The design that developed was a circular format with a handle, like the old paddle ball games. Additionally I wanted to store two balls on the game in the hope that they might not get lost as readily. Old timers disease was making me forget that a job always takes more time and money than expected, along with opportunities (substitute, “problems”), to be had.
Step 1: Your STUFF
Small steelie, ball bearing, BuckyBalls, marble, etc.
Graph paper, pencil, and good eraser.
Vector Drawing Program
Mach3, EMC, or similar (http://www.machsupport.com/) (http://www.linuxcnc.org/)
CNC Router or a contract fabricator – (www.100Kgarages.com)
X-acto, utility knife, something sharp
Sandpaper or foam blocks
Children for Beta test
Step 2: My STUFF
Dust collection system
Step 3: Measure and Sketch
BIG MATH SECTION: Ok, you have the diameter of the ball you have chosen, You are about to determine the width of the race (the groove the ball will travel in). Take the diameter of the ball and multiply it by 1.25. Write that down. Do it again by 1.5. Write that down also. This is the width range of the race that I have found to work well. An example is like this. I am using a BuckeyBall Magnet (you will see later why) that is .200” in diameter. So 1.25 x .200” = .250”, and multiplying .200” x 1.5 = .300”. So the range of the width of the race should be between .250” and .300”.
I drew the maze within a circle and added a handle to it to make it a one handed game (of course, you must use your non-dominant hand, to make it harder). I chose 10 races (that is 10 concentric circles), plus the center goal (.75), and a rim around the circle to keep the ball more likely to avoid the floor. I selected pine, a 1/4” end mill and a width of .200 for the dividers.
Now take out the graph paper, pencil and eraser and get to work. You’ll think this step is soooo… old-fashioned in this day of computers. It may be, (so am I, at least somewhat advanced in years) but having it figured on paper saved me a lot of wasted time.
Step 4: Drawing Programs
I drew two circles from the center, .75” (goal) and .325” (starting circle) then a series of concentric circles .45” apart (.25” bit plus .20” for divider) outward to the rim, then another .5” for the rim itself. Then I drew a handle. Now, I made a bunch of .45” circles and drug them into place as sketched out on the graph paper. After a lot of clipping and joining vectors, I had a drawing.
Step 5: Output to CAM
Some drawing (CAD) programs have no way to get g-code from them. G-code is a language defining where the router must go to perform the task you have in mind and is generated by the CAM. Some CADs have CAM with them but they tend to be the pay for types. For those of you who are using a CAD program that does not have this function, you’re going to have to find a separate one to do this. Here is some links. (http://www.rhino3d.com/resources/display.asp?language=en&listing=545)
Step 6: Selecting the Bit
Our router only goes one speed in rotation and maxes out at 25 linear inches per minute, so the only control we have is how deep it cuts per pass, and the inches per minute speed it travels thru the material. I planned for each pass at .25”. Before any machinery is turned on, install the bit into the router you have. Be VERY careful, they are quite sharp. I wouldn’t know that, but, there are a wide range of band aids and compresses readily available in our shop, just in case.
Step 7: Load the Material
Make sure that the piece you load on the machine is bigger than the project. Seems obvious, doesn’t it. Also that it is oriented correctly in the X and Y plane. I never make that mistake.
Stabilize the foam (or the pine). Many treacherous opportunities lie here. Cut the foam/pine larger than the project. You want extra room for clamping down the outer edges with screws, cam locking devices, or even double-sided tape. In this case I clamped it down with sticks and screws. Regardless of the method, one wouldn’t want the highly rotating router bit or the router itself crashing into something hard and unyielding. Some very interesting results WILL occur and you really don’t want that experience. The least is you may lose some steps in the g-code and get the remainder of the cut all cockety-wampuss, the worst is flying bits of high speed steel flying around. Which brings us to the all-time favorite subject of OSHA, da-da… SAFETY.
Step 8: SAFETY
---Ears - CNC machines are loud. I like to put on noise cancelling earphones with my favorite music playing in the background. Not too loud as you want to lightly hear the machine as it runs, giving you a heads-up to any problems.
---Eyes and face – Flying objects do sometimes come from the machine, best to protect them. I use a face shield.
---Breathing – All materials have some dust created during the cut. Use at least a filter mask for non-toxic woods and cardboard something better for MDF and plastics.
---(If at all possible make or buy a dust collection system to keep the fumes and dust to a minimum. That’s the next project for us after this contest. Wish I had done it earlier.) (http://solsylva.com/cnc/vacuum.shtml)
Step 9: Power the Machine and Computer
Step 10: Zero, Zero, Zero
Step 11: The Magic
When the cycle ends, and the router comes back to zero, turn it off. Then remove all the clamps, screws, staples, or what-have-you that is holding the material firmly. Pick up the piece and be amazed. Remove the waste sections, and vacuum or blow off the dust so the machine is ready for the next fabulous project.
Step 12: Examine
If you think it needs improving, return to Step 4, and go for Plan-B, or Plan-C, etc. Most of the time, it takes several tests and iterations to get it right.
Step 13: Finishing
I used another Porter Cable Trim Router to round over the top and bottom of the paddle, prior to hand sanding.
Using foam sanding pads, I smoothed all the surfaces, especially the races and dividers.
Clean the paddle with air or a brush.
Apply stain carefully to the wood, and wipe excess off with a rag, especially the races.
Allow to dry.
Finish with spray polyurethane. Do this outside and wear a mask anyway.
Allow to dry completely.
Glue in the small washers in the storage holes and stick Bucky Balls to them
Step 14: The Real Test
Thank you for reading this far. Hope it was instructive. Please post any questions, comments, suggestions or ideas, and I’ll get back as soon as I can.
Step 15: Why We Want to Win
Our club of makers would continue to explore the vast world of CNC routing. We have in mind a large backlog of ideas that would be furthered by winning the PRS Standard 96-48-6 ShopBot . Our homemade CNC can cut 31” x 21” and cuts at a maximum of 25”/ min. The 4’ x 8’ table and 300”/min will vastly improve our ability to produce prototypes, develop and improve designs, create larger projects and test out 2.5D, then move to full 3D sculpting.
Here is a small selection of my personal list of projects:
Mazes for more than one player
Giant mazes on a half sphere to be played by young children
Interchangeable mazes of increasing difficulty
Picture frame mazes
Spirographs – small 8.5 x 11
Giant Spirographs using chalk for outside
Wing Ribs for Experimental Aircraft
Patterns for Cabinet doors
Wood Blocks for printing from ancient lithographs
Negatives for molds
Thank you for considering this submission