Fun

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New Toys: EzMobile

I have a theory that it’s the adults that think the fancy plastic toys are somehow cooler than their simple counterparts.  Kids on the other hand are using their imagination (at least should be), and don’t really care how pixel-perfect it is.

My theory was verified when 5 minutes after taking this photo, Ezra flew a $15 toy helicopter past me with this little EzMobile guy hanging out the door  :)

 

 

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A new stock for rubber band gun #6

In anticipation of receiving the assembly for Rubber Band Gun #6 from Dixon Tool and Die, Inc., we have been making a new rubber band gun stock to complete the package.

This stock was hand crafted out of solid 1.75″ x 6.0″ x 48″ slab of maple.  The primary tools were bandsaw (for the profile), hammer and chisel, random orbit sander, end mill, jointer, sand paper, and lots of elbow grease.

There is a technique that we implemented called “raising the grain”.  It involves rubbing the wood with a wet rag, and then letting it dry.  Loose pieces of grain swell up and in turn raise up out of the wood, where they can be sanded off.

At the bottom-left corner of this photo, you can see another blank ready to be cut.

A lot of thought and testing went into this simple design and it works really well.  The catch (no pun intended) is to allow the rubber bands to release cleanly with no interference.

Here is Mr. E holding the shop-vac to keep the end mill from clogging up.  My Sherline milling machine is not large enough to hold this stock conveniently, so we used a drill press and cross-slide vice to mill it out.  Drill presses are not as rigid as milling machines, so we had to take it slow.

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Melting table salt in a red hot spoon.

We were using a bunsen burner hooked up to a propane tank to heat a spoon, and the salt in the spoon, red hot in order to melt the salt.

According to the wikipedia article on salt, the melting point is 1474 °F.  See further comments after this picture…

Melting salt in a spoon over a propane burner

It took a while, but we did get it to melt.  I “poured” it onto a metal surface, and you can see it still glowing here:

And for reference, here is what a Sodium Chloride crystal looks like up close:

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Making a “working” toy shotgun

Some time ago, Eli asked me to build a toy shotgun.  We wanted something that would give a real “bang”, but be simple and safe.

Provided that a large mass of metal was collided into another at sufficient speed, the user would experience both a “bang” and a “kick” (although inverse).

We milled, drilled, and fit a bolt into a square aluminum tube.  A spring connected the front of the bolt to the front of the tube.  When the bolt was retracted and released, it would collide into the square tube with the desired effect.


The end result is here:

And, enjoy the pictures.

 

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A big measuring tape and a right triangle

Just a good picture of Eli (with Ezra and Anna in the background) holding a 300′ measuring tape.

We needed to make a right angle, so I explained to them that a triangle with the sides

3, 4, 5

will be a 100% right triangle.  So we measured 15′, 20′, and 25′ around three stakes, and that is how we got our right angle :)

For anyone who has been out of high-school long enough to forget, the equation is:

A*A + B*B = C*C

That is…

3*3 + 4*4 = 5*5
9 + 16 = 25
25=25
True

See more about Pythagoras and his Pythagorean Theorem at Wikipedia…

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Rubber Band Gun #6 – springs, etc…

I visited Dixon Tool and Die, Inc. today to see about having some machining done.  Bill Dixon Jr. was very helpful, and explained many of the points that will make the process go easier.

  1. Design for available parts and sizes
  2. Buy everything you can stock (pins, springs, aluminum channel, etc…)
  3. Minimize milling by doing the above

To that end, I did a bit of springy research, and found that neither McMaster Carr or Manhattan Supply Co. had really small springs in bulk (only precision (eg expensive) springs in those sizes).

So I re-placed one of the pins to fit a standard (cheap) McMaster spring, and got pricing from http://centuryspring.aitrk.com/products/extension.html for a special spring.  The trigger spring has ~ a 2/1 leverage (finger/spring), so we need to have several lbs of spring pull to equal a decent trigger pull.  They have a spring with these dimensions:

Part #80127
Diameter: 3/16″
Rest: 0.63″
Max Travel: 0.39″
Load at max: 3.9lbs
ID of loops at ends: .132
$1.20 each at 100

While $1.20 is more than I wanted to pay, it sure beats $2.00 to $3.00 per spring that I was looking at from McMaster.

With a shorter spring, I was able to re-design the pin placement, which resulted in this: