【转帖】need clarity on runout issue

yang686526

need clarity on runout issue
hello,
i have a tolerance on a motor shaft that needs clarity:
the dim is now as follows: (metric)
single-arrow runout: "0.0381"
position referenced to the housing boss:  "dia 0.0381"
does the positional tolerance restrict the runout to be within a 'cylinder' of dia 0.0381 along the entire length?
thanks
it seems like a redundant callout.  using runout restricts the axis of the shaft to fim of 0.0381" to the referenced datum.  although, runout is picking a few points on the surface whereas, tp is controlling perpendicularity to the referenced datums.  without seeing the entire drawing, i can't really make the call.  i can tell you from an inspection stand point that runout is easier to check on a shaft verse tp.
best regards,
heckler
do you trust your intuition or go with the flow?
i agree with heckler.  i would drop the position and keep the r/o because you are dealing with a rotating part.
if the datums for the positin and runout are the same (housing boss?) then the runout would make the position redundant.  position by itself would not guarantee runout, though.
i agree with the others.
also, with a motor shaft, it would be spinning. wouldn't total runout be more appropriate? i'm not sure without seeing the part.
chris
sr. mechanical designer, cad
solidworks 05 sp1.1 / pdmworks 05
the position tolerance may also be locating axial features on the shaft (i.e. controlling shaft protrusion)?
runout is rfs and i beleive tp would have to have the modifier as well to be the same. would need to look at the drawing.
macduff
chris,
total runout would make for an extremely costly shaft.  i've seen pump shafts with multiple bearing and element diamters having runouts of .0005" to grind centers.  if this was total runout it would mean that the entire surface would have to fall within this tolerance band.
i think kim needs to give us more information to correctly answer her inquiry.
best regards,
heckler
sr. mechanical engineer
sw2005 sp 2.0 & pro/e 2001
dell precision 370
p4 3.6 ghz, 1gb ram
xp pro sp2.0
nivida quadro fx 1400
do you trust your intuition or go with the flow?
yes, i agree i need more info.
chris
sr. mechanical designer, cad
solidworks 05 sp1.1 / pdmworks 05