The Life of a Bolt

I started out my career designing military and defense systems. One of the key points that was impressed on me, and many other engineers, early was that "every detail matters." What may seem trivial to some can have sudden and extreme consequences if not given the proper respect and consideration.

What we do - and how we do it, can impact those that depend on us.

Here's a Great Story by Red Bull Racing about the life of a single Bolt.

http://www.redbullracing.com/article/life-bolt

If I had a Hammer

It's not a surprise that - as a Mechanical Engineer - I've used hammers.  What has impressed me about hammers is their diversity.  They come in all shapes and sizes from small micro hammers that you hold between thumb and forefinger to sledge hammers for applying not so subtle "mechanical alignment."

In carpentry, I've become acquainted with a type of hammer brand called Stiletto.  What makes the Stiletto unique is the use of Titanium in its head versus steel.  As a mechanical engineer, I'm  impressed with a material that:

  • Has superior corrosion resistance
  • Has a density 56 percent that of steel

The second property is what makes a titanium hammer so useful.  In using a hammer, the more speed that can be generated at the head for a given torque (generated by the user), the greater impact applied to the fastener.  More impact equals deeper nail.

With a lighter head, the user can generate more head speed for a given amount of effort.  Less effort equals longer work capacity.  Can't argue with that.

If you happen to watch "This Old House" , take a look at the hammer that Tom Silva uses. Titanium? Yes, Titanium. 

 

Drip, Drip, Drip

We have a leak in the downstairs bathroom -  again!

This leak has been with us, off and on, over the course of 4 years. First, a little background.

Our home is constructed such that the upstairs bathroom is located directly above the downstairs bathroom.  Plumbers and builders love this because it enables them to minimize plumbing distances and reduce material costs.  Great in theory.  In real world, not so much.

The problem is that the upstairs bathtub lies directly over the downstairs bathroom ceiling. In the upstairs bathtub there exists silicone caulk at multiple joints in the tub.  No rocket science!

The same scenario occurs.  I purchase the best silicone caulk from GE at Home Depot.  You know the tube with the 30 year guarantee.  Interesting guarantee.  It states the the caulk will not:

  • shrink
  • crack
  • break down 
  • wash away

What is not guaranteed is that the caulk will  adhere to the wall.  So after 3 or 4 months, the caulk fails, the leak reappears downstairs, I recaulk and the problem stops (temporarily).

It's embarrassing when an ME can't fix a leak, but I have designed several unique features that help minimize the problem.

First, drywall has been replaced with a removable wood access panel.  Second the access panel's interior is coated with a water resistant tape used in roofing applications.  The leak is detected when water is noted dripping from the edge of the access panel.

After fixing the leak again, I decided to be a bit more proactive about my leak detection system and automate my early warning system.  Typical engineer, my mind began to consider the internet of things (IOT) and how I could incorporate this technology into leak detection.  

Which system to choose? Smart Things? Spark? Raspberry Pi? There are already a great number of very capable methods to detect and alert the homeowner to water leaks.

The problem is competing hardware. There is still a great deal of learning on the part of these new upstart IOT home automation systems.  Unfortunately, that learning is being played out by early adopters of the systems.

The reviews on some of these systems are not exactly stellar. 

Please see reviews for SmartThings hub on Amazon

Ease of adding components, interoperablity are questions and concerns with picking a home automation system.  Does anyone remember VHS versus Betamax?

I've decided to wait awhile before committing to a particular standard.  I also consider the question, "Do I really need to know that the upstairs tub has a slow leak from across town?"   Despite being a fan of new technology, the fundamental question to ask is " Just because it's newer - Is it better?"

I opted to go with an old school Honeywell sensor with a slightly unique twist.  The sensor has a 4 feet long cable that senses water along its entire length. When moisture contacts the cable, an alarm sounds.  Please see the "final" solution photo above.

 

 

 

The Little Perk that Could(n't)

We had a minor emergency in our home this morning.  The Keurig K-cup brewer stopped working.

The Keurig brand of brewer has a large share of the single cup brewer market.  It's a very convenient brewer - when it works.  

My wife purchased the first brewer about 6 months ago. It stopped delivering coffee in a fit of protest.  Hmmmm. As a typical engineer I began to perform a diagnosis.

Descale: Check.  Test pump: Check.   Valves: Check   Obstructions: Check

The Internet is loaded with those who Love, or Hate, their Keurig brewers. It appears that the system depends on moving fluids through very small tubing that can be obstructed by something as small as an air bubble. 

There are posts that describe turning the unit over and spanking its bottom. Tried it. Bad Coffee brewer!

Still no luck.

We replaced the first unit with a second same unit.  Unfortunately, this is the unit that passed away this morning.

As I tried to explain bathtub reliability curves to my wife, she headed out in search of caffeine.

There is a great website that discusses the fails of our modern technological world. It's called "Made by Monkeys".  You can find the link here

Now, let's take another look at that  brewer..........

Staring at Stairs, Part 3

The Worm Winch has arrived!  It has been mated to the test stand and has gone through preliminary testing.  With a simulated 40 pound load and a battery powered 0.5 In. drill, the system is able to move the load in about 12 seconds.

Please see the test video below.

The other critical test is the self braking test.  If the drill is stopped at midpoint, the load does not move back down the track.  In winch speak, this means there is no freewheeling.  This also means that when the cart is empty, Dave must reverse the drill to move the cart to base of the stairs.  Safety appears to have been attained with lifting. My only other concern is pinch points.

As the worm gear is exposed, there is the risk of pinching / entanglement. A guard will need to be designed to eliminate this risk.  Overall, very pleased with  lab testing.

Next step, field testing!

Staring at Stairs, Part 2

After fussing with the finicky clutch mechanism on a Zebco casting reel for about an hour, I decided to take a second look at a winch based approach.

My next iteration was a type of winch called a lashing winch. This type of winch is typically placed along the perimeter of flat bed trucks and is used to tighten 2 inch straps.  Please see the Figure below.

Lashing Winch

Lashing Winch

The threaded rod is about 2 Feet in length and installs into the winch by the crossdrilled set of holes.  My hope was that the lever length would provide Dave the minimal effort required to comfortably rotate the winch.

Please see a first pass test of lashing winch below.  Simulated grocery mass is a 40 pound bag of water softener salt. 

 

Testing revealed two issues with the lashing winch concept.  Both issues relate to the clutch release mechanism. This is the gold colored feature in the top right corner of the winch.

The first issue is that the latch  permits the load to freewheel downward. In other words, if the weight of groceries is not removed prior to releasing the clutch two things happen very quickly.  First, the cart returns  to the bottom of the ramp.  Broken eggs anyone?

Second, the rod separates from the winch by centripetal acceleration.  Depending on where the rod is positioned when the clutch is released, the rod becomes a projectile.  Again, not cool.

Human Factors 101

I can not guarantee that Dave will follow the safe procedure of:

1. Wind winch

2. Remove groceries

3. Release latch

Only 3 steps right? There's an interesting book that I read recently called "The Checklist Manifesto" by Atul Gawande.  Doctor Gawande is a surgeon. who presents the idea that virtually all processes, no matter how simple, can benefit from the use of a checklist.

In the book, Dr. Gawande describes a study performed by a colleague at Johns Hopkins involving the placing of a central line in a patient. This procedure had only 5 steps which were:

1. Wash hands with soap

2. Clean the patient's skin with antiseptic

3. Put sterile drape over entire patient

4. Wear a mask, sterile hat, gown and gloves

5. Place a dressing over the site 

As a patient, we'd hope that these are common steps any healthcare practitioner would take. But many doctors did not follow procedure.

A checklist was created and nurses were empowered to stop a doctor who did not follow the checklist.  End result? Over the one year study  period, 43 infections, 8 deaths and 2 million dollars in costs were saved. This is for one hospital.

So what does this have to do with engineering? A lot more than we might expect.

Even with a simple 3 step process, I can not ask Dave to use a checklist to lift his groceries.  People are not perfect. We forget things. We get distracted.  I need to find a winch that will hold the load - even if the force is removed. So on to the next style of winch.

The Worm Winch

One of the premier manufacturers of winches is Dutton-Lainson Company, a company that has been producing winches since 1886. More types of winches than this ME has ever seen.  The most intriguing is the worm winch.

Driven by a worm gear, the winch holds loads stable, with and without load.  It also can be driven by a drill, rather than a hand crank.  Perfect for Dave. Please see below.

Worm Winch

Worm Winch

Please see next post for Worm winch testing.

 

 

 

Staring at Stairs

For the past several years, I have been fortunate to be able to volunteer as a handyman for local families in need.  My current client, Dave, is a very nice gentlemen who has some difficulty moving groceries up his outside stairs due to some health issues.  Please see the picture below.

 

Dave had suggested the idea of a winch to move the groceries from the ground to his porch.  We explored that idea together and due to Dave’s limited mobility in his shoulders decided that the hand cranking  of  a winch might be difficult for him. So, on to Idea 2.

 

What I’m currently suggesting to Dave is a milk crate, mounted on wheels, that rides on top of his stair rail as shown below.

Milk Crate and Track

Milk Crate and Track

Now onto the lifting mechanism.  A preliminary survey of electric outdoor winches shows a huge disparity between this application and most current designs.  What is needed is a method to move a mass of approximately 30 pounds a distance of about 6 feet.  We don't need to move 1500 pounds 30 plus feet - typical Jeep winch work.

Hmmmm, need to simplify. As my friend the art major in College said "Less is More."

Another idea occurred to me last evening.  A fishing reel!  It is Minnesota after all. Should be one or two around here.

Advantages:

  • Low cost 
  • Less stress on shoulders
  • 25 to 30 Pound Force Rating
  • Clutch mechanism to prevent backsliding on lifting 
  • Press release to allow cart to return to start

Questions:

  • How to mount fish line to avoid abrasion?
  • Will reel work in snow and ice. How can I protect it?

Please see next post for next steps.

 

Are We Done Making Improvements?

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I had a client recently that was  involved in vehicle telematics. They had just celebrated 20 years in the business and had done well developing an outstanding  operating  system .

 They had also developed the subscription model for their software so they had a good stable source of income – as long as the hardware that carried their software performed. If not, they faced “performance clauses” with their customers for any software downtime. If their system was down, they paid money back to their customers in the form of fines.

But then there was hardware.

I was brought in as a mechanical engineer to review their hardware and help improve its reliability.  The client had become what many refer to as a “virtual” hardware company.  Hardware was built by assembly houses using primarily components from domestic and offshore suppliers. 

There had been virtually no mechanical oversight of suppliers and it showed.  Tolerances were out, if they were even monitored. Workmanship for electronic boards and cables was poor.

So, I rolled up my sleeves and went to work.

The point of this post is not to belabor the QC process but to discuss a question that still troubles me today.

I was in the corporate boardroom presenting my latest recommendations to senior management. The usual titles, CEO, COO, CTO.  I had just finished my list when the CEO asked “Jim, when are we going to stop making improvements?”

I collected myself and began an explanation of how new enhancements come to light as more time is spent with a particular product but I don’t think he was buying it.

The client did not appear to be familiar with Kaizen, Japanese for “Good Change.”   The main philosophy of Kaizen is that improvement of a product or process never stops.  We can always build a product better, faster, simpler and, in the client’s case, more reliable.

I came across an article by Fast Company Design recently that you might find interesting.  It’s about the company Fiskars – the company with the orange handle scissors.  The article discusses Fiskar’s ongoing goal to improve their scissors – for 48 years. Great read. 

You can find it here.

 

not impossible labs

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When I first started college, I thought about majoring in physical therapy as a way of helping people.  Then, my dominant mechanical gene guided me into mechanical engineering.  I came across this great group of people who are working on both sides of this equation.  Great use of technology!  Full speed ahead!

Please, if you have a moment, see:

www.notimpossiblelabs.com

 

 

Universal Principles of Design

A book that I have read - and intend to reread is "Universal Principles of Design," by William Lidwell, Kritina Holden and Jill Butler.  This text treats the broad topic of Human centered design in a broad and thoughtful manner.

Being a good mechanical engineer demands a strong foundation in the classic engineering arts but there is a discipline that is often under served - Human Factors. This is not just in the sense of the measurements of the average hand or foot but in the design adaptations that make us uniquely human. It is also what can move our designs from pedestrian to truly exceptional.

 

To Engineer is Human

I have written a stack of Engineering Change Orders (ECO's) that would most likely be taller than the tree in my front yard over my career.  That is in paper form. In digital form, much less.

I came across the book To Engineer is Human by Henry Petroski several years ago. Its an interesting read about how and why failures occur in engineering design. 

As engineers we are often asked to review and fix designs that have not proven functional or durable in the field.  Tools employed ranged from Root Cause Analysis to Failure Mode Effects Analysis (FMEA).  This all being employed within the environment of Cost, Time and Performance.

Classic engineering failures such as the Space Shuttle, automobiles and suspension bridges are thoughtfully reviewed.  With the current struggles of General Motors and Air Bag manufacturers, it might be time for a review of this great book.

Why We Left the Nest

I was an early adopter of the Nest Thermostat. Stylish design, energy savings and the chance to start a Smart Home, the Nest appeared to have it all.  But as many Beta customers will testify, the early road can be rocky sometimes.......

First, there was the user interface.  Designed by what I'm sure are twentysomethings, the users neglected one key detail.  Presbyopia - otherwise known as age related nearsightedness.  The Nest  temperature display for the Set Point Temperature  is quite small.  Couple that with a 3 AM need for some heat and the lack of reading glasses at hand and you have a problem. Solution? Find reading glasses or an extra blanket.  Could this be solved with a software update? Unsure.

The second problem was with the learning algorithm.  Nest's argument was that over 70 percent of programmable thermostats are never programmed. Users simply fall back on whatever settings they get by default from the factory.  Better to learn our heating habits  than not to learn? Nest says lets learn.

Over a two week period, the Nest, tracks usage habits on the ups and downs of thermostat settings.  The problem lies in its tendency to never stop learning.  Go for a run? Turn down the AC. That becomes part of the schedule.  What I spent a great deal of time doing with the Nest was adjusting the schedule that it thought that I wanted to what I actually wanted.  

Wait, don't they have product for that need? Oh yes , it's called a programmable thermostat.

 

 

All for Want of a Connector.......

I had a customer recently, PeopleNet,  that develops Hardware and Software for Over the Road Trucking applications.  As I'm sure that you're aware, Telematics and Transportation are quickly converging on our highways. Cars and Trucks are becoming smarter and more autonomous.

I was asked to review and improve the design of a handheld tablet and docking system that was suffering from frequent disconnects while in the field.  The initial design had been based on the use of a poorly designed pogo pin style connector that linked the tablet to the dock.

A pogo style contact gets its name from the pogo stick toy that we used as children.  It relies on a plunger coated with Gold to make the electrical interface to the tablet.  The plunger, in turn, is pressed upon by a compressed spring to apply force.

Simple right? Not really.  What is created is a the electrical equivalent of a shock absorber. If the tablet moves , the contact must follow its motion with virtually no error.  If not, electrical discontinuities (shorts) appear in the communication link.

Software communication protocols have different levels of interrupt tolerance. In the customer's case, they were shipping USB 2.0. Not the fastest form of comm. - but also not the slowest.

After reviewing the overall mechanical design, I was convinced that the electrical connector had several mechanical issues ranging from minimal Gold plating to overly large assembly tolerances.  They simply were not going to build a reliable dock using the current connector.  I recommended a higher reliability connector that would have increased system cost by approx. 15 percent.

The customer was hesitant, even though they were spending significant amounts on retrofits, service calls and reputation. This was over the course of a 2 year period.

A connector is a critical design element in any system.  Marginalize it, trivialize it and you will pay so  much more in the long run.

 

 

Improving Thermal Modeling Efficiency of Curtain Walls

One of the things that most engineers would agree on is that modeling is fun. Structural, Thermal, DFM, DFA, the list seems endless.  Most engineers would also agree that importing the dimensional information, cleaning up the model to prepare it for modeling is about as fun as the root canal that I just had.

As a mechanical engineer at Enclos corP (not a misprint, the trendy marketing way of spelling), I led the thermal and energy analysis of curtain wall assemblies.  For those not familiar with the  term, a curtain wall is the exterior glass and aluminum on a modern building. It is the "face" of the building that most of us associate with the design of the building.   It is called a curtain wall because it must support itself only, not the building.

Transient

Enclos designs curtain walls for large 40 to 50 story buildings. Each unique structural element of the curtain wall must be modeled to determine its thermal resistance and interior temperatures.  Most projects had between 8 to 10 elements to be analyzed.

Enclos had adopted software and analysis methods that required between 2 and 3 hours to model and solve each thermal detail.  A large portion of this time was the cleaning up of details created in AutoCad for the successful import into their thermal modeling software called THERM and prior to THERM, Algor.

One of the facets that most design engineers learn about themselves and other designers is that no one of us creates layouts in the same manner.  Power users may have the best technique and create models that are easily imported . But others can leave a great deal of features  in a mode that the analysis software may have a hard time interpreting.

This was the case at Enclos.  Designers created the details that were then given to engineers who then dutifully recreated the details in a level of accuracy that THERM and Algor would accept.  The best analogy that I have is that we would burn down the house - and rebuild it.

Efficient? No. Enjoyable? No.

I recall when I arrived at Enclos, I asked the engineer who had developed the method if he enjoyed the current modeling method. He firmly said No.

One of the great things about the Internet is that designers can share with one another.  This is where I started.  On a CFD support website, I explained my situation to my peers.  A voice from Germany suggested trying software that they had had great success with called Flixo.

What was great about Flixo was that it wasn't flustered by all of the personal loose ends that we as designers frequently leave.  It effectively said " I know what your intent is.  I'll take it from there."  Importing the model ,applying materials and running the model became a 15 minute pleasure instead of a 3 hour ordeal.

 

Transient

More time for modeling. Less time on clean up.

As October rolls around, I think about how grateful I am that another engineer was kind enough to share. And I think about Octoberfest and Beer.

It Makes the Smart Car Look Like a 747

In USA Today yesterday, I read an article on the smallest production car ever made, a 1962 Peel P50.

 

Transient

The Peel was an attempt to evaluate the absolute minimum dimensions necessary to build a car. An interesting feature of the car was that it had no reverse gear.  There was a handle on the rear of the car.  When you wanted to change direction, you simply picked up the rear of the car and turned it around.  

With one seat, the car is far from practical for almost everyone.  But, it did get me to thinking bout the choices of features that people select when they choose virtually any product.

One design rule that has stuck with me through the years is the "20/80" rule. The rule states that we use only 20 percent of all features on our products 80 percent of the time.  That iPod, or washing machine - how often do we deviate from a few preferred settings?

Just another reminder to designers to keep it simple.

Here's Top Gear's take on it: