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  1. EnglishMuffin

    PE Application Reference Choice

    BigInch : I'm not surprised that "somebody" didn't know the meaning of "renumeration" - it's not in our big office dictionary. I suppose it could mean "The process of renumbering" (grin).
  2. EnglishMuffin

    Micrometers

    I do like a friction thimble on a depth micrometer, but direct feel on an external micrometer.
  3. EnglishMuffin

    general question on splines

    There are also metric involute splines which have addendum shifted teeth as standard.
  4. EnglishMuffin

    Friction and contact area

    I did not notice the two posts after my last one until now. Even today, friction is a controversial subject, but the following quotes are taken from a relatively old book I possess entitled : "The Friction and Lubrication of Elastomers". I think they basically support the comments I have made in...
  5. EnglishMuffin

    why use nut factor instead of coefficient of friction?

    MintJulep - Just out of interest, why did lockwashers ever become prevalent in the first place ? They used to be all over the place on cars and electrical equipment, and in some cases still are. Were no tests ever done ? When was it discovered that they are in fact useless ? Wouldn't the kind...
  6. EnglishMuffin

    Friction and contact area

    For rigid materials, friction force is often said to be largely independent of the apparent contact surface area. Friction force is mainly dependent on the actual contact area, which is usually much less, and is heavily influenced by the normal force, having little relationship with the apparent...
  7. EnglishMuffin

    Helical Spring Lateral stiffness Value

    Since the lateral deflection of a coil spring involves both bending and torsion, wes616's formula must be incorrect, or at least incomplete, since it would have to involve both E & G. See the following - although it may be a little overcomplicated for what you need ...
  8. EnglishMuffin

    How does Carousel slide projector work?

    The slides drop out of the tray utilizing gravity - that may or may not rule it out for you.
  9. EnglishMuffin

    What effect does heat have on deflection of valve blade

    From your post,the geometry and temperature distribution (possibly non-uniform)is not clear. If these are known, and assuming this is not a creep problem, you could almost certainly compute the effects using FEA. For these relatively high temperatures, you will also need to know the relation...
  10. EnglishMuffin

    Machining accuracy

    Any good Jig Boring machine can do this. Just search for Jig Boring, Jig Borers etc.
  11. EnglishMuffin

    Dimensioning Twist Drills

    Diamondjim : Are you implying that back taper is new technology, or just that some of the stuff mentioned in the link I posted is new technology ? Back taper has been around for as long as I can remember - I first learned about it from a fellow student 35 years ago and it was old technology then...
  12. EnglishMuffin

    Dimensioning Twist Drills

    I would rather doubt that every manufacturer uses .001"/inch back taper on every drill they make. Did a bit of web research. According to this, http://www.mmsonline.com/articles/069902.html, it seems as if it can vary in some cases from .0005"/inch to .004"/inch at least. This reference also...
  13. EnglishMuffin

    Dimensioning Twist Drills

    There is one thing worth mentioning that not many people are aware of, which is that twist drills have a very slight taper (ie the diameter decreases as you move back from the tip), which is done to lessen the chance of binding. Don't ask me what the amount of the taper is though.
  14. EnglishMuffin

    Force to Straighten Curved Beam

    For a "back of the envelope" ball park estimate, you might consider something like P = 8*del*E*I/(e*L^2), where E I & are the usual, del = required lateral translation at middle of length L, and e = eccentricity of axial load P. This equation is basically from Timoshenko, and is for a short...
  15. EnglishMuffin

    Force to Straighten Curved Beam

    Prex : There is nothing wrong with saying y" = 1/R (approximately). But that y" cannot be the same as the y" in the energy integral you have quoted - the second differential of y for a curved beam is not zero when the deflection is zero, although the value of the strain energy integral should...
  16. EnglishMuffin

    Force to Straighten Curved Beam

    For a hanging cable, for which the formulae are readily available and discussed on other threads, there is no question that the cable cannot be made absolutely straight regardless of the tension. Although this case is slightly different, it is highly unlikely that you could straighten a beam...
  17. EnglishMuffin

    Force to Straighten Curved Beam

    I believe it requires an infinite amount of axial force to make such a beam absolutely straight, so you would first have to define some tolerance within which you considered it to be "straight".
  18. EnglishMuffin

    Axial and radial load on bearings due to thermal expansion

    If you know the radial and axial expansion amounts ahead of time, then it's not too difficult if you have enough detailed data about the bearing, although that data can be very hard to get, depending on the type of bearing. However, if you want to predict the expansion, it can get very...
  19. EnglishMuffin

    effect of backlash on durability of straight gears

    There is a make of lathe known as a Binns roll turning lathe. These are very big machines used for turning very large rough blanks. They have zero backlash main drive gears, and I think this is achieved by preloading the gears slightly by reducing the center distance. This of course runs...
  20. EnglishMuffin

    Formula for change in length of a shaft under torsion?

    To demonstrate such tiny effects in practice, I presume you would have to be very careful about specifying the exact details of the end fixities of the shaft, especially if it is short. After all, the torsion has to be applied to the shaft somehow. I'd bet Belluzzi's assumptions, whatever they...

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