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  • Users: KevinH673
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  1. KevinH673

    Bending a pipe

    Also, I've looked in two of my books and neither seems to give a good explanation of the Stress=My/I equation's derivation. Does anyone have a link explaining how to derive it? I've done a quick Google search without luck, but I honestly have not really dug around. Please, no one spend any time...
  2. KevinH673

    Bending a pipe

    Trick question because one creates the other? I'd say it's easier to analyze this as a moment, no? You're right on the cantilever approach, if you split the pipe in half, as you said. Interesting because I wouldn't have thought to solve it like that.
  3. KevinH673

    Bending a pipe

    I agree with that, looking through my handbooks it seemed a cantilever equation was incorrect. Seems obvious, but was worth it to ask. Thanks for the help!
  4. KevinH673

    Bending a pipe

    Is the above equation analyzing it as a cantilever? My book doesn't mention end constraints. This stress will be before any plastic deformation occurs. Thanks for the help.
  5. KevinH673

    Bending a pipe

    If you are bending a pipe similiar to this picture: http://image.shutterstock.com/display_pic_with_logo/85366/85366,1246641681,4/stock-vector-illustration-of-a-powerful-man-bending-a-rod-33069904.jpg Do you still analyze it as a cantilever beam held on both ends? I would assume you would use...
  6. KevinH673

    Stress/Deflection of Plate

    rb, ok this makes sense then. I thought the x was an actual value. Thanks.
  7. KevinH673

    Stress/Deflection of Plate

    "The force at A is equivalent to a force at B plus the moment F(A-B)." prex, wouldn't that mean the force at A is larger than the force at B? Shouldn't it be the opposite? Also, this claims slope is the integral of M/EI with respect to x, so slope = Mx/EI, or F(A-B)*B/EI as has been posted...
  8. KevinH673

    Stress/Deflection of Plate

    Well, I'm trying to make sure I have all my "ducks in a row" so that I can predict how this thing will behave. I can control the deflection at A, as there will be a bolt pressing against it controlling it. My goal is to predict how point "B" will deflect relative to "A". I also have FEA to...
  9. KevinH673

    Stress/Deflection of Plate

    Hi guys. This project was put on the backburner for a little while, and I've been back to it. I took your advice and went to the textbooks. I'm really not trying to use this site as a crutch, but I do find it as a good source to clear things up. It may prove the design doesn't work. It is not...
  10. KevinH673

    Bearing for optic travel

    Can anyone recommend a high precision rod manufacturer to accompany these bearings? The bearing company recommended one to me, but when I contact them, they only do custom orders.
  11. KevinH673

    Bearing for optic travel

    Clyde, thanks. I gave them a call, they're going to get back to me with radial tolerance/play figures. Pretty pricey, though I suppose you have to pay to get precision parts. They quoted me at $91.10 with a minimum purchase of 10. Do you guys have any other recommendations? I'd like to try a...
  12. KevinH673

    Bearing for optic travel

    Thanks for the link, Clyde. Do you know the tolerancing/precision on these? They don't seem to list it. I clickd on one of the products to get more detailed information on sizing, etc. They list property dimensions by assigning them a letter, but don't seem to list an illustration showing you...
  13. KevinH673

    Bearing for optic travel

    Mike, thank you for the suggestion. I cannot use grease, because the optic will be in a sealed, vacuum tight chamber where any dust or dirt getting in would cause big issues. Would I have some "shaving" if I use dissimilar materials? What would you recommend ?
  14. KevinH673

    Bearing for optic travel

    Could I possibly make some design that would use O-Rings, or maybe some spring washers, that would use three ball bearings. Two with forces in one direction, one with a force in the opposite directin, to try to make any play almost zero? Also drew a possible V design, but I'm leaning more...
  15. KevinH673

    Bearing for optic travel

    caoimhin1 thank you for the help, I will look into this.
  16. KevinH673

    Bearing for optic travel

    Could anyone recommend a good bearing manufacturer for tight tolerance applications? I have a metal optic holder(CAD drawing picture provided) holding an optic. I would like to use some linear ball bearing to slide this metal optic holder on rails that would eliminate almost any "wobble" down to...
  17. KevinH673

    Stress/Deflection of Plate

    I have considered a hinge when we were first looking at this concept here. The problem with it would be too much movement in the "forward and backward" directions. The optic needs to stay, as best as possible, in the same position, while only changing angle. In practice, it of course wont work...
  18. KevinH673

    Stress/Deflection of Plate

    I'm unsure on calculating the slope. I know the deflection at A by how many turns of the bolt I do. I am not sure on the translation to B, though. I dont expect any bending, or not much, between points A and B due to the thickness of it, I would think that would act almost as a straight line...
  19. KevinH673

    Stress/Deflection of Plate

    rb, We need the thickness to be about 10 mm for threading in the optic holder. The reason the undercut is to such a small thickness is because we arent using a large amount of force to cause deflection, just a bolt (double threaded, so internal thread moves micrometers per turn). The part where...
  20. KevinH673

    Stress/Deflection of Plate

    denghr, thanks for suggestions but this needs to be air tight. I can not go in and add weights, as the box this will go in needs to be sealed. I'm trying to use hand calculations, not FEA, to design it. I am here for guidance on using the correct equations. prex, thank you for the help. I have...

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