NorthGateInside SouthGateInside

New gates seen from the backyard: Left-hand outswing gate on north side of house, Narrower right-hand outswing gate on south side of house

by George Taniwaki

There are two gates between the front and back yards of my mother’s house, one on the north side and one on the south side. In my mom’s neighborhood, all fences have six-foot cedar pickets. All the gates are hung so that their hinges are attached to adjacent 4"x4" posts. The gates swing toward the front yard and the gate hinges and latches face the front yard. Views of the new gates from the backyard are shown above.

Both old gates at my mom’s house are probably three decades old. They are weathered and sag so much that they drag on the ground. Neither was particularly well-designed or was hung properly when new, so the problem has been festering for a while. I finally decided to replace them both. Each new gate took about three days to build and install. (Yes, I’m a really slow woodworker and I could never make a living doing this.)

Why gates fail

Before I begin to build the new gates, I think about why the old gates failed. There seems to be two problems. They were not designed to absorb the forces on them and they were not built using good construction practices.

The main force on the gate is gravity. This force is transferred to the hinges. The gravitational force is spread across the entire width of the gate (Fig 1a). But the hinge support is not. This causes torque which also has to be absorbed by the hinge and the gate frame.

This torque causes stress which can cause the gate to fail. The hinge post can rot or get loose or the screws on hinge can come loose (whole gate tips), the gate can split at the joint between the stiles and rails, or the gate can rack (Fig 1b).

GateStaticForces GateFailureModes

Figure 1a, b. Forces on the gate, Failure modes include failure at hinge, failure at joint between rails and stiles, and racking

Prepare the opening

To reduce the chance of early failure, I want to carefully prepare both the hinge post and the latch post before hanging the new gate. First, ensure the posts are stable and plumb (Fig 2a). Even if the post does not wobble, check if it is attached securely to the fence rails. Remove any nails used to attach rails to the post and replace them with a combination of urethane glue and corrosion resistant lag screws (Fig 2b) to stabilize them. If needed, add pressure-treated 2×4 lumber as blocking to support the gate hinges and latch. If the post is near a building wall, use an angle bracket to anchor the post (Fig 2c).

CheckPlumb LagScrews

AnchorPost

Figure 2 a, b, c. Check for plumb, Replace nails with lag screws, Anchor post to wall

Make the frame

There are three common options for making a gate frame. The stiles can be full height, the rails can be full-width, or the corners can be mitered (Fig 3a). Once screwed together, the gate needs support to prevent it from sagging. You can use either pressure-treated lumber to make an angled brace to take compression load or a corrosion resistant cable tightened with a turnbuckle to take tension load (Fig 3b).

The frame of the gate should be made of pressure-treated lumber. To ensure stability, use pocket screws, not nails, to hold the gate frame together. First, drill the pocket screw holes using a jig (Fig 3c). Before installing the screws, measure the diagonals to ensure the frame is square (Fig 3d). I used a cable to support the load (Fig 3e).

Finally, if possible, cut any holes, mortises, or notches needed for the latch hardware now. My gate latch requires a single notch (Fig 3f). More on installing the latch later.

GateFrameOptions GateSupportOptions

DrillPocektHoles CheckDiagonals

AddCable CutLatchMortise

Figure 3a, b, c, d, e, f. Gate frame options (Full-height stiles, Full-width rails, Mitered corners), Support options (Brace, Cable), Drilling pocket screws, Measure the diagonals to ensure square, Add cable, Cut a notch for the latch

Prepare and attach the pickets

The cedar pickets at the store are very rough and not very attractive and need to be cleaned up. I use a random orbit sander to smooth the faces (Fig 4a). Then I use a block plane to smooth the sides (Fig 4b) and to chamfer the edges (Fig 4c). Once all the pickets are ready, use corrosion resistant screws to attach them to the gate frame. I start from the hinge side and align the first picket flush to the edge. Then I insert spacers (pieces of cardboard folded in half) and attach the next picket (Fig 4d). I continue until until only 2 pickets remain. I leave them off. I will attach them after the gate is hung.

If possible, attach the hinges now. Lay the hinges on the gate, place a straight edge (I use a loose picket) on top of the hinges to align them, and screw the hinges into the frame (Fig 4e).

At this point, the gate is ready to stain and varnish, but I did not do this.

SandPickets PlanePickets

EaseEdges AttachPickets

AttachHinges

Figure 4a, b, c, d, e. Sand the faces, Plane the sides, Chamfer the edges, Screw the pickets to the frame, Attach the hinges

Hang the gate

I am going the install this gate by myself. To hold it in place temporarily while I screw in the hinges, I make a shim. Place scrap wood (I used pickets from the old gate) at the base of the gate opening and ensure they are level and exactly at the height you want the bottom of the gate. Push dirt around as needed (Fig 5a). Rest the gate on top of the shim, ensure it is plumb, and screw the hinges to the post (Fig 5b). Remove the shim and test that the gate is level, swings freely, and does not bind.

There are three pickets left to install, one on the latch post and two on the gate itself. Measure the width needed to be covered by these three pickets, subtract the width of two spacers. Now divide by three. That will be the width of each picket. Rip the pickets to the correct width (Fig 5c). Use a block plane to joint the pickets (Fig 5d). Attach one picket to the latch post (Fig 5e) and the other two to the gate (Fig 5f). The picket on the gate may overlap the post. This is fine.

TemporaryShim AttachGate

RipPickets FinalMeasure

LastPicketsDetail LastPicketsDetail2

Figure 5a, b, c, d, e, f. A temporary base to hold the gate, Gate is hung, Rip the final pickets to width, Finish with block plane, Attach one picket on latch post, Attach two pickets to gate

Install the latch

I use a low-profile 2-way latch by Fenix. Unfortunately, there is a design flaw in the spring action. The latch bar will bind unless the hole for it in the latch handle is cut slightly larger and at an angle so that the bottom of the hole is wider than the top. I mark the outline for the larger hole using a red marker (Fig 6a) and use a file to enlarge the hole. I cut notches in the pickets in the gate to allow the latch handle through (no photo).

In another design flaw, the screws that come with the Fenix latch are too short to securely attach the latch handle to the gate. I pick two 5mm x 60mm (#8 x 2-1/2") corrosion resistant deck screws, paint the heads black, and use them to attach the latch handle to the gate. I attach the latch keep to the post and adjust its height until the latch opens and shuts smoothly. The gate is done (Fig 6b).

MarkHandle 

NorthGateOutside

Figure 6a, b. Modifying the latch hardware, The finished north gate

TrayClamps

Find three mistakes with this package design

by George Taniwaki

I bought a box of assorted hose clamps and was excited when they arrived. I opened the box but could not easily find the 3/4-inch clamp I needed (see photo above). The guide seems to indicate they should be in the right-most slot and there should be six of them. Instead, the slot contains the 1-inch clamps and there are only two of them.

What’s up with that? Then I noticed the three annoying problems. Do you see them too? First, there are five clamp sizes in the box, but there are only 4 slots. The slot second from the left contains two different sized clamps.

Second, even within the limitations of not having the same number of slots as sizes, the clamps are not sorted in the same order as the guide. The sizes in the guide are listed as 7/8", 1", 1/2", 5/8", and 3/4". The sizes in the slots are 5/8", 1/2" and 7/8", 3/4", and 1". None of the clamps in the guide line up to a slot. Further, neither the guide or the clamps are sorted in size order.

Finally, the guide contains pictures of clamps. They do not match the actual clamps. The images of the 7/8", 1" and 1/2" clamps seem correct, but the images for 5/8" and 3/4" seem to be reversed.

Bad design makes me anxious. My solution was to put the hose clamps in a Plano fishing tackle box in size order, label the slots, and throw away the original package. I even tossed in a 1-1/2" clamp I found in my parts drawer.

TrayClamspAfter

There, fixed it

* * * *

A similar problem occurred with an order of assorted springs I bought on Amazon. They came delivered in an identical size tray as the hose clamps. But this tray has seven slots instead of just four. Unfortunately, the package contains 29 different size springs, so there still more sizes than slots.

TraySprings

So many springs, so few slots

Springs are specified by their wire size, diameter, and length. For instance 0.035"x0.25"x0.5" indicates the spring is made from a wire with a diameter of 0.035" wound into a spring with diameter of 0.25" and a length of 0.5".

Ugh. The springs are sorted into slots by their least useful dimension, length. Length is not useful because you can easily use a pair of wire cutters to shorten a spring that is too long. A much more useful way to sort springs is by wire diameter and spring diameter.

Also, like the pictures on the hose clamps guide, the pictures on the spring guide do not match the springs specified. It appears that all seven pictures are identical, although the two on the left are reduced in size.

Again, my solution was put the springs in a Plano tackle box sorted by wire diameter and then spring diameter (mixing different lengths in the same slot), label the slots, and throw away the original package.

TraySpringsAfter

Again, fixed. My anxiety alleviated

* * * *

Incidentally, you can estimate the springiness of a spring using the following formula. Start with Hooke’s law:

F = kx

The spring constant, k, can be estimated by

k = G*d4/(8*D3*n)

where G is shear modulus of the spring material (about 11×106 lb/in2 for steel)
    d is diameter of wire
    D is mean diameter of spring (or outside diameter – wire diameter)
    n is number of active coils (coils at ends usually are not active, so total coils – 2)

A handy calculator with explanation can be found at eFunda.com (membership required).

2019-08-10 14_ChrisPineSpideyBellsYouTube

Captain Kirk is filled with deep regret. Still from Chris Pine on YouTube

by George Taniwaki

There are not very many popular culture references about getting a degree in chemical engineering. But there should be. I’m only aware of three. That’s not enough to fill a blog post so I added a few extra.

Spidey Bells–2018

If you watch a Marvel movie all the way to the end, hidden in the credits are wonderful Easter eggs that tend to be somewhat unrelated to the movie.

In the opening of the 2018 animated movie Spider-Man:Into the Spider-Verse, the first Peter Parker, voiced by Chris Pine, says that he has recorded an album and is selling some related merchandise. At the end of the movie, as the credits roll, one of the songs from that supposed album plays. It is a Christmas carol called Spidey Bells (A Hero’s Lament). In the song’s middle bridge, he reveals a dark secret:

“Why did I agree to do this stupid song?
I have a degree in chemical engineering”

Who knew? We know that Peter Parker dropped out of college to become a photographer for the Daily Bugle. But until now, we didn’t know what his major was.

Wildside–1991

Long before Mark Wahlberg became famous as a restaurant franchisor, he was known as Marky Mark, the lead singer of the Funky Bunch. They had a hit in 1991 with a cover version of Lou Reed’s Walk on the Wild Side. Their version includes samples from the original but had different lyrics and was retitled Wildside. The song include these great lines:

“Cause deep inside Annie had aspirations
Besides that she had expectations
Wanted to be a chemical engineer”

Unfortunately, it does not end well for Annie, who is played by an uncredited actress in the music video.

MarkyMarkWildsideYouTube

A ChemE major takes a hit on the wild side. Still from Marky Mark on YouTube

The Future’s So Bright, I Gotta Wear Shades–1986

In 1986, the U.S. band Timbuk 3 released their debut album which contained the hit song  The Future’s So Bright, I Gotta Wear Shades. The music video got extended play on MTV, back when MTV consisted almost entirely of music videos in rotation. The video features a burro, the mascot for my alma mater, Colorado School of Mines. The song refers to nuclear science rather than chemical engineering, but really, that burro and the harmonica solo.

Incidentally, The Future’s So Bright, I Gotta Wear Shades is the title of a 1990 episode of ALF, a television sit-com.

Timbuk3FuturesSoBrightYouTube

The future’s so bright I put a TV on a burro. Still from Timbuk3 on YouTube

Doonesbury–1981

Just a few weeks before I graduated from college in 1981 there was a Doonesbury cartoon that became wildly popular among my classmates. It became the buzz at school because it pointed out how crazy high the demand for chemical engineers had become.

Earlier in the year, all of us seniors were flying around the country interviewing with the major oil companies and receiving job offers from every company we talked to. It was madness. I interviewed with eight firms from California to Louisiana and received offers from all of them at starting salaries that exceeded what my parents made combined.

Little did we know, the oil industry would collapse a year later, throwing many of us, including me, into unemployment.

Doonesbury19810510

BD is tired of coddling lazy chemical engineers. Image from GoComics.com

The Graduate–1967

The granddaddy of all chemical engineering pop culture references is a famous scene in The Graduate, the 1967 movie directed by Mike Nichols (who won the Academy Award for his work) and co-written by Calder Willingham and Buck Henry. In the scene Mr McGuire (Walter Brooke) advises young Ben (Dustin Hoffman) that that there is a great future in plastics. However, he doesn’t say you have to know anything about chemistry to reap the rewards of that future.

GraduateScenePlasticsYouTube

I just want to say one word to you. Still from Movieclips on YouTube

Space Oddity–2013

And finally, I want to point to a 2013 cover version of David Bowie’s Space Oddity performed by Canadian astronaut Chris Hadfield while onboard the International Space Station (ISS). This song has nothing to do with chemical engineering and Mr Hadfield is a mechanical engineer, not a chemical engineer. I just like the song and the visuals of the earth zipping by in the background of this music video.

I’m glad David Bowie had an opportunity to see this before his death just over two years later. In fact, without his intervention, the video may not have been made available (Independent Jan 2016).

According to NASA, Mr Hadfield is the first and so far only astronaut to record music videos in space.

ChrisHadfieldSpaceOddityYouTube

Can you hear me major Tom? Still from Canadian Space Agency on YouTube.

Update1: To complete the circle, check out this video of the "real" Captain Kirk, William Shatner, and a fellow Canadian, singing Rocket Man at the Science Fiction Film Awards.

Update2: Inquiring minds want to know. If Peter Parker dropped out of college, when did he earn a degree in chemical engineering.

Intersection

Westbound on Evan at Santa Fe. Photo by James Taniwaki

by George Taniwaki

Take a look at the intersection above of two busy streets in Denver. The photo was taken from the left-hand turn lane of westbound W. Evan Av. turning to southbound S. Santa Fe Dr. From this angle you cannot see the on-ramp you are turning onto. It is obscured by a concrete jersey barrier.

In fact, the end of the barrier is separate from the rest of it. One gets the impression that it was originally connected to the rest of barrier but was accidentally hit, forcing it to be perpendicular to the remaining section. This creates the illusion that there is no road behind it, and you should turn left before the barrier, not after.

If you do turn left into the lane on the east side of the barrier, then you will be headed the wrong direction into oncoming traffic on Santa Fe Dr. This is really dangerous.

IntersectionSatellite

Synthetic aerial view of same intersection. Image from Google Maps

A better view of the intersection can be seen using the 3D tilt view feature of Google Maps. Looking at the synthetic aerial view, one can see that the intersection is directly over Santa Fe Dr. This allows large volumes of traffic to flow without taking up a lot of real estate. This configuration is called a single-point diamond interchange.

Two changes would probably make this intersection safer. First, the end of the jersey barrier should be a continuous piece of rounded concrete, not jagged, so the user can imagine there is a traffic lane behind the barrier. Second, the barrier should be set back about 3m (10’) so that a driver in the left-hand turn lane can clearly see there is a paved surface beyond the barrier before entering the intersection.

I don’t know how many accidents happen at this intersection and I don’t know how the state of  Colorado measures the social costs of traffic accidents. But if there are ten accidents (some with injuries) per year here, and the lifespan of the interchange is twenty years, then it is probably worth spending the one million dollars I estimate it would cost to make the suggested modifications to this intersection.

[Update: There was a paragraph here describing a fatal accident on Santa Fe and Dartmouth involving a driver going the wrong direction. However, that accident is unlikely to have been caused by a driver entering the highway at Santa Fe and Evans. I have deleted the paragraph.]

DoorLatch

Righty tighty, lefty loosy, when viewed using a mirror

by George Taniwaki

On a visit to the University of Washington Medical Center laboratory, I was asked to provide a urine specimen. As I approach the restroom, I notice the door is about 1m (40") wide to accommodate a wheelchair, which is good.

Both the outside and inside of the restroom door have solid metal lever handles. You push down to open the door. Levers are easier to grip than knobs and are now the preferred method to open and shut doors. Also good.

Once inside the restroom, there is an easy to grip lever above the handle that controls a lock for privacy. Good again.

As shown in the image above, the hinge for the lever is on top of a circular escutcheon and it flips left or right. But which way locks the door?

The rotation direction to lock the door is ambiguous. Apparently, there have been complaints, so someone printed a sign and taped it above the lever. But the sign is somewhat ambiguous as well since it is posted above the hinge, but the lever is below it.

Finally, it seems one of the lab techs used a grease pencil to indicate the direction to turn the lever to lock the door. But the grease is now smeared and illegible. The hand-drawn arrow points in the direction to lock the door, meaning the bottom toward the door edge or a counterclockwise turn. This is not standard in the U.S. and the likely source of confusion. Oh well, good thing I don’t have a shy bladder and don’t care if someone accidentally walks in on me.

Oddly, the convention to rotate a lock lever so that when the top points toward the door edge to mean the door is locked is not universal. In Japan, most locks are installed so that when the bottom points toward the door edge it is locked. You may notice this on some Japanese car doors.

* * * *

P.S. Ever have trouble knowing if a door opens toward you or away from you? To learn more about this design problem, read this blog post from 99% Invisible. Also watch the video. And read Don Norman’s book, The Design of Everyday Things.

[Update: Clarified the description of locks in Japan.]

Gillette

Pretty label undone by chemistry

by George Taniwaki

When it was new, the travel-size container of Gillette Series sensitive skin shaving cream was pretty. Rather than print directly on the can, they print the design on a sheet of plastic. It’s either polypropylene or polyester film, I am guessing. Printing on film provides a wider range of color options and allows for printing of finer details and at higher resolutions. That’s especially important if you have small text.

The film is transparent, so the design is printed in reverse and then the label wrapped around the can with the printed side on the inside. The plastic protects the label from scratches.

Seems like a clever design. One problem though. The ink on the label is soluble in one of the ingredients in the shaving cream, likely the triethanolamine. The shaving cream comes out as a gel and expands. If the gel gets under the label, it dissolves the ink and then oozes back out and onto your hands. The problem is worse if you get water on the container.

Another problem, why does sensitive skin shaving cream contain triethanolamine? I believe that ingredient can cause allergic contact dermatitis.

Outlet

Don’t touch that button… oops too late

by George Taniwaki

In terminal S at the Seattle-Tacoma International Airport, they retrofitted all the old seats by adding outlets and USB ports. Very thoughtful!

The outlets are  inPower Flex model 2. They are specifically designed for those black leather and chrome seats you see at the airport. They attach to the beam underneath the seat with a bracket. Each unit has two ground fault circuit interrupt (GFCI) protected, 3-prong polarized outlets and two high-current (2A) USB ports protected by the same GFCI.

GFCI outlets are required wherever there is a chance stray current could pass through your body, like in a wet area such as a bathroom, kitchen, or outdoors. A standard GFCI outlet has two buttons and an indicator light. A green light means the outlet is active. To check if the GFCI protector is working, you press the test button, which creates a short. The GFCI should shut off power to the outlet and the indicator light should glow red. To force the outlet back to the active state, you press the reset button. Simple right?

Not exactly. In a public setting, the facility owner is responsible for safety, even if the guest is doing something dangerous. The airport staff didn’t want passengers to electrocute themselves by bypassing the GFCI. So they removed the reset button. (See the hole in the middle of the outlet in the photo above.)

But they didn’t remove the test button. (See the white button at the top of the outlet in the photo above.) Of course, people press the test button, maybe accidentally, or out of curiosity to see what it does, or even maliciously. This disables the outlets and USB ports, making them useless. There is no way for a passenger to reset the outlets or ports back to their active state after this happens.

Every.single.outlet.in.the.terminal.is.disabled.like.this.