This is awesome.

http://www.washingtonpost.com/news/speaking-of-science/wp/2014/12/17/meet-derby-the-dog-who-runs-on-3-d-printed-legs/?tid=hpModule_9d3add6c-8a79-11e2-98d9-3012c1cd8d1e&hpid=z11

cool.

https://makezine.com/2014/12/03/3d-scanning-and-printing-the-president/

Projects

Here is what I see happening right now (more or less):

- electric cello (Nina)
Up and running.  Neck soon to be ordered.

- multi-Theremin (Abram)
Parts to be ordered soon?

- Go-cart and/or moped rebuild, etc.
Scour Craigslist for good rehab candidates.

- Space launch
Research/read what other people have done.  What equipment is needed?  GPS?  Etc.?

- 3D print yourself
Find the appropriate app/program.  Read and prep.

- Solar panel
Read/research.  What do we need to buy/order?

- Solar charger
This?
http://www.instructables.com/id/portable-20w-solar-charger/

- Bike/blender
I haven't seen this up close before.  It seems as though the hardest element will be connecting the back sprocket to the blender and converting the vertical sprocket motion to a horizontal one for the blender.  This isn't exactly trivial, particularly since the horizontal sprocket will need to be connected well to the blender.  See what others have done.

- Hovercraft/Drone
There are lots of Make-type articles on this.  Shouldn't be impossible to follow.

- AI Chess engine (Ben?)
Very much out of my expertise.

- Rockets
Lots of ideas here:  using large (E, F) engines, using on-board camera and other instruments, using/making a wind tunnel (see plans online), using wind tunnel apps (there's a great one for the iPad), and so forth.  Look into Apogee Rockets (http://www.apogeerockets.com/) for other ideas like high-powered rocketry.

- Guitar (Danielle)
Decide on body shape and wood.  Will you start with a "body blank" that has already been routed?  Once the body is ready and routed, the electronics and neck are relatively straight-forward installs.  If you're making pickups, that just takes a little time.

Other ideas?

Laser build
Wind turbine
Cost analysis on how to convert the campus to wind/solar/etc.
Electronics project and/or Arduino
Raspberry Pi
Weather station (an idea from sophomore Aaron E.)

Here are some cool things worth a look - either for projects or just fun:

http://www.instructables.com/id/Interactive-LED-Programmable-Canvas/

http://www.instructables.com/id/Recycled-Hard-Drive-Clock-FuneLab/

http://www.instructables.com/id/Easy-Build-Burning-Laser-For-Less-Than-20/

Theremin related:

http://makezine.com/video/play-that-funky-tune-with-weekend-projects/

Code etc.

Here is a download link for code for several Arduino projects in the Sik guide:

sparkfun.com/sikcode

And the guide is here:

http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Kits/SFE03-0012-SIK.Guide-300dpi-01.pdf

Tuesday

Gang:

I'll be in a bit late this morning - around 11:20 or so.  Please get to work on some Arduino and/or electronics stuff.  Around noon, Hannah Block will visit to chat about her project.

You can use the handout I gave last time - maybe start playing around with push buttons on a separate boards, to control the LED.

If you haven't yet seen it, this (the Sik manual) may be useful:

http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Kits/SFE03-0012-SIK.Guide-300dpi-01.pdf

File under: Pretty Cool

http://gizmodo.com/the-british-museum-will-now-let-you-3d-print-copies-of-1654077136

Circuit practice

Blinky!

HW

Sorry for delay -please solve this circuit

Intro electronics manual

Located at:

goo.gl/l5Mzpi

HW, and intro to bridge designer

Read chapter 12 - or at least start reading it.

Bridge Design – Using West Point Bridge Designer

Now that you have at least a little understanding of how trusses work, it’s time to play around with some bridge building. The United States Military Academy—hereafter referred to as West Point—has been running a Bridge Design contest for high school and middle school students for more than 10 years. Students design a bridge that must satisfy certain specifications, while minimizing the overall cost. Cost is, of course, a real-world concern since materials and labor cost money. While we will not be entering the West Point contest, we can use the software to play around with bridge design and learn, we hope, some more about some basic engineering principles.

The link below is to the website where you can find the bridge design software. After you go to the website, you should see in the middle of the screen a link to the download area. Once you get to the downloads area, read carefully so that you’ll pick the correct link for downloading (basically, you need to know whether your Macintosh computer has Apple Java). After you install the software come back to this document.

http://bridgecontest.org

There’s a 26-minute video tutorial that you can view at the bridge contest website. You can find it under the “Resources” tab at the top. After going through this video, you’ll need to learn one more thing about the program, so open up the program and load up the sample design for the continuous arch. Select one of the members—remember that a “member” is a bar or cable. On the right side of the screen you should see the member you selected highlighted in blue. At the top of that window where the member has been highlighted is the tab “Member Details”. Click on this tab. You should now be seeing more detail about this particular member, including information regarding the member’s material properties, dimensions, and cost.

1.     As a check of your understanding, find the member numbered 10 and write down its mass density, moment of inertia, and member cost.

2.     Start up a new bridge design in the program.  Try to design a bridge that doesn’t look exactly like one of the pre-loaded designs. Make sure to test it out so that it will pass the load test. Lastly, print out a copy of your design.

Project to start next week:

Now, build a truss-style bridge, either based on this design or an entirely different one.  You will use basswood and gusset “plates” made from manila folder material.  We will test it to failure using a method described in class.

HW

Solve for the practical lab problems completed in class - do the "left torques" equal the "right torques"?  Don't forget about the mass of the meter stick.

Reconsider the scaffold problem.  You have a 4-m long scaffold (60 kg), supported by cables at the extreme ends.  Two workers are standing on it:  Jack (75 kg, 1-m from the left) and Jill (65 kg, 2.5-m from the left).  What is the tension in each cable?

Have a look at the ladder problem in the student guide.  Note that there is an error in the text.  Under rotational equilibrium, it should actually say:

Rotational equilibrium:

W (L/2 cos q) = F (L sin q)

Note the change from L to L/2 --- this is because the weight of the ladder acts through its center of gravity.

Try to make sense of the ladder problem and solve the one in the homework if you can.  I'll post a solution before class meets again.

Sean out today. Try these.

HW

Read the notes on static equilibrium in the student guide - particularly the painter/scaffold problem and ladder problem.  Also, start reading the text chapter on civil engineering and bridges.

cross product HW

A = 20i + 3j - 12k

B = 12i - 4j + 5k

Find:

magnitudes A and B
dot product
angle between
cross product of A X B
cross product of B X A

Feel free to use the matrix/determinant method for the last two problems.

Review the right hand rule for problems like:

i X i
i X k
North X West
etc

HW for Tuesday

Two vectors:

X = 4i - 5j + 9k
Y = 10i - 12j + 3k

Find:

X + Y
X - Y
X  (magnitude)
Y (magnitude)
dot product of X and Y
angle between X and Y

Read ahead in the student guide through cross products.  Note the differences between the cross product and dot product.

Also recall the dot products of:  i dot i, etc., and i dot j etc.  Note how they differ in the cross product.

the faux lab

Solve the 3 problems thusly:

1.  The equal tension "stoplight".

Break the tensions into "vertical" components:  T cos (theta) each, where theta is actually half of the angle you measure.

Solving this:

2 T cos (theta) = W

See how closely the left side of this equation (with your values plugged in) matches the right side.

2.  The unequal tension problem.

Similar to above:

T1 cos (theta 1) + T2 (theta 2) = W

Also:

T1 sin (theta 1) + T2 sin (theta 2)

See how closely the left side of this equation (with your values plugged in) matches the right side.

3.  Using the angle and weight designation from the board (where angles are measured with respect to a "horizontal" axis, it should be true that:

"Lefts" equal "rights"

W1 cos (theta 1) + W3 cos (theta 3) = W2 cos (theta 2) + W4 cos (theta 4)

and

"ups" = "downs"

W1 sin (theta 1) + W2 sin (theta 2) = W3 sin (theta 3) + W4 sin (theta 4)

Pictures forthcoming.

vector problems to play with

1.  Find the resultant of these vectors:

a.  You ride your bike 12 km north, then 7 km east.  Find the displacement from your starting point (magnitude and angle).

b.  Two force vectors (100 N and 250 N) are separated by an angle of 40-degrees.  Find the resultant vector of these vectors added concurrently.

c.  If you have a stoplight weighing 75 pounds, hanging between 2 cables of equal length but separated by an angle of 100-degrees, what is the tension in each cable?

d.  Bonus, if you're interested.  In c above, show that the tension goes to infinity as the angle increases to 180-degrees (perfectly horizontal cable).

2.  Find the perpendicular components of a velocity vector (40 m/s, at 20-degrees with respect to horizontal).

3.  Add these three 3-d vectors together:

A = 4i + 6j - 10k
B = 2i - 15j + 32k
C = 11i + 8j - 16k

Also, find the magnitude of this new vector (A + B + C).

Finally, play around with Sketchup by next Wednesday.  If possible, create something and take a screen-shot of it to print and bring to class.

Sketchup time!

Google Sketchup

For our CAD platform, we will use Google Sketchup.  You may find it online  (http://www.sketchup.com/) and download the free “Make” version.  Alternately, use a school computer equipped with it and start to play around.

If you find Sketchup too limiting, feel free to try one of the many available alternatives.  See this article, for example:

http://www.makerbot.com/blog/2011/02/25/3d-design-software-101/

Run the video tutorial 1.  Here are things to keep in mind:

v Pick a template.

v Be mindful of the (default) units.

v Choose your starting views (ISO, or isometric is great for 3D).

v Get used to “click and release.”

v Get used to Edit (undo).

Start drawing – note the dimensions and scale.

Also note these features:

v Inference points

v Push/pull tool

v Eraser

v The flexibility of using a 3 button mouse (scroll, to change viewing size)

v Orbit

v Pan

v Rotate

v Move tool

v Shift and mouse

v R G B axes (for alignment)

After you are sufficiently comfortable making designs, go through the other tutorials at your leisure.

Your first project is to do a mock-up of a building (your house or a favorite structure), to scale and (3D) printed.  Take photographs first and work from these.  The 3D print process will be described in class.

HW

Skim chapter 1, and read as much of chapter 2 as you can.

Thanks!

conversions etc. - play with these.

Unit Conversion

AKA Dimensional analysis (factor-label method)

Ideally, this will be a stroll down memory lane – converting from one unit to another.  Let us look at an conversion example:

m                     mile

 

sec                   hour

We are trying to change meters to miles and seconds to hours.  We could reason through each, multiplying or dividing as necessary.   However, if this is approached carelessly, it is easy to make mistakes.  Look at this methodical approach, wherein we multiply by conversion factors.  Note how the numerators cancel with denominators, leaving us with the desired units (and multiplication factor).  Also note – and this is the beauty of the endeavor – you’re really just multiplying by 1 with each factor.

m         km                   mile                 60 sec             60 min                        =          2.24 mile

 

sec       1000m            1.609 km        1 min              1 hour                            hour

Use this technique to make the following conversion factors:

m/s à furlong/fortnight

mile/gallon à km/liter

gallon/minute à cubic meter / day

parsec/century à ft/sec

cm/minute à Park/Kardashian

·         Park is an unofficial unit equal to the approximate length of our campus (2750 feet), and Kardashian is equivalent to 72 days (or marriage).

Related problems, some of which may require orders of magnitude estimations:

1.  How many times will you blink in your lifetime?

2.  How many rotations does the average tire make in its lifetime

3.  How long does it take a photon of light to orbit the Earth once?

4.  How many hairs are on your head?

5.  If all people in the world were gathered at once, how great an area is needed?

6.  How many gallons of paint do you need to paint the roof of the athletic center?

7.  How long should it take a spaceship to reach Mars?  Alpha Centauri?