Aaron's Blog – Page 20 – My mental shelf

Writing a “math” book…

So I have this nagging desire to write a math / puzzle book. I had a really hard time with math in high school and early college since I think about problems and how to solve them very differently from most people. After about your freshman year of college people don’t really care how you solve problems – just that you can solve them. So I have always wanted to go back and write up math book for young minds that provides some tools for solving problems that had I known them would have made my life a lot easier.

Not sure if I am actually going to write the book – but I decided to collect 80-100 problems and write-ups on how to solve them and then decided. This section is for collecting my general thoughts on how the book. Could be structured.

Koei-Kan

Penan Sandan Kata

Only got the first 10 moves or so of this kata the other night at the dojo. Since I am about the slowest person at the dojo for learning kata I am going to start keeping notes. It should also help capture the subtle comments that sensei only makes every once in a while.

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Pictures of my “new” lathe in better light

Post author By Aaron
Post date January 24, 2010
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So I had to wait until daytime to take some better pictures of my lathe. Unfortunately I was using my iPhone, which means I got like 2 pictures that were OK for the 10 I tried to take. I really need to buy a real camera. And just to be clear I was not using the hammer to adjust anything on my lathe!

The integrated gearbox quick-change gearbox means I can cut threads on this lathe – which I am fairly excited to try. Yeah, I need to get out more. I am thinking the stand will also give me a nice place for mounting the DRO hardware (a digital readout that tells me where the cutting tool is currently positioned).

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My “new” lathe

Well, today I went and got a “New” lathe. Actually, as close I can figure it is from the late 60s – but that still makes it about 20 – 30 years younger than my other lathe. It is a Craftsman 12”x36” – like these.

I was already looking to add a quick change gearbox to my older Atlas lathe, and build a stand for it. So when I saw this one come up on craigslist I figured I would break even over upgrading my old lathe if I can sell the old one for a decent price.

Looks like I will need to make a new motor pulley, and replace the headstock bearings soonish – but I am kind of excited.

Here you can see the lathe wrestled into the corner of the shop. Joel came over and bailed my ass out big time. It was clear I would have dropped the lathe and maybe screwed up my truck the way I was planning on moving it if none of my friends could come over.

Shop

Wire rack

Helping my friend Joel move I noticed this wire rack in the corner. He said he just threw it together to hold all the different spools of wire he was using on a car rebuild he was doing. I really liked the design. I use a hanging rod to hold my wire at the moment but think I will replace it with a rod held by a wooden rack like this.

Workbench

Adding a leg vise to a cheap Grizzly workbench

Post author By Aaron
Post date January 16, 2010
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Since I cant afford the time or money to make or buy a cabinetmakers workbench I decided to improve the Grizzly bench (H7724) I already had. I already added a plane stop – so the next thing to add is a leg vice. I already had two of these benches in the garage – so I am steeling the vice hardware off of one of the benches to make the leg vice.

The first thing I did was to attach a 2×10 to the leg of the workbench. This will act as the base for me to build out one leg of the bench so it is big enough for a leg vise. I used the plane stop to plane down stock from the lumberyard so it was flat and without twist. Then I roughed up the leg of the workbench and glued the board to the leg. I used woodscrews to help secure the board to the leg.

Once the glue had dried I came back and glued another flattened 2×10 to the first. The combination should give me a solid foundation for the leg vise. I also made sure to plane down the second board so that it was flush to the edge of the table

And now to wait for the glue to finish drying…

Projects Woodworking

Adding a plane stop to a cheap Grizzly workbench

Post author By Aaron
Post date January 15, 2010
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Grizzly sells a really nice bench with lots of drawer space. I already had two of these benches in the garage – and rather than buy or build a cabinetmakers workbench I decided to improve the bench I had and use it until my woodworking projects outgrew it.

The first thing I wanted was a plane stop. The stop is basically a board that sticks up proud of the table surface by an adjustable amount. Here you can see a profile of the stop.

The stop attaches to the end of the bench by two bolts. I milled slots in the stop board to allow it to slide up and down. The board is held in place by friction and adjusted by a quick light taps with a hammer. I have some ideas for a screw lock for the stop – but so figured I would use the friction adjustment first and it seems to work great.

Below you can see the stop in use. A board rest against the stop so the length of the board can be planed right out over the edge of the board. This is useful for thicknessing stock by hand.

Calculus Math

Find the rate problem

Problem 179 from http://mathproblems.info/group9.html

A drag racer accelerates at a uniform rate from its starting point. It travels the last one fourth of the distance from the starting point to the finish line in 3 seconds. How long did it take to travel the entire distance from starting point to finish line?

Puzzles

Find a buiried cable digging a trench

Post author By Aaron
Post date June 24, 2009
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Problem nummber 110 from http://mathproblems.info/group6.html

There is a straight cable buried under a unit square field. You must dig one or more ditches to locate the buried cable. Where should you dig to guarantee finding the cable and to minimize digging? For example you could dig an X shape for total ditch length of 2*sqr(2) but there is a better answer.

Solution….

continuing…

continuing…

Weighing Problems

12 ball weighing problem – find the fake

Post author By Aaron
Post date June 24, 2009
1 Comment on 12 ball weighing problem – find the fake

Problem 85 from http://mathproblems.info/group5.html

In front of you are 12 pearls, 11 being real and one fake. The real ones all weigh the same and the fake one differs in weight from the real ones (may weigh more or less). With a balance scale and three weighings how can you weed out the fake one and determine whether it is too heavy or too light?