Line Cutter Blade

When scuba diving, it is important to be able to cut your way out of tangles. This is especially true if you are diving in places where people go fishing. It is difficult to see monofilament fishing line underwater. Entanglement is a real hazard.

For this reason, most scuba divers carry a dive knife with them. It is also a good idea to have an easily accessible backup, just in case your normal knife is lost or cannot be reached.

I own a Dive Rite Z-Knife line cutter as a backup.

It is based on the design of a parachute line cutter for cutting away a tangled chute before opening the spare. It has a razor sharp blade, and its shape minimizes the risk of accidentally cutting yourself when using it.

I like it, but there is one disappointing drawback. If you happen to try to cut steel fishing cable, you will only succeed in destroying that sharp little blade. It also has the tendency to rust over time. (Mine lasted a few months before rusting, but only one trip before I tried cutting something it couldn't.)

They don't sell replacement blades.

Or at least not ones that I could find.
These people couldn't find them either.
These people had some ideas, but nothing readily available.

So. Since it appeared that the only option was replacing the whole thing, I had nothing to lose by trying to modify mine.

First, I removed the old blade. It measured 26 mm by 8 mm.

Next, I scoured the internet trying to find an identical replacement. No luck.

Finally I went to the local hardware store and found this. It has a stainless blade (not sure what grade, but we'll see how it lasts), and the blade width of 9 mm is very close to the 8 mm blade I removed.

I broke off a section that consisted of four segments of the blade, and ended up with this piece. It is remarkably close in size to the blade I removed.

Next, I partially pushed in the new blade. It was a little difficult. I could tell that the blade was larger. To fix this, I used the pencil torch from my arsenal. I heated the point of the blade for a few seconds and then used needle-nosed pliers to pull the hot blade into place. This melted away some of the plastic, making room for the different-shaped blade end. It still interfered with the screw hole after the first time, so I pulled it back, reheated, and pushed it a little further. Below you can see the before and after.

Using the needle-nose pliers, it was pretty easy to remove and install the blade at this point. (I took the comparison pictures of the two blades after doing this. That's why the tip of the new blade is discolored in the pictures at the beginning.)

Here you can see the final result. The blade is firmly held in place by the screw.

There was enough left of the box cutter blade to make 3 more of these replacements. We'll see how long they last, but this appears to be much more economical than replacing it each time the blade is damaged or rusts.

Planting Guide

Something brilliant was shared with me on Facebook the other day.

It is a guide for which common garden plants should be grown together.

I am posting a version of it here that I cleaned up a bit.

A Tale of Two Phones

I am eligible for a cell phone upgrade. I currently use an HTC Evo 3D. I have been semi-happy with this phone. The 3D camera and screen is rather fun. It does a good job overall. 

These are my complaints: 

• It was from a time before NFC, and I want to play with NFC tags. 
• The camera does a poor job in low-light. 
• HTC is not great about rolling out new versions of Android. 
• No wireless charging option. (Wireless charging is cool!)

Of those complaints, one that bothered me the most was the lack of updates. I thought there was an easy answer to this. The Google Nexus 4. 

Pros:

• It is made by Google. It runs stock Android. Updates will be immediately available. +++
• It has NFC. +
• It has built-in wireless charging capability. +
• It was given a 7 out of 10 repairability score on ifixit.com. This matters to me since I had to replace the digitizer (front glass) on my Evo 3D on three separate occasions. ++
• Decent technical specs and a very reasonable price. ++

Cons:

• It is not available on Sprint, and doesn't look like it will be. There is really no reason to continue. 

Time to look at phones that will actually be available on the carrier I would like to continue using. That may be a better place to start...

The HTC One seems pretty nice. Let's see what it has to offer.

Pros:

• It is made by HTC. There is a good chance it can be rooted to allow for more customization. +
• The camera is especially designed for good performance in low-light. +++
• It has NFC. +
• Decent technical specs and a reasonable price. ++
• Beautiful and durable aluminum construction. +

Cons:

• It is made by HTC. Android updates will be slow. And they will stop altogether after about a year. -
• It was given a 0 out of 10 repairability score on ifixit.com. Non-removable battery. -----
• No built-in wireless charging capability. -

How about the Samsung Galaxy S4? 

Pros:

• It has NFC. +
• It was given an 8 out of 10 repairability score on ifixit.com. ++
• Potential for a replacement back to enable wireless charging. 
• Decent technical specs but slightly more expensive price. +
• Wide variety of interesting sensors including gyro, accelerometer, proximity, ambient light, gesture, barometer, temperature, and humidity. +

Cons:

• Normal camera compared to the HTC One's low light version. --
• Plastic construction. 
• Samsung has a slightly worse update history than HTC. - 

I think I am leaning toward the Samsung Galaxy S4, but it is not perfect. It may be good enough, though. I will have to think on this further, and see what it is like in person as soon as it shows up at the Sprint store. 

Brake Pads

I ran across this article from the car talk guys. It had good information about different types of brake pads. Just thought I would pass this along in an off-week post.

http://www.cartalk.com/content/today-all-about-brake-pads

An Egg Timer

I just had a perfectly cooked boiled egg. That's not terribly unusual. The unusual part is that for once I have confidence that I can do it again whenever I want. All thanks to a brilliantly designed egg timer.




Sabrina found this when we were wandering through Crate and Barrel. I'm going to provide some info on exactly how it works, since the packaging leaves a little to be desired.

The timer is simply a clear plastic egg with a layer of temperature sensitive material in the middle. It is placed in the boiling water with the eggs, and the red portion slowly changes to black as the eggs cook.

This is what it looks like as time progresses:



























Note the difference in how the scale looks between the first picture and these two. When the egg is under water, the scale is easier to read, partially due to the curvature of the top surface.

I store it in the fridge with my eggs. I figure it is important that they start off at the same temperature. Then I drop it into the boiling water at the same time as the eggs.

The brilliance of this design is that it doesn't matter what temperature the water is. (Like if you add a bunch of eggs to a small amount of water, if you cook at a different altitude, if you sometimes salt the water, or even if you turn off the heat at some point.) The time fluctuates, but the timer compensates and reads correctly based on heat transfer. Not bad for $5.

The one downside is that there is no audible alert that your eggs have reached the desired level of hardness. You have to check on it periodically. For me, this is not a big deal. I have started cooking eggs while doing other things in the kitchen. (Like washing dishes, cleaning, cooking, etc.) This keeps me in the same room, so it is easy to glance into the pot every few minutes  (Or to fish out the timer with a spoon if it is too difficult to see through the bubbling water and steam.)

Mash Starch Test

I homebrew beer. I haven't talked about it much since February 2012 where I described the chest freezer I use to control fermentation and lagering temperatures.

Today I'm going to describe an experiment Sabrina and I did testing the effectiveness of my mashing procedure.

Mashing is the first step in making beer from malted barley and other grains. During the mash, you heat a mixture of crushed grain and water up to certain temperatures. You hold the temperature constant at one or many different points to allow the naturally occurring enzymes in the malt to convert starches into simpler sugars. Mashing usually involves holding temperatures for up to 90 minutes.

One method of testing the progress of this conversion is to perform an iodine starch test. A good description of what is going on can be found here. In brief, when an iodine solution is exposed to starch, the iodine changes color from dark brown to intense purple/black. Once all the long-chain starches are broken down, the iodine test will be negative. There will be no color change when the iodine solution is mixed with the wort. (Wort is the liquid sugar solution produced in the mash, or unfermented beer.)

The first experiment we did was to perform the iodine test every 10 to 15 minutes during a 90 minute mash rest. We also measured pH using test strips. We recorded time and temperature on the end of each test strip.  Here you can see the results:

The test was done by placing several drops of wort on a piece of chalk. A medicine dropper makes this much easier, just be sure to rinse it well between samples. Next, a couple drops of iodine solution were placed on the same piece of chalk. If you are careful to ensure that the iodine drops cover both part of the chalk soaked in wort and part of the dry chalk, it is very easy to detect if a subtle color change occurs.  You can see this effect rather clearly in the 80 minute and 90 minute samples above.

One thing I was not expecting was that once the iodine and wort evaporated from the chalk, the color disappeared. You can see how the color from the earlier samples is fading away. The color of the pH test strips also faded away as they dried.


I still had questions after this first experiment. All samples had been taken from the drain at the bottom of the mash container immediately after the mash had been stirred up.

The next time I made beer, we continued the experiment and collected more detailed data. This time we took samples from various locations in the mash, both with and without stirring. The pH was written down at each step so this time I have an accurate record of pH changes. Samples were taken every 15 minutes during a 60 minute mash.

The sample at the start of the mash was taken immediately after stirring together the water and grain. There was a clear purple color. 15 minutes later, three samples were tested. One from the drain without mixing or stirring (N), one at the top of the mash where the grain and water are mixed together (T), and one from the drain after mixing (M).

Without mixing, there was no reaction. This leads me to believe that the enzymes rather quickly convert the starches that are dissolved in solution. The top and mixed samples showed varying degrees of reaction. My conclusion is that at the top, starches continue to dissolve into the wort from the grain, and after stirring, these starches are distributed throughout the mixture.

The results from the rest of the mash were relatively unexciting. The reaction showed negative at 30, 45, and 60 minutes. This indicates that starch conversion finished rather early. A negative starch test doesn't necessarily mean that the mash was finished this early since the enzymes will continue to break down sugars. However, it is a good indication that the mash is progressing well.


A quick word on the iodine solution used for this. I bought 10% providone-iodine solution from the first aid section of my local pharmacy. I then diluted it 10 to 1 with rubbing alcohol. This lightens the color of the iodine so that the more subtle purple reaction can be seen. Otherwise the iodine is very dark and can mask a partially positive reaction.

I have heard that this test also works well using iodophor, a no-rinse sanitizer that is often used in homebrewing. Simply dilute the iodophor 10 to 1 with rubbing alcohol and it should work the same.

The Container Store sells some amber glass bottles with built-in medicine droppers that worked very well for storing and dispensing the iodine solution. It made it easier to avoid spills, which is important since iodine stains.


A couple months after I did my experiments, I ran across an episode of the Basic Brewing Radio podcast that goes into great detail on the subject. If you are interested, look for the March 3, 2011 episode.

Adventures in Plumbing

My parents' house has a well that supplies their water. About a year ago, they had a less-than-competent contractor install a storage cistern and a booster pump. 

The contractor didn't anchor down the pump base, depending entirely on the weak PVC pipe and gravity to hold it in place against constant vibration. The electrical work he did had to be completely redone by someone else. The concrete cistern has leaked since day one, even after several repair attempts by the original contractor 

The pump started leaking much more recently, and much worse. What looks like a blurry water drop at the rightmost corner is a constant stream. This is what the leak looked like with the booster pump turned off and the piping downstream depressured. 

The first step I took was to disconnect the piping from the downstream union and I began to unscrew it from the pump. The pipe was loose! It wasn't even screwed in tightly. The piping configuration makes it impossible for the pipe to unscrew itself from the pump without disconnecting it downstream. Here is an overview of the pump and piping configuration. The piece that I removed comes out of the top of the pump and connects to the half of the union seen above and to the right of the opening.

Once I had the piping removed, I took a closer look at the opening on the pump. This is what I saw. 

There was metal sticking out into the bottom portion of the threaded opening. It looked like it might be flash left over from when the pump housing was cast. It deserved a closer look. 

That's strange... It looks like the threads abruptly stop.

Yup. The threads definitely stop. My only thought is that this might have been done to prevent threading the pipe in too far. If the pipe went past the inside surface of the pump case, it could hit the impeller (the part that spins.) 

Let's take a close look at the pipe I removed. 

The first thread at the end of the pipe is rather screwed up. It's as if it were tightened past that point where the threads in the pump stopped. It's almost exactly like that. 

At this point it is important to understand how tapered pipe threads are supposed to seal. The seal occurs at the threads as they fit tightly together. This site provides excellent diagrams of what should be happening. I have modified them below to illustrate what was happening in this specific case. When the pipe bottomed out, the threads were still loosely engaged. This allowed the water to leak out past the threads. I used a saw to shorten the pipe, removing the two smallest threads at the end. It was then able to seal tightly. A small amount of Teflon tape or joint compound seals any small gaps left in the imperfect threads. 

Below you can see the before and after pictures of the pipe. 

Based on what I showed above, this is what I think happened. The contractor screwed the pipe in place, tightened it to the point it became difficult, and then discovered that it leaked. When it leaked, he tightened the crap out of it until it stopped leaking, damaging the plastic pipe thread as it bottomed out in the hole. However, the threads were still not properly tight. The only reason it stopped leaking was due to the rather excessive amount of joint compound that was used. 

This is pipe joint compound. More is not better... 

The contractor saw the opening of the pump when he assembled the system. He failed to notice the rather obvious metal bits extending into where the pipe should be threaded. This is one more example of the shoddy job that was done all-around. 

Here is the final result after my repairs. If you compare this to the original picture of the leak, you can see that the pipe threaded in further. This created a good tight seal that should last. 

The leak started shortly after we had replaced the filter downstream of the pump. What we did must have been just enough to disturb the loose joint and start the leak. Both the inlet and outlet connections on the pump had the same problem, and were fixed the same way.

I dislike incompetence. Consistency doesn't make it better.