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  1. SpringDingaling

    Planetary Gearbox Design Selection

    I'm not sure I get what you mean. I'm using long addendum already, these are plastic gears and I'm using 95% of pointed tooth length. What are you referring to by 50% sun and 25% planets? Also, is there any reason to use a different combination of teeth to achieve the end ratio? i.e. Case I...
  2. SpringDingaling

    Planetary Gearbox Design Selection

    I am an engineer working with a planetary gearbox reduction that needs to lie in the 18-20:1 reduction range. I am limited strictly in the diameter of the part, and will be using two stages in a fixed ring configuration. I have determined that there are about 8 arrangements that will fit my...
  3. SpringDingaling

    Effect of Preset on Fatigue Life

    One more question.....for preset to take effect, does the preset have to be outside the working range? e.g.....I have a spring that yields at 60%UTS, is solid at 75% UTS, and has a working point at 70% UTS. Do I derive any benefit from the spring set between 60 and 70%, or is it only the preset...
  4. SpringDingaling

    Effect of Preset on Fatigue Life

    We require a certain amount of counterbalance for a door that requires lifting. The package dimensions come from customer requirements. I guess we'll have to rethink the problem! Thanks for your comments.
  5. SpringDingaling

    Effect of Preset on Fatigue Life

    Unfortunately I haven't been able to figure out a way to change the dimensions. I had thought about the buckling issue and had made our inner and outer tubes from plastic to reduce the wear on the spring. How much load variation do you figure could happen? Also, is there a good way to estimate...
  6. SpringDingaling

    Effect of Preset on Fatigue Life

    Thank you for your correction. You're right. I have no experience in spring design. I was copying what spring designer V5 is giving me. It states tensile in the top right hand corner. The corrected stress levels it gives corresond to 65% of the value given under "tensile", although yes I...
  7. SpringDingaling

    Effect of Preset on Fatigue Life

    What would be an acceptable level of design stress in music wire material for presetting to have enough effect for me to make my cycle life. For ex. Two Springs: Spring 1 is 29mm OD, 3.1mm wire diameter, 600N @ 250mm, 375N @ 450mm. Corrected Stress is 1562 MPa, or 84% of tensile strength...
  8. SpringDingaling

    Effect of Preset on Fatigue Life

    I have also been told that someone has seen in a design handbook that presetting can reduce the resultant stresses by up to 1/3. Is this true? If so, does this hold true for low cycle fatigue or is this only good for static applications? I am currently trying to get the attention of some...
  9. SpringDingaling

    Effect of Preset on Fatigue Life

    I'm having a problem with designing a spring/springs that fits my application. Here are the design constraints I am currently working with: Cycle Life Requirement: 50,000 cycles Load Point 1: 450mm Force1: 600N Load Point2: 250mm (deflection required: 200mm) Force2: 1000N Min ID: 16mm Max OD...

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