3d scanner structured light
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disciple
I'm new to this, but does anyone know what medium I would use to make a mold from a stone. In other words, There is an old building with a beautiful design sculpted in to it. I want to copy this design. I know there is a material out there that I can press against the original design and make a mold of it and then cast the design in plaster. I just don't know what material I would use to do this without hurting the stone.... Help!!!
Answer
I think the sculpey or any clay will work. If you use normal clay, any residue left will dissolve in the next rain, just don't use brown clay on light stone... if you use water based clay you would have to cast your plaster into the mold while the clay is still wet.
As the clay won't be very stable just on its own, you should consider making a mother mold on top of that. That is a hard shell, which just gives support to the soft part of your mold so it doesn't deform. It depends on the size of what you want to copy if you need it. You could make the mothermold from plaster bandages, but don't put plaster directly on the stone.
Before you start, consider carefully the shape of what you want to copy and where undercuts are and where you have to put in parting lines. What technique you use for mold making really depends on the exact shape of what you want to copy. If the structure is something complicated, you may want to practice how to make molds from more simple structures first so you are aware what causes problems and get some experience in how to solve them.
Another completely contact free method is if you happen to be at a university where they have a 3D laser scanning camera you can borrow, you could use the 3D laser scanner then make a model of your structure in the computer from the scans. That you could print out using a 3D printer. that way you can scale the model to any size (though anything large will be expensive to print)
what are some reverse engineering techniques?
Kevin7
Answer
Reverse engineering of machines
As computer-aided design (CAD) has become more popular, reverse engineering has become a viable method to create a 3D virtual model of an existing physical part for use in 3D CAD, CAM, CAE or other software. The reverse-engineering process involves measuring an object and then reconstructing it as a 3D model. The physical object can be measured using 3D scanning technologies like CMMs, laser scanners, structured light digitizers or computed tomography. The measured data alone, usually represented as a point cloud, lacks topological information and is therefore often processed and modeled into a more usable format such as a triangular-faced mesh, a set of NURBS surfaces or a CAD model.
Reverse engineering is also used by businesses to bring existing physical geometry into digital product development environments, to make a digital 3D record of their own products or to assess competitors' products. It is used to analyse, for instance, how a product works, what it does, and what components it consists of, estimate costs, and identify potential patent infringement, etc. Value engineering is a related activity also used by businesses. It involves de-constructing and analysing products, but the objective is to find opportunities for cost cutting.
Reverse engineering of software
The three main groups of software reverse engineering are
1. Analysis through observation of information exchange, most prevalent in protocol reverse engineering, which involves using bus analyzers and packet sniffers, for example, for accessing a computer bus or computer network connection and revealing the traffic data thereon. Bus or network behaviour can then be analyzed to produce a stand-alone implementation that mimics that behaviour. This is especially useful for reverse engineering device drivers. Sometimes, reverse engineering on embedded systems is greatly assisted by tools deliberately introduced by the manufacturer, such as JTAG ports or other debugging means. In Microsoft Windows, low-level debuggers such as SoftICE are popular.
2. Disassembly using a disassembler, meaning the raw machine language of the program is read and understood in its own terms, only with the aid of machine-language mnemonics. This works on any computer program but can take quite some time, especially for someone not used to machine code. The Interactive Disassembler is a particularly popular tool.
3. Decompilation using a decompiler, a process that tries, with varying results, to recreate the source code in some high-level language for a program only available in machine code or bytecode.
Reverse engineering of integrated circuits/smart cards
Reverse engineering is an invasive and destructive form of analyzing a smart card. The attacker grinds away layer by layer of the smart card and takes pictures with an electron microscope. With this technique, it is possible to reveal the complete hardware and software part of the smart card. The major problem for the attacker is to bring everything into the right order to find out how everything works. Engineers try to hide keys and operations by mixing up memory positions, for example, busscrambling. In some cases, it is even possible to attach a probe to measure voltages while the smart card is still operational. Engineers employ sensors to detect and prevent this attack. This attack is not very common because it requires a large investment in effort and special equipment that is generally only available to large chip manufacturers. Furthermore, the payoff from this attack is low since other security techniques are often employed such as shadow accounts.
http://en.wikipedia.org/wiki/Reverse_engineering
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