Ayers Concepts

This is the most important area for you to spend your time and money!!! A patent is typically the first place where a new inventor decides to spent his money. For upwards of $3000-6000, you are betting on some high stakes, when less than 5% of all U.S. patents which issue develop into products which eventually become sold! Also, prototyping your invention first often leads to improvements you may have wished you'd included in the claims of your patent. Remember, you do not need a patent to negotiate a contract for royalties on an invention.

Don't be afraid to make your first prototype! Think of a prototype as a scaffold on which you stand to see how to construct your next model.

Prototype the difficult, trickier part of the invention first! So much of the rest of your prototype (even patent claims) are determined by how this works out.

Prototyping: Things to determine

• What is the purpose of your prototype?
  • A "rough draft" to see how to make a better one.
  • A study of how to solve the more difficult features.
  • To play test.
  • To make a demonstration video. (The action can be simulated so that the prototype doesn't have to actually work.)
  • To show to a toy or game company.
  • To solve manufacturing problems.
  • What scale should you make your prototype?
    • Actual scale.
    • Larger scale: e.g., it may make it easier to make and prove the smaller mechanisms.
    • Smaller scale: e.g., if it would take too much space to demonstrate a full-size model.

  • How will your prototype be built? (the following topics are discussed later on this page)
    • Paper or cardboard.
    • Machine shop.
    • Model making.
    • Electronic Breadboarding.
    • Sewing of Fabric.
    • Plastic Molding.

  • What materials can be used on your prototype?
    • Wood. Pine, balsa wood, hardwoods.
    • Aluminum, Steel, Brass, Copper. Tubing, strips, sheets and extruded shapes can be obtained at hobby shops.
    • Polystyrene plastic. You should keep sheets of this in thicknesses of 1/64, 1/32, 1/16, 1/8, and 1/4" -- check a plastic supply company. Tubing, strips, sheets and extruded shapes can be obtained at hobby shops.
    • Acrylic plastic sheet. Adhesives are availble to fashion structures from this. Useful when transparancy is required.

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  Prototyping: Sources of Components

  • Buy toys, take them apart, and build your prototypes from them.
  • Low cost components from: 99-cent stores, hobby and craft stores
  • Teacher Supply Stores -- they'll give you a 1-in thick catalog with photos and descriptions of all they sell which you can keep on hand to look through.
  • You can get all sorts of compontents, material, and gadgets from American Science and Surplus, 847-982-0874. Get their catalog and visit their website.
  • Same thing for Edmund Scientific Co., 609-573-6250, though not at surplus prices. Get their catalog and visit their website.
  • Look for an electronics parts source in your town and visit there. Something more obscure than a Radio Shack. You're likely to find hard to find mechanical components there, too.

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  Prototyping: Using Adhesives.

  Adhesives provide one of the most useful means of fastening items when you are prototyping. The choice of adhesive will be determined by the type of material you are joining.

  • Cyanoacrylate (super glue)
    • A quick drying brittle adhesive joins almost anything with a little quantity.
    • Will not join polyproylene.
    • It is worth using an accelerator with cyanoacrylate. An acceletator (one trade name is "Zip-Kicker") is sprayed onto the adhesive from a pump bottle and will instantly freeze it. Get cyanoacrylate and its accelerator at hobby stores. Also sprinkling baking soda onto the wet adhesive fills it in and causes it to set up. You can build up areas this way. Try it!

  • Methyl Chloride
    • This is a solvent which joins some plastics together. Use it on ABS and especially polystyrene. Get it at hobby stores.

  • Hot-Melt Glue
    • If you don't have a hot-melt glue gun, get one. This is a very convenient method of joining things. It bonds somewhat to polypropylene. It is great for strengthening and supporting joints you have already made with cyanoacrylate. You can get the glue sticks in different colors and can squirt the hot glue (really a plastic) into molds. Get it at discount, craft, and hadware stores.

  • Shoe Goop^TM
    If all else fails, this product is extremely versatile. I use it especially if I need to bond cloth to something else. It will also bond to difficult polypropylene. Find it at discount and hardware stores.

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  Prototyping by Using a Machine shop

  • This requires mechanical drawings to describe how a machinist must cut the parts from metal, wood, or plastic on a mill or lathe. These drawings explain the geometry of the part with shape and dimensions.

  Prototyping by Model Making

  • This is the means of prototyping primarily described in this body of information. Try to utilize this method instead of using a machine shop if possible.
  • I had been creating mechanical drawings for many prototypes which were unnecessary. Model making is "build as you go" whereas machining requires that you commit to your dimensions on everything before making anything.

  Electronic Breadboarding

  • Required to control lights, sounds, motors, sensors, information, etc. A breadboard is a prototype electronic circuit laid out by descrete components. It is acceptable to solve these issues outside the prototype and allow wires to enter the interior for the electronic features. It is understood that all electronics will be hidden in the final product. Also, there are chips which can be programmed to do what you want.

  Sewing a Prototype of Fabric

  • Do it yourself or hire a seamstress.

  Molding a Prototype in Plastic

  • There are a great variety of materials which can be used for the mold and used for the molded prototype.
  • An original can be sculpted out of wax. Or the original can be fashioned by cutting up sections of other products, gluing them together, and filling seams with clay or wax. The molded prototype will be a one-piece solid.
  • Artists make their bronze castings using the "lost wax" process. Visit an art supply store or school art department t o learn how this works.
  • Materials for the mold: Silicone and Latex mold compounds, Sculpey^TM, Flexwax 120, Plaster of Paris.
  • Materials for the molded part: Acrylic casting compound, various latex and urethane compounds. These materials can be selected to affect the hardness and flexibility of your prototype.
    

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  Prototyping: Focus on Model Making

  • General operations
    • Cut plastic or metal tubing with a tubing cutter--an adjustable clamping device with two sharp wheels.
    • Use rubber bands instead of springs wherever possible. Springs are more difficult to adjust.
  • Working with Paper & Cardboard
    • Many times you can make elements of your invention prototype from paper or cardboard. Pins through the pieces can act as axles or pivot points to see how parts will move together. String can be fastened between pieces to act as linkages.
    • To cut: scissors, Exacto-knife.
    • To join: tape, glue, staple.
  • Working with polystyrene
    • To cut: score with a razor blade or Exacto-knife, bend it on the score and it will snap apart. Thicker sheets may need to be cut with a hobby saw.
    • To join: methlyl chloride is fast & easy. Also, cyanoacrylate and hot-melt glue. Hot melt may warp or melt the plastic.
    • Many toys are made from the styrene family, a relatively brittle and easy to mold compound. You will find parts of toys which are made of this which will respond to the solvent methyl chloride.
    • You can get more information on working with this material from the manufacturers, two of which are Evergreen Models (the have a small guide for sale) and Plastruct.
  • Working with brass and copper
    • To cut: tin snips and tubing cutters.
    • To join: silver soldering, fastening with screws and nuts.
  • Working with polypropylene
    • This material is used in many toys because it is quite inexpensive, flexible (durable), easy to injection and blow mold, and easy to color. It is used to make Frisbees and wiffle balls. It is very difficult to glue or adhere to.
    • To cut: Razor blade, utilty knife, or hobby saw.
    • To join:
      • Shoe Goop is a good adhesive.
      • You might "sandwich" a wall between two sheets of polystyrene; punch holes in the wall and fill them with circles of the same thickness of p-styrene, and bond a surface of p-styrene to each side of these fillers.
      • I have joined brass to polypropylene using metal craft decorative buttons. These have four sharp tines extending from a disk. Cut tiny slots in both pieces in the pattern of the tines, push the tines through both pieces and bend the tines over.
      • Or simply use sewing eyelets which crimp in holes to fasten two materials.

  Here is some additional prototyping advice from Bob Hudson, an inventor I've come to know over the years --Thanks for the great input, Bob!

  • As for inventors doing prototype model making, I have found that PVC pipe comes in quite handy; it's readily available at home improvement stores, it's easy to cut, drill, glue with super glue or PVC glue, can be heat-formed and it's cheap. It comes in several diameters and uses easy-to-assemble fittings which are glued on.
  • Another material which is readily available is auto body filler (Bondo). It sets up quickly and is rather easy to form into complex shapes, it sticks to itself, so it can be built up in layers and it is compatable with fiberglas resin with which can be mixed to thin it out if desired. It sticks well to metal and wood which can be used as armatures for models. It can also be used over some plastic foams, but will eat into others, so test it first.
  • Readily available plastic foams are floral foam which comes in blocks and construction insulating foam which comes in sheets. There are also pressurized cans of insulating foam which harden quickly and may be cut and formed with a knife. While not for the final finish, all the foams can be cut with a knife and are easily formed into basic underlying shapes such a doll bodies or teddy bears which will be covered with some other material.
  • Brass and copper tubing can be joined with regular, low-temp solder quite well; we prefer electrical solder since the flux is non- corrosive. Silver solder can be used for joints that require exceptional strength; however, for telescoping and joining one tube within another we rarely use anything but super glue.
  • A good source of toys to be used for prototyping is second-hand stores (Salvation Army, etc.). They may have toys that are not currently on the market and may be just what one needs for a project (if nothing else they will be cheaper). We recently built a complete prototype this way; 100% of it was recycled and it was a combination of two popular toys. Maybe the best is yet to happen; it was grabbed up by the first company we showed it to (which makes one of those products AND is looking for a product to expand that line), so now we just have to see if a contract follows.
  Hope these are helpful suggestions.
  Bob

  Advanced methods

  • Stereolithography is one of several means of creating a "rapid prototype". It uses 3-D CAD information to create an "instant" model by printing it (solidifying plastic resin with a laser dancing on the surface of the liquid) layer by layer. HERE is an article of how Mattel has used this method to speed up their design process!

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