A reader recently asked if ToolGuyd can verify manufacturer’s cordless drill max torque specs.
I have considered this over the years, and it’s complicated. I’m thinking about it again, and brushed up on what this would require.
With cordless drills now delivering over 1000 in-lbs max torque, and impact wrenches delivering over 1000 ft-lbs max torque, specific equipment us needed.
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Where Drill Torque Specs Come From
The Power Tool Institute – the industry group that most cordless power tool brands belong to – have guidelines as to how drill torque can be measured and advertised.
Their guidelines are very outdated, and nobody got back to me about whether they’ve updated their recommendations for drills that deliver above 1000 in-lbs max torque.
Anyway, there’s a set procedure that cordless power tool brands are presumed to follow for determining the max torque specs they put on a tool’s packaging. They’re voluntary guidelines, but I’d expect that all of the brands partnered in an industry group would adhere to them.
Max torque specs aren’t the most helpful metric in the world, but should be a consistent and a fair comparison point between different brands’ cordless drills and impact drivers.
Basic Torque Testers
Here’s a Gearwrench torque tester, available on Amazon. These are really meant for checking the calibration of torque wrenches and other such tools.
Some, like this one from AWS, are rated for use with continuous-drive tools – such as powered screwdrivers and possibly cordless drills – if used with a rundown adapter.
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Rundown Adapters and Joint Simulators
Here’s a low-strength rundown adapter from Mountz.
Here’s a joint simulator rundown adapter from CDI.
Lower strength adapters tend to have springs, higher strength ones have stacks of belleville spring washers.
Here’s what belleville spring washers look like, courtesy of bellevillesprings.com. Compressing belleville washers requires a bit of force. Stack them up, and you can create a repeatable compressive load.
Joint simulators use stacks of these springs – sometimes in different configurations – to simulate real-world applications.
It’s not exactly the same, but offers a repeatable and somewhat controllable way to push a cordless drill to its maximum torque.
Types of Fastening Joints
There are two types of joints – hard joints and soft joints. Some joints are in between and have characteristics of both.
An example of a hard joint would be metal-to-metal fastening where a fraction of a turn takes a bolt from loose to tight. An example of a soft joint would be screwing wood to wood, where friction builds and the wood can compress. The resistive force builds as you turn tighten a fastener.
Some brands give their cordless drills both hard and soft joint max torque ratings. You’ll see that in European spec sheets, but rarely here in the USA. Here, we generally only see the highest rating of the two.
In theory, a rundown adapter or joint simulator can be used with any torque tester or transducer, but it seems like a better idea to use testers designed for use with such tools.
This limits things, but it’s not the only consideration.
Testing Ranges
What’s the testing range? For cordless drills, we would need capacities up to at least 1500 in-lbs. Modern cordless drills are rated up to 1400 in-lbs the last I checked, and it would be good to have some headroom.
But, the majority of cordless drills deliver less than 750 in-lbs of max torque.
As the torque testing range increases, so does the size of the transducer and its drive size or interface.
Is it the best idea to test a cordless drill rated to 400 in-lbs on a 2000 in-lbs tester?
If you can source or build an appropriately spec’ed and well-sized rundown adapter, it’s not a big deal. What you don’t want to do is have to add a stack of size adapters. The less you have between the tool and tester, aside for the rundown adapter or joint simulator, the better.
Most torque adapters are calibrated from 10% to the full value. What if we want to also test the torque clutch settings? A 2000 in-lbs transducer or tester might help us test a drill that is spec’ed to 1400 in-lbs max torque, but won’t provide accurate measurements below 200 in-lbs. For a 400 in-lb drill, we wouldn’t be able to test the torque across most of its adjustable clutch settings.
Torque Testing Accuracy
Accuracy is also an important consideration.
Some torque testers have accuracy values relative to indicated measurements. For such testers, a measurement of say 400 in-lbs max torque with 1% accuracy would actually be 400 ± 4 in-lbs.
Let’s say a different torque tester with 2000 in-lbs max testing limit is rated to 0.5% accuracy across the full scale. This would mean the 400 in-lbs measurement would be 400 ± 10 in-lbs. That ± 10 in-lbs component won’t change with the measurement.
So if you have two transducers, both with 2000 in-lbs max torque testing capabilities, one with ±1% accuracy relative to the measurement, and the other with ±0.5% accuracy relative to the full scale, there are different points in the range where one will yield more accurate measurements than the other.
What does ± mean for a value? Let’s say you have a measurement of 100 ± 5 in-lbs. This that the actual value could be between 95 and 105 in-lbs. There will also likely be an error due to the least significant digit, similar to how there’s an uncertainty when reading between markings in a ruler.
Impact Driver and Wrench Torque Testing
How do we test impact drivers or wrenches?
There are some models that can handle continuous rotation and impact action, but it would probably be best to go with something like the AWS IMP series of testers shown here. These have a very beefy torque transducer and rundown adapter, and a display that can work with other models of AWS torque testers.
These retail starting at $4K and according to the lead time I was given yesterday by a dealer, they’re backordered into at least early 2024. I asked AWS for lead times as well but haven’t heard back.
Selecting a Torque Tester
The CDI electronic torque tester that the Power Tool Institute specifies in their outdated torque measurement guidelines tops out at 1000 in-lbs. And it’s not rated for impact tools.
All of the impact-rated testers I’ve seen have full-scale accuracy values. Let’s say we test an impact driver on a tester designed to max out at 1000 ft-lbs, which still won’t accommodate brands’ top models. A 1% accuracy could then mean a measurement of say 1800 ± 120 in-lbs max torque.
1000 ft-lbs is 12,000 in-lbs. 1% full scale accuracy would then be 120 in-lbs.
Imada has a line of continuous and impact tool torque testers, as well as non-impact testers.
But… they have full scale accuracy, as opposed to measurement-relative. Their low-range model tops out at 440 in-lbs, their mid-range model tops out at 1740 in-lbs, and their higher-range model can measure up to 362 ft-lbs (4344 in-lbs) of torque.
The mid-range model should be able to handle most cordless drills, but with lower absolute value accuracy at the bottom end of the range, due to having a full scale accuracy rating. It also can’t test most 18V-class impact drivers, which exceed its torque testing limit. The higher range model can test impact drivers, but will lead to much lower accuracy when testing drills, especially lower powered ones.
If we have a drill that tests at 200 in-lbs, the accuracy on the high-range model would mean a measurement of 200 ± 22 in-lbs (due to ±0.5% accuracy based on the 4344 torque testing range), which is an unacceptably high uncertainty range in my opinion.
I should point out that Imada’s are among very few models that extend below the 10% of full range floor. In the case of the high-range model, it tests from 3 to 362 ft-lbs. Their mid-range model tests from 30 to 1740 in-lbs. Most other testers are not calibrated below 10% of the upper end of the range.
Why Not Use a Torque Adapter?
Why not just use something like this, an inexpensive torque adapter?
First, where’s the rundown adapter? Lots of YouTubers claim measurements, but without a joint simulator, those measurements can be wildly far-off and inaccurate. Second, they’re designed for use with manual torque wrenches. This one has an accuracy of ±2%.
What’s the rotational speed of a ratchet? What about a cordless drill?
Torque adapters are designed to be used in place of a torque wrench. They’re not designed for testing or calibrating the torque of manual or powered tools.
I have only ever seen one decent DIY/shop-made torque tester, and it appears to be well-calibrated for relative numbers.
Torque adapters are not an appropriate way to measure the max torque capabilities of cordless power tools.
Why is Any of this Important?
Let’s say you were to take out your cell phone and measure its length. What’s the value? How did you measure it?
Let’s say 10 other people have the same phone. What measurement did they get?
There are two types of data – qualitative and quantitative. Qualitative can be based on observations. Quantitative are based on measurements and numbers.
Would you measure the length of a phone in sugar cubes? Graham crackers? Not all sugar cubes and crackers are the same size.
Numbers need to be accurate and repeatable. This requires the proper tools and established techniques.
Repeatability has to be demonstrated.
What’s the point in taking measurements if the numbers aren’t reliable?
If a cordless drill is spec’ed at 600 in-lbs max torque, but tests at 400 in-lbs, are the specs inflated and bogus? That could be a big deal.
Or are the measurements inaccurate or otherwise flawed?
Maybe you can buy a torque adapter with 2% accuracy, lock one end in a vise, attach a drill, and get a reasonably close max torque measurement. Or it could be wildly off. Are the numbers trustworthy?
So What are the Options?
All that said, it seems that accurately checking the max torque specs of most 12V and 18V class cordless drills, and some 12V class and 18V class impact drivers can be done with one torque transducer. Modern brushless 18V class impact drivers will generally require a separate transducer. Mid-range and high-powered impact wrenches will require a heavy duty and appropriately-spec’ed setup.
It would take two setups for testing the max torque of most cordless drills, most impact drivers, cordless ratchets, and the least powerful compact impact wrenches. A third setup would be needed for the most powerful impact wrenches on the market. A fourth setup might be needed for greater accuracy when testing tools with lower max torque, such as 4V-class cordless drills, or the repeatability and torque stopping points of adjustable clutches.
The testing apparatus seems more important with reactionary tools, such as cordless drills, than impact drivers or wrenches. You can’t just hold the tool in-hand; drills under test should not be allowed to counter-rotate.
There are some multi-transducer testers, which shaves a little off the price by sharing a common display.
But there’s no escaping the need for multiple testing apparatus. There are 1/4″ hex to 1/2″ square drive adapters for testing lower powered impacts on mid-range transducers, but can we trust measurements if a stack of adapters are needed to adapt a 1/4″ hex impact driver to the 1″ drive (or larger) featured in higher torque range testers?
CDI’s electronic torque testers top out at 1000 in-lbs, or at least the product range that seems most suitable for testing cordless drills with a rundown adapter. They’re not rated for impact tools. It would run about $2400 plus the cost of adapters.
Joint simulators and rundown adapters are $400 to $700 depending on the brand, style, and size sometimes more. They’re available with different torque limits.
So to test say a tool spec’ed at 300 in-lbs, we’d want a rundown adapter of maybe 500 in-lbs. One that’s spec’ed to 1500 in-lbs might not allow for much rotation before the tool stalls.
Most tools are advertised with respect to their hard torque. Their soft torque is usually far lower, but provides a more useful comparative measure with respect to driving screws into wood and similar.
AWS’s smaller transducers are available in less and higher accurate varieties, and also display-less models. But they have a very long lead time.
The same brand’s impact transducers are very pricey and have ±1% full scale accuracy values, meaning that it would be hard to use just one to test the full range of 18V-class impact drivers and wrenches. These start at $4000, but don’t need additional rundown adapters. Not much information is available, but it looks like the rundown adapters are designed for hard joints. If they’re adjustable, it would be ideal to have a 250 ft lbs (3000 in-lb) transducer for testing impact drivers and a higher range for testing higher powered wrenches.
A 250 ft lbs model might suffice for impact drivers and compact impact wrenches. A 1000 ft lbs or higher model would be needed to test modern mid-size and higher-end models.
Impact wrench testers are pricey, but it’s not surprising; 1000 ft lbs exerts a lot of force for a transducer to hold up against.
It makes sense that a popular YouTube designed and built their own calibrated hydraulic ram-based tester.
Impact tools can quickly damage or degrade equipment not meant for the forces involved. It seems like a good way to ruin an expensive torque tester.
One brand says their torque specs are derived from 15 second test durations. 15 seconds of impact duration is going to require a heavy duty transducer and rundown adapter, and not just one that’s approved for impact testing. A quick calibration check wouldn’t be as hard on a torque tester, but doesn’t seem like the best way to test for max impact torque.
Narrowing Things Down
When looking into the different testing options now, I found a couple of more options previously unknown to me.
There’s no “do it all” test setup, however.
A torque tester that can handle all 12V and 18V-class cordless drills, cordless ratchets, and some impact drivers, plus 2 or 3 rundown adapters and joint simulators across the range, would be about $3500, maybe a little more depending on the brand or source of one of the adapters. Plus the cost of building a fixture around it. Computer cables and software are extra.
Two brands make heavy duty impact testers. One is limited to 180 ft-lbs (2160 in-lbs), the other has a wide range that goes well beyond the maximum torque that cordless 1/2″ impacts can deliver. These all start at $4000.
There’s a lighter duty impact tester that maxes out at around 362 ft-lbs.
Most of the lower-range torque testers I’ve seen are also around $2000 and up.
If a consumer wants to test numbers for themselves, why not use a $50 torque adapter with low accuracy. I’m not saying YOU need to go out and buy expensive testing equipment.
In order for ToolGuyd to publish numbers to satisfy the reader’s requests for independent torque testing, or in the pursuit of other torque-based insights, I must take every step to ensure the fidelity of the measurements.
For the data is to be trusted, the methods need to be sound and measurements need to be reproducible. The transducer needs to be designed for use with powered tools, and impact-rated if tested with impact tools.
Justifying the Investment
Give me two cordless drills, and I can quickly and inexpensively tell you which one can deliver a higher max torque. Qualitative testing is fairly easy.
Measurements that are accurate, repeatable, and as reproducible as possible, are not quick or inexpensive. Quantitative testing – the right way – is not easy.
Ideally, a one-tester-fits-all solution would be great, but that’s not happening. I’m also not spending what it would take to test tools across the entire practical torque spectrum.
There are some DIY or homebrew options, but I have enough projects. A turnkey solution that I could just use with high confidence would be nice. I’ll keep looking into it.
Will it be worth it? In my opinion, no, at least not just for the sake of measurements. A couple of thousands of dollars worth of equipment, just to verify technical specs that aren’t the most useful anyway? But if it’s something readers want to see, I can find other ways to use use the same equipment.
How repeatable are torque clutches? Can we test the differences in mechanical and electronic clutches in this regard? How might adjustable torque clutch characteristics change for different brands or models?
A cordless power tool brand recently updated their 12V-class impacts, and on top of the well-advertised updates, they changed how the trigger switch is tuned to control output speed. Rather than a mostly linear relationship between trigger switch travel and “percentage of total power,” the output is a lot flatter from 10 to 50% than with the previous model. They redesigned the trigger switch to give a lot more speed and torque control in the mid-range. This is something that would be very hard to show without measurement-based testing. That kind of data is interesting to me, especially because it’s not something tool brands will readily share.
Five plus years ago, tool brands were still racing to one-up each other with respect to torque and power. Now, we’re starting to see more differences “under the hood.”
If such data is to be collected with any reproducibility, misusing a consumer torque adapter with low accuracy is out of the question.
So that’s why I’m looking into this again. The reader request suggested there’s interest in measurements, and I am interested in comparing max torque against advertising claims and different brands’ models. And, there are even more things we can look at. Most of the equipment I’ve looked at so far, except for the impact-only ones, can also be used to check the calibration of manual torque wrenches and the like as well – within their measurement ranges – which would also be useful.
I’m not about to invest 10 grand or more in a suite of torque testers, but I can budget for a tester that might handle a majority of what I’m looking to do with cordless drills.
I can justify some investment in test equipment, just not as much as it would take to test every type of drill and impact tool 1/2″ driver and under – at least not all at once. A prudent approach would be to start with a torque tester that can test as broad a range of tools as possible, and to see how things go from there. When I run out of things to test, maybe then I can look at additional investments.
All of this is partially to clear my head, and mostly because a couple of regulars mentioned in the past that they liked seeing my behind-the-curtain thinking about things like this. Whatever setup I land on, a lot of what was discussed here will have went into the decision-making process.
ToolGuyDan
I think you may have missed one of the biggest advantages to a 2-tester setup (one midrange, one high): having the ability to inter-validate/calibrate. In the overlap range, testing on both machines allows you to be sure both are still in calibration, and also gives you a chance to suss out any variation rooted in things like the 1/4″-to-1″ adapter you mentioned.
As to the low end, I don’t think most folks care about what “7” corresponds to in inch-lbs., especially since I sort of doubt that even within the same model, the QC at the factory would reject a perfectly good drill whose clutch varied 30% from the spec across the board, so long as the max spec was still being achieved. After all, one of those is something they have advertised (and can thus be sued over), whereas they never promised anything but relative adjustment out of the clutch. Thus, as a consumer, even if you had rock-solid data showing a DCD997 at “4” was such-and-such in-lbs, I still wouldn’t assume my DCD997 would slip at even +/- 10% of your number.
Anyway, point is, buy two: mid and high. For bonus points, make ’em different brands, too.
Stuart
A 2-tester setup also allows for a ballpark torque measurement, for easier rundown adapter selection, and assurance the max torque is within the range of a higher accuracy lower-range tester.
Two is better than one, one is better than none.
The exact torque of say clutch setting 7 isn’t as interesting or important as its ability to hold to a value under different conditions or RPM being used. Overall the trend is important or at least interesting. Some tools ramp up quickly, making them almost unusable for smaller fasteners such as #6 and #8 wood screws.
I generally don’t like electronic clutches as well as mechanical – they work alright for larger fasteners, but can be all over the place for smaller ones. All indications point to the slip or stop torque spread, and it would be nice to quantitatively see why one type is better than the other.
There are a couple of models suited for testing drills with >1000 in-lbs max torques. Going to high range that will also cover impact wrenches will have terribly unusable accuracy for drills. A 1000 ft-lb tester with ±1% accuracy means that a 1400 in-lb reading could be 1400 ± 120 in-lbs. With 10% of range being 1200 in-lbs, it wouldn’t be possible to test any but the most powerful drills.
This means looking at 2 drill-suited testers now and potentially 2 higher range impact testers later.
The range is tricky. 750 -in-lbs seems like a good ceiling for most cordless drills except for the highest power flagship models, which a higher range model can cover. But the floor will then be 75 in-lbs, which isn’t enough for testing lower torque tools or things like clutch setting steps.
Because of all that, I would think that it might be best to start with a model that covers all cordless drills, then add either a model that adds low-torque range with higher accuracy, or mid-range impact torque. After that, the third model would be the other choice, and the fourth would be a high-range impact tester.
With only two, there’s the question of which is better for the second test station – being able to measure lower torque values and with higher accuracy, or being able to test all impact drivers and compact or lighter duty impact wrenches?
The first test station would be the same – a model with appropriate rundown adapters for testing the max torque of any modern construction-grade cordless drill.
John
Have you not seen the Torque Test Channel on youtube? He’s been doing this for a year or two. He tests drills, impacts, cordless ratchets etc. I think you would just be duplicating something already out there.
Between Project Farm and Torque Test Channel, most everything tool testing is covered or will be covered in short time.
Stuart
TTC’s impact dyno is the only reasonable-looking apparatus I’ve seen, and I trust their adherence to calibrating it appropriately and regularly.
I’m under the belief TTC isn’t a one-person channel, and their core focus is torque testing. They can afford the time for a team member to design and build different apparatuses.
Their main torque tester is based on compressing two hydraulic rams, with the value translated to torque seemingly based on calibration points. Those data points will have to be calibrated regularly, presumably with a torque wrench that will also have to be calibration-checked.
I’ve got enough projects – a turnkey torque tester will work better for me.
I’ve seen other channels’ measurement data, and do not trust them for quantitative purposes; there are too many holes, and the methods frequently unscientific. You can still show trends with untrusted numbers.
There are also too many YouTubers who think joining two drills together with a common bit and counter-rotating them can be considered scientific testing.
MM
TTC seems very good about their calibration and validating it by comparison with 3rd party equipment. They also borrow larger equipment when they test the heavy-duty impact wrenches that exceed the capacity of their standard test rig. I also remember them talking about having their home-built integration sphere used for testing flashlight intensity tested by an outside lab. And yes, there are multiple people involved, they mention this fairly often in their videos.
Project Farm is hit and miss. A lot of the testing makes sense but there is some that is incredibly flawed.
JR Ramos
I get the impression they have real jobs/a shop doing heavy truck work and the videos took off in a way they didn’t anticipate…one buddy/relative/someone took off and is employed with Astro Pneumatic now (largely as a result of their work). They’re smart and thorough and have a solid approach to the testing…near as I can tell.
Their newer braking dyno setup is the one to look at – much more valuable data from that rig vs. simple torque testing which is how they got their start. They covered its design and construction maybe 2-3 times now (inception and evolution). It’s proven to tell an awful lot about max power vs. sustained power on both drills and angle grinders (they recently did a few circular saws as well). But that’s what I’d be trying to emulate if I were investing in this…I think.
That Skidmore tester they have is quite a piece but I think its limitations are what caused them to branch out into fabbing the equipment they use now…seems like they mentioned that there was nothing off-the-shelf, too.
On rigid tool holding…I dunno. Seems like a better real-world indicator for handheld impact wrenches but the effect may be a washout anyway. On their grinder/drill tests for power they did position them such that the tool body was immobilized, which is more important there.
I like the idea of clutch setting tests, mostly because I don’t think I’ve ever seen or heard it mentioned in the past. It would be kind of neat to see a relative range even if the numbers aren’t completely accurate or repeatable across individual tools or different models.
mark
Yeah TTC is clear that he works in R&D for astro pneumatics, fwiw.
But yeah that’s the best Ive seen for this sort of thing.
MM
A big problem which I think also needs mentioning is that if you truly want trustworthy data you can’t test just one tool, you need several examples of each. It does you little good to have an incredibly precise test setup if you’re only going to be testing one sample. It’s not just a question of can you afford the test setup, it’s also a question of can you afford the samples to test. Buying one each of all the cordless drills on the market would be very expensive. How about buying ten each?
Stuart
PTI says their brands’ tools should be tested in sets of 5 tools with 5 measurements each.
I’m okay testing one representative model. If any brand or reader wants 5 or 10 copies of a particular cordless drill tested, they can supply them.
There’s always variation across multiple industries. Optics labs test one copy of camera lenses, tech publications test one copy of CPUs, video cards, monitors, and TVs, and so forth.
In a similar manner, I typically only test one copy of a cordless power tool at a time. I don’t grab 5 of the same to see if there’s variation in how they drill a 3/4″ hole through 2x material.
MM
You appear to be approaching this topic with a lot more academic rigor than most. The kind of standard you’re talking about seems well above the average magazine review, and I think that duplication makes sense at this level of rigor.
Stuart
I can’t help it?
If I’m going to put the time and effort towards quantitative measurements, shouldn’t I do it right?
A W
I think what MM meant is that given your level of academic rigor, wouldn’t it be good to test a larger sample size of one tool at a time?
Stuart
Ah, I’m sorry; I took it as an “you’re overthinking it” comment, which I’ve gotten before.
Sorry @MM!
Testing 2 copies is perhaps better than 1, but isn’t enough to see if there’s any patterns in deviation from spec.
I think 3 would be the minimum, but even that will drive costs up quickly.
I can test multiple copies over time, but all at once?
Testing more than one copy is something that can always be done down the line, as long as I have the right equipment.
The protocol can also be modified, such as x-number of minutes between tests to ensure the tool and rundown adapter are cool.
Selecting appropriate test equipment is still a good starting point.
Multiple tests could perhaps be done for just one flagship model from each brand to test specifically for potential variability between copies.
John
Could you request manufacturers loan you multiples? Don’t you often get loaners? Even if they say no it seems like it would be worth trying.
Jared
That’s what I was thinking as I read. Even TTC’s rig, as sophisticated as it is, is really concerned with relative values, not specific numbers (hence they talk about measuring “beans” not in/lbs) – which seems more than adequate for most consumers.
It’s impressive and would basically make Toolguyd the defacto leader in independent review testing… but are you sure that you’re not taking things too far?
It would be really cool to have a means of comparing drills and impact drivers across brands despite their reliance of different metrics. I’m just not sure whether Toolguyd would get $10,000 of value in return for that investment.
Stuart
“but are you sure that you’re not taking things too far”
That’s partly what this post is for – an interest/reality check.
Franco
I understand the very large expense, and questioning if it is worthwhile for the expense involved.
However, “I’m okay testing one representative model.”…I believe this makes the expense and work involved, not worth the trouble. I believe at least 3 of a given product should give a reasonable result. In doing such tests, one lot of product X has 3 very different results, that in itself would beg for further digging into QC for that company and possibly getting a couple of other examples to see if the inconsistencies continue. Then that would also raise eyebrows as to what is PTI doing.
Just testing 1 of each, in my mind, leaves too much incertitude as to how exact the result is…you just do not know. If you test only 1, and it is 100% dead on to MFR claim, or only 60% of MFR claim; it is just 1, which in my mind is, like you said, better than none…but marginally. A minimum of 3 would give a pretty decent indication of how QC if they are within X% of each other.
You would be investing good money + time, to get zero consistency with the testing of just 1.
I am one that believes that just about any tool from the 10 biggest/popular brands would be excellent tools when it comes to driving screws, cutting or whatever the product does. I care about numbers a bit, but not much. For you to do this testing and use 1 example of each, to me would mean very little because I believe that if you test impact wrenches that are in the 500 ft/lbs range, regardless if who comes 1st, 3rd, or 5th, they will all do the job well. Keep in mind, these would all be models rated at or very close to 500 ft/lbs. This would be the same if you test smaller, space saving impacts that are in the 250 ft/lbs range, or bigger brutes that are in the 750 ft/lbs range.
A tool that specs say it is 500 ft/lbs and comes in at 450, is 10% less than claimed, but in real world would probably work as well,or almost as well as one that came in at 500 ft/lbs. Other factors such as tool weight, ergonomics, batteries…and other items are more important.
Obviously you can do whatever you please, whatever you think is right.
I believe that either leave things as they are, as there are already torque testers + PTI out there. Or, if you are going to go through the expense and time, do it right (meaning 1 example is not worth testing).
Stuart
A sample size of one is better than none.
More copies can always be tested in the future. Nothing can be done without the proper equipment.
Doug N
So true; this is the only complaint I have about Project Farm and similar testers. Just because their single sample test finds that brand x outperforms brand y, it doesn’t necessarily follow that the model I buy will perform equally well.
This could be a scientific niche for ToolGuyd to occupy.
Collin
Thanks for this comment.
I see basically 0 actual statistics being applied in consumer testing, whether it be power tools or refrigerators.
Everyone seems to be stuck on the idea of testing one drill or one dishwasher and generalizing their findings to the population.
Sometimes, there’s some handwaving about “sample sizes” and they’ll test not one but maybe 3. Or 5. And then, again, they’ll generalize from this sample to the population.
I’m not a statistician but I know there’s more to statistics than “sample size” and I know there’s more rigorous ways of determining an appropriate sample size instead of pulling a number out of thin air or letting your sample size be dictated by your budget.
I would like to see a discussion on power tools that involves things such as the Central Limit Theorem, chi-squared tests, ANOVA tests, null hypotheses, etc.
Stuart
When a product is reviewed, here or elsewhere, there is the expectation for its quality and performance to be representative of the group.
When this turns out to not be the case, you will often hear about it.
For example, there’s the concept of TV and computer monitor “lotteries.” If reviews are positive, but it turns out there are different quality levels depending on which OEM brand’s components are used, it’s widely shared about via media channels and online communities.
Sufficiently large sampling sizes can help show irregularities or inconsistencies, but it’s not practical.
Fast forward to 5 years from now, and I have a suite of torque testers. A reader asks “hey, can you characterize and measure this model of drill?” and I should be able to accommodate the request. Will it be feasible for me to request or buy 5 copies to test? No.
But let’s say a brand says “hey, we want to commission independent testing of our new drill.” That’s where there’s greater value and need in testing multiple copies.
Can a reviewer spend a month testing five different copies of a cordless drill in organic and controlled conditions? Sure. Is that a productive use of time and effort?
How important is that to the actual review? Are ergonomics or build quality likely to vary between copies? Features and functions? Is it just speed and power? How large is the spread?
By the time these things can be well understood enough to please statistical testing, the product has already reached its end of life and anything gleaned is too late to help anyone.
I used to think that it was worth holding onto older samples as long as possible before giving them away, so as to be able to answer questions and conduct different comparisons as need. This was unsustainable and grew to be a problem. So now I am much more prompt about giving away tools I don’t expect to revisit. I can always buy another copy in the future if the need arises.
JR Ramos
I think that kind of thing greatly depends on a) your investment (e.g. the actual manufacturer or an approval/standards organization), and b) the type of product. I can see larger pools (and ongoing batches) being more useful with things like flat wrenches and sockets than I can with power hand tools. Or items like brackets and screws and such…chemicals perhaps, all kinds of other things. Once a design is settled, dies and processes are created, modern manufacturing won’t let too much variation creep into a finished product – more likely to see the occasional material or assembly defects which are expected to some degree.
Longevity testing would be neat but sometimes that’s just not feasible for transient products that may only stick around for a few years, and it’s a huge added expense for a manufacturer so they need to absorb that and manage the process/data as well.
And tools being what they are, we want to avoid obvious lemons (like that Type B/2 impact fiasco with Milwaukee not long ago) but for so many tools wear and replacement is just expected (and most often they’ve paid for themselves and replacement is cheaper/more desired for those that work with them for a living). Teardowns that identify things like triggers and pack cells can lead to starting point data about those items, usually.
I think it’s great that we have so many testers (and “testers”) these days and the information is easy to share and find. Even when it’s somewhat limited or flawed it’s usually still valuable. Not too long ago it was nothing but word of mouth and opinion (skilled, trained, subjective, or…otherwise). I appreciate Project Farm’s efforts and energy, and I think nearly all of his videos have value, often useful, but most really aren’t all that scientific or necessarily representing normal or best use cases, and quite often it seems he doesn’t really have expert knowledge so a product test may be really flawed somewhere (or poor comparisons in the lineup)…but it’s still great for what it does give. It’d be nice if we could trust the manufacturers and drop most of the BS marketing…but until then any testing is probably good.
fred
My experience is limited and dated – but we had a Sturtevant-Richmont torque wrench tester in the tool room of our fabrication shop. I don’t know if any of their modern offerings would be of any use (we used it to calibrate/verify hand torque wrenches not impact tools) – but you might have a look:
https://www.srtorque.com/error-proofing-tools/digital-torque-testers-and-calibration-equipment/
We also had some torque calibration instruments for our Hios and Mountz tools – but I suspect that what they might offer today would be at the low-end of the torque range that you want to check.
Stuart
Thank you, I’ll take a look!
I’ve looked at Mountz. They have transducers that they advertise as being suitable for electric screwdriver calibration, which in a lot of cases should apply to cordless drills. The models I looked at cost $3825 and have an accuracy of 0.5% from 20% to 100% of scale, and 1% of reading at 10-20%.
The start of a modular setup might consist of a 100 ft-lb transducer at $2325, plus torque analyzer electronics package at $2755, plus cable at $305. The BMX transducers have high accuracy – ± 0.25% of full scale.
I would need to gauge intertest before going down this path. A sub-$2500 tester (not including rundown adapters) seems like a better way to get started.
A suite of Mountz transducers and single readout analyzer would be a good path for ensuring optimal accuracy for any manual or powered non-impact tool. But it still wouldn’t cover impact tool use.
If paid testing were a possibility, or torque testing was something I *needed* to do, that would be different. For magazine publication purposes, Mountz sensors are a bit too much for an initial investment.
I have not looked at HIOS, but my limited familiarity with their tooling aligns with your belief their range would be too low for what I’m looking to test.
Steve
Project Farm and AVE use these too. Maybe eyeball what they’ve got.
TonyT
For believable measurements, you do need repeatability and accuracy, but you also need correlation: the ability to do the same measurement on another machine, and get the same answer (well, the same answer within a reasonable %).
I highly doubt most of the youtube channel torque measurements have any correlation to any other channel’s results, let alone professionally done measurements.
Andrew
It’s reproducibility that’s required, which is a higher standard than correlation
John
Yeah this is important. For example when I’m using a 1″ impact wrench on stuck lug nuts I’ve noticed that how I hold the wrench makes big difference – holding the body of it vs the handle and how hard I press down on it. You either need to find some way to clamp the body of each tool or accept the variability of how the operator is holding it.
Albert
Can this be done using first principles, say 10 pounds of water suspended 10 feet away?
John
For a torque wrench, yes, but not for anything that outputs impulses like an impact wrench. At least that I know of.
Nathan
First off do you have a need or want to test impact tools. I think alot of the question on drills comes from some makers with fairly crazy claims on drill torque coupled with various thoughts on how much is actually enough vs one big maker doesn’t represent torque.
so spec comparision doesn’t match and you see test reviews where the low “torque” drill competes close to the higher model. for drills I could see making a simple joint apparatus and using one of those 1/2 drive torque adapters would work relatively speaking.
IE say a piece of plate bolted to a tapped hole in a block as the joint – us a 1/2 drive adapter on the drill though the torque adapter – to a socket of ___ that matches the bolt head. Use drill to run down the bolt until it can’t with drill in drill mode. do 3-5 passes and average them. and that would be relatively accurate
you might use the same test for say cordless ratchets but NOT IMPACTS. and I wouldn’t bother testing impact wrenches anyway. They are rated at torque rating and most do a decent job of staying what they do correctly.
I wouldn’t go much deeper than that as again with a drill there are a number of factors that raw brake torque isn’t really the fair. not to mention I think all the big name drills do more than plenty today – the new battle ground appears to be body size and overall weight.
A W
Since you’re asking for feedback on interest, my $0.02 would be to pass.
I find your current approach to covering tool reviews and news to be incredibly valuable, which is the reason that I check this site daily.
If you were to start objectively testing torque specs, you would owe it to yourself, your readers, and the reputation of Toolguyd to do so meticulously. Such a project would divert some of your limited time away from what you currently do so well.
There are other Internet sources (of varying credibility) that already do this, and I don’t think that Toolguyd adding additional research would be a big value add for me personally.
Hon Cho
Ditto. Unless you’ve got some business plan that you haven’t shared with your readers, I can’t see Toolguyd torque testing as particularly value-added for your readers.
Travis
Yeah, I agree. When considering the time and money involved I would probably pass on this unless you are able to re-coup your money. I just don’t usually find the torque spec to be the limiting factor when I purchase tools. Usually, I am more likely to stick with a battery system I already have an investment in or whatever feels better in my hand. Most of these tools have more power than I know what to do with.
Aaron SD
I’m definitely curious on the technical level but not so sure the value spending lots of time and money.
What might work is the comparison route. Create one reasonable real world test that would require lots of torque, even allow impacts. Or better, ask readers when they didn’t have enough power in their drill and use that. Can then use a manual torque gauge to test the final torque level.
Getting good data does require more samples, even 5 is a little low.
At a factory I had products built, we had specs for the screws and it was a real pain calibrating them- even testing 10 times the repeatability was all over the place. We never encountered a failure that could be traced to the screws and I’d bet never was. This was also due to over designing and thoroughly testing our products during development.
Before spending money, I’m wondering how many readers have bought drills that didn’t meet their needs based on the specs on the box?
Loving the discussion
Nate
Stuart, I know you’ll do this well if you decide to do it. However, I don’t really think it’s necessary. I personally think that a subjective, qualitative review of tools is more meaningful to me. I got the Triple Hammer on your rec, and I think it’s a great tool. For me, the ergonomics, modes, cost, battery cost, and “competitive” performance matter way more than torque. I could really care less if the Triple Hammer makes 100-200lbs less of torque than competition. I could also care less about the “issue” (designed feature) that TTC “discovered” with it only using two impact strikes in power mode. Frankly, my little Bosch 12v Flexiclick is usually sufficient for anything but construction work.
That said, if this test rig helps drive some traffic to your website and helps you and your family, I’m all for it. 🙂
Andrew
Without knowing the manufacturer’s test methodology, and pass/fail criteria, I would expect the most likely outcome is your measurements being discrepant with theirs. I think closing the gap will most likely prove fruitless, and potentially frustrating.
MM
Obviously there will be a gap. But the goal isn’t to “close” the gap. If that was the point we could just skip testing and take the manufacturer’s quoted specs and be done with it. The goal is to examine the gap, and reveal just how different marketing numbers are from real-life.
Andrew
I think we’re saying the same thing.
On one hand their will be marketing numbers, on the other there will be a small (single?) sample test. Neither are dependable, particularly without understanding what the manufacturer is really doing.
I think comparing them will be very challenging
MM
I do agree that tests with small sample sets aren’t very trustworthy so if we want academic-grade data we need to do an academic grade test complete with controls, traceable calibration, and a statistically significant number of units tested. But I disagree regarding our need to know or understand anything about the manufacturer’s test methodology. We don’t need to know how they arrived at their numbers to compare real world tests with their marketing claims.
Stuart
Testing 1 or 5 copies of each model wouldn’t change the type of equipment used.
Well, it could. If we’re testing 5 samples of each drill, we’d ideally want the highest accuracy possible.
If accuracy is 0.5% or 1% full scale, and we’re testing at 15-20% of the full scale, the error is going to be pretty big compared to say 0.25% of full scale and testing at the higher end of the range, or 0.5% of reading.
With a large error, are deviations due to the accuracy of the equipment, or variability between models?
I can do academic and industrial-level testing. But it’s not a good idea to start off there.
A (comparatively) small investment, testing 1 copy per drill, and sticking to modest protocols can satisfy personal and reader interests without a 5-figure credit card bill.
You are not wrong.
However, in academia, most research activities are usually funded in some manner. When a grant is awarded, it might have a separate equipment budget.
If you’re doing work on say high pressure materials, a grant might pay for the forging press.
I’m willing to spend a bit of money on exploratory equipment. Proof of concept testing will help determine whether there’s reader interest. If readers want more, I can figure out how to scale up over time.
As for testing 5 of each drill tested, the cost will add up fast, especially since some models are priced at $300 and up. When test samples are provided for review purposes, there might be times I can request 2 copies, but certainly not 5. Maybe we can do a giveaway or similar. That’s something we can figure out later.
Regarding calibration, there are weight wheels that allow for self-checks. Buy the wheel or attachable apparatus, different test weights, and ensure the measured torque matches the calculated torque.
Traceable calibration would be a needless cost for something like this. If I were making and selling cordless drills and advertising max torque specs – that’s where traceable calibration certificates are needed.
Stuart
As mentioned, all major cordless power tool manufacturers are part of an industry group called the Power Tool Institute.
The PTI has outdated but reasonable-sounding voluntary testing protocols for measuring max torque.
It spells out exactly how tool brands should be testing for max torque. It’s pretty close to how I would assume such testing should be done, with added guidelines regarding battery charge status.
If there’s a discrepancy between my numbers and brands’ numbers, it will be important to find out why. If enough numbers match, and some don’t, we can ask questions.
Andrew
I think this is the reference you’re referring to?
https://www.powertoolinstitute.com/pti-includes/pdfs/TorqueLTP.pdf
My understanding is 5 drills, 5 measurements per drill, including battery conditioning, and a defined supplier of the torque meter.
My point, and I’ll not labour it any more, is that I expect you’ll have one drill and a different supplier of torque meter (as minimum differences).
That sounds like quite a lot of work to me, to compare two differently-derived numbers. I personally would carefully mull this over, before committing my money to it.
mattd
I don’t know if you watch much of the recent torque test channel vids but they seem very comprehensive with the way they test drills instead of a skidmore like test that they do with the impacts. https://www.youtube.com/watch?v=dURmHsnh1IE
Stuart
I look into it every few years. The brake is pretty much the only challenge, but it’s a big one.
I’ve considered building a mechanical brake dyno, but always felt there are too many variables to control for high repeatability. A magnetic brake is a better idea – in my opinion – but pricey and can also be complex.
A hysteresis magnetic brushes doesn’t require speed for resistive torque generation, and this seems great for drills with widely varying speed ranges.
A large flywheel in a prony brake could work, but would it be accurate enough?
A turn-key system with magnetic brake costs $21K to buy, and $6K to rent for one month. This was a few years ago, the prices might have gone up. I checked recently and there aren’t any more affordable options that I could find.
Building a dyno can be done for considerably less, but would still require a substantial investment in funds, time, and effort.
It isn’t exactly a common project. There are plenty of examples of DIY car dynos, and almost no examples of power tool dynos.
I’m definitely still interested in the idea, but it’s a much bigger project than simply setting up a torque tester. Qualitative testing is easier done with 2x material and self-feeding drill bits, and I haven’t found an affordable way to source or design a brake for consistent and repeatable quantitative measurements.
There’s also the nature of how power output can be interpreted.
Does the average tool user thoroughly understand what Dewalt’s UWO unit watts out spec means?
Most tool reviewers get it wrong; they try to hunt down a conversion factor that doesn’t exist, and then resort to guessing.
Collin
The only thing I understand about UWO is that watts out must be less than watts going into the tool thanks to conservation of energy and of course various losses going from the battery to powering the motor.
UWO > 1800 suggests to me greater than (15 amp) corded power delivered by the battery.
UWO of 2300, which I think at least one of the Flexvolt grinders delivers, suggests to me that DeWalt has a very capable battery delivering > 2300 watts, much more capable than most brands.
MFC
So yeah, part of the process. Choose what you want to focus on. Look at various machines and then that will tell you what you CAN focus on. Once you determine what you will actually focus on then you can come back and look at machines again.
As a contractor I can certainly say that I can get a good estimate from the basic tests that most guys do on Youtube. TTC is able to give me a good understanding of the tools I might be interested in for heavier tasks.
However, what these channels don’t give us is repetition and longevity. I would like to know how long I can expect a tool to last. I know that’s not what you’re looking at now, and it’s hard to put years on a tool in a short span, but I wonder…
Stuart
In theory one could model a magnetic brake to match different application loads. Connect a tool to a DC power supply, press the trigger with a pneumatic cylinder, have the brake simulate a drill being bored or fasteners being driven, and repeat.
Realistically, how is that tool being kept cool? Most tool use isn’t continuous, but sequential.
I’ve experimented a little with cycling batteries in such a manner. Measure the voltage and current draw of an application, and then program a DC load to drain a cordless power tool battery in a similar manner. It didn’t provide any useful insights.
MFC
Yeah, getting a setup where you can take a/c power and convert to a constant 18v and then run drills until they drop could be useful for figuring out basic longevity of the motors. Obviously there are more things to test than that such as parasitic draw (if left with a battery on the tool), electronic sensitivity to dust/water/humidity, weak links in the system from high demand applications, runtime with different variables, torque, etc.
If you could come up with 4-6 standardized tests to compare these types of stats you could do something similar to TTC where you compare all of the models and rate them with each other.
There are many categories that could be rated:
Specialty Drill/driver that is for installation. Hardly pushed at all but pushed 8 hour per day 5 days per week. Needs to be very ergonomical. Low power consumption is a bonus.
Consumer level Drill/driver. Occasional use. Keep parasitic draw at a minimum (Long battery life health when left on the tool)
Mid level drill/driver. Drilling holes in lumber, driving small screws 3″ or less. Tool Longevity and low power consumption preferred.
Top tier Drill/Impact Driver. Used like mid level plus occasionally mixing mortar, driving lags and drilling with hole-saws. Needs to be heavy enough to handle the amount of force applied to it, power consumption is not important, but ability to handle high demand without burnout is.
Impact wrenches would be a whole other category…
Stuart
The difficulty is in testing or observing useful traits vs less helpful ones.
Testing a ratcheting wrench to failure, for example, is not a useful trait. How many people break or bend wrenches regularly? Testing it for engagement angle or clearance width would be better. Breaking strength sounds good in YouTube comparisons, but brand-name wrenches should exceed ANSI strength requirements. If a tool user is putting a 6-foot cheater bar on an 8-inch long wrench, few tools will stand a chance at escaping damage.
I’ve seen plenty of YouTubers destroy wrenches to declare a victor, but none that simply tested them to ANSI strength requirements.
The line between what’s interesting to readers and visitors and what can better inform their purchasing decisions is a very fuzzy one.
Long-term bench testing is something I’ve considered and deemed impractical multiple times due to the time, space, and cost involved.
Unless the entire effort would be externally funded, it’s hard to justify testing power tools to failure.
Eric
I design machines to measure torque (very different than power tools, however). We use transducers from Transducer Techniques – they offer both static (reactionary) and dynamic (rotational) torque transducers as well as various options for data logging and recording. Their stuff isn’t cheap, and it’s just the bare transducers, so you’d need to find a way to integrate it into a tester. I’d think using one of their rotational transducers paired with a dynamic brake (maybe not unlike Torque Test Channel’s setup) would work well. It’s not cheap, though – you’d be starting over $5k for a turn-key, calibrated system with logging…
MFC
Not sure what’s going on but I can’t post anything here. This is a test.
MFC
Weird, but if I try to post my message it says page not found…. Test #2
If you could come up with 4-6 standardized tests to compare these types of stats you could do something similar to TTC where you compare all of the models and rate them with each other. Torque would be a part of that.
JR Ramos
I’ve had that happen several times recently. In replies-to-replies-to-more-replies mostly. I thought maybe there was a limit or possibly my post was too long. One went through after I think a third try, but trying a different browser and refreshing the pages didn’t help. Maybe some server work on the back end or something.
Stuart
“Maybe some server work on the back end or something.”
We use Akismet https://akismet.com/ and the last I asked, they weren’t able to provide answers.
When a comment is blocked, it’s blocked. It will fail via different browsers and devices. If you send me the comment and I try to post it via the front end, it’ll get blocked too.
The only way to get that comment posted is if you leave a placeholder, creating the comment entry in the database, and I edit it via the backend, replacing the placeholder phrase with the intended comment. As that is done locally via ToolGuyd’s server, it doesn’t go through the spam filter.
It’s often in replies, and sometimes it seems like comment authoring time or duration could be a factor.
There’s no pattern. If a comment has 3 paragraphs, A, B, and C, removing any of them doesn’t work. But it might let you post 3 comments each with a different part of the comment. It could be phrase proximity or any other unclear factors.
Why does it outright block those comments instead of sending them to moderation for manual human approval? Or even to the spam folder? I couldn’t tell you.
It’s not repeatable. That’s one of the reasons I ask for placeholder comments and the comment to be emailed. But every time I try to analyze the phrasing, there’s no pattern.
The server has anti-bot measures, but that’s not the cause, otherwise I wouldn’t also be blocked from submitting the same comments as readers.
All I can tell you is that it’s the spam filter. There’s no way to whitelist regulars, or even myself for that matter.
Paul C
Not sure why but torque measurement devices are notoriously outrageously expensive. It’s a just a strain gauge with a slip ring system. But for some reason they have always been outrageously overpriced.