Milwaukee claims that their Stud Gen II tape measure can survive an 80′ drop.
Dewalt claims that their new Tough Series tape measures is rated to still work after a 100′ drop.
Both brands make their claims with respect to packed soil, which complicated things a little bit. Does Milwaukee’s “packed soil” have more clay and rock contents, and Dewalt’s more organic materials? Or do they use an engineered fill according to professional standards?
Unless both brands are testing their tape measures by dropping them off the tops of buildings or cranes why are they using packed soil as an impact surface?
The drop surface is important because it can influence impact force. Would you rather jump barefoot in soil (packed or not), or concrete? Soil is a softer, deformable, and energy absorbing surface. But I digress – more about this in a bit.
In yesterday’s post about the Tough Series tapes, Tom D made a good point:
I’m kinda worried where someone could be that a tape could have a 100’ drop without being tied off – hope those down below are hard hatting!
There are two ways to interpret the drop rating claims – you can take them literally, or you can translate it into comparative impact resistance.
It’s common to drop a tape measure off a ladder, but is anyone really dropping their tape measures from 80 feet or 100 feet up? They really shouldn’t be. At heights, safety tethers should be used to avoid injury to anyone who could be working below.
Let’s talk about energy.
Ignoring the impact surface, we’re only going to look at the energy of a falling tape measure.
For a falling object that starts motionless at x-height, the speed is:
a is the acceleration due to gravity, 9.8 m/s² (or 32.17 ft/s²). You can learn more via HyperPhysics.
So for tape measures being dropped from height, the impact speed is:
- 71.7 ft/s from 80′
- 80.2 ft/s from 100′
Kinetic energy, the energy of an object in motion, is:
For simplicity’s sake, let’s say the two tape measures weigh the same. I’ll use 0.5 kg (1.10 lbs) as a ballpark estimate.
Kinetic energy just before impact:
- 119 Joules for either tape dropped from 80′
- 149 Joules for either tape dropped from 100′
For perspective 119 Joules is about the same impact energy as dropping a 44 pound steel weight from a height of 2 feet, and 149 Joules is about the same impact energy as dropping a 55 pound steel weight from the same height.
(Please feel free to check or correct my math!)
Or, just before impact, with m being the mass (in kg), g being the acceleration due to gravity (9.8 m/s²), and h being the drop height.
So, if a tape measure can survive a 100′ foot drop and still work, it can in theory endure a 55 pound weight being dropped on it from a height of 2 feet. If a tape can survive a drop from 80′, it can in theory endure the impact of a 44 pound weight dropped from 2 feet.
If the impact resistance claims are perfectly accurate, the orientation of the tape measure – front, side, top, etc. – shouldn’t matter.
I’m not sure how the packed soil impact surface changes things. Let’s say you have a tape measure on concrete and drop a heavy weight on it. It’s going to absorb much more energy from the impact than if it was placed on packed soil where it could potentially help to dissipate some of the impact energy.
Think of it this way – you place one glass marble on concrete, and one on packed soil. Now drop a brick on it. On concrete, the glass marble might crack or even shatter. On packed soil, might the marble indent or even become embedded in the surface?
How does all this translate to real-world drops? It doesn’t!
Tape measures rated to 80′ or 100′ should both be able to survive drops from a stepladder, your truck bed, your benchtop, or other common work heights.
Things get really complicated without context.
Which tape measure weighs more? Due to the constant acceleration of gravity that’s independent of mass, any two tape measures dropped from the same height will have the same impact velocity, barring any aerodynamic differences at extreme heights and speeds.
But, with energy being mass-dependent, that factors into impact energy.
Let’s say that Dewalt’s tape measure is lighter than Milwaukee’s. Well, different drop height ratings can potentially be misleading. Basically, it’s possible for a heavier tape measure with a lower drop height rating to endure harder impacts than a lighter tape measure with a higher drop height rating.
How many high impact drops can a tape measure endure? Are brands testing them to x-number of drops?
All this isn’t to say that drop rating are meaningless, because they’re not, they’re just very hard to interpret.
As far as I can tell, both brands’ drop ratings don’t seem to adhere to any disclosed standards.
Flashlights, on the other hand, have published drop rating standards. ANSI FL1 standards, for example, require that a flashlight be dropped from the rated height (of at least 1m) onto cured concrete (6) times from different cubic-face orientations, and the products must remain fully functional without any visible cracks or breaks.
Brands that advertise flashlights according to ANSI FL1 standards are ideally using comparable test methods, and their test results should be repeatable by competitors, users, or really anyone.
I would guess that brands use drop weight towers to simulate drop impact energy, but it’s unclear how that might translate to “packed soil” drop height ratings. Without official standards – at least those that are openly disclosed and described – it’s impossible to really compare different brands’ drop ratings against each other.
Most brands test competing products, keeping each other in check from making false claims, but the seeming absence of known test conditions means you can’t take competing claims to be directly compatible.
Will Dewalt’s new Tough Series tape measure be more durable than Milwaukee’s? Can it endure harder impacts? Will Milwaukee have to drop their claims of making the industry’s most durable tape measure? Maybe, maybe not.
The point I’m trying to make is that a drop height rating is a very imperfect comparative measure unless greater context and details are known. The maximum impact energy from any orientation is the important comparative factor, and I doubt we’re going to get that from either brand.
Long story short, both brands’ tape measures are extremely tough. The question of which is stronger, tougher, or more durable isn’t one that can be answered with a drop height rating.
Acme dropped the Lufkin 80 something feet onto concrete years ago, just saying. Some dude blew one up (sorta) as well lol
Boron line is that they design these tests around marketing figures, more specifically, how this specific test will support a bold marketing claim, no matter how tenuous the data. A lot of these marketing claims are not regulated by any kind of governing authority. Drop tests on tapes is analogous to “nut busting torque” on impacts; they’re not advertising how much torque the gun is making, rather, a fastener it will remove that was torqued to that value, on a freshly greased nut. In other words. Absolute best case sensation, the impact will remove a fastener that was just torqued to that value. Lossening torque only require about 80% of fastening torque, and with fresh grease used, it greatly reduces the coefficient of friction. A good rule for nut busting torque is to half that number. That’s what the gun will probably make in a real world best case scenario. Anyhow I digress. For tape measure drops, the game is the same. I’m the case of “packed soil” both those words are ambiguous. If you drop any tape from the better part of 10 stories, plan on getting a new one. But on the other side of the coin, regardless of the manufactured test conditions, they still managed to make a tape that will survive that kind of test in some specific circumstances, and I’d say that’s pretty good. Maybe it’ll equate to 20’ onto cement, or 40’ onto dense dried out dirt. Either way, just remember, they tests they perform are to are meant to support a marketing claim by design – not suply transparent data. Subjectivity is marketings best friend.
I think it’s extremely simple: there is no ASTM or ISO or whatever other standard for a tape-measure drop test, so the manufacturers can make up whatever test methodology they want.
Why do they use dirt as a surface? It’s relatively soft so it gives high numbers and high numbers are good for marketing. “survives 100 foot drop*” with (*onto dirt) in the fine print sounds a lot more impressive than “survives 10 foot drop onto concrete” to the average person.
It’s the same nonsense we see when manufacturers quote intermittent peak ratings, such as inrush current, to come up with impossibly high horsepower ratings for corded power tools. They’re being technically correct but are spinning things as much as possible for a marketing angle.
Precisely, the test is designed to support a bold marketing plain that they can print on the packaging, not to test to a standard benchmark, or provide meaningful data. People need to remember they’re in the business of selling tools. It’s not about testing under real world situations, it’s about printing a bigger number on the box than your competitor.
Brands are continuously reaching to stand out with bigger numbers than their closest competitors … any number will do to be ome the headline.
Which I say, looking back at my 17 ft reach ladder that of course is only 14 ft long … but was listed and sold as a 17 ft ladder … and 17 was longer than 16 ft actual which I need … sigh.
Ladder measurements seem to be somewhat consistent, but differ across different styles.
TIA driveway/down the road flashback LOL
One of them should team up with Richard Branson and drop one from space
If I were to drop my tape from 80+/- feet from any site I’m working on getting it back in one piece is the least of my worries. I know they are showing the overall toughness though.
Next will be tape measures with self-deploying parachutes.
It’s all about impulse and max force. Imagine a graph with time as the x axis and force as the y axis. As the tape measure hits the floor surface, the force from the floor onto the tape measure spikes from zero to some fairly high value, then back down to just enough to support the weight of the tape measure.
In this graph, the area under the curve is impulse (in units force*time) and impulse describes how much change in momentum is present (momentum is mass*velocity).
Between a hard and soft surface, the impulse must be the same, but on a more compliant surface, the force is spread out over a longer time, thus the max force is decreased. Max force, of course, is what actually causes damage as various structural elements are stressed.
True impact testing is extremely difficult to do rigorously. Manufacturers can used specialized test rigs that hold the product at very specific orientations until just prior to impact, as even the smallest variation in orientation at impact can make a material difference in the test outcome.
> If a tape can survive a drop from 80′, it can in theory endure the impact of a 44 pound weight dropped from 2 feet.
Here’s a simpler way to think about it. Both the tape measure and steel weights, if dropped on a seesaw, would launch an object sitting on the opposite end of the seesaw to the same height. In terms of impact resistance, however, what you proposed is probably not true as the total impulse (area under the aforementioned graph) is the same, but they’re spread out over different impact durations and thus have different max force.
I think I can see the point you’re trying to make (equating PE to impact KE), but the seesaw analogy is imperfect as the launch heights would actually be different.
My instinct was to think of the drop rating as a measure of impact energy because there’s nothing we know of impact force.
If a tape measure can endure x-number of Joules of impact energy, that could be a drop, or something being dropped onto the tape measure.
The problem with impact force discussions is that it’s impossible to make any calculations or comparisons without knowing the distance the object travels after impact. If the tape measure lands hook-end-down, does it make a bigger indentation in the packed soil than if it lands on its side? Does the tape bounce back?
The change in kinetic energy is equal to the impact force x the distance traveled. Or, F = KE/d.
And yes, you can drop a tape measure 10 times and get 10 different impact force measurements, depending on orientation differences at time of impact. But, drop the tape from the same height, and the kinetic energy just prior to impact should be consistent since it’s based solely on the mass and height of the object being dropped.
Impact energy is going to be much more repeatable for gauging impact resistance.
As you say, the softer the impact surface, the longer the impact time, the softer the impact. It’s like tossing a hard ball in the air. Hold your hand stationary to catch it, and it’ll hurt your hand when it comes down. Drop your hand with the ball to catch and decelerate (uch not a real word) it over time, and your hand won’t sting as much.
But, are drop ratings better considered as reflections of a tape measure’s ability to absorb impact energy, or as a measure of impact force? Maybe that’s the point of packed earth qualification – there might be far less impact variability than say a concrete surface.
When I was working for one of the above-mentioned companies we reached out to see if ASTM standards could be created to create a level playing field for all brands. Never got a response.
80 feet, 100 feet, it doesn’t matter. All that matters to me is either one should be able to survive a fall off of a ladder, and that’s the most I’d need.
Now, you really want to impress me? Give either tape measure to my 3 year old twins for an hour, let’s see if either can survive that.
I’d love to see that scenario made as a tool commercial (or a parody of a tool commercial).
Voiceover: “We knew our tools were tough, and set out to prove it. We know they can survive 100 foot falls, being run over by trucks and being hit with a hammer [footage plays showing tools surviving these tests], but that wasn’t good enough for us, so we came up with the ultimate test.
[voiceover interrupted by sound of toddler tantrum]. That’s right, we left them in the toddler room of a day care center for a week.
[Footage of people bringing in tools through the entrance to a day care center] 40 hours of toddler abuse and 7 tantrums later [footage of toddlers throwing tools at each other, onto the floors, into the walls, etc], there were no boo-boos and our tools still work. [Brand name] tools:. Tough enough for the job site. Tough enough for toddlers. Tough enough for you!”
Milwaukee tapes (so far) are garbage compared to Dewalt’s. I love Milwaukee (and own their power tools almost exclusively), but I gave my Milwaukee tape to my wife for her little pink tool box. Milwaukee needs to scrap their entire current line of tape measures and start over.
I don’t know about dropping the Milwaukee tape measure, but my expensive 25’ Milwaukee tape got two tears in it within 6 months of shop use, not even outside building anything. I am not impressed.
I’ve never used a tape measure in a situation where dropping it 80′ would even be a remote possibility.
I’ve been working in the home improvement field for 45 years & only had 1 case crack in all that time. It was a Stanley that’s dropped from a 24′ roof onto a sidewalk.
And I wrapped a piece of packing tape around it and still have it in the shop 21 years later as a backup.
I’ve had a few cheapo ones over the years that were promotional items that I’ve used if they were the first one I could get my hands on.
Those are inferior quality and wouldn’t hold up long on a job site, so I’ll disregard those.
The only thing that really matters to me is that the tape itself holds up without breaking, becoming unreadable or failing to retract.
Of all the professional quality tape measures I’ve used in all the years I’ve been working in the field, the absolute worst, and it’s not even close enough to debate, was the $30. 30′ Milwaukee POS I bought a few months ago.
Never dropped it. Never got it wet or dirty. Only used it for some normal inside carpentry work: doors, trim & flooring.
The tape cracked about 3′ from the end, and is no longer usable.
It’s supposed to have a lifetime warranty, but from the BS double talk I saw when I looked for info regarding a replacement I decided it wasn’t worth the trouble even if they would give me another one free, since it would be the same POS as the one that broke after about 3 months of easy use.
I bought a new DeWalt to replace it & it’s been flawless for the past few months, which is already longer than I got out of the Milwaukee.
Terminal speed must be also taken into account. Basically anything falling through the atmosphere will reach a speed where the atmospheric drag equals gravity pull.
Don’t know for these, but I’ll not be surprised it’s under 80′, so marketing guys can write wathever they want.
I’ll bet they did not drop the tapes from a tower, probably they hit the tape with an impactor with a certain mass, and calculated the height like you did but backwards.
Anyway, marketing BS, if you drop something 80′ you’ll better have another spare with you or you’ll need a bit of time to get it back.
For simplicity, I took both tape measures to be approximately the size and weight of a baseball. Terminal velocity is not reached for a baseball-shaped mass dropped from 100 feet, and so it’s not a factor here.
Is it possible that terminal velocity could still be a factor here? Yes. Do I believe that brands are taking it into consideration when making their drop rating claims? No.