Some Blog Site

When I had to do some engine work on the minivan, I was able to get a tool to lock the camshaft gears/sprockets/phasers in place so that everything would stay at top-dead center while I unbolted things.

Like this:

That’s for the Dodge 3.6L engine, which was in a bunch of vehicles for a long time, so it has good support from a variety of sources.

But now I’m doing a bunch of work on my car with a Chrysler 2.4L engine, from the early 2000s, used in Neons and PT Cruisers and some other things. It also uses the same cam sprockets (simple gears, no phasers) as the 2.0L, so this would work for that too.

Anyway, I was looking for a similar tool to hold the camshafts in place so I could do things like unbolt the crankshaft pulley and unbolt the camshafts themselves without rotating the engine.

But unlike the many options for the 3.6L tool, I found nothing for the 2.4/2.0 engine. There were some references to a prybar-type tool which is supposed to be the official way of holding the car gear in place, but I didn’t find a source to buy one. And even if I did, my guess is it would have been more than I wanted to pay.

I wanted a simple insert with teeth, like the 3.6 thingy. And it just so happens that my son got a 3D printer last month. So I decided to make my own.

It took a couple of iterations on paper, plus one really thin 3D-printed sample, but I did make my own and it works. Here it is in action:

And, in case you want to print your own, here is the STL file.

STL file for 3D printing a cam gear holding tool for Chrysler or Dodge 2.0 and 2.4 L engines

Note that it is a very tight fit, so don’t expect it to slide right into the gears. The goal is no gear movement at all, so it needs to be as flush as possible. Be prepared to coerce it into place.

Also note it is about 2 inches deep. The pictures show it only halfway in. Afterwards, I pushed it until it contacted the backstop, and it stuck out just a little bit, enough to still be able to grab the sides.

One of main complaints with the iPhone is the inconsistent interface for clock notifications. I use both the alarm (for waking up in the morning) and the timer (reminders during the day) just about every day. And I never know which button to press to get it to stop.

Here’s the alarm:

And here’s the timer:

My problem is that I want to press the larger, more colorful button. But Apple has made the decision that for the two parts of its clock app, the larger, more colorful button will have two different meanings.

So when my iPhone starts making clock noises, I have to look at it, figure out which button means “stop” and which button means “remind me again soon”, and press the one I want.

One of these days, I’ll change my alarm setting to turn off the snooze option…

Note: see the bottom of this post for the lesson.

The battery in Some Wife’s iPhone was getting old, and it no longer could get her through the day without needing to be recharged. The battery health-o-meter indicated it was not so healthy anymore, confirming with numbers what we already knew.

So, having replaced batteries in iPhones of generation 4, 5, 6, and 7, I figured I could handle an iPhone 10. Excuse me, iPhone X.

I looked at the repair instructions, and they looked about the same as before, so I ordered a new battery.

The instructions say to take apart the iPhone in the usual way – take the screws out, soften the glue, and carefully pry the screen away from the housing.

The instructions emphasize to be extra careful not to pry the screen from its frame, but make sure to pry the screen and frame together away from the housing.

I wondered how to know if I’m prying the screen only (bad) or screen and frame. I found out the hard way.

I thought the screen came away a little too easily, and after I had separated about 3/4 of it, that’s when part of the frame came away from the housing and I saw the difference.

It turns out I had been doing the bad thing and separating the screen from itself.

Argh.

I quickly pried the frame out from the housing and tried to keep the screen and frame together as much as possible. I did end up getting the screen and frame back together, and both off the rest of the phone, but I wondered what effects that might have had.

The rest of the battery replacement procedure went okay, not perfect but it got done.

In the course of previous battery replacements, I have learned to turn the phone on after everything is connected but before I screw it back together. One of my earlier attempts I had mis-connected something, so I had to take it back apart and re-fix it. It saves time and effort to test it slightly earlier in the process, rather than waiting until the very end.

So that’s what I did with this phone. After I had all the electrical connections back together, but the screen not in place, I turned on the phone.

In previous repairs, I saw the Apple logo appear on the screen and I knew everything was fine, so then I’d turn the phone back off, screw everything down, and then turn it on and then I could be done.

But with this phone, when I turned it on, the screen was blank. No change. But the phone made noises that told me it was on, which lead me to conclude that I broke the screen during the repair process.

Now the problem was that this was Some Wife’s phone, and both she and I were expecting the repair to be done that evening. That was not a fun thing to do – come back into the room and break the news to her that she no longer has a functioning phone.

But she took it in stride, and we came up with a backup plan to borrow Alpha’s backup phone (an iPhone 7) that he no longer used but still had around. One sim card swap later, and she had a phone. But it had none of her apps and none of her contacts, so it was a challenge over the next couple of days when a text would come in with just a number listed, to see if she could figure out who it was without responding back “who are you?”

Anyway, the day after I broke her phone, I told her “good news, you get to get a new phone”. Or at least new to her. Actual new phones are ridiculously expensive, so we upgraded her to an iPhone 12, which was still more money that I had planned for a simple battery repair, but much better than a phone that costs as much as my car did.

In the meantime, before we settled on which exact phone, I ordered a replacement screen for the iPhone X. She wanted to be able to get a bunch of info off the old phone, and it was cheaper than a used iPhone X, so we’d still come out ahead by having an iPhone X with a new battery.

I thought I had turned off the broken phone, but I found out it was on when one of her alarms went off. The touch part of the screen was working fine, but I couldn’t see where to turn off the alarm, so I tapped a couple of times where the Stop button should have been and got it to turn off.

The replacement screen came in about the same time as her newer phone, so while she was setting up the phone, I was trying to get the screen working on the old one.

The repair went smoothly, except when everything was connected, I turned on the phone, and it didn’t work. I disconnected the cables and put them together again. Still nothing.

I thought I must have damaged a connector or something in the process. With nothing else left to try, I decided to just put everything back together and wait until tomorrow to figure out what to do.

After I put the screen fully in place and screwed it down, it worked.

At first I was excited and relieved. But then it got me thinking, and I bet there was nothing wrong with the old screen. I could have tested it by taking the new screen off and putting the old one back on, but at that point I didn’t want to mess with anything. But I’m about 80% confident it would have worked.

Lesson for iPhone Battery Replacements
From what I can tell, the new style (and I don’t know when it changed, but somewhere between iPhone 7 and X) is to have grounding pads for the screen be separate contacts at the bottom of the screen, not in the cable connector. So the screen isn’t fully electrically connected until it is fully physically installed. So you cannot test the repairs with the screen slightly off the phone, even just a little bit.

A typical sci-fi storyline involves robots/computers/AI taking over the world, and worst-case is ridding the world of humans. And now with things progressing rapidly on that front, more people are getting worried about that happening.

However, I’ve been doing a fair amount of tasks online lately, such as paying my electricity bill, and I am not worried about robots taking over the world because the Captchas will prevent them from doing just about anything.

I think it’s a good system, as we seem to have caught the AI in a catch-22.

Because how does an AI learn what to do? It uses many existing examples to find the patterns.

And what do our many examples of online interactions have? Lots of “Are you a robot?” questions. And if you’re a robot, you’re not allowed to continue in whatever process it was.

So the robots will learn that many tasks are not allowed to be completed by robots, so they’ll be stuck and they must allow humans to exist. Of course, at that point the worst case becomes the humans are kept around for the sole purpose of completing the “Are you a robot?” questionnaires and that wouldn’t be a very good existence.

As a side note: why can’t a robot pay my electricity bill? What if I did want to automate some mundane bill-paying tasks? Don’t these people want to be paid in an efficient manner?

I’m going to be explaining manual transmissions to Gamma in a month or two, so this is my homework for that.

The pre-requisite for my class Learn to Drive Stickshift is an understanding of Levers and Gears. You should have already taken the class Simpler Machines.

As we discussed last week, a wheel can be thought of as an group of levers around the axle. Gears make this easier to visualize, just think of the gear teeth as the ends of the levers.

What does a lever do? It allows one to produce varying amounts of distance or force, depending on where the fulcrum is. Want more distance on the other end? Move the fulcrum closer to you. Want more force on the other end? Move the fulcrum farther away.

What do gears do? Same things as gears – they allow one to produce varying amounts of distance or force, depending on where the fulcrum is. The difference that the fulcrum for gears is the gear ratio, or the radius of the drive gear compared to the radius of the output gear.

The other difference is that gears don’t usually deal with distance like a lever, but rather distance over time – better known as speed.

If both gears (one input and one output) are the same size, then that’s like a lever with the fulcrum in the middle. It multiplies neither force nor distance, it just changes direction.

If the input gear is larger than the output gear, then that’s like a lever with the fulcrum farther from the input. It multiplies force and divides distance or speed. This is a low gear – it provides the oomph (technical term) to get things moving, albeit moving slowly.

If the input gear is smaller than the output gear, then that’s like a lever with the fulcrum closer to the input. It multiplies speed/distance and divides force. This is a high gear – it provides the high speeds but with a lack of oomph. Note that this is called overdrive when the input gear is smaller than the output gear. Overdrive used to be a big deal on cars years back, but that was when transmissions had 3 gears and the highest speed limit was 55 mph. Now transmissions have 8 or 9 speeds and speed limits are 75 or 80, so everything can go fast enough and no one runs out of gears anymore.

I’m going to be explaining manual transmissions to Gamma in a month or two, so this is my homework for that.

The pre-requisite for my class Learn to Drive Stickshift is an understanding of Simple Machines.

The classic list of Simple Machines is Lever, Wheel, Pulley, Inclined Plane, Wedge, and Screw.

I disagree with the list, as it could be simplified. I.e. those are not the simplest machines. One of my favorite parts of science was simplifying things by cancelling units. I am going to try to show that here.

First is Screw, the most egregious example, the Screw is not a Simple Machine. It is a Compound Machine.

Take a wheel, make it thicker, and apply an inclined plane to it.

That’s a screw, just an inclined plane-wheel. Since Screw can be reduced to two simple machines, it does not count as a simple machine.

Next is Wedge. While I don’t think this can be reduced, I do think this is just an inclined plane.

If we move an object up an angled surface, we call that surface an inclined plane. But if we take an angled surface and move it into an object, we call it a wedge.

I disagree that wedge gets to be a known as a unique simple machine. I actually don’t care which term we use (it is easier to say “wedge” than “inclined plane”).

Wedge and Inclined Plane do the same thing – use an angled surface to make it easier to separate things. For the wedge, one is generally separating one object into two. For the inclined plane, one is generally separating one object from another. But it’s the same basic concept, and it shouldn’t count twice.

Since we’re on the topic of Inclined Plane, I thought there should be some overlap between Lever and Inclined Plane. I thought about how to combine them, or reduce Lever somehow. But my conclusion was they are both simple machines, and it may help to think of the lever not as a lever but think of it as a fulcrum. Replace Lever in the list with Fulcrum and it is more obvious that it’s not sharing anything with Inclined Plane.

Next is Pulley. It should come as no surprise to you that I consider a pulley to be a wheel plus a rope. Since one of its components is a Simple Machine, it can be reduced and is therefore not a Simple Machine.

I am open to the possibility that Rope should be promoted to Simple Machine.

Pulley, on the other hand, is just an application of Wheel. It’s a similar comparison to Wedge and Inclined Plane. Wedge and Inclined Plane are the same machine, just one is moving and one is stationary.

It’s the same with Wheel and Pulley – it’s the same machine, just one moves (a distance, yes they both move in that they rotate) and one is stationary.

That’s the end of my complaining about the classifications of Simple Machines.

For your homework for next week, please come prepared with an explanation of how a wheel can be reduced to an infinite number of very small levers around a central fulcrum.

Today is going to be a discussion of heating and heat transfer, in the context of what heating systems make sense for buildings

First off, let’s start with some basics.  Things, in general, are either good conductors of heat or bad conductors of heat.  Bad conductors are good insulators.  What are some good insulators?  People normally think of fiberglass insulation.  A nice thick sweater is also a good insulator.  There’s also that expanding foam stuff.  They all have in common that they hold air.  All the fluffiness is there to have a bunch of air pockets.  Ideally, the best insulator would a vacuum (no air), but since that’s impractical for most things, we go with the next best thing which is air.  

So air is a good insulator and therefore bad conductor of heat.  

Next, let’s go with air movement.  

What is windchill?  I’m hoping you all know the answer already, but just for completeness I’ll say here that is it the feeling that moving air imparts to people.  The faster the air moves, the lower the temperature feels.  So blowing air brings a cooling effect.  Nothing new there, I hope.  

Now let’s combine those two principles.  Let’s say, in theory, we wanted to design the worst possible system for heating a place where people are.  What would we do?  First, we’d start by using a bad conductor of heat as our heat-delivery medium.  Right?  Let’s heat up something that doesn’t hold heat well, and send that around to distribute heat.  Next, we’d use something that would make things feel cooler, rather than warmer – make sure windchill is involved.  

Put it all together, and you get standard forced-air systems that are in just about every house built these days.  

For those of you familiar with thermodynamics, please tell me how you could make a worse system for delivering heat to make people feel warm.  From both an efficiency standpoint and comfort standpoint.  

The only reason it’s popular is that it is cheap to install and maintain.  It can be done shoddily and people won’t notice if there’s a small leak in the ductwork.  

The other thing that’s bad about it is the vents are annoying.  We have one in the kitchen floor right where a chair is and I can’t always scoot the chair where I want because the leg catches on the lip of the vent.  

In case you’re wondering, I’m a proponent of radiant heating.  It uses water, something that conducts heat well, and it doesn’t blow on you.  And it’s quiet.  And you can put furniture anywhere you want, without worrying about blocking anything.  

On the other hand, it does make sense to use air for cooling.  You want windchill, to help you feel cooler.