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  1. cjholl0

    Falling Object Calculation

    Sorry...the second equation should be FD = PE+KE
  2. cjholl0

    Falling Object Calculation

    I'm trying to determine the impact force of an object when it comes to a sudden stop after a fall. The object weighs approximately 500lbs and has a safety cable designed to catch it in the event of a fall. I have looked at several sources on the web and have seen 2 schools of thought. One...
  3. cjholl0

    Torque when rotating mass stops

    The object is a fan rotating at a constant, max speed. I'm concerned about the reaction at the fan support if the blades were to crash into an object. I know in reality nothing is instantaneous but I also don't have a way to measure the time from impact to actual stoppage(it's very short). I...
  4. cjholl0

    Torque when rotating mass stops

    I mean the object is rotating at a constant speed and then it suddenly strikes an object. Think maybe a gear or fan where the tooth/blade hits something massive that doesn't move.
  5. cjholl0

    Torque when rotating mass stops

    I'm trying to calculate the torque on a structure when a rotating mass comes to a sudden stop. I know the moment of inertia and angular speed so I can get the energy involved. I've been going through old books trying to get a relationship between that energy and the torque back on the...
  6. cjholl0

    Codes regarding swimming pool applications

    Perhaps I wasn't clear enough but I thought it went without saying the fan wasn't intended to be submersible. The concern was for the proximity of electrical devices (in this case the fan) and what kind of protection they needed to have in order to be placed around a swimming pool. What...
  7. cjholl0

    Codes regarding swimming pool applications

    I was wondering if anyone knew of an electrical code requiring electrical devices to be submersible if within a certain proximity to water? Specifically, someone wants to hang a large ceiling fan 9 feet over a salt water swimming pool. A colleague mentioned a requirement that it had to be...
  8. cjholl0

    Steel fasteners for use in Aquatic centers

    Thanks Strider. That was a very helpful article that had exactly what I was looking for. Thanks again.
  9. cjholl0

    Steel fasteners for use in Aquatic centers

    I'm hoping to get some help on the selection of fasteners for use in aquatic centers. We currently use standard grade 8 bolts for our products which hang overhead. We don't have much experience with customers using them in aquatic centers but one concern I have is the effect of chloramine on...
  10. cjholl0

    Strength of cast threads

    Im trying to specify a torque value for a bolt that is screwed into a cast iron box. The recommended torque, using the recommended preload, is pretty straightforward from the Machinery's Handbook. But, this also assumes your using a similiar grade of nut (I think). I'm using a grade 8 bolt so...
  11. cjholl0

    Sample size for capability

    What exactly is meant by homogeneous? For the 3 station example you mentioned not running 30/station, instead 20/station. Is the key to run the same number per station? Also, why is 30 needed for a normal distribution? If you have only 20 do certain statistical tools not apply? Does it...
  12. cjholl0

    Sample size for capability

    I work for an automotive supplier and our QA dept routinely uses a sample size of 32 for CpK data. I've asked several people what the basis for this number is but nobody has been able to tell me, just that's what we've always done. It seems to me that there would have to be some consideration...
  13. cjholl0

    Understanding Resonance

    I was wondering if anyone could explain some basic resonance ideas? If I'm designing a throttle body that incorporates a DC motor, is the concern that the motor may operate at or near the nat freq of the body, which would cause some body deformation? I'm assuming all objects have a NF right...
  14. cjholl0

    Inspecting bar stock for machining

    My company will begin machining throttle shafts in-house and so we will need to inspect the bar stock as it arrives. We're using SUS 303 and 430F, maybe 12ft lengths. Does anyone have any thoughts on what to inspect the material for? I was thinkning straightness, verifying material certs...
  15. cjholl0

    Sample Sizes

    The QA guys at my company (Automotive Supplier), are always running samples and doing studies to evaluate all sorts of things. They've stated a 32 piece sample is a statistically significant size and they use that size all the time. In my memory from Engineering School, the sample size had to...
  16. cjholl0

    Sulphur Content in Laser Welding

    303 is what we're currently using (wasn't my idea). I'd like to pursue other options because we're having a rough time getting 303 with .2max Sulphur. Do you think 304 is easily available with .2Su? Have a contact at a supplier? I appreciate your input.
  17. cjholl0

    Sulphur Content in Laser Welding

    I've been told the sulphur content must be very low to weld 303 stainless steel (maybe .2 max). Getting 303 with this low of a sulphur content is very difficult. Does anybody know how low you have to go to weld with 303? Could a process parameter compensate for higher sulphur? Thanks

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