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  1. EnglishMuffin

    Over pin measurement of odd teeth helical gear

    We use neither pins nor balls - we use matching block sets consisting of one female and two male rack shapes instead. You can't really beat these in my view. Unfortunately, the outfit that made them long ago is no longer in business. The shop guys lost one of the very small ones inside a...
  2. EnglishMuffin

    How to calculate centre distance of spur gears?

    See this thread : thread406-146377
  3. EnglishMuffin

    Calculating corrected center distance

    Philrock : Changing the CD does not change the profile shift of either gear if you have already defined them. The profile shift of a gear can be defined and measured quite independently of any center distance you intend to use. In addition, when measuring a gear, you cannot distinguish between...
  4. EnglishMuffin

    Calculating corrected center distance

    Philrock : Well - I think we are a little at cross purposes here. If you design a pair of gears from scratch, for a known center distance, then the backlash is introduced at the end, being incorporated in the over-pin dimensions or base tangent, or whatever, and is not incorporated in the...
  5. EnglishMuffin

    Calculating corrected center distance

    OK - found my mistake - looked in the wrong part of the interpolation table. I get 109.541 which agrees with everyone else. But I do not agree with this earlier statement of Philrock's "Backlash does not enter into center distance / profile shift calculations. If you change the backlash by...
  6. EnglishMuffin

    Calculating corrected center distance

    Gearcutter : Although you are addressing this question to Philrock, nevertheless, since Isrealkk says the equations I presented are correct, then assuming he is right, you should be able to see it from them. They could all be combined into one large equation, but as presented, what you have to...
  7. EnglishMuffin

    Calculating corrected center distance

    israelkk: Yes - that would be near enough I guess, if it's not a critical application, or small teeth and small shifts. But I don't know why we all got different answers. I expect yours is right if you used a program - I'm too busy to track down my error - maybe it came from linearly...
  8. EnglishMuffin

    Calculating corrected center distance

    Well, using my old Maag gear handbook, and interpolating from the tables in it, (ie not using a computer), I get 109.731. Israelkk probably used a computer program, so maybe I have screwed up, but the equations should be correct (hopefully). The number was found from the following equations...
  9. EnglishMuffin

    Calculating corrected center distance

    It might be worth adding that: 1. If the center distance is C, the numbers of teeth on the two gears are Z1 and Z2, and the operating pitch diameters are D1 and D2, then : D1 = 2*C*Z1/(Z1+Z2) and D2 = 2*C*Z2/(Z1+Z2) 2. According to ISO international standards, I believe the...
  10. EnglishMuffin

    Calculating corrected center distance

    It is incorrect. If you truly know what the operating pitch circle diameters are, then you know the center distance. But to find the operating pitch circle diameters, you must either already know the center distance, or everything about both gears, including addendum shift, and the backlash...
  11. EnglishMuffin

    drawing an elliptical gear teeth profile

    Suggest you start by checking out everything in this recent thread :thread406-132225, assuming you haven't already.
  12. EnglishMuffin

    Creation of geometry for elliptical gears

    Assuming you are allowing one gear to drive the other, the ellipses are the same size, and are initially arranged such that their major axes are orthogonal to each other, with the major axis of one ellipse intersecting the center of the other, I can't see your problem. But for some arrangement...
  13. EnglishMuffin

    Specific sliding of external gear pair

    The trick (if possible) is to apply addendum modification such that the modulus of the slide/roll ratio is the same at the highest and lowest points of tooth contact - this results in the lowest possible maximum value for a given situation. For very high speed gears, the value of the slide/roll...
  14. EnglishMuffin

    Gear lube nozzle placement

    Variable speed - anywhere between 10 and 8350 fpm - helical gears. Can occasionally run in reverse.
  15. EnglishMuffin

    Gear lube nozzle placement

    But the churning effect here would be miniscule - we are talking about an oil supply rate of less than a cc/hour. The question I have is whether it is really true that oil will not find it's way into the mesh as readily with oil/air lube positioned on the in-running side as it would on the...
  16. EnglishMuffin

    Gear lube nozzle placement

    Well, I would think the power losses created by oil-air lubrication would be fairly small, regardless of nozzle placement. I also recall Ray Drago (another well known gear expert) telling me that there were counter arguments to the out-running mesh theory, but I can't remember what they were...
  17. EnglishMuffin

    Gear lube nozzle placement

    I was once told by Ken Gitchel of UTS that the correct way to position gear lube nozzles is to direct them at the out-running side of the mesh, because there is actually a negative air pressure there. Does anyone else concur with this ? (In this case I am using oil-air lubrication).
  18. EnglishMuffin

    Helical Gear Hob Runout

    It depends partly on knowing the hob details, because hobs have a lead-in at the end before you get to the full tooth form section. If you know the length of that lead-in, you can figure out how much "offset" the hob will stand, assuming that you want to minimize the distance from the end of the...
  19. EnglishMuffin

    Curvic coupling

    Contact Gleason. They have booklets which explain how to design them (or they used to, cause I've got em). Gleason are the only people who make the machines which are used to make them, as far as I am aware. However, you would probably be better off with a Hirth coupling these days - and they...
  20. EnglishMuffin

    What are the steps to draw a crown face gear?

    Are you really making Wildhaber Novikov gears? (These are circular arc types, not involute, and very unusual). Note that they have misspelled "Wildhaber" on that site. Regarding your problem, assuming you are talking about an involute face gear, when you say you used the theory behind a "rack"...

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