【转帖】otal runou

yang686526

total runout
we have a part that has two shafts opposite each other. (.187 dias.x .375 long each) each shaft has individual datum callouts (a & b) with a total runout callout of .0005 to a-b. we have a few interpretations here on how this should correctly be inspected. at the moment we are simply placing one shaft in a "v" block and rotating it with an indicator on the opposite shaft. use of a c.m.m. is out of the question because each part needs to be inspected, once it comes off the machine in production quantity's. any insight would be appreciated.
the callout requires that the related surfaces be verified with respect to the axis a-b. it is not clear from your statement what surface is related to a-b.  however the setup that you indicate verifies the relationship of one end to the other.  this is not consistent.
clarification required!
seems like the indicator would vary with both the profile of the shaft it is resting on and any misalignment between the axes of the two shafts.  do you care if the shafts are cylinders?
what is this part used for?  i am curious because total runout of .0005 is a costly callout.
best regards,
heckler
sr. mechanical engineer
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never argue with an idiot. they'll bring you down to their level and beat you with experience every time.
please let us know what diameters are datum a & b. are they countersunk ends?? once i have the datums, i can tell you how to measure these on a divider head or chuck.
dave d
it would be more clear what datums a & b are. i agree with heckler about .0005 being a costly callout.
chris
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israelkk,
the examples in tec-ease are not compatable with the problem stated.  it requires an axis a-b.
try figs 6-49 and 6-51 of the y14.5 std.
thanks for all the replys!!! sorry for the confusion.
datum a is one of the .1870 dias which is a male feature. the opposite dia. of .1871 is the b datum, which is also a male feature, they are separated by a rectangular section. at each diameter callout the total runout of .0005 a b is attached. the width of the rectangular feature that separates the two shafts is .750
the part is for a military application...the whole part is critical, and very expensive for its size.
hope this clears things up!!
i assume this is a gimbal part.
i do not understand why there are a and b. why not use just a and then give the other shaft with total run-out of 0.0005" with respect to a. usually such a part is turned on a lathe using centering holes. this way you can get the 0.0005" run-out quite easily.
anyway, if this is a given drawing i think you need to place both shafts on two very accurately aligned v blocks and then while you rotate the part measure the run-out on both shafts while they are supported on the two v blocks. if the part has two centering holes (one on each shaft edge) then you can use the centring holes as a-b and measure the run-out on both shafts.
i assume this is a gimbal part.