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Mechanical Engineering


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Everything posted by DrD

  1. Perhaps we are not communicating clearly. If you want to send me a PM with a better figure and a more clear statement, I will look at your problem. DrD
  2. That's not what I would conclude, so please do not say that I said those things. DrD
  3. I'm certainly not a magnet expert, but I doubt that this is workable. Heat tends to destroy magnetism, and 2500 C is pretty hot. DrD
  4. At the levels of precision indicated by the instrument shown at your URL, you have to ask yourself if the bore is truly circular or not. DrD
  5. It depends to some degree on what constitutes failure. Gases will leak through smaller openings than liquids, so the pneumatic test will be more severe. Also, the pneumatic test is more dangerous to conduct because of the compressibility of the gas. The compressed gas stores a large amount of energy which is released suddenly if the vessel explodes. Conversely, the hydro test, using essentially incompressible water, releases very little energy if the vessel ruptures. DrD
  6. The use of the g unit simply expresses acceleration in multiples of the acceleration of gravity. This is true in regard to vibration, linear motion, etc. Thus if an acceleration of 10 m/s^2 is slightly over 1 g = 9.81 m/s^2. DrD
  7. Change your mechanism so that it operates over a different range (same total rotation, but different end points). Then you can attach an arm to the crank to have the required motion. DrD
  8. Runge-Kutta is for solving differential equations. All that is needed here is simple quadrature, such as the trapezoidal rule. DrD
  9. Theory is important, but it needs to be tied to practice. Practice comes in two forms, but necessary. 1) The first is personal practice. Try designing and constructing things. When they fail, ask yourself why, in terms of the theory? What bit of theory would predict that failure? What additional theory do I need to understand this failure? When they work, ask if the theory can guide you to something that works even better. 2) Look at the work of other engineers, always asking yourself "Why was it done this way? Is there a better way? Does this approach avoid any particular problems." I've been an engineer for many years, but I continue to learn new things. Just a few days ago, I toured a river dam and lock system (the lock allows boats to pass through the dam in both directions). I saw things I've never seen before, and thought a lot about why things were done this way. To be a good engineer, you must never stop learning and thinking. DrD
  10. With the devices you have pictured, the pneumatic cylinder must accelerate at the same rate as the plane. What about using leverage? I'm thinking of something like a sling-shot, where the plane would be attached to an arm rotating about a fixed pivot point? Then the pneumatic cylinder can move much more slowly (but with higher loads), and you should be able to release the plane at the proper point to go in the intended direction. DrD
  11. Do you have any idea what sort of launcher you want to build? I can imagine several different mechanisms for doing this, which makes your question too broad to be answered. If you have no idea, perhaps that is where you should start. DrD
  12. Why is there a sudden change in spacing on p. 8 and again on p. 11? This makes for a strange looking document. DrD
  13. Dear Alban, Absolute symmetry is truly rare. Consider the case of a table on four legs of equal length. By your argument, all four legs each carry 1/4 of the total weight. Everything is perfect, the floor is level, the table is flat, the legs are all equally long. But now enter a tiny bit of reality (ever so slightly!). One of the legs is short by 0.0001 mm. To the eye, it appears that perfect symmetry still exists, but in actual fact, one of the four legs no even longer touches the floor. Do you still think that each leg in contact with the floor carries only 1/4 of the weight? What holds up the remaining quarter of the weight? DrD
  14. If you are serious about this, why not design a better screw and have a machine shop make some for you?
  15. Looks to me like the kinetic energy of your systems is T=(1/2)*m1*xdot^2+(1/2)*m2*ydot^2 and the potential energy is V=(1/2)*K1*(x-xc)^2+(1/2)*K2*(y-x)^2+(1/2)*K3*y^2 if we understand that all springs are relaxed when xc=x=y=0. All of this raises a question for me. Why do you want this if you did not know how to develop it in the first place? DrD
  16. Do you know about Newton's Second Law? If so, start there. DrD
  17. Whatever in the world is meant by "inverting the rotation" of the turbine? I have no idea what this question is about. DrD
  18. Whatever in the world does it mean to "invert the rotation"? I've never heard such a term, and I cannot imagine what it means. DrD
  19. When I suggested a picture, I was referring to a drawing, not a photograph. DrD
  20. Who said there was a screw? Did I miss something? DrD
  21. This is a really fine post by JAG, and I'm sorry I only saw it so late (today). That said, I would add just a little bit. Lawyers are only lawyers because the choose to be lawyers. This is a free choice. They volunteer for that sort of work. In making that choice, volunteering as it were, they abandon morality and make themselves volunteer hostages to a system that has no interest in truth, only an interest in winning. In my view, to make that choice, and those who make it, completely immoral. I have to add that my sister is a lawyer, and we have had many battle over this matter. Now, we rarely speak about it because there is no resolution possible. In life, that is how things work. Those who sell their souls to the devil cannot be talked back. DrD
  22. It would help if you posted a picture of the situation with dimensions, wind load direction, etc. DrD
  23. I think it was Einstein who said, "Everything should be explained as simply as possible, but no more so." DrD PS: I'm sorry it is all Greek to you. Perhaps you should not call yourself a mechanical engineer?
  24. Looks like you have identified the key items you need to learn in this internship. Now it is up to you to investigate and learn them. DrD
  25. DrD

    gearbox lubrication

    I think Sergio may have missed the point (or else I have). As I understand the question, the concern is lubrication of the external gear train. No oil will get to it unless you provide oil to it. The crankcase oil cannot get there. DrD
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