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Metalcasting forums. Scrap Metal Forum - The Official Scrap Metal Recycling Community. Manufacturing Process. Metal Casting Suppliers, Foundry Supplies, Casting Manufacturers, Metal Casting Companies. Woodworking for engineers. Free Flight Fantasies. Propeller carving. I carved my first model airplane propeller about two years ago, inspired by David Dodge's (alias Dannysoar) original propeller carving instructions on the Free Flight Mailing list.

Propeller carving

I am deeply indebted to him for introducing me to this very rewarding aspect of the hobby. Since then, Thayer Syme has illustrated and published these wonderful instructions on his web site, Free Flight Fantasies. I encourage you to visit it. It is certainly one of the best model airplane web sites on the Internet. Recently on the FFML, the subject of propeller carving came up again. I wondered if I could really do one in only 30 minutes, so I gave it a shot and took some pictures to document the attempt. These notes are intended to complement, not replace Dannysoar's original instructions. On the following pages you'll find: Propeller carving tips. Propeller block dimension calculators. A photo sequence of my most recent propeller carving attempt. I hope you find this useful. Last update: May 7, 2000. Viscosity Chart. How To Cover Up Dings in Wooden Furniture Home Hacks. TRAFFIC WAVE EXPERIMENTS.

Eddy current brake. An eddy current brake of a German ICE 3 in action.

Eddy current brake

An eddy current brake, like a conventional friction brake, is responsible for slowing an object, such as a train or a roller coaster. However, unlike electro-mechanical brakes, which apply mechanical pressure on two separate objects, eddy current brakes slow an object by creating eddy currents through electromagnetic induction which create resistance, and in turn either heat or electricity.

Construction and operation[edit] Circular eddy current brake[edit] Principle of the linear eddy current brake. The future of Electrochemical capacitors as energy storage devices. Tesla_coil_sparks. "Eye of Sauron" Rotating long breakout point 2007 This uses a motorized 6 foot aluminium tube connected to the top of the TC.


Transformers. In the photograph, note that the coil on the left has fewer coils than that at right (the insets show close-ups).


The sketch and circuit show a step-up transformer. To make a step-down transformer, one only has to put the source on the right and the load on the left. (Important safety note: for a real transformer, you could only 'plug it in backwards' only after verifying that the voltage rating were appropriate.) So, how does s transformer work? The core (shaded) has high magnetic permeability (ie a material that forms a magnetic field much more easily than free space does, due to the orientation of atomic dipoles).

Vp = − Np.dφ/dt . VpIp = VsIs, whence. RepRap Project. RepRap version 1.0 (Darwin) RepRap version 2.0 (Mendel) First part ever made by a Reprap to make a Reprap, fabricated by the Zaphod prototype, by Vik Olliver (2006/09/13) The RepRap project is a British initiative to develop a 3D printer that can print most of its own components.[1] RepRap (short for replicating rapid prototyper) uses an additive manufacturing technique called Fused filament fabrication (FFF) to lay down material in layers; a plastic filament or metal wire is unwound from a coil and supplies material to produce a part.

RepRap Project

The project calls it Fused Filament Fabrication (FFF) to avoid trademark issues around the "fused deposition modeling" term. As an open design, all of the designs produced by the project are released under a free software license, the GNU General Public License.[2] History[edit] Thingiverse - Digital Designs for Physical Objects.

Screws Small Encyclopedia Sometimes. Sometimes You do not know, what screw you need to turn this piece of furniture.

Screws Small Encyclopedia Sometimes

That is why this little encyclopedia was created. Screws Head Style Drive Types Washer Type Nut Types. Shoe Lacing Methods. Mathematics tells us that there are more than 2 Trillion ways of feeding a lace through the six pairs of eyelets on an average shoe.

Shoe Lacing Methods

This section presents a fairly extensive selection of 50 shoe lacing tutorials. They include traditional and alternative lacing methods that are either widely used, have a particular feature or benefit, or that I just like the look of. 50 Different Ways To Lace Shoes Criss Cross Lacing This is probably the most common method of lacing normal shoes & boots. Over Under Lacing This method reduces friction, making the lacing easier to tighten and loosen plus reducing wear and tear.

How to Make a Paper Airplane. What is acoustic impedance? Acoustic impedance, which has the symbol Z, is the ratio of acoustic pressure p to acoustic volume flow U.

What is acoustic impedance?

So we define Z = p/U. Z usually varies strongly when you change the frequency. The acoustic impedance at a particular frequency indicates how much sound pressure is generated by a given air vibration at that frequency. This introduction explains its use in understanding the operation of musical instruments. A more general introduction, in physical terms, is given in Sound: impedance, power and intensity. The specific acoustic impedance z is a ratio of acoustic pressure to specific flow, which is the same as flow per unit area, or flow velocity. We discuss acoustic impedance on this music acoustics site because, for musical wind instruments, acoustic impedance has the advantage of being a physical property of the instrument alone – it can be measured (or calculated) for the instrument without a player.