Being an Engineer

S2E20 Load Cells, Strain Gauges, & Learning Strategies | Robert Fuge

April 30, 2021 Robert Fuge Season 2 Episode 20
Being an Engineer
S2E20 Load Cells, Strain Gauges, & Learning Strategies | Robert Fuge
Show Notes Transcript

Robert grew up thinking he wasn’t any good at math. He would do anything to avoid further exposure to mathematics curriculum from grade school all the way through high school. Then one professor drew a picture, paired it with y=x^2, and changed everything for Robert. In the course of a few weeks he began truly understanding math for the first time, and decided he could, in fact, become an engineer (which, aside from the math, had been the obvious career choice for him ever since he was young). These days, not only is Robert an engineer, but runs his own business (Epsilon Laboratory) helping engineering teams solve measurement problems as relates to load cells and strain gauges. And doing some math here and there. 

The Being An Engineer podcast is brought to you by Pipeline Design & Engineering. Pipeline partners with medical & other device engineering teams who need turnkey equipment such as cycle test machines, custom test fixtures, automation equipment, assembly jigs, inspection stations and more. You can find us on the web at www.teampipeline.us.  

About Being An Engineer

The Being An Engineer podcast is a repository for industry knowledge and a tool through which engineers learn about and connect with relevant companies, technologies, people resources, and opportunities. We feature successful mechanical engineers and interview engineers who are passionate about their work and who made a great impact on the engineering community.

The Being An Engineer podcast is brought to you by Pipeline Design & Engineering. Pipeline partners with medical & other device engineering teams who need turnkey equipment such as cycle test machines, custom test fixtures, automation equipment, assembly jigs, inspection stations and more. You can find us on the web at www.teampipeline.us

Presenter:

The Being an Engineer Podcast is a repository for industry knowledge and a tool through which engineers learn about and connect with relevant companies, technologies, people, resources and opportunities. Enjoy the show.

Robert Fuge:

This college algebra teacher drew a parabola on the board. And he wrote y equals x squared. And he said,'Put away everything we're going to talk about why this equation in this picture are the same thing.' And the rest of that semester, I learned Math. I learned Algebra for real for the first time, because he taught the way that I learned.

Aaron Moncur:

Hello, and welcome to another episode of the Being an Engineer pPodcast. We are speaking today with Robert Fuge, who is a mechanical engineer, and over the years has become an expert at measurement and instrumentation, especially when it comes to load cells, strain gauges and thermocouples. Robert has worked for Honeywell Interface, a high end load cell manufacturer, a number of other engineering companies and currently owns his own business Epsilon Laboratory where he helps engineering team solve measurement problems. Robert, thank you so much for hanging out with us today on the podcast.

Robert Fuge:

Oh, thank you for having me.

Aaron Moncur:

So how did you decide to become an engineer?

Robert Fuge:

Well, I, when I was a little kid, I lived in rural New Mexico, it was a farm town. We weren't farmers or anything. But it was in the middle of nowhere. And I was left to my own devices all day. And I decided that I loved science, even though my elementary school actually didn't even have a science program because it was too poor. So you could sign up for an after hours club, and pay extra and have a science class. And so my parents did that for me. And I came home after about the third class or so this was I was in kindergarten. And I was really obviously disappointed. And my mom asked what the matter was, and I said, Well, I just want to know when we're gonna get to invent things and blow things up. So I had the spark from a young age. But I really struggled in school, because I did not learn Math the way it was taught. And so by the time I got to graduating high schoo, I wanted nothing to do with ma h ever again. And I thought I as horrible at it. And that I would basically just do whatever I could to not have to do any ma h, I applied to college as a business major, hoping to get hrough that with as little math as I possibly could. And my firs semester at community coll ge, I had this teacher at t is point, I was 20 years old, had a teacher, and he is for C llege Algebra, I actually fail d Algebra twice in high sch ol to give you an idea of ho little I learned Math the wa it was taught. And so I was aking it again in college, and his college algebra teacher dre a parabola on the board. An he wrote y equals x squared. And he said, 'Put away everythin we're going to talk a out why this equation in this icture are the same thing. And he rest of that semester, I lea ned Math, I learned Algebra or real for the first time, bec use he taught the way that I learned. And it taught me that I could learn math, I just had to each myself if the teacher wasn t going to be able to teach me the way that that I learned. nd so I decided, I, I'm religio s, and I prayed about it. And decided that I was going t be an engineer, because I was really into cars. I wanted t spend time working on cars. An I thought mechanical engineer ng would be a great wa to do that. So...

Aaron Moncur:

That's awesome. What What was the difference in how this college professor taught versus how it had been taught in high school was we see more like pictorial about it?

Robert Fuge:

Yeah, I think a lot of how math is taught is very algorithmic. And he really wanted you to understand it, not just pictorially but conceptually, it as a visual concept. So not just, here's a picture, but really making the connection, why this picture in this equation are the same thing. And I found that every time I could do that, Math really made a lot more sense to me. So in differential equations, it might have been vector fields. In Linear Algebra, it might have been talking about some multi dimensional, shape or in statistics, it might be a, an n dimensional statistical football that helped you picture the point cloud of all your data points. And as long as I could make that connection, then my mind was able to get everything else. And I could make up the differences between how the teacher taught and how I learned.

Aaron Moncur:

I think that's a really important point that just because you're not learning something doesn't mean you're not good at it might just mean you need to learn it a different way. And that could probably be expanded to more than just education. Just because you don't enjoy something, or you're not good at it. Some general thing doesn't mean, you don't like that thing, or you're really truly not good at it, it might just mean that you're not doing it in the right way. My son, who's in seventh grade now went to this elementary school here locally, that's a fantastic school. And they have a very particular way of teaching. It's, it's really the Socratic method or inquiry-based education is what they call it. And he did great there in elementary school, K-6, then he went to the local middle school and just did terrible. I mean, he hated it, he came home, he was he was upset. He didn't like his teachers, he, there's just a dark cloud over him. And he was doing really poorly in school as well. And he was failing half his classes, these receipts and the rest. And it was such a huge departure from elementary school. We didn't know what was going on. And so we started looking at different schools. And turns out, there's another middle school near us that uses that same inquiry based education system, and we switched them mid semester. And I mean, immediately, he turned around and did great. So I think that's a really important point, if you're not learning something, I might not be because you're not good at it, you might just need to try a different approach at the learning style.

Robert Fuge:

Yeah, it's interesting, we, we started homeschooling, actually, a year before the pandemic, I'm for four kids. And my, several of my kids have now found passions in things that they hated before. And it's because if the way you're teaching, it doesn't work, you can just try a different way. There's a ton of free curriculums out there for homeschooling. And so we went through a couple of different curriculums for different subjects for different kids, before we found something that worked, my daughter used to just cry, when we would have her just do any art, any drawing, that's because she was great on it at the school that she was at. And now, we've removed that, and instead of it being, replicating this picture that's in front of you, we've given a lot more freedom and done, some exercises to expose them to new mediums and whatever. And I happen, my oldest daughter just is an absolute artist to the core, which I never would have guessed, a couple of years ago. So

Aaron Moncur:

Well, that's scary, isn't it? I mean, to think about, like, what are we robbing our kids of? Because they're not learning in the right way? Or selves, for that matter? Yeah. Well, that's fantastic. Let's, let's talk about load cells and strain gauges and thermocouples, which is where you live? Can can you start by giving us an explanation? I mean, dumb it down for us. What what are the physics behind how load cells and strain gauges and thermocouples work?

Robert Fuge:

Yeah. So let's start with a with a string gauge. A string gauge basically measures how much the material that it's attached to stretches. So if you picture a rubber band, one of those fat rubber bands that newspapers use come rolled up in, as you stretch it, it gets longer and thinner. And metals behave the same way ceramics, most materials behave that same way. There are a few materials out there that don't behave that same way, which are really interesting case studies. But probably 99% of everything that you'll encounter in your day to day life behaves that same way. As you stretch it, it gets longer and it gets skinnier as you compress it to get shorter, and it gets fatter, and may not be as visible as the rubber band. But it does that. And so a strain gauge is a special resistor that responds to that and it changes resistance with that either tension or that compression that either stretching or squishing. And so now, if you take that string gauge and put it on something, you can use it to calculate the strain, which is a relevant, parameter for mechanical engineers who are designing things that hold up that hold the load that respond to dynamic forces. And they can get feedback for their design, they can find out if their design is behaving as planned, if the loads that they expected to see actually are the loads that they're seeing. If their design has maybe some spike in in stress or strain that might cause it to break that they don't expect. So that's a really useful tool to have. The string cage was invented the fought World War Two but really came into its own in World War Two. It's a very interesting story. And if anyone wants to, to hear it, you can reach out to me, I won't bore you all with it here. But it's a simultaneous patent. It was a patent that was granted to two men, separately at the same time. And so they both held the rights to it, even though they discussed they file patents separately and discovered it separately on opposite ends of the country.

Aaron Moncur:

How interesting.

Robert Fuge:

Yep. And so. So strain gauge is a very useful sensor, it doesn't have a very drastic change in resistance, though. So it's useful to put it into what's called a Wheatstone bridge, basically pairing it with, with other resistors to amplify the signal. Also, resistance is harder to measure with great precision compared to voltage, thought easier to measure small voltages with great precision. And so if you apply a voltage to the top and the bottom of the Wheatstone bridge, and then measure at the midpoints, then you can get a better signal that's easier to measure. And then so now, if we put all the resistors if each of those resistors is a strain gauge, and we design a special mechanical element to put them on, that gives a very linear strain response to an applied load. Well, now we have a load so so that is a device that is a spring, that is custom machined, very, specially designed, so that

Aaron Moncur:

And when when you say spring, you're still talking about a piece of like a chunk of metal, right, some machined aluminum or something like that. It's like a compression spring, or coil spring

Robert Fuge:

It doesn't like the coil spring. But it is a spring in the sense that it has a an elastic response to an applied load. So it not only deflects linearly, but it returns, it doesn't deform. It doesn't stay deformed after that load is applied just

Aaron Moncur:

Doesn't plastically deform.

Robert Fuge:

Yeah, but it doesn't, you're right, it doesn't look like a coil spring or a leaf spring, something you might see in a car or something you might switch, see if you had disassembled a relay or a switch.

Aaron Moncur:

So your point about deformation, that's why load cells have max limits, right, because if you exceed the max load limit of your load cell, you're going to plastically deform the quote unquote spring. That and and and at that point, the strain gauge is not going to return to its original position, because it's it's rigidly adhered to that metal spring.

Robert Fuge:

Yeah. And also, the, it's important to note that the typical mechanical properties that we use to define like the yield point, the point 2%, yield stress, or actually much, that is a stress that is much higher than that design point for the load cell, that maximum design point, because the strain gauge is so sensitive, it can actually detect a yield at a much, much lower applied for applied load on much lower strain. And so what is typically used to determine the yield strength of a material is not a relevant boundary when you're designing a load. So the load cell is actually much smaller.

Aaron Moncur:

Yeah, that's interesting.

Robert Fuge:

That's a load cell, if you have like a maximum load for, say, a bolt, a load, so that could hold that same load might often be a larger diameter, even if it was made out of the same material, because you're trying to stay in that truly repeatable, truly repeatable range.

Aaron Moncur:

So I see, you're saying that the the, the yield strength for a material? How do I ask this question that's been set?

Robert Fuge:

Right? So we've said, Okay, well, this is how we're going to test it, it's when the zero, you apply a load, and then you you remove the load, and you measure how much it has stretched. And we wait until it has stretched point 2%. And at that point, that's what we call the yield strength, that is a that is a relative, or that is a standard or a convention that we've used. But really, for a load cell, you need to stay in the 0% range for that. And if you go to the end, that, that, that that point where it breaks over and starts yielding is not a sharp corner, it happens very gradually. So yes, materials got to be characterized. And there's a lot of work that goes into understanding exactly what you're putting it up. Lodestone Manufacturers are very secretive about their heat treat profiles, and what glue they use and all sorts of different things because it all adds up. They're extremely sensitive instruments. So,

Aaron Moncur:

Well, that leads me to my next question, which is how are load sales manufactured? Can you talk about that at all without giving away any trade secrets.

Robert Fuge:

Yeah, I mean, so the general process that you can see a lot of this on on YouTube with just googling how to install strain gauge, but generally, the manufacturer, you you have your your spring element design and your machine that typically there are very tight tolerances to keep everything parallel, everything symmetric and everything aligned. Because if you don't have those, all the features symmetric, then things become nonlinear, very quickly, least nonlinear on a scale that matters to load cells, maybe not on a scale that matters to a lot of other things. And then you install your strength gauges, there's very special surface preparation method. And there's many, there's many different methods, different manufacturers use, I've seen probably four or five different methods, titanium is the one that always cracks me out, because everybody you talked to has a different method for installing strain gauges on titanium and, and some of them, they, they, they span the gamut of things, some of them are a 20-step process, some of them are a one step process, you just do over and over and over again, until it works. It just it's amusing that way. So you install the strain gauges by indicating location, gluing them down, clamping them, baking them to your preferred schedule for the epoxy to cure, then you install the wires and route the wires over to where you're going to make your connector. Some manufacturers only do batch temperature temperature compensation. So they will do a statistical average and then compensate all the load cells in the group. According to that other manufacturers measure every single load cell and compensate each one individually.

Aaron Moncur:

How do you compensate the load cell?

Robert Fuge:

So the way you compensate load cell is by adding resistance, either that is more temperature sensitive than the strain gauges into a certain part of the Wheatstone bridge, or adding resistance that is less temperature sensitive, and basically making it balance. So you measure the two halves of the bridge. And if one half is more sensitive than the other, or less sensitive than the other, then you can make an adjustment by either adding resistance that is more or less temperature sensitive appropriately.

Aaron Moncur:

And to add resistance is that just like adding more solder on one side?

Robert Fuge:

No, there's different ways Some manufacturers provide some strain gauge manufacturers provide little upgradable resistors. So little resistors, that you can either trim with a razor blade or rub with an eraser to gradually vary the resistance to just the right amount. So you should measure the temperature sensitivity, use their equation to do a calculation and then apply it appropriately. Other other manufacturers might use discrete resistors, they might just use off the shelf components, okay? Enough, and do it that way. And then other manufacturers have a digital board on the load so that they program, they have a analog digital converter, and then a digital analog converter. And in the middle, they modified the signal based on temperature and they have a thermistor or an RTD RTD on the little.

Aaron Moncur:

So for manufacturers that are that are producing really high precision load cells, it becomes a very manual process to check each one individually and add a resistor or add two resistors or whatever it needs to be done.

Robert Fuge:

I think making load cells was one of the least automated products that I've ever seen. And that's one of the things that draws me to it, it's very difficult to automate, because every single part has, if you're making precision parts, every single part gets attended to individually. Each one gets hand adjusted. It's really the strain gauges end up on surfaces that are not always easy to get to by, some robotic arm. And so there ends up being a lot of craftsman type of work, and they're good paying jobs for people, and it's real American manufacturing. And even most of the load cells that go overseas, they, they're, they're hand built, there's really not a lot of automation in the, in the industry, there's some I'm not gonna say there isn't any, there definitely is some but the more precision, precision oriented it gets, the more hand built they are and I love that about their, the comparison to them being the Ferrari of the, to, certain boats as being maybe the Ferrari of the load cell industry. It's it's a good one in more ways than one, not just that they outperform others, but that they're really hand built and this finicky, pushy little thing that you have to nudge into shape and, and work with it to get it to perform just right, so

Aaron Moncur:

Yeah, how interesting.

Robert Fuge:

Yeah, there's a lot of documentation and you build processes that are that are robust, but that robustness just means that you've got a technician working with each with each piece, following steps that you've already outlined. But

Aaron Moncur:

Yeah.

Robert Fuge:

It's, it's definitely an interesting process

Aaron Moncur:

Well worth all the attention each one gets, it's no wonder some of these high end load cells are so expensive.

Robert Fuge:

Yeah, I mean, it's, I've worked with load cells that cost from $200 on the low end, for high volume, and maybe specs that were a little more open up to load cells that cost $50,000 on the high end for very, very custom parameters, lots of validation testing, that are going into a critical point environment where it's millions and millions of dollars of the fail. So

Aaron Moncur:

Yeah, okay. Well, I'll take a very short break here and share with the listeners that teampipeline.us is where you can learn more about how we help medical device and other product engineering or manufacturing teams develop turnkey equipment, custom fixtures and automated machines to characterize inspect assemble manufacturer and perform verification testing on your devices. And we occasionally use load cells. So I've been excited to talk to you, Robert for a little while, what what are the gotchas that engineers should be aware of when working with measurement systems and sensors?

Robert Fuge:

I think one of the big things, especially with load cells, it's other sensors have their pitfalls, but I think load cells are particularly prone to this, what's on the spec sheet is often under ideal circumstances, and so you need to be able to verify in your application, that it's going to work for you. So they might have a specification that says, well, it's got, it's got this much accuracy or precision that I don't want to get into that whole, nuanced conversation, but that that really is in the calibration lab, under ideal circumstances, there's a lot of ways with a load soul to introduce error, it could be thermal, but it could be off center loading or bending moment, or a slight torque, or slightly loose joints in your stackup, that as you go from tension to compression, or loading it in two different ways. And so there's a lot of things that that can cause headache and problems that you have to attend to, if you really are trying to maximize your performance. And the big companies like Boeing, or Raytheon or somebody like that, they have departments of metrology engineers that, that handle that, they they are very well attuned, they have tested measurement engineers who go to conferences and learn all about this. But for smaller companies, where you basically have one engineer with a load cell, trying to get the best measurement he can, and he might be ascribing some of the errors to his part, his machine or whatever, when really, it might be the implementation of the test that is actually causing the problem. And that that might, he might have spent extra money on that high performance load cell thinking it's gonna solve his problems, when really, there's no way to solve this problem, besides tightening up his desk.

Aaron Moncur:

And that is, correct me if I'm wrong, where epsilon laboratory can step in and help right, especially for those smaller companies that maybe don't have an entire department dedicated to metrology.

Robert Fuge:

Yeah, I mean, I'd love to help people basically make the most out of their tests, whether it be just as a service, installing strain gauges for them on parts, or whether it's helping them with a design review for how they're implementing a load cell into their procedure, and helping them avoid those gotchas and get the most out of the measurement that they're already paying for. I'm always up for a quick question or whatever. But, I think there's a lot of great resources out there too, on manufacturers websites. And so people should probably start by reading there and, and finding out but if they're, if they're really looking to maximize that, but I'm, of course happy to help them I, that's that's what I'm in business for.

Aaron Moncur:

Yeah. Aside from the sensors themselves, what are the ancillary hardware or systems that engineers will need to fully utilize the load cells, strain gauges, thermocouples.

Robert Fuge:

There's obviously the data collection, one of the things that they need to worry about is how fast they need to collect data, because that's probably the biggest driver in price tag. It's not too hard to find a measurement an instrument that can measure six and a half digits or whatever with pretty good accuracy, something that can measure microvolts. But it is hard to find something for an affordable price that can measure 50 kilo samples per second on multiple channels, that that's not going to happen. So, the first step is being real about what rate you need to collect your data at. With load cells, you can cobbled together a data acquisition setup, using a good quality laboratory grade multimeter. And something to record the output of that meter, whether it be some of the program, you write yourself to take the serial output and a very stable power supply. But most load cell meters have a built in power supply, they, they take care of the ratio metric measurement itself, ratio metric, meaning that the output is relative to the input voltage. So, if you have one volt excitation, and then you change to 10 volts excitation, you're going to get 10 times as much signal. So, they need to, I think it'd be best to buy an instrument that is dedicated to the measurement that you're trying to take. But the first question you need to answer is, how seriously you need to be serious about how fast you need to collect your data, because that will be the single biggest driver of your budget.

Aaron Moncur:

Got it? Great pro tip. Can you walk us through the process of setting up a new load cell, you go to whoever vendor XYZ you purchase a load cell from them, you get it in, and you're getting ready to do whatever test you're trying to do? What are the steps that you go through to validate that load, so before you start actually using it for testing.

Robert Fuge:

I mean, the best thing that you can do is, if you're able to do some sort of an in situ calibration, then that is the best possible possible thing you can do. If you have some thing that applies a known force, just to make sure that everything's working right, and that your whole assembly works together, then that's the best thing to do. Because if you are applying, 20 pounds, and you're only indicating 19, then you have a pretty substantial, you have 5% drag somewhere, you have a pretty substantial amount of your force that is lost to friction. And so you need to identify where that's coming from. And so just a sanity check on your, on your test. The other thing that I would recommend is taking your test apart and putting it back together multiple times. So take the load cell out and put it back in and see how installation sensitive your Moselle is, because some of them are, can be pretty sensitive. And so you need to be able to figure out what test method is going or what assembly method is going to give you the most repeatability. So if you have a machine that you've designed, that is going to be testing hundreds of parts you need to make sure that the part two part repeatability of your test is good. And so there might be some work to make sure that oh, well, if I tighten the top threads, but I keep the bottom threads loose. Or if I tighten both of them, really tight, then that is how I get my most repeatable results.

Aaron Moncur:

That's a great point, because I don't think most people would think to try installing and uninstalling and reinstalling the load. So multiple times, we just put it in and assume is good and started testing.

Robert Fuge:

Yeah, but actually, how tight the threads are, how it's mounted, if there's any slop if you're if you have, for example, a through hole, that you're just putting screws through the bolted, then how tight is the fit on those threads, all those things that that all adds up, it's part of a stack up that eventually determines the total error of your test. And so you need to account for all those things. And again, if you are on a big budget, then you're gonna have a lot of work put into doing that if you're one of the big boys, but if you're not one of the big boys, and you're just an engineer with a load cell trying to get a test done, then a little bit of time spent up front, Jim paid big dividends and making sure that you don't at the end, look at your data and wonder what's going on.

Aaron Moncur:

Is there anything else so you talked about calibrating it and having a known weight and using that to verify that your load cell is giving you the correct data, the loads that you expect? And then you talked about multiple installations to make sure that your installation your assembly process is producing valid data, anything beyond that, that engineers should be doing before actually using a load cell?

Robert Fuge:

I think one thing is just making sure that you have your, the factory calibration, which is what you're going to ultimately use to, to compute your measurement, right? Make sure that that is programmed into whatever meter you're using. So that you get the appropriate data out of that, you definitely want to double check that. Also, load cells have a warmup time. So if you're really, really worried about getting the most of your measurement, let the thing warm up for 10 or 15 minutes, those string gauges, each of them is a little as a little mini miniature, flexible heating circuit. And so it's got to warm up the material beneath that to get stable. The other thing is just to look at the zero balance stability and watch that and make sure that it gets stable before you start, before we start your test. If that, if you give it five minutes, and it's still moving, give it five more minutes. So

Aaron Moncur:

Yeah, these are great tips. I mean, that's another one I would never have thought of to let your load cell warm up. It's a good way to put it. It's a little heating pad, right, basically

Robert Fuge:

Yep, yeah, it's a resistor, it's a resistor, it dissipates heat. And so it needs to warm up the thing beneath it, because that thing beneath it is going to expand as it warms up. And that's going to stretch that string gauge and ever so slightly change that resistance, change that voltage.

Aaron Moncur:

Can you share any interesting cases where you developed or helped engineering teams implement sensor solutions, maybe it was a particularly challenging environment, or an unusual implementation of the technology, any stories come to mind?

Robert Fuge:

Interesting applications. I did a lot of work in energy industry, and it never cease to amaze me the extreme environments that, that they were putting things in. That was always interesting. And I really got exposed to some, but new corners of material science that I had never been exposed to before we had to work with customers all the time on using new materials that, we hadn't made load cells out of before. So it's always a challenge, we always have to count, characterize material and, and get it work loads has been around for a long time, though. So it's hard to, it's hard to think of something that was really, really odd ball. Yeah, definitely. There's definitely things that come up. But most of the really interesting stuff is pro stuff I can't talk about I'm sorry.

Aaron Moncur:

Well, I did a tour of a local load cell manufacturer, I'll just leave it at that. And they should be some pretty big load cells, bigger than I realized even existed. At pipeline, we're typically using load cells that are maybe 10 pounds or less, sometimes much less. So we were exposed to pretty small things. But like, guess there's some load cells out there that are used for like aerospace, that they're measuring up to like a million pounds or so. Right?

Robert Fuge:

Yep.

Aaron Moncur:

Incredible.

Robert Fuge:

Yeah. And it gets really interesting because at some point, you have to ask how you calibrate something like that. So ultimately, there's this red point, there's this chain of traceability and you in in the United States, our national laboratory is NIST National Institute for Standards, something I forget what the T stands for, but that is, you always when you're using instruments, you want a NIST traceable instrument, right? You want to be able to have that chain of calibration going back? Well, the NIST their biggest calibration for facility for force, they have a 1 million pound dead weight calibrator with a dead weight, we have a 1 million pound

Aaron Moncur:

Oh, my goodness

Robert Fuge:

Well, it's several weights, that app that add up to a total of 1 million pounds.

Aaron Moncur:

I would love to see that.

Robert Fuge:

And it goes down this big shaft if you if you go to YouTube, you can find videos about it, because they

Aaron Moncur:

Really?

Robert Fuge:

Restored it. Yeah, they just restored it. They basically rebuilt the whole thing a few years ago. And so they did a whole bunch of media coverage on it when when they put it back in the commission. So but how do you do something that's more than a million pounds, that that becomes to be a very interesting challenge in it, that former place of employment to interface. They actually just before I started, there had shipped, I think, a 2.3 million pound rentable load cell, which is crazy, but they can only calibrate it to a million pounds. So it's up to the customer to figure out how to do that, how to do the rest, you can apply more force than that, using hydraulics and leverage and things. And so you just have to extrapolate and say, Well, this should be about a minute, 2.3 million pounds. She said that calibration problem is an interesting one, that's a difficult problem to solve

Aaron Moncur:

I'm gonna go find that million pound dead weight on YouTube, that sounds fascinating. I want to see what a million pound precision calibrated dead weight looks like.

Robert Fuge:

That's It's all I believe it's all stainless steel, it goes down several stories down a vertical shaft. And it's a really, really cool thing. They have all these crazy tolerances on it. And it's interesting, too, they compensate for buoyancy effect. So they very carefully measure the air pressure, and the humidity and all that so they can calculate the buoyancy on those dead weights. They also correct for local gravity. So they've done very precise surveys of the gravity at that exact place. So there's a lot of, there's a lot of work that goes into making a really high end calibration work.

Aaron Moncur:

That sounds like it, wow, fascinating. Well, when, when engineering teams or manufacturing teams, they can't find the right load cell or the right technology, this is one they go to you, I was can you talk a little bit about how you work with engineering teams.

Robert Fuge:

Oh, so, I've spent most of my career, the my business is, is still pretty young, I spent most of my career on engineering teams, trying to solve these problems, or trying to help customers solve their specific problems. And I think the best thing to do is just really get all of the information out on the table, because stuff that's held back might be important when you're dealing with someone who is a subject matter matter expert, whether it be me or be, a local manufacturer directly or, whatever they, they are very in tune with their product specifically, and all of the nuance that goes into making it work. And you're very in tune with your product, your test what it is that you need to get done. And if the two of you are holding things back from each other, then you're not going to get to the, to the best possible solution. There's been. There's a really good example, years ago, we had a, I had a customer who had a very demanding application, they were reluctant to share very many details with us. They basically presented, a list of demands that they, they said, Well, what needs to be this? And we said, okay, well, if you could tell us how it's being used, what exactly you're hoping to get out of it, whatever, we can do something a lot better for you. And they spent a lot of money on a custom load cell that didn't work very good. Because of that. And so they came back for round two, several months later, and basically said, Alright, I'm sorry about that, let's, let's try again, and they

Aaron Moncur:

It's on the table now.

Robert Fuge:

Yeah, they gave us a lot more control over the things that were relevant to the load. So they, they took a lot more of our input, and they got something that worked a lot better. So I think just that communication is really important to be able to share details. I know, people have to protect their IP and their interests. And so sometimes that there's a bit of a problem there. But, for me, personally, I would really love, I love helping people solve their problems, I love seeing a great test come out, that's something that gets me really excited. And so, the more that we're able to share it together, the better we can plan and execute on that plan to get the information that is so vital to be able to make whatever it is work. In the end when it finally hits its, its real purpose, after all the tests are done.

Aaron Moncur:

Yeah. Okay. Are you seeing any trends? In particular, the industry is it relates to load cells and strain gauges.

Robert Fuge:

Yeah, I mean, I think one thing is that with the rise and all of the analysis technologies that has come around, so FEA has is so accessible now, in fact, there's even a lot of sweets that, that you can use online, that will let us for free for non commercial purposes. So there's a lot of different opportunities to do finite element analysis. So, strain gauges, they're an expense that doesn't need to be born. That doesn't need to be boring for a lot of applications. And people are getting very cautious about spending money on those on those tests as they should tests are expensive. The only thing more exciting so that an expensive test is a cheap test, isn't it? Well, yeah, just a test that isn't well thought out well. And so I think people are being very, very cautious. And that is, that is to their credit. What I'd like to see, though is a formal development of that analysis process. Again, this is something that the the big boys have, but the smaller companies, they just wing it, a lot of times with tests, they just say, well, we tested the failure on two pieces, and it was good, or we test it, we did our FEA. And that seems like it was good enough. But what you're not capturing, and all those things are all of the unbounded constraints that that might leak into a test that provide you valuable, valuable information. And so I think that there's probably a middle ground, that is the healthiest thing that says, we're going to take our prototype, and work at test to do whatever. And we're going to make sure that we collect the most important data, and then we'll go back to the drawing board with the FEA, instead of starting with going really, really, really heavy at the FEA and optimizing for design that maybe doesn't account for all of the realities that are there. If you don't mind, I'd actually like to, there's a shot, do a little shout out, there's a company called True Load. And they have a really fascinating piece of software that basically helps you design a test to discover all of those hidden loads. So basically, you plug your FEA results into it, it tells you where to put strain gauges, and then you do a test, and then it tells you what your actual loads are. And so if people are having test results that don't match with their FEA, that's, I mean, that is just a perfect place to go. So it's interesting, true load. I don't have any with them or anything. Okay. There. It's a company. It's called Wolf Star Technologies, I think. I don't have any affiliation with them. I just saw a presentation that he did and, and have attended a couple of their webinars, and I'm just absolutely in awe of it. I just think it's the coolest thing so

Aaron Moncur:

That's awesome, pretty cool.

Robert Fuge:

That middle ground between old school testing a ton and new wave. We're going to FEA everything, even if we don't fully understand it. So

Aaron Moncur:

All right. Well, as we wrap up here, a quick note to all of you, dear listeners out there, if there are topics or specific individuals from whom you would like to hear, please send us a note at info at tea,pipeline.us, or leave a comment wherever you're listening to the episode. Robert, how can people get ahold of you?

Robert Fuge:

They can get ahold of me on LinkedIn, just search Robert Fuge. There's not that many of us. So I think I'm the only engineer Robert Fuge out there. And then also they can go to epsilonlaboratory.com. And check out how to contact me there.

Aaron Moncur:

Excellent. Is there anything else that we should have talked about that we haven't?

Robert Fuge:

Um, well, I was I listened to several of your other podcasts. And I did, there's one question I would hope you would ask, which was who, who are your engineering heroes. And so I did actually just say, want to say, I have two engineering heroes. One is Dan Gurney, he designed, built and drove his car to a Formula One victory. And wow, he was an American. And he was the last one to do that. So he's a, he's a personal hero of mine. Just a really impressive achievement. And then the other one is, Joseph Whitworth, he made drastic improvements in accurate measurements. And in 1848, he invented a method for making a length measurement that was accurate to 1,000,000th of an inch. So that was a really

Aaron Moncur:

1840?

Robert Fuge:

Yeah, back in 1840.

Aaron Moncur:

Incredible.

Robert Fuge:

And that really was one of those pieces that what the manufacturing revolution, be prepared to happen. So those, those two guys are two of my engineering heroes. So I'd hoped that you would ask you that question.

Aaron Moncur:

Well, thank you for the shout out. That's the second one in particular making large strides to higher precision and measurement. I think about that sometimes, right? If we're back in the stone age's, we had to start all over. Like how do you start, you have to have someone that figures figures out these accurate ways of measuring things and like, how do you how do you create a shaft that has a perfect diameter and that rotates perfectly smoothly. without all the machinery we already have to do that thing, right? It's chicken, the chicken or the egg, ugly But it's an interesting mental exercise. And I've thought about that in the past a lot. So it's interesting to hear that one of your one of your personal heroes was a key contributor in that sense. All right. Well, Robert, thank you so much for hanging out on the podcast today. Really appreciate your time and sharing some of your knowledge. And that's it for today. Thank you. It was a pleasure. I'm Aaron Moncur, founder of Pipeline Design & Engineering. If you liked what you heard today, please share the episode. To learn how your team can leverage our team's expertise developing turnkey equipment, custom fixtures and automated machines and with product design, visit us at teampipeline.us. Thanks for listening.