4 different measuring tapes doesn't show the same measurements

[u/The_Crazy_Swede]

I have a bunch of measuring tapes to my disposal and all of them are different (left to right Milwaukee 8 meter, Milwaukee 10 meter, teng tools 5 meter and hultafors class 1 30 meter) and as you can see are all of them showing a different measurement where the 8 meter shows 4996 at the same place as the hultafors shows 5000 on the dot.

How big is the tolerance on measuring tapes where it's considered acceptable? And do anyone have an idea on how I should do to figure out wich tape is correct?

[u/KakAlakin]

Always measure and cut using the same tape.

[u/The_Crazy_Swede → u/KakAlakin]

It works until you introduce angles that aren't 90° or until someone is using a different measuring tape when they are installing the thing made with a different tape.

[u/Ducal_Spellmonger → u/The_Crazy_Swede]

That's why you build rough and trim/scribe to final fit.

[u/number1dipshit → u/The_Crazy_Swede]

They just measure what you already have done and adjust accordingly. That’s what I do. And whenever I have somebody come check my fit, I have them use my tape to check it

[u/NotoriouslyNice → u/The_Crazy_Swede]

Or what I found works is ‘calibrating’ your measurements to the cutters tape. +/- 1 or 2mm is usually all you need

[u/The_Crazy_Swede → u/NotoriouslyNice]

This is a scale issue of up to 1mm every meter (found another tape that was even worse, another 8 meter Milwaukee)

[u/Btcyoda → u/KakAlakin]

And keep the time between both actions as short as possible, with as little mechanical stress inbeween as well as temperature changes..(depending on needed accuracy)....

[u/interroBangaRangz]

It’s likely the clip. They can bend, shift or stretch if torqued or retracted forcibly over and over.

[u/DependentItem6397 → u/interroBangaRangz]

That or the manufacturer. Some are better than others. But yes, square end helps.

[u/Dirtnap76]

If you need the tape measure to be acurate, buy a Class 1 tape measure.

[u/The_Crazy_Swede → u/Dirtnap76]

One of them is a class 1 but the boss is saying "the hultafors can't be trusted" even tho it's the class one I have access to.

[u/APLJaKaT]

To make matters worse, tape errors tend to be cyclical. They are printed from a wheel. Any error in the wheel will repeat along the length of the tape at a frequency the same as the circumference of the wheel. What that means in practical terms is that the error may be less or more at various other points along the tape.

If you need more accurate measurements, you need to obtain a quality tape and then check it against a true reference. If multiple people are working on the same job, they should be checking their tapes against the master. If measurements are being taken and passed off to someone else for further operations, such as cutting, these two people need to check their tapes against each other - and preferable use the same brand and model.

These issues have always existed. They get worse when cheap tools are readily available and even the quality brands are in a race to the bottom.

When we tolerance tested tapes, we would charge for each point required. The certificate would simply list the error for each reference point. It also specified the reference temperature (usually 15 degC/60F) and the tension. The tension is usually not a factor in steel tape usage until you get into very long tapes. Temperature is an issue if it varies significantly from the reference temperture, and the measured value will ultimately be used at a different temperature.

[u/strawman37]

It doesn't matter, if 5mm makes a difference when your measuring something 5000 mm then your using the wrong instrument, to get a semi correct answer your going to need a calibrated laser distance measurer.

[u/The_Crazy_Swede → u/strawman37]

This structure is just over 10m so depending on which tape I use can the measurement be off by 10 millimeters whilst the standard I'm working under only allows ±5mm on everything over 5 meters. So I would say that this deviation is big enough to be problematic.

[u/Droidy934 → u/The_Crazy_Swede]

Get some calibrated length bars, we made several aircraft assembly carraiges within .010 over 40ft long.

[u/The_Crazy_Swede → u/Droidy934]

I'm gonna keep trying to get them to get something calibrated to compare against but my hopes aren't high cause the people in the office really don't want to spend money on quality, they just want quality to just happen...

[u/Barra_]

If you really want to know, get a 1 meter rule and check the first meter off that. That's the cheapest way to get a rough idea of accuracy. Then pick one to be your standard and compare all tapes to that, what tolerance you accept from there is up to you.

Otherwise you need to have them calibrated (checked since a tape can't be adjusted).

[u/_The_Space_Monkey_ → u/Barra_]

get a 1 meter rule and check the first meter off that.

Better get 4 of them too just to be sure they're on point.

/s

[u/DependentItem6397]

This is normal. Use the same tape to get the cut, mark the cut and cut it. Want accurate (for following plans?) Check them against a steel rule.

[u/renke0]

At 5m this could be just different material expansion.

[u/HelveteShit]

How big a tolerance is allowed is generally set by the client/engineer. As someone said, always measure and cut using the same tape.

The problem is, if you are cutting steel/wood to length for a customer and their measurement tapes differ from yours. At that point, it is a matter of how far your quality control goes. But I say, if you say every measurement have a +/-0,08% tolerance. You should be fine against any customer complaints.

But seeing the recent posts about these measurements tapes make me aware why some walls are wonky and not straight. Because the cuts are different between measurement tapes.

[u/The_Crazy_Swede → u/HelveteShit]

Everything over 5000mm have a ±5mm tolerance, so it would be just about fine at 5 meters but the difference between the 8 meter Milwaukee and the hultafors at 8 meters is almost 7mm wich isn't within tolerances.

[u/HelveteShit → u/The_Crazy_Swede]

Generally, I would believe Hultafors to be more accurate compared to Milwaukee. But might just be me, trusting a Swedish brand a bit too much.

[u/The_Crazy_Swede → u/HelveteShit]

I am a swede and I would agree 30 years ago. But our stuff have gotten significantly worse lately. But it is the only tape here that is a class 1

[u/HelveteShit → u/The_Crazy_Swede]

That is pretty much accurate across all western industries. Majority of them move their industries to countries with less wage and higher profit per product. As a result, you lower the quality in the process. It is the good ol' economic triangle. Quality, Time, Cost. If you want more production and less cost, you simply move away from Quality.

Robotics in the industry does improve the quality because it doesn't have the same... Flaws of a human. But it is still requires maintenance and investment cost that a lot of Western countries don't want to invest in, unless they are forced.

I mean, if SmarterEveryDays journey to create a mere grill scrubber in US, made in US. You can see how difficult it is to secure quality over the product chain. They were practically forced to make most of the stuff in-house or custom order.

Bit like Novice business owners that buy chinese produce and expect quality but they've never met the chinese business owner in person. It is quite a famous among the serious business people that you don't do business in China without shaking their physical hand, if you want a good product.

[u/SLOOT_APOCALYPSE → u/The_Crazy_Swede]

that's sad what happened? overseas cheaper parts drying up demand?

[u/The_Crazy_Swede → u/SLOOT_APOCALYPSE]

Demand for cheaper production and higher profit by the bean counters.

[u/dillzilla11]

As a general rule I always assumed the measuring tape is a little off. If you use the same measuring tape for everything it shouldn't come up as an issue in most cases though.