Swell Ideas
Spirograph Design for CSWP Contest
I’m going SolidWorks World next week and I’ve been told that the CSWP event on Monday night should be a good time. I remember seeing details about last year’s event where everyone got to play with the iCoaster. It looked cool. This year everyone gets to test drive an RC car. I’m not very good with RC cars, but there’s a design contest too. That’s something I can do.
The Problem: design a new wheel in SolidWorks for the SC10 RC car.
The Rules: Points will be awarded in these key areas: 1) Is the wheel designed and supplied in SolidWorks format? 2) Is the wheel rendered and/or animated in a cool way? 3) Is the wheel construction feasible? (decided by Team Associated engineers/designers)
The rules seem a bit awkward to me – the company obviously wants some free design work, but I want to have some fun. My best designs come when I ignore the Rules and just get creative (notice I said “ignore” and not “forget” – eventually you need to come back to the rules, but if you can ignore them for awhile, your creativity will not be limited.)
My wife still has her childhood Spirograph!
The first idea that comes to mind is an old toy – the Spirograph. What if my RC car wheel had spokes that looped around in a continuous weave that looked like one of those designs you can make with a Spirograph?
There must be a mathematical equation to describe the path made when a point on one circle is plotted as it rotates around another circle. If I can plot the path mathematically, maybe I can create a 3D path in SolidWorks to describe a sweep for the spokes of my wheel. After searching for “spirograph equation”, I discovered David Little’s page at Penn State University. As it turns out, the path of a Spirograph is called an epicycloid. It’s described by a pair of equations:
x(t)=(R+r)cos(t) + p*cos((R+r)t/r)
y(t)=(R+r)sin(t) + p*sin((R+r)t/r)
R and r are the radii of the 2 circles, p is the position along the radius of the first circle (the hole you put your pencil in on a Spirograph). Mr Little’s website has a cool Java applet that draws epicycloids based upon your input. If you experiment with this tool, you can discover all sorts of interesting geometry. After a few iterations, I found a combination that I thought might look like the spokes of a wheel using the values R=72, r=66 and p=67.
Where would engineers be without the spreadsheet? I remember seeing a documentary on PBS called Nerds where I learned that the first spreadsheet was called Visicalc and it was for accountants. Excel is the tool that I am most familiar with – version 2003 being most preferred. The Excel version of these formulas seems a bit more complicated. First, cells are made for all of the constants (R, r, p). I added a few extra for scaling – the final goal is an equation of a curve that will intersect the hub and rim of our wheel. Examination of the formula quickly reveals that t is an angular variable. I made a column for t in degrees because I know this is a cyclical function that will repeat every 360º (remember, it’s a circle rotating around a circle). I also made a column for radians (degrees times pi divided by 180) because Excel evaluates sine and cosine in radians. I probably could change this default somewhere, but that is something I would probably forget later and it’s easy to remember how to convert degrees to radians.
I know I want X and Y coordinates for the entire path and that they will eventually return to zero. I wasn’t sure how to know how many points to plot so I made some check formulas that subtract the current X and Y values from the original X and Y values – when the check columns both hit zero, I know I’ve returned home. The last step for X and Y is to plot a curve using Excel’s graph tool. The Excel graph matches the epicycloid plot so I know I’m on the right track. (Actually, I’m thoroughly appreciating the same feature that the original users of Visicalc appreciated, Excel’s power to iterate until I get it right.)
Some interesting observations: my epicycloid has 12 loops and the equation to describe it requires 3960 points at one degree increments. If I made another with 22 loops, I would expect it to take 7560 points to describe it (360 x 21). For some reason, my check equations did not exactly return to zero until I placed a round function into my formulas – I added a variable for the number of rounded decimal places as well.
What about Z? The equations for an epicycloid are only in 2 dimensions, but I want a 3D path for my wheel spokes. The options are limitless, but a sine function would make a nice smooth equation and it would behave in a similar way as the epicycloid equations. Some constants are necessary to vary how often the equation returns to zero and vary its scale. Graphing the function over the same range gives a clue how the path will vary in Z.
Excel’s worksheet functionality makes it easy to create formatted output. It turns out that the way the wheel was originally created, I need my X and Z data points to be swapped. By creating a new worksheet with only X, Y and Z values, I can swap the values very easily. The final result is a text file with 3960 points of X, Y and Z data.
Now to SolidWorks! The Insert Curve Through XYZ Points tool quickly creates a 3D path.
As a point of interest, I believe it was because of this tool that Walt Disney Imagineering chose SolidWorks as it’s 3D design tool – they had 3D points to describe the path of a rollercoaster and needed a tool to model the track. I created a second sketch on a principal plane perpendicular to the path. I started with just a sketch point and some dimensions tieing it down to the path.
Then I made the geometry for my sweep all tied to the sketch point. This way, if I want to change the profile from a circle to a square, I don’t lose my dimensions when I delete the circle. The Sweep tool turns all this hard work into an effortless expression of mathematical beauty. A few features to tie the spokes to the wheel and I have my entry.
Of course, I must return to the rules. I already know I will not win because, although my design is interesting, it cannot be molded which is the intent of rule 3. Rule 1 is easy – SolidWorks makes the whole thing possible. So Rule 2 is the only one left to satisfy.
I’m running out of time so a quick assembly with a cut-away view and a few minutes of rendering in PhotoView 360 and, at last, I have an entry.
Here are all of the files I used to create this design. -Amos
AEA Entry 1 of 2
AEA Entry 2 of 2
Followup: SolidWorks World was great. The CSWP event was very fun even though I am a very poor RC driver. 
I did not win the design contest (for obvious reasons). I did, however, win one of 40 SC-10 RC cars, which is VERY cool!
How to make a Booger Ball
Here it is, the original story. I’ve only modified it slightly since it was first written, adding the update note from my daughter. I am keeping the old page intact here as it is fun to watch the counter. This is the “product” I was talking about in the post about Product Development.
| When my daughter Ellen was four I started teasing her that I was saving all of my boogers in a big booger ball. I don’t know why I told her that except that it was fun to watch her make that “grossed-out” face that kids make when they smell something bad or see a squished cat on the road. She always begged to see it so finally I told her that she couldn’t see it now but I would give it to her for her eighteenth birthday. Well, guess what – she’s turning eighteen and I’ve got to come through with a booger ball! Here’s the basic steps to successful Booger Ball manufacturing: |
||
| 1. You’ll need rubber cement. I used four 4oz bottles from a local office store to make a ball 2” in diameter (it cost around $6-7 total for the four bottles). 2. Colored markers are used to add color to the boogers. Rubber cement dries in a nice neutral mucus color which is great. Boogers, however, are not all the same color. If you’re sick, they might be bright green or if you’re working hard in a dirty building they might be nearly black – remember that your nose is your body’s air filter protecting your lungs from the junk in the air. |
 |
|
 |
If you pick too hard or if the air is especially dry, you might find a bit of blood in your boogers. The colored markers in an assortment of colors helps to simulate the array of boogers you might accumulate over 14 years if you were really saving them. 3. A plastic tray, a plastic counter-top or a lid to a plastic tub to spread the cement on is needed also. I used two plastic lids from some storage tubs I had LEGO in. The cement comes off fairly easily but you might want to use something you are not especially attached to just in case there are some unforeseen problems in the project. |
|
| 4. Rubber cement doesn’t come out of porous surfaces so be careful not to get any on the carpet like I did. Take your time and work in an area suited for craft projects. Rubber cement is also a bit smelly and rather flammable – read the bottle and heed the warnings there. 5. Spread the cement on the plastic surface in a uniform layer that’s not too thick. I was tempted to goop it on but when I did the boogers did not turn out as well as they took much longer to dry. |
 |
|
 |
6. Allow some time to let the rubber cement to dry. I used two plastic lids so while one was drying I worked on the other. This proved especially efficient. 7. Choose your color palate from the colored markers. Think of all the boogers that you have picked over the years and remember the colors. Purple and pink may not be useful (unless you’ve snorted dry Kool-Aid – ouch!) but the shades of green and brown with the addition of red and black or gray will work great. |
|
 |
 |
|
| 8. Using the colored markers, apply thin stripes of color. I tended to use only one or two colors at a time. You will be making MANY batches of boogers so don’t worry about trying to add too much color in each batch. The rubber cement is a good natural mucus color that only needs an occasional accent from the markers. You may even make several batches without adding color as I did. |  |
|
 |
9. Start in a corner and rub the dried rubber cement with your fingers making a rolled booger. Continue rolling until the booger roll is the desired thickness. Tear the booger from the plastic surface. You may end up with a long string that can be torn into smaller pieces. Roll some of the cement into little balls. Lump pieces together into interesting shapes. | |
 |
10. MAKE BOOGERS – you’re a pro already! |
 |
| 11. Pile all of the completed boogers into one corner of your plastic surface or save them on a paper plate for later. You may choose to be truly artistic and make a booger painting. If so, I would separate the colors of boogers keeping all of the red ones in one pile with the greens and browns in other piles. |  |
|
 |
12. Start making your booger ball. These boogers stick together rather nicely without any added glue. Clump a bunch together to start the ball and continue to roll the ball in the pile until all of the boogers are stuck to it. |
|
| 13. REPEAT. |  |
|
 |
14. If you’re anxious to have a big ball without the time investment to really make a “real” one, you can start with a superball or other rubber ball. I haven’t tried this but I imagine if you coat the ball with rubber cement and let it dry, the new boogers should stick nicely and you’ll have a big fat ball of boogers in no time. | |
 |
 |
|
 |
15. You might find a cool box to put your booger ball in like I did at a craft store. If you get your ball big enough, you can use those display products designed for baseballs – that would be WAY cool. 16. Be careful – this booger ball is NOT edible! |
|
| There are some things to consider before you begin to make your booger ball: • Why in the world would anyone want to make a booger ball? • You may not score points with your significant other for taking on this craft project – no matter how creative your final creation ends up. • Kids LOVE boogers and the idea of anyone really having a booger ball fascinates them. Keep your ball a secret, saving it only for special occasions. Your grandkids/nieces/nephews will think you’re the coolest grandpa/grandma/aunt/uncle ever. • Life is too short not to make our own booger ball! • This is a messy project using harmful chemical glue products – don’t let kids get hurt. The markers will stain your fingers for a time (even though they claim to be washable). • Your fingers may become sore and a bit raw after a few hours of booger manufacturing. • Please don’t eat your boogers. So there it is; how to make a booger ball. If you enjoy this tutorial you might consider hiring me to develop one of your wacky ideas. Check out our site to see what else we do and how we can help you in the future. God gave us way too much creativity, but we’re willing to share! Send us a photo of your booger ball creation and we might add it to the Booger Ball Hall of Phlegm. Update: Ellen loved her booger ball. Here’s the note she sent me:
|
||
Product Development
Ever since I was young, I’ve had an obsession with the idea of “product development”. Every new idea I’ve had is accompanied by 10 more about how to manufacture, package, brand and market the idea. I can’t explain the obsession, it’s just what rolls out of my brain next. I’ve created products like CookieCrumbs, the Toad Stool, the KingKol and A Place In Your Heart. My biggest frustration in all this is that I cannot seem to get even one of these products successfully to market. Like everyone else, I blame lack of time and resources. This year I want to try something different. Like Captain Kirk who rewrote the Kobayashi Maru test, I’m going to redefine success. All this time, I’ve been judging my self by units sold and since I’ve sold very few units of any of my products (except maybe LolliPop Toppers™), I feel unsuccessful. One product of my design is going to change that.
The product I’m contemplating is the BoogerBall story I penned.
I know, roll your eyes and say, “Oh brother, what absurdity is he talking about now?” Well, I wrote a mildly humorous story some years ago called, “How to Make a BoogerBall” for my daughter Ellen. I posted it here, on my company website for the world to see. To my amazement, the world has seen it.
So that’s my product. Not a BoogerBall, not a book about BoogerBalls, but the story itself, How to Make a BoogerBall by Amos E. Avery. Why does this redefine success for me? Because it’s already a success. My goal is not to sell the story, but to get people to read it. My first website counter reached 4000 plus readers before I changed web hosts. The new site has over 29000 hits on that page. Blogs around the world have pages of comments about my story. It’s already a success. Anything I can do to gain more readers is a success and anything I can sell along the way is icing on the cake.
So here’s the plan. Launch BoogerBall.com as a legitimate site (it’s just forwarding to a page on my company site right now). Do all of the “product development” things I can’t help but do (you should see the pages of notes and drawings I have for just this idea alone). Develop manufacturing techniques, logos, packaging, identities, marketing strategies, support products, tag lines, graphics and compelling stories. Most importantly, write about all of it as I do it. BoogerBall.com will be the recipient of the finished product – the story and all of its supporting stuff. Averyswellidea.com will be the recipient of this first entry and all subsequent entries along the way. So, if you want to learn more about creativity mixed with faith mixed with foolishness mixed with practical product development insights, stay tuned.
-Amos