom: I just determined the torque exerted by the 175 lb applied 1/2" from the bottom. I used the 4 3/4" length from center of the spring to the bottom of the handle less the 1/2" up from the bottom, less what appears to be about a 1/2" factor PDA used to account for spring compression, leaving a net 3.75" lever arm. 3.75" times 175lb equals about 650 in-lbs (not what I said above I realize). The equivalent weight at the center of the handle that would apply the same 650 in-lbs of torque is just 650/2.375 or about 276 lbs. Coincidentally close to the 280lb marketed number, as is the 220 lb number I measured for my #4 at the same point, equivalent to 350 lb at the center ! If I remember correctly, 1stCOC tested his #3 at about 220 lbs at the end of the gripper, similar to what Gorilla came up with. I believe Gorilla also measured 245 lbs for the Elite at the end and 310 for the #4. I'm just saying I'm puzzled why reasonable and simple approachs that both the weight plate methods and the PDA methods are don't appear to yield similar results. Quote Link to comment Share on other sites More sharing options...
Gorilla Hands Posted August 30, 2001 Share Posted August 30, 2001 Roger, how are you. long time my friend. Let me see if I can explain what Bill's unquenchable sarcasm can't. First thing that will make things simpler is that both me and Richard tested our grippers in the same general manner. Richard and I also got the near same numbers within 5-10 pounds. Those are the ones you quoted. Given the known inconsistencies Richard and I had similiar gripper tensions, accept that as a nice coincidence. Now here's the missing link: My grippers were not fatigued when I tested them. In testing them over several times I kept getting lower numbers and now they have settled to about 190/#3 210/E & 250/#4 at handle tips. These numbers would translate over more naturally to PDA figures given some tolerance for different methodology. I can further explain this if you get in touch with me. I discussed these inconsistencies at length with Richard and John. Don't be too hard on Bill's sarcasm. It has been said one must be intelligent to manufacture sarcasm, good for Bill that he can defy this rule (ha,ha,ha of course I jest Bill). Regards, David Quote Link to comment Share on other sites More sharing options...
Gorilla Hands Posted August 30, 2001 Share Posted August 30, 2001 Roger, how are you. long time my friend. Let me see if I can explain what Bill's unquenchable sarcasm can't. First thing that will make things simpler is that both me and Richard tested our grippers in the same general manner. Richard and I also got the near same numbers within 5-10 pounds. Those are the ones you quoted. Given the known inconsistencies Richard and I had similiar gripper tensions, accept that as a nice coincidence. Now here's the missing link: My grippers were not fatigued when I tested them. In testing them over several times I kept getting lower numbers and now they have settled to about 190/#3 210/E & 250/#4 at handle tips. These numbers would translate over more naturally to PDA figures given some tolerance for different methodology. I can further explain this if you get in touch with me. I discussed these inconsistencies at length with Richard and John. Don't be too hard on Bill's sarcasm. It has been said one must be intelligent to manufacture sarcasm, good for Bill that he can defy this rule (ha,ha,ha of course I jest Bill). Regards, David Quote Link to comment Share on other sites More sharing options...
Bill Piche Posted August 30, 2001 Share Posted August 30, 2001 Often, I am just trying to inject a little humor into things. Also, when emotion seems to be guiding people's posts rather than facts and common sense I have been known to inject some in response. Roger, it would be interesting to see what your grippers measure at by PDA. Especially since I think you closed the Elite as well? I do believe the Free #3 offer for COC's still is in effect. For example, a funny line in response could be: "Roger, have you seen the instrument PDA uses to measure the pressure? I don't think John picked it up in the bathroom dept. at K-mart." BAAAAAAHAHAHA! Quote Link to comment Share on other sites More sharing options...
Guest kINGPIN Posted September 1, 2001 Share Posted September 1, 2001 I don't think he did either wannagrip, but since there is a sale on the week he might of saved some money if he did. Quote Link to comment Share on other sites More sharing options...
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