House of Hacks

Monday, November 16, 2015

How to quiet a shop vac - efficiency measurements


Description

How well did Harley meet his goals by setting up the shop vac to be a centralized system? In this episode, the changes are quantified with measurements for noise, vacuum and air flow.

Related videos:

For a written transcript, go to How to quiet a shop vac - efficiency measurements

Music and sound effects under Creative Commons License By Attribution 3.0 or 4.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod at http://incompetech.com
Light switch effect: http://freesound.org/people/AlienXXX/sounds/151347/

Transcript

Today at the House of Hacks we compare some efficiency parameters of the shop vac's original configuration and its new one.

[Music]

In this earlier episode, I presented some problems I had using my shop vac, some goals I wanted to meet by reconfiguring how I use it and how I actually made some of the changes. In this episode I want to show some of the before and after measurements to see what actually changed.

To recap, my goals were to 1) have minimal daily setup; 2) be convenient to use; 3) be much quieter; 4) and all this at minimal cost. I attempted to do this by converting it to a DIY central vac system.

Today I am going to show how well I accomplished my goals. I’ll show what it takes to use the new configuration, a couple specifications between the old and new systems: the loudness, the vacuum pressure and the air flow.

Overall I’m really pleased with the ease of operation. I typically just leave everything plugged in, setup and ready to go. All I need to do is grab the hose and press the power button. Of course if I’m working on a piece of equipment, I have to do some setup, but that is pretty minimal. I just move the hose to the closest outlet and connect to the equipment.

One of the goals was noise reduction. I used a freely available decibel app on my tablet to measure the noise levels. Admittedly this is an uncalibrated device and won't give exact results, but it does give a good idea as to relative differences.

In the shop, the vacuum runs around 85 db.

And when it's outside the box on the other side of the wall, it runs about 70 db.

When it's inside the box I made for it, it drops down to about 62-63 db.

Overall a reduction of over 20 db. Quite a bit. For comparison purposes, that's like going from being next to a food blender to being in an office.

A side effect of adding the plumbing is reduced efficiency of the vacuum pressure and air flow. Devices are available to measure these parameters accurately, but they're not cheap and I was more interested in relative loss, so I hacked together a couple instruments.

First vacuum. This is a simple DIY vacuum gauge that I made out of a simple loop of vinyl tubing, some water and a ruler. I explained how I made it in this other video over here. One end is open to the atmosphere and the other is connected to our vacuum. The difference in water levels tells us how much vacuum is being generated.

As you can see, we’re getting about 38, 39 inches of water here. And I'll consider this 100% of baseline for what the vacuum is capable generating, for comparison in future measurements.

Connected to the first port it reads 31.5 inches.

Connected to the second port it reads 32 inches.

Connected to the third port it reads 31 inches.

So, the ports have a reading of about 31.5 inches of water on average or a loss of about 20%.

To measure air flow, I picked up an inexpensive anemometer off Amazon.

Connected directly to the shop vac, this reads as an overload. The vacuum is advertised as 150 mph, but I suspect, based on the noise of the anemometer, that it’s not really that fast. For the purposes of this test I’ll estimate this to be about 110 miles per hour (MPH). Like before, this will be the 100% baseline for the other measurements.

Connected to the first port it reads 89 mph.

Connected to the second port it reads 88.5 mph.

Connected to the third port it reads 86 mph.

So, on average, the ports read 87.8 mph or a loss of about 20%.

While there's a loss of 20% in both vacuum and air flow, in practical application, I don't really notice any difference. It still picks up about what I need it to in about the same way.

In summary, I'm really pleased with the new setup. It's much easier to work with so I'm more diligent at keeping things cleaner.

In conclusion, I’d love to hear in the comments below what you think about vacuums versus dust collectors as a means of keeping the shop clean.

If this is your first time here at House of Hacks: Welcome, glad you’re here. We’d love to have you subscribe. Through these videos I hope to inspire, educate and inform makers in their creative endeavors. Usually this involves various physical media like wood, metal, electronics, photographs and other similar materials. Thanks for letting me encourage your creativity. So subscribe and I’ll see you again in the next video.

Now, go make something. It doesn’t have to be perfect, just have fun!

Monday, September 21, 2015

How to make a vacuum (or pressure) gauge


Description

Vacuum and pressure are two sides of the same coin. A manometer can measure both. In this episode, Harley shows how to make a DIY gauge to measure relatively low vacuums and pressures for shop use.

Part 1: How to quiet a shop vac
Part 2: Central shop vac efficiency: https://www.youtube.com/watch?v=UbLElnfZmno

Unit conversion web site:
The unit converter

For a written transcript, go to How to make a vacuum (or pressure) gauge

Music and photos under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod (http://incompetech.com)
Incidental music:
“George Street Shuffle” by Kevin MacLeod (http://incompetech.com)
“Mining by Moonlight” by Kevin MacLeod (http://incompetech.com)

SU Carbs photo: by Cgxke at https://commons.wikimedia.org/wiki/File:Carbs-SU-HD8.jpg

Photos under Creative Commons Attribution 2.5 Generic:
Organ pipes photo: by Xauxa at https://commons.wikimedia.org/wiki/File:Forkarla_kyrka_organ_pipes.jpg

Transcript

Need a vacuum gauge to sync your carbs, test your pipe organ or shop vac? Today at the House of Hacks I’m going to make an instrument to measure low-pressure vacuums.

Hi Makers, Builders and Do-it-yourselfers. Harley here.

I recently made some changes to my shop vac system and want to quantify the changes to the vacuum’s efficiency. One of the things I need is a vacuum gauge, also known as a manometer. Because I’m thrifty, I decided to make my own.

Since some people find it interesting, I want to start with the theory of operation. If you want to skip directly to the build, you can click here.

There are three types of pressure measurement: absolute pressure, differential pressure and gauge pressure.

Imagine a perfect vacuum. Like absolute zero in temperature, this is an ideal that cannot actually be accomplished, but is useful as a standard to measure from. Now let’s put a container with a gas inside that vacuum. The pressure the gas exerts on the container is the absolute pressure. Or said a different way, absolute pressure is the pressure measured on a scale where zero is a perfect vacuum.

Now let’s put another container inside that vacuum with a different pressure. If we subtract one pressure from the other, we get the differential pressure. Differential pressure is the pressure difference between two systems. If we now connect these two containers together with a U shaped tube and put some heavy liquid in it, like mercury, we can directly measure the difference in pressures. If the pressures are the same, the liquid will be at the same height on both sides of the tube. If the pressure is greater in one side, it will push down on the liquid with more force and cause a difference in the height of the liquid on both sides of the tube. Measuring the difference in heights will tell us the difference in pressures.

Now let’s add a rock that’s big enough to have gravity that will hold onto gas, creating an atmosphere. With our containers next to the rock, instead of being in a vacuum, they are now in this atmosphere. The atmosphere will create a pressure from all the gas above our containers pressing down. Here on earth at sea level, this is about 15 pounds per square inch. If we eliminate one of the containers, the U shaped tube will now measure the pressure inside the remaining container relative to the atmosphere’s pressure.

This is known as gauge pressure. It is the pressure of one system relative to the current atmospheric pressure. For convenience, we set the zero point to atmospheric pressure.

In this context, vacuum and pressure are two sides of the same thing; they both measure the pressure of a gas relative to a known point, in this case atmospheric pressure. Vacuum is simply a pressure lower than atmospheric pressure, or said a different way, a negative pressure.

And this U shaped device is what our manometer will look like.

For this build you’ll need:

A flat mounting surface; I used some left over peg board but it could be a piece of wood or even cardboard if it’s rigid enough. It does need to be moderately long. The longer it is, the higher pressure you can test. I’m making mine about 6 feet long. If it's a lighter color the readings will be easier to make.

Clear tubing. The size isn’t critical; I used some with 3/8” inside diameter and 20’ long.

A means of attaching the tubing to the mounting surface. I used zip ties. If you use wood for the mounting surface, you could also use j-hooks or tubing clamps or anything else to attach the tubing.

Some sort of measuring stick. I used a yard stick but you could use a tape measure or even mark out your own lines with a ruler and marker.

A means of filling the tubing. I used a turkey baster but you could also use something with a small nozzle or funnel.

Some water and dark food coloring. I used blue for high contrast but you can use any color you want, or no color at all.

To make the manometer, start by attaching one end of the tubing close to a corner of the mounting surface. Continue to attach the tubing in a straight line next to the edge until you get close to the other end of the mounting surface. Then create a U in the tube and run it up the opposite edge of the mounting surface.

You should have a long bit of tubing left over. Leave this attached. It is where you will do your testing from.

Attach the apparatus so it’s hanging straight down.

Color the water so it’s fairly vibrant. Again, I used blue to get high contrast, but you can use any color you want.

Pour the water into the tube. The amount of water you use will impact the amount of pressure you can test. If you fill to the half way point of your height, then you have the maximum measurement for the size of your instrument. If everything is setup properly, the water will be at the same height on both sides of the tube.

Attach the ruler so it starts at the top of the water.

Your vacuum gauge is now ready to use.

And it is really easy to use. Simply apply a vacuum to the long end of the tube. The amount of vacuum pressure is indicated by reading how high the water comes up on the ruler and then multiply that number by two. This will give you a measurement in units called “inches of water." In this example I’ve got 7 inches of water.

If you wanted to get real fancy, you could make your own direct reading scale. Just mark off every half inch and label the marks with whole numbers starting with 0. Doing this, you don’t need to remember to multiply by two.

There are websites where you can convert this measurement to other pressure measurements such as inches of mercury or bars or pascals. If you do use other units of measurement, you could mark their values directly on the ruler for convenience.

Depending on your vacuum source, you may need to make an adapter for the tubing. For my shop vac I used a flexible connector and plug found in the ABS area of the plumbing aisle along with a pronged tubing to MPT brass fitting.

I’ll put this to use in a follow-up video for the shop vac system.

In conclusion, I’d love to hear in the comments below what you think about making your own instruments. Is it worth the effort to do it yourself or is it better to just buy something ready made? Am I being too cheap?

Finally, if this is your first time here at House of Hacks: Welcome, glad you’re here. We’d love to have you subscribe. Through these videos I hope to inspire, educate and inform makers in their creative endeavors. Usually this involves various physical media like wood, metal, electronics, photographs and other similar materials. Thanks for letting me encourage your creativity. So subscribe and I’ll see you again in the next video.

Now, go make something. It doesn’t have to be perfect, just have fun!

Thursday, August 6, 2015

How to quickly and cleanly finish paracord ends


Description

Here are two quick tips for making a fast seal and clean finish on kernmatle rope (e.g. paracord) ends. It's common knowledge to use a match to melt the end of nylon rope. In this video Harley shows two alternative tips to seal the ends faster and with a better end result.

For a written transcript, go to How to quickly and cleanly finish paracord ends

Music and sound effects under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod

Transcript


Hi Makers, Builders and Do-it-yourselfers. Harley here.

Today at the House of Hacks I've got a 2-part quick tip for working with nylon cord.

Specifically the kind that has an outer sheath and an inner core; like paracord in this particular case.

Most people know that they can take a match and fuse the ends together by just putting the end in the match and it melts together so it doesn't come un-frayed.

This works well when you have one or two ends to do. I had a recent project where I had a whole pile of them to do and using matches was just going to be too tedious. So, the solution to that is part one: more power.

Oh, yeah.

A torch gives you a lot of heat, constantly. And so when you have a lot of ends to do, all you have to do is put each end in there for a couple seconds, and they melt together, and you're golden. It takes no time at all and you can get through an awful lot of them real fast.

The problem that I've found, and this is where part two of the tip comes in, is when you cut these off square you end up with a lot of fraying on the end. And when you melt that, you end up with a big blob of melted nylon that is kind of ugly and sometimes can get in the way of whatever it is you're working on.

The solution to that I've found is to pull the sheath back to expose the inner core, and you need to expose an inch or two, and then cut off about half an inch to an inch, somewhere in that range, of the inner core.

And now you can pull the outer sheath back over that section and you end up with the outer sheath extending beyond the inner core by about a couple millimeters, an eighth of an inch or something like that.

Now, when you melt that in your flame, the outer sheath shrinks around the end of the inner core, melts everything together, and you end up with a very nice end at the end of the day.

So that’s it for today’s quick tip. Until next time, go make something. It doesn’t have to be perfect, just have fun!

Sunday, April 5, 2015

Bits of Binary: How to subtract binary numbers



Description

Subtraction can be done two ways using binary numbers. This episode talks about unsigned subtraction, very similar to how we do it in decimal notation. We'll dive into the details in this episode of Bits of Binary at the House of Hacks.

Links

Bits of binary playlist
What is binary?
How to count in binary
How to convert between binary and decimal
How to add binary numbers

For a written transcript, go to How to subtract binary numbers.

Credits

Music under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod at http://incompetech.com

Transcript

That may look confusing on the surface, but if you saw the last Bits of Binary episode, it might make some sense. I'll explain it in more detail in this episode of the House of Hacks.

Hi Makers, Builders and Do-It-Yourselfers. Harley here.

This is a continuation in the series on Bits of Binary. In previous episodes I explored the concept of binary numbers, how to count in binary, how to convert between binary and decimal and, in the last episode, I showed how to add binary numbers together. In this episode, I'll show the simple, obvious way to subtract them that's analogous to how we first learned it in decimal. In a future episode I plan to introduce the non-intuitive way negative numbers are stored in computers and how that impacts subtracting binary numbers.

Remember last time when we talked about addition, we looked at these two tables...

Let's remember how we use this with decimal numbers. We'll ignore negative numbers for now so we'll establish the rule that the first number has to be larger than the second. Since this half of the table is the same as this half, we’ll just ignore one side.

When describing the process, we'll use the example 8 - 5.

The process is to first find the entries in the table for the first number. Then, of those entries, you find the one with the other number in the header. The answer is the other header value.

Binary is exactly the same way, just with the much smaller table. Or written as a series of equations, it looks like this.

The first three probably make intuitive sense as they are the same as decimal. But the last one may not be quite so obvious. Remember that in binary the value for two is represented by 1, 0.

If we recall from grade school, with multi-column numbers, when we subtract a larger number from a smaller one, we have to borrow from the next higher column. Let's take for example 21 - 13 in decimal. The units column is 1 - 3. Well, we can't do that, so we borrow a one from the 2 in the second column giving us 11 - 3. This gives us 8. Moving to the next column we now have 1 - 1, giving us 0.

Binary works exactly the same way. Let's look at some examples in binary.

First something simple: 6 - 2. The units column is 0 - 0 equals 0. The next column is 1 - 1 equals 0 again. The final column is 1 - 0, giving us 1. This gives us an overall result of 100, or the value 4.

Now let's do something with some borrowing: 6 - 3. The units column is 0 - 1. We can't do that so we're going to borrow a 1 from the next column. Now we have 10 - 1 giving a result of 1. Because of the previous borrow, the second column is 0 - 1. So again we borrow from the next higher column giving us 10 - 1 with a result of 1. The final column is 0 (because of the previous borrow) - 0 giving us 0. Overall, the result is 11, or a value of three.

And that's it. Subtraction is a bit more complicated due to the borrowing, but again, it's a known concept just applied in a slightly different way.

Thanks for watching this episode of Bits of Binary. As I mentioned earlier, a future episode will explain how negative numbers are handled in a computer and a less-intuitive but ultimately easier way to handle subtraction. But in the next episode, I'll look at multiplying binary numbers together.

I've created a playlist over here that will be filled in as more episodes in this series are added.

If you liked this, let me know with a "thumbs up.".

If you have any thoughts or questions on this topic, I'd love to hear them in the comments below.

If you're already a subscriber, "thank you!" and if you haven't done so already, be sure to "subscribe" so you don't miss future on topics such as this one, high-speed photography, making a digital computer with 19th century technology and much more.

Until next time, go make something. It doesn't have to be perfect, just have fun.

Saturday, February 21, 2015

How to easily read a histogram


Description

The camera’s histogram can be intimidating if you don't understand it, but it's actually really simple. In the first of a short series, Harley introduces this powerful tool to facilitate photographers' quests for the perfect exposure.

For a written transcript, go to How to easily read a histogram

Music and sound effects under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod

Photo credits for Creative Commons license 2
Illusive Photography: Photo
Alessandro Valli: Photo

Sound effects credits for Creative Commons license 3
fasten: Slide projector
VlatkoBlazek: Mechanical Whirring
leosalom: Fire

Transcript


[Click]

Besides the basic controls for making an image, I find the histogram to be one of the most used features of my digital camera. Today at the House of Hacks I'm going to explain what it is and the meaning of what it shows.

[Music]

Occasionally I work with people in photography related teaching situations. Many times I've found individuals trying to evaluate an exposure based on the preview image on the back of their screen.

This is a really bad idea. Chimping is great to evaluate the composition and relative exposure but there are many factors that control how the image is displayed that make it a poor representation of the actual exposure.

The histogram is a powerful tool in the photographer's arsenal to evaluate an image for proper exposure. And it's one of the few features that can't be duplicated on a film camera.

The closest we can get in the film world is an exposure meter. But in the digital world, the histogram provides a whole lot more information. In this episode, my goal is to explain the basics of what the histogram is and the meaning of what it shows.

In future episodes I plan to show how to use it when making an image. They'll be added to this playlist when they're posted.

Simply, the histogram is a chart showing the various brightness levels of an image. The left side of the x-axis represents black and the right side represents white. The values in between are levels of gray from dark to light. The y-axis represents how much of the image is at each value on the x-axis.

Let's look at some simple examples. To make things a bit easier, let's visit an alternate universe.

[Finger snap]

In this world, things are much more pixelated with higher contrast and fewer colors so our histograms can be smaller. When the sun goes down everything goes to black and white and a couple shades of grey.

Here's a nighttime image. Let's construct a histogram for it. First, we'll draw the x- and y- axes.

Since our image only has four values, black, white, dark grey and light grey, the x-axis has four points.

First we count the number of black pixels. Then we draw a bar that high.

Then we count the number of dark grey pixels and draw a bar that high.

We continue the same process with light grey and white.

And there we have it. A histogram for this image.

Let's change the image a little... and see how it changes the histogram.

More grey in the image increases the grey column of the histogram and decreases the white side.

Here is the same scene during day... with it's histogram.

A color image can be treated as a black and white image, with many shades of grey.

In this case, the histogram just has more grey levels on the x-axix.

Let's look at a couple generated images to get an intuitive feel for how the image impacts the histogram.

Previously I've shown simplified histograms with just the number of items on the grey scale x-axis as there are in the image. From now on, the histograms will be configured to have 256 values on the x-axis from black to white.

This black and white image gives us two bars in just the black and white columns on the two edges.

This black and white image gives us the same histogram because the relative amount of black and white portions of the image are the same.

It doesn't matter how we divide this up, as long as we have the same number of black and white pixels, the histogram remains the same.

Similarly, if we have this black and white image with one-third of the image white and two-thirds black, we can see the black side is twice the size as the white because we have twice the number of black pixels.

And again, we can divide those pixels up anyway we want, but the histogram doesn't change.

Now let's look at this gradient image.

Its histogram is a straight light.

Does this surprise you?

If we look at the image, we have a black band and a white band and all these grey bands that are the same size. So the graph reflects this with a straight line.

If we move the black and white start points, then the histogram will have taller ends with a dip in the middle.

But if we move the black and white start points off the image, then the histogram will shorten on the ends and rise in the middle.

[Finger snap]

And the default histogram on your camera works exactly the same way. Each image is treated as black and white and then the histogram constructed from that.

I don't know about all cameras, but all my Canons have two types of histograms: luminance and RGB. The luminance histogram is a single chart that shows the combined luminance values for the overall image. The same thing as what we’ve been looking at here.

The RGB histograms work exactly the same way except there are three charts showing the intensity in each of the color channels.

The default is to show the luminance but it can e changed to the RGB histogram by changing a custom setting in the menus.

This can be useful in situations where you have colored lights or part of your image that is more predominant in one color than the others. In these cases, one channel might become overexposed but it won't be obvious in the luminance histogram. However, when you change to the RGB histogram it becomes quite obvious.

And that's how you read a histogram. The left side shows how much black you have and the right says how much white you have and everything in the middle indicates shade of grey.

In future episodes I plan to show how to use this information while making an image and what it means to shoot to the right. If you want to be notified when that, or any other maker related episodes, are released, hit the subscribe button.

Thanks for watching. If this helped you, I'd appreciate knowing about it with a "like." If you have any other questions or other comments, I'd love to hear them in the comment section below.

Until next time, go make something. It doesn't have to be perfect, just have fun!