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  1. jstluise

    Frictional Torque at Low Temps (high viscosity) - D1478 Test

    I'd like to estimate the torques in a radial bearing at low temps due to the high viscosity of the grease. SKF has a friction model but it is not valid for these high of viscocities, so I am wondering if there is any other way to estimate without actual testing. The oil viscosity at -54C is...
  2. jstluise

    WPDM: Revision & Lifecycle Suggestion?

    Asit, Yes, if you move to PDM a lot of your headaches will go away. Before we started using PDM we had lots of trouble keeping everything straight between users since files moved between our network storage and local machines. If you are just looking for vault storage and revision control...
  3. jstluise

    WPDM: Revision & Lifecycle Suggestion?

    Hi Asit, If I understand you correctly, you are having trouble with figuring out the best way to deal with drawing and part revisions? First, are you using PDM? If you are, your file names should be "dumb", meaning they don't have any data/properties within the file name (e.g. revision...
  4. jstluise

    WPDM: Revision & Lifecycle Suggestion?

    Thanks, GRF. Lots of good info and it sounds like your scheme would work well with our workflow. The only difference being that we rarely go into "Production", so I think we would release a part when it is first sent out for machining, be it a prototype or actual part we are selling. I think...
  5. jstluise

    WPDM: Revision & Lifecycle Suggestion?

    Exactly. That's why no one has used or attempted to use our current scheme...just way to complicated. Just like ctopher, I plan to have just Development and Released lifecycles. I don't think Obsolete is necessary as long as previous released versions remain saved (rather than moving them...
  6. jstluise

    WPDM: Revision & Lifecycle Suggestion?

    Thanks for the response. We've been running WPDM for quite a few years now and it has worked fine for our needs so far. But all we've really used it for is storing our files on the server in the vault...no lifecyle/revision utilization. We'll have to adapt to the new version of PDM when it...
  7. jstluise

    WPDM: Revision & Lifecycle Suggestion?

    I apologize in advance if this would be better suited for the Configuration Management forum, but I thought it fit well here since it is kind of specific to Workgroup PDM. I'm working on organizing a revision scheme for my company since it really hasn't been utilized at all. I realize that...
  8. jstluise

    Diameter change for compression spring (free end)

    Here are the two sources I found: Wahl, A. M., 1963, Mechanical Springs, 2nd ed., McGraw-Hill, New York, Chap. 20. T. S. Bockwoldt and G. A. Munsick, Correction to Design Equation for Spring Diametral Growth Upon Compression The paper that provides a correction to Wahl's equation can be found...
  9. jstluise

    Diameter change for compression spring (free end)

    I should also note that equation that Wahl and the other paper derives is for diametral change for compressing a spring completely to its solid height. So, given the starting pitch, spring wire diameter, and starting spring mean coil diameter, the equation will tell you the change in diameter...
  10. jstluise

    Diameter change for compression spring (free end)

    The ends are free to rotate because my means of compressing the spring are three longitudinal control lines, instead of a compression force from each end. The control lines run along the length of the spring and each line is fixed to the spring at each intersection. Basically the control lines...
  11. jstluise

    Diameter change for compression spring (free end)

    I am trying to find some equations for calculating the diameter change of a compression spring when it is compressed a known distance and one end is free to rotate. Thus, the ends rotate relative to eachother (spring unwinds) and the diameter changes (increases). In the case of fixed ends, the...
  12. jstluise

    Solar Absorption of Hardcoat Anodizing

    I am trying to find some data on the solar absorption of hardcoat anodized aluminum (MIL-A-8625 Type III Class 1, non-dyed). Since it is mil spec, I thought there would be some info somewhere, but I cannot find anything. I was able to find some number on emissivity (0.83-0.86), but that was...
  13. jstluise

    Gear Strength Calculation - Too Conservative?

    Excellent response, Terry! Just what I was looking for!
  14. jstluise

    Gear Strength Calculation - Too Conservative?

    I have a question about using the Lewis formula for calculating the maximum torque that can be applied to a gear. A project uses involves bevel gear sets that are subject to high torques. Our concern was whether or not the bevel gear set could withstand the high torques. Our independent...

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