【转帖】an plane

yang686526

tan plane
is it possible that someone in this forum might be able to give me a link (?) to an example of 'tan plane', as defined in asme y14.5-1994, being used on a part?. i am searching for a 'real world part' rather than a partial example in text or training manuals. i am trying to improve my understanding of y14.5 and how it relates to geometry.
tia,
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lack of responses is reinforcing my opinion that the tan plane concept is 'moderately invalid'.  anyone with an example that really exists?
tangent plane is not used too often since most people don't know it exists but in most cases where the mating surface contacts a plane, tangent to the plane is real life. one would only contact on the high points on the plane during assembly.
if one had a 45 degree angle with a +/- 30 minute tolerance, the shop floor would use a protractor and contact tangent to the axis or high points and read the actual angle from the protractor. this is an axis and not a plane.
on a tangent plane, one would need a checking flat the exact size of the plane. place the checking flat on the plane then then check the tilt in both directions (both axis)and report the highest reading. tangent plane just takes the flatness out of the equation.
if you think people don't understand gd & t now, just place a "t" with a circle around it and insert it in the feature control frame after the tolerance and watch the reaction.
there are good uses but i don't believe that we are at that level yet in industry. this forum kind of proves it.
dave d.
i had an application recently that required the tangent modifier.
in the drawing we want to control the lowest point of the terminal insulation crimp relative to datum j (box of the receptacle). this controls the "bend" of the crimped terminal in one direction. since the form of the insulation crimp can vary from sample to sample, indicating a specific point is not funcionally feasible.
difficult to imagine the functional requirements for the tan plane callout.  the profile control of an element would seem to do the job quite adequately.  i believe though, for the profile control to be legitimate, the element requires a specified relationship to the datums j and e.  (e is apparently missing.)
who and why was the tan suggested?.
the drawing in in accord with y14.5-1994, correct?
the tan modifying is not used correctly here in the example. one can use the tan modifier on angles but not profiles.
looking at the drawing, since datum j is on the same plane, one should have placed phantom lines between datum j and the feature. do not use a basic dimension of 0. i could not find datum e either??
profile of a surface controls the angle of the surface, flatness and location all in one.
dave
the dimension 0.00 is meaningless.  it would be better to extend the .030 dim. to the 0.00 dim. location.  not what was asked, but it is glaring.
e is missing because i only posted one view from the drawing. it is a feature of size defined by the 2 outside surfaces adjacent to datum j.
the phantom line instead of 0.00 basic makes sense. thank you.
the objective was to control how high or low the surface identified by the profile of a line can shift relative to datum j. essentially we want to control how much the terminal can bend about the insulation crimp. one problem is that the insulation crimp is a very imperfect surface who's shape can vary substantially from sample to sample
one mistake was assuming that the tangent would always be a point that a plane parallel to datum j would contact.
if i changed the profile of a line to parallelism, would that make this correct? (i'm thinking not)
what method might be best for my purpose?
take out the tangent symbol and there you go. this will control everything you need.
dave
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