Gripper Calibrator Finished

[bwwm]

RichAZ - I don't know if you happened to have noticed this yet, but I took your CoC data for 1,2,2.5,3,3.5,4 and plotted the 'actual' that you measured versus what IM rates them for. I then put a trend line to the data, and the R^2 of the fit is 0.9883. Actual = 0.5663 * Rated + 1.6723 A 0.988 R^2 suggests to me that what you are doing has a very repeatable technique to it. Granted it's only 6 data points. Assuming a linear correlation gives the following estimates for the 'average' CoC: CoC Estimates (lbs) 1 78 2 109 2.5 133 3 157 3.5 181 4 205 {sorry for the editing - formatting of the table is not coming out very nice}

Are the estimate numbers you listed all based on my #s ? Very neat what you did. Are you a math major? Keep in mind if you used my 2.5 that is 140# that is a freak 2.5 I have an other that was 127# Thanks for what you did!

Hi @RichAZ,

My background is in engineering. I had a typo in one my equations (it happens), but it didn't change things much. Yes it is from only your data. Here's the updated table showing all of the data the analysis is based on. RATED is what IM says. ACTUAL is what you measured. PREDICTED is what the regression 'averages' it to be.

CoC RATED ACTUAL PREDICTED

1 140 84 81.0

2 195 116 112.1

2.5 237 127 135.9

3 280 158 160.2

3.5 322 183.6 184.0

4 365 213 208.4

Regression data: slope = 0.57, intercept = 1.67, R^2 = 0.988

As I mentioned before, I think if you moved the strap down the handle a bit, your numbers would probably come close to IM ratings.

[macaz]

I've been thinking about this, and I'm guessing the reason for the 0.56 slope is that they are probably assuming that the hand closing the gripper exerts the vector of force about maybe half way up the handle. In other words, and hand would exert force distributed along the handle, but the center point would be about half way up the handle. I wonder what your numbers would read if you centered your strap on the center of the handle. I'm guessing the slope would be closer to 1 for this correlation.

OK I have reread this an get what you mean finally. (please don’t use hard words like vector in the future).

Yes if I held the strap in the middle of the gripper I would be in line with the "advertized rating" of the grippers. If I had the strap at the top the #s would be probably twice the rating. Having the strap at the very end (most leverage) is standard for RGC. I think this is to have an easy reference point to get. If we tried to get the strap in the "middle” there would be more estimations and bigger variances in #s. The point of the RGC is simplicity for comparing relative "hardness" of grippers

[junior]

I recently rated several grippers (#2 and up) and used what I informally referred to as a baseline at the beginning. Specifically, I used a combination of plates, with strap an pin, that equalled 102 pounds. After measuring the spread of each in mm, I loaded the 102 pounds onto each gripper and noted the number of mm remaining (remaining spread in mm). Its been several weeks and I don't have the notes in front of me, but the results were interesting.

I next used a "baseline" just above 150 pounds and did the same with my MM1R and above.

Next, I rated each all the way to close and compared the previous information to these numbers in terms of percentages. This seemed to take spread and possibly other factors into account.

The last mm or two is very finicky during the full ratings.

[bwwm]

I've been thinking about this, and I'm guessing the reason for the 0.56 slope is that they are probably assuming that the hand closing the gripper exerts the vector of force about maybe half way up the handle. In other words, and hand would exert force distributed along the handle, but the center point would be about half way up the handle. I wonder what your numbers would read if you centered your strap on the center of the handle. I'm guessing the slope would be closer to 1 for this correlation.

OK I have reread this an get what you mean finally. (please don’t use hard words like vector in the future).

Yes if I held the strap in the middle of the gripper I would be in line with the "advertized rating" of the grippers. If I had the strap at the top the #s would be probably twice the rating. Having the strap at the very end (most leverage) is standard for RGC. I think this is to have an easy reference point to get. If we tried to get the strap in the "middle” there would be more estimations and bigger variances in #s. The point of the RGC is simplicity for comparing relative "hardness" of grippers

Rich - I completely understand what you are getting at. Makes sense.

[macaz]

I recently rated several grippers (#2 and up) and used what I informally referred to as a baseline at the beginning. Specifically, I used a combination of plates, with strap an pin, that equalled 102 pounds. After measuring the spread of each in mm, I loaded the 102 pounds onto each gripper and noted the number of mm remaining (remaining spread in mm). Its been several weeks and I don't have the notes in front of me, but the results were interesting.

I next used a "baseline" just above 150 pounds and did the same with my MM1R and above.

Next, I rated each all the way to close and compared the previous information to these numbers in terms of percentages. This seemed to take spread and possibly other factors into account.

The last mm or two is very finicky during the full ratings.

Please post your data when you have a chance. Do you think the numbers can show the relative difficulty of the sweep?

[macaz]

Today I recalibrated my RB adjustable. I also did the in-between levels which I didn’t do before.

RB Adjustable

Silver Spring

#1 = 20.3

#2 = 26.5

#3 = 32.8

#4 = 40.7

#5 = 49.7

#6 = 59.0

#7 = 67.7

#8 = 79.9

#9 = 89.7

#10 = 101.7

Gold Spring Gold spring on 11-6-11

#1 = 55.3 1-1=50.7

#2 = 69.8 1-2=56.0

#3 = 86.8 2-2=64.5

#4 = 107.0 2-3=70.6

#5 = 125.9 3-3=80.1

#6 = 147.2 3-4=87.9

#7 = 168.3 4-4=97.4

#8 = 191.7 4-5=106.7

#9 = 216.7 5-5=115.3

#10 = 243.1 5-6=127.4

6-6=138.3

6-7=148.7

7-7=161.3

[macaz]

Well the tabs did not come out when posted so its hard to read here is just the new data

Gold spring on 11-6-11

1-1=50.7

1-2=56.0

2-2=64.5

2-3=70.6

3-3=80.1

3-4=87.9

4-4=97.4

4-5=106.7

5-5=115.3

5-6=127.4

6-6=138.3

6-7=148.7

7-7=161.3

[Gift2k1]

Today I recalibrated my RB adjustable. I also did the in-between levels which I didn’t do before.

RB Adjustable

Silver Spring

#1 = 20.3

#2 = 26.5

#3 = 32.8

#4 = 40.7

#5 = 49.7

#6 = 59.0

#7 = 67.7

#8 = 79.9

#9 = 89.7

#10 = 101.7

Gold Spring Gold spring on 11-6-11

#1 = 55.3 1-1=50.7

#2 = 69.8 1-2=56.0

#3 = 86.8 2-2=64.5

#4 = 107.0 2-3=70.6

#5 = 125.9 3-3=80.1

#6 = 147.2 3-4=87.9

#7 = 168.3 4-4=97.4

#8 = 191.7 4-5=106.7

#9 = 216.7 5-5=115.3

#10 = 243.1 5-6=127.4

6-6=138.3

6-7=148.7

7-7=161.3

Do you know if your silver and gold springs are the same as the "weak" and "hard" spring that come with the black RB adjustable?

[macaz]

One more thing that is interesting (to me) is that my max on the RB is level 5-6 @ 127#. My max on the V2 is level 17 @ 126#... Consistant results.

^{"Do you know if your silver and gold springs are the same as the "weak" and "hard" spring that come with the black RB adjustable?"}

^{Yes it is the weak and hard spring.}

[junior]

RB Adj - gold spring (rounded down, slightly filed)

5/5 = 116

5/6 = 127

6/6 = 136

6/7 = 146

7/7 = 156

7/8 = 170

8/8 = 174

Here is the results I mentioned before:

102 pounds (including strap and pin) applied to the following grippers resulted in the following (spread/mm remaining)

#2 - 88/5, -94.3%, 1.23 lbs per mm (111 total, 1,82 lbs per mm to close remaining distance)

#2.5 - 88/18, -79.5%, 1.46 lbs per mm (130 total, 1.59 lbs per mm to close remaining)

#3 - 93/28, -69.9%, 1.57 lbs per mm (148 total, 1.64 lbs per mm to close remaining)

BBGM - 82/24, -70.7%, 1.76 lbs per mm (151 total, 2.04 lbs per mm to close remaining)

RB300N - 74/26, -64.9%, 2.13 lbs per mm (160.5 total, 2.26 lbs per mm to close remaining)

153.7 pounds (including strap and pin) applied to the following grippers resulted in the following (spread/mm remaining)

RB300N - 74/3, -95.9%, 2.16 lbs per mm (160.5 total, 2.37 lbs per mm to close remaining)

MM1R - 81/3, -96.3%, 1.97 lbs per mm (160.5 total, 2.37 lbs per mm to close remaining)

MM2R - 81/4, -95.1%, 1.2 lbs per mm (163.5 total, 2.56 lbs per mm to close remaining)

BBE - 81/7, -91.4%, 2.1 lbs per mm (169 total, 2.1 lbs per mm to close remaining)

Atomz 4 band - 89/7, -91.8%, 1.97 lbs per mm (169 total, 2.19 lbs per mm to close remaining)

#3.5 - 89/9, -89.9%, 1.92 lbs per mm (172.5 total, 2.13 lbs per mm to close remaining)

[macaz]

Greg AKA Earl, Our RB adjustable results are very close.

Your data is very interesting. I get that It takes (say for the 300N 2.16 average pounds to close each mm and then at the last 3mm it takes 2.37 pounds to close each remaining mm showing that the gripper gets harder as it goes as they should (I don’t know what is up with your BBE)

As far as finding out the relative hardness of the sweep I think you can take the average pounds to close a mm (for the beginning #s per mm) and divide that into the total pounds to close the gripper. The result will give a number that is inversely proportionate to the relative difficulty of the sweep. For the MM2 I got 136 which would be the easiest relative sweep. The hardest sweep (relative to how hard the actual gripper is) is the 300N @ 74

The order of relative sweep hardness (easy to hard) would be MM2, COC3.5, 4band, MM1, BBE and 300N

This doesn’t mean much comparing the sweep of the 300N to the 3.5 because the 3.5 would feel harder at the sweep because it is a harder gripper.

I think it would be only useful at comparing grippers of the same RRG rating, like the 300N vs. the MM1. both 160.5# but the RB300N has a much harder sweep. Now does the 300N feel like it has a harder sweep than the MM1??? If not than I better re think this

[junior]

Hey Rich, I just did it that way because I was using a starting load anyway, went ahead and wrote the measurements down in case it showed consistency somewhere. Haven't yet looked at similarities or predictability yet, just typed in what I wrote down. I have more grippers with data but can't find the page I wrote on at the moment. My #4 was between 216 - 217.

The RB300n is in fact stouter throughout the ROM compared to the MM1, but it does fit in the hand better at the start. I guess I just measured the obvious, haha

[junior]

Oh yeah, the elite, no idea what the deal with that was. It was very odd. I'll redo that one, but I reset each one a few times and got those numbers. The last few mm on grippers is very finicky.

[macaz]

I have some results from calibrating Joe's RB grippers

Not sure were to put them but wanted to share so I dug this old thread up.

RB

70=54.8

100=60.4

130=95.5

160=109.7

180=119.4

210N=116.1

210=124.3

240=135.0

260=142.9

280=168.5

300=181.8

330N=174.5

365N=185.0

365=238.5

400=215.4

[junior]

All over the place. Thanks for the info Rich.

[macaz]

Yes they are. I re checked the ones that were strange, like the 365 and 400. Keep in mind that the N is the narrow ones.

[mightyjoe]

Thanks Rich!

I knew my RB 365 would be a BEAST!

It's worth noting that the spread on my 365 is the widest I've seen on a torsion spring gripper.

I really like some of the #'s because they fill in many gaps in my collection as far as calibrated

grippers go.

Rich is the Man!!!

[macaz]

I have been calibrating a lot of grippers lately but not posting. I will try to get on the ball more.

Here is some GHPs for comparison mine vs Joe’s and two of Daniel’s.

Mine .. . ... . Joe’s ..... Daniels

GHP1= 47.5 .... 48.5

GHP2= 62.9 .... 63.7

GHP3= 87.7 .... 86.3

GHP4= 92.8 .... 92.4

GHP5= 112.3 .... 114.5

GHP6= 135.0 .... 133.5

GHP7= 149.1 .... 151.1 .... 150.0

GHP8= 169.4 .... 176.0 .... 176.2

GHP9= 226.3 .... 218.8

GHP10=268.9 .... ????

[macaz]

A few more.

Mine .. . …..... . Joe’s ......... Daniels ……..……Bens

GHP1= 47.5 .... 48.5

GHP2= 62.9 .... 63.7

GHP3= 87.7 .... 86.3

GHP4= 92.8 .... 92.4…………………………91.3

GHP5= 112.3 .... 114.5………….………….110.1

GHP6= 135.0 .... 133.5……………..………136.2

GHP7= 149.1 .... 151.1 …... 150.0

GHP8= 169.4 .... 176.0 ...... 176.2

GHP9= 226.3 .... 218.8

GHP10=268.9 .... ????

[macaz]

Got some of the BB 5/8 grippers from the gripper superstore today. Still bummed they are not selling BB and MM.

B=57.4

SM=124.0

GM=156.5

E=180.4

SE=210.8

P=270.0

Here is the Pro

[macaz]

most of the 5/8 grippers went easy but the Pro was realy hard to keep lined up because of the huge spring and the long distance that 5/8 handle had to travel.

[Shoggoth]

I can't see anyone closing that 5/8" elite any time soon. Holy crap!

(null)

[KRC]

Not to mention the SE--both of them seem to be on the very high end of each grippers range.

[macaz]

The SM was a creampuff.

[macaz]

A few more grippers from the GSS.

All extended handle Beef Builders.

GM=201.2

P=271.3

WC=261.2 (weak for a World Class)