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Showing posts from 2019

Precise Cutting of Heavy Brass Tube

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I had a need to make bearings out of a brass tube and each piece had to be within a thousandth of spec. I had a brainstorm to use my ShopBot CNC as a measuring device and came up with this contraption.

The rod is 1/2" diameter with a 1/4" inside diameter.
The multitool is level and square to the machine and locked to a piece of 2x4 by landscaping tape and hot glue. Not exactly a permanent fixture but good enough for the job.
To actually cut the rod, I used the keyboard function, "D" set at 0.001" and set the zero position within 0.02" of the multitool blade. Then I just arrow keyed the tube into the rod with the RPM's at 6,000. The wire runs up the tube a short distance and catches the rings as they separate.
To repeat, I move Y to zero, zero Z and lowered the Z to the desired depth for the next cut.
I made a couple of test cuts to calculate kerf and see how good the cut quality was and then subsequent cuts were good. I needed 12 at 0.250" and 4…

Copying a Profile Using Liquid Urethane Foam

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I needed to copy the basic shape of a part of my car so I could work with it without damaging the original. It's part of the rollbar which is covered in leather. If I had a fancy scanner and 3D printer, I could have easily done this. Instead, I did it the manual way using aluminum foil and liquid urethane foam.

Liquid urethane foam comes in two parts that are mixed together in equal measures. The amount of rise from the foam is dependent on the weight per cubic foot. The range of densities goes from a very light half pound per cubic foot to a very hard and dense sixteen pounds per cubic foot and even more. The more dense the foam, the harder it is and the more abuse it will take to damage it.

Once mixed, the foam rises very fast, in the order of a few minutes, and then sets to a very hard material in about twenty minutes total. While it is rising, the foam itself exerts very little force on the material constraining it if it is allowed room to rise completely. Constraining the fo…

Four Sided Machining With an Indexer

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I'm working on a project that requires hundreds of precisely machined components. Most of them can be produced easily from sheet stock or scrap lumber using 2D cutting methods. A few I've made by hand as they were just a one off.

One part I need for the project, a piece about nine inches by three inches by one inch thick, is machined on four sides. The shape is a trapezoid, or more correctly, a parallelogram with two sides offset by six degrees. Two nearly vertical slices chopped out of one side are also offset by six degrees. Various holes are drilled for pegs and other things. It's also 3D shaped on the top and bottom (three inch sides).


The problem with multi-side machining is registration. A part is accurately registered if it is placed on the machining bed exactly in the place it should be. Knowing where the part is physically located is critical when attempting to machine it. The machining tool has no idea what is where. It only knows what to do. If the part isn'…

First Day at IO 2019

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This picture pretty much sums up my first day at IO 2019:
Why? Because I brought these back to the hotel. The capsule is a headache killer and the large circular one is a Tums. So IO day one was pretty smooth, no headache and the food didn't cause me heartburn.

Great sessions and information. Going to take a while to digest it all.

Inside IO:

Funny Story

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I recently went through the PreCheck line at an airport and instead of the usual thirty second security screening, they singled me out because they wanted to check my nuts. The officer implied they exceeded tolerance and wanted to check my "bag". Naturally, I complied like any citizen would and when the officer was satisfied that my nuts, although excessive, were no threat to the flying safety of the general public, he left me with my nuts on the examination table without so much as a goodbye.


PVC Schedule 40 Flexible Pipe

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Anyone who has had to use numerous fittings to connect two pieces of PVC pipe will love the new Schedule 40 flexible PVC pipe. There are a lot of really great reasons to use this innovation in PVC piping:

1. It's virtually unbreakable. Unlike rigid PVC pipe, flexible pipe can withstand a lot of tortue before failing.

2. Instead of using numerous fittings to connect two pipes together, flexible pipe can be connected with nothing more than standard couplings.

3. Water will flow better through a complex join between pipes using flexible PVC since there are no sharp bends like elbows.

4. Even though flexible PVC is more expensive by the foot, it can be cheaper to use since the installation of this material is far simpler since fewer fittings are required.

5. Less fittings means less chance for mistakes and leaks.

The only drawback to flexible PVC that I can see is that it costs more per linear foot than rigid PVC.

Some pictures of this material in use:

Home Depot sells this stuff onli…

Zip Code Boundary Maps

In 2005, I wrote one of my first custom mapping projects using the recently released Google Maps API. It was a fairly crude map that used the Census Tiger ZCTA's (Zip Code Tabulation Area) to display a representation of a Zip Code area. Matt Cutts, at the time, a major player at Google in search, wrote a blog post called "Fun with Zip Codes" that caused my site to get an average of 70,000 unique visitors a day for about a week.

The traffic that Matt's blog post caused made me consider that there could be a market for this type of site so I looked deeper into the issue and learned a number of interesting things.

The most important thing I learned was that Zip Codes are not areas. They are delivery routes. The USPS draws these delivery routes based on the efficient delivery of mail and nothing else. They can cross city, county and even state lines if it means the mail gets delivered efficiently.

Not every address in the US has a Zip Code. This is not obvious for people…

Google AI-powered Doodle

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Today's Google AI-powered Doodle was fun and entertaining. It's a tribute to Johann Sebastian Bach and allows the user to create their own harmonized tune with the harmony created by AI. Very cool!

Interesting video explaining how it was created: https://youtu.be/XBfYPp6KF2g

The entire story: https://www.google.com/doodles/celebrating-johann-sebastian-bach

Here's the one I created: https://g.co/doodle/uurrb3


Hawk Likes our Bird Feeder

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We've had bird feeders in our yard for many years. Sometimes as many as fifty birds might be enjoying them at once. All that activity has drawn more than birds. Squirrels, chipmunks, opossums and raccoons show up regularly too.

Then there are the predators.  Cats are most common. They are either strays dumped in our neighborhood or callous neighbors who let their cats roam freely. They usually don't stay around too long as they get squashed in the road by passing cars. I guess that's a Darwin moment for the owners.

We also get the natural predators and one seems to have become quite bold.


This hawk has been around for quite a while. When he's (I don't know if he is a he or she but I call him he) in the trees waiting for a meal, I can walk right by and he just looks at me. I've seen him take birds, usually doves, when they are in the driveway pecking at seeds on the ground. He'll swoop down and in a flash, the bird is gone. I've found evidence that he…

Flyers in the Mailbox Without a Stamp

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Pretty much everyone has found a flyer in their mailbox from someone who drove by and physically placed it in their box. This is sort of a right of passage for the young and jobless and also those industrious individuals starting a new business like window washing or lawn service.


The problem with people using your mailbox as an advertising vehicle is that it is against US Federal Law and US Postal regulations to do so.

These folks might have nothing but good intentions, however, they can also be using this as an excuse to steal your mail. That is why it's illegal.

Here's the actual statute from the USPS:

https://about.usps.com/news/state-releases/tx/2010/tx_2010_0909.htm

From the link:

“We know many customers might not object to having a particular item placed in their mailbox from time to time, but the reasons for restricting use of mailboxes is really two-fold,” said Postmaster Keith Jackson. “First, if there is not enough room in a mailbox due to unauthorized items, the P…

Best Sandpaper for Hand Sanding

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I do a lot of finish sanding on every project. A lot more than I'd like to do. It's impossible to get around and having the right bit of sandpaper for the job takes a lot of the pain and suffering out of the task.

My old favorite was just a piece of standard sandpaper folded in half. That works reasonably well except that the paper has no strength and can bunch up and crumble into a wad pretty easily. It also wears unevenly and cannot be washed or cleaned effectively.

I stumbled onto my new favorite by accident. I was looking for a tough sandpaper with an adhesive backing to make a long (6 foot) sanding block. I needed this for finish sanding edges of stock for glue up. A final edge sanding removed any gaps or bows in the work and makes for a much better job.

I bought a roll of Porter Cable resin coated sandpaper for the task and it worked great. The roll is 4 1/2" wide by 30 feet. Lots and lots of sandpaper. A lot more than I needed for my project.


The comments for this …

Catherine in Concert

My daughter Catherine playing a small piece of Vivaldi's Spring during her school's "Lausannia" concert.



The Saturn 1B Story

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This film from NASA is an interesting bit of history and nostalgia for an age gone by when government programs had the "can do" spirit instead of the "better not do" as in today.

https://youtu.be/pwOF57LidFM


This Person Does Not Exist

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Amazing process created by NVIDIA to produce extremely realistic looking fake pictures.
Video:
https://youtu.be/kSLJriaOumA



Website:
https://thispersondoesnotexist.com

Each time the website is refreshed, a new, never existed human is produced.

Too Funny

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Ok, so the subject is controversial and the topic isn't funny, but this meme is.


RadarNow! Milestone

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Today we reached a perfect 4.500 rating for RadarNow!. It has shown in the Google Play Store as 4.5 for quite a while but now, we've got a 4.5 with no rounding. Yay!


Google Opinion Rewards

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When I first started using this app and taking their surveys, I thought it was kind of silly and maybe a waste of time. Turns out to be quite a valuable little app. I've earned $260 so far answering surveys that take a few seconds.

https://play.google.com/store/apps/details?id=com.google.android.apps.paidtasks&hl=en_US


Phishing 101

This test is one that everyone needs to take and fully understand. If you can't get 8/8, take it again until you understand all the cases perfectly. Many people get tripped up by these fakeouts.

https://phishingquiz.withgoogle.com/

Ring Thunder

One of the cool things about the Ring video doorbell is that it captures video all the time and when motion is detected, records not only from that moment, but for several seconds before. Here's a video of lightning and thunder that happened this evening (January 18th).


Debugging a Three Way Switch

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We had a number of three way switches in our house that didn't work when we moved in. In fact, not one worked right. Whomever wired the house back in 1986 either didn't care or didn't know how to hook them up correctly.

If you're not an electrician, or are not familiar with their standardized technical terms, the troubleshooting guides available might be confusing or useless. The information that comes with the switches seems to be the same. After pondering this issue for a few minutes the answer presented itself.

1. The "common" wire is either the load (to the light) or the hot wire (from the breaker box).

2. A "traveler" wire is just a wire that only connects to the switch. It doesn't lead to the load or the breaker box.

To identify the "common" wires, the simplest method is to disconnect the switches and use a voltage detector pen (such as a Fluke VoltAlert Non-Contact Voltage Tester) to find the hot wire. Once the hot wire is locat…

Cool Picture

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This is a picture of condensation on the inside of a lid on a pot of crab legs cooking on the stove. The water is seconds away from boiling. Crab legs.... yummy.