Thanks for the warning, Sean. I would have thought they would have better quality control than that.

Cheers ...... Charles

 

Guys ,rubber that mic's up at different thicknesses actually can be a benefit. I've had rubber with as much as a .020" difference between one side then the other. What you do is make it into a "Gauge"Taper. Cut your bands so that the thinner dimension is at the pouch along with your smaller width taper-in effect you'll have a double taper. You can also put the thick end at the pouch and they will last longer. SEts such as this are really pretty high performing sets with as much as a 20% speed increase depending upon thickness difference from one end to the other and of course temps. Hope it helps! Flatband

 

All rubber has tolerances. Hygenic, the maker of Thera-band and pure Latex has the tightest tolerances of sheet rubber that I know of in the industry. -- Tex

 

@Sean: Interesting, but I think measuring the thickness of latex with a common caliper is not so convincing. You got a deviation of 0.13 mm. I could imagine you get containing errors when measuring a very soft material like latex, because everytime you measure the result is depending on how far you squeezed the caliper. So I think this is not an easy measuring job. Please tell me if I am wrong.

Cheers, Simon

 

I measure with a caliper all the time. If you use enough of the surface face of the tips it is quite accurate. -- Tex

 

With enough experience you can be accurate and repeatable measuring sheet latex with normal dial calipers. A good way for someone who wants to measure accurately from the start is to get a pair of something metal that is accurate and flat, and measure them together face to face, then put the band or sheet to be measured in between them and measure again, then subtract the first measurement. I usually use a set of machinest 1-2-3 blocks to do this because it's easy to subtract 2 inches, but you can do it with just about anything that is really metal and flat. If you have two metal rules, like from a combination square that you use to cut bands, or whatever, that will work too. The idea is to spread the pressure of the caliper jaws out over a larger flat surface so they don't compress the rubber.

 

Hi guys, thanks for all the good informative responses! Caliper or not, being as accurate as we'd like, it was just an
education for me as having not much experience as some of you, I was surprised at the difference in pull in bands
cut the same way, and length, and visually being able to see the thickness differences.
I just thought thera band gold was thera-gold, and it would have been to tolerance pretty much bang on time after
time considering it's intended uses.

Thanks again for your knowledge.

 

Hi Sean,

The few pieces of TBG that I have bought over the last couple of years have measured .028" to .032".

Cheers,
Northerner

 

that's pretty close to bang on, thanks for taking the time to check.

 

Hey Skeen-1-2-3- blocks! Man ,that brought back some memories! Haven't used them since I was working magic on a Bridgeport. I spent 10 years as a machinist after High School. I used all the machines but if you ask 10 old machinists what their favorite all time machine was,I guarantee at least 7 would say a Bridgeport Milling machine. Getting back to rubber, I like using Mic's rather then Calibers. I just feel more comfortable with them. I just get a better feel. Either way I always measure any sheets I get-all four corners then mark plus or minus on all edges. Aren't we insane with all this accuracy??? When you think of it,does it really matter. How many times have all of us shot a set of bands that was almost torn clean through one side and yet we were still hitting the Bull and wondering how in the heck is this happening? Those bands are certainly not equal but they still shot straight. To quote an old Laugh in Comedian-Verrrrrry Interesting!!!!!

Flatband

 

Sean, I`ve made the same experiences with TB thicknesses!
An other problem is the QUALITY which varies very often! Sometimes you have very little air bubbles in the latex - so the bands break much earlier then bands without these bubbles!
We can get different speeds, draws and a different life span out of band sets that have the same color and the same measurements.

Latex is a fairly good stuff for slingshot bands. But it has some disadvantages - it is just an natural product.

Regards
Torsten

 

Sometimes you have very little air bubbles in the latex - so the bands break much earlier then bands without these bubbles!

I saw this at the end of a piece I just finished. It was a 6 foot piece and the bands cut out of the first 4 feet (3/4 straight, 10 inches) were getting around 500 to 600 shots. The last 2 feet (about 10 bands) got me about 200 shots. Some broke after as little as 50 shots.

 

I come from the paper industry and we use thickness gauges like this where you can change the size of the foot. anything compressible like paper or rubber should be measured with a large foot size and light pressure.

 

I only spot check my sheet and not every band or foot, but I have learned that the Hygenic latex does not change in thickness very quickly. I understand that there are tools that do a better job, but I don't have one and I can measure latex to about .0005 with my digital caliper, which is close enough for checking thickness. A more critical measure of the latex is the firmness. I use a given weigh with a known foot print and a dial indicator for that since I don't have a Rockwell tester. I also spot notch test the latex to make sure that I have a good product. I have found that the first couple of feet and the last few feet of a roll will usually not pass a notch test so I use that rubber for other items. Because I handle a lot of ".030 latex" I usually catch a problem by feel first. Seeing that I don't handle Thera-Band, But have a little on hand for testing, I don't know near as much about it, I would assume that since it is a Hygenic product it is of top quality also. -- Tex

 

Interesting thread here guys and thanks for the input. My big thing about this was this... I wouldn't have noticed the band thickness difference
at all if it weren't for the "substantial" difference in pull between two identical bands.
Also interesting is the bubbles that Torsten and kennyC have been noticing affects band life etc.
Looks like a fantastic measuring device Gopher posted as well! That I can see giving a good indication.

Tex, what is a notch test? Is the reason you feel that the first few feet on both ends of a roll not up to standard due to it's being exposed to
the elements etc? Thanks.

 

I use a micrometer to measure thickness. My micrometers have a friction knob for fine measurements. The friction knob will close the micrometer, but when a certain pressure is reached, the friction knob just spins. That way all measures are made with the same degree of pressure. So when measuring compressible material, the measurements are very comparable to each other ... not based on "feel" of the individual making the measurement.

Cheers ...... Charles

 

The notch is where you cut a strip about 1/4 inch wide, then make a cut about 1/32 of a inch in the side and see how much stretch it will take before breaking. The first and last few feet is where they get the roller and compound set up! -- Tex

 

Interesting way to test strength. Thanks.

 

Not really any surprise to any of us now but here was the official response from the Thera-band folk, which was nice of them to get back
to me.

Dear Sean

Thank you for your inquiry below.

Yes all Thera-band products are manufacutured with tolerances.

On the Gold Thera-Band the thickness is .026" with a tolerance of +/-.005".

This means that we can run from .021" to .031" thick.

Which in mm is .53mm to .78mm so all of the Gold Thera-band that you have is in fact in spec and is quality product.

Please advise if you require any additional information.

Best regards
Jan Nelson

Intl Sr Customer Service Rep
The Hygenic Corporation
1245 Home Ave.
Akron OH 44310 USA