Suggested concentricity tolerances
Suggested concentricity tolerances
(OP)
Can anyone steer me toward a resource offering suggested concentricity tolerances for rotating elements at - say - various speeds?
Chris in NC NASCAR Country
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Suggested concentricity tolerances
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Suggested concentricity tolerancesSuggested concentricity tolerances(OP)
Can anyone steer me toward a resource offering suggested concentricity tolerances for rotating elements at - say - various speeds? Chris in NC NASCAR Country Red Flag SubmittedThank you for helping keep Eng-Tips Forums free from inappropriate posts. Reply To This ThreadPosting in the Eng-Tips forums is a member-only feature.Click Here to join Eng-Tips and talk with other members! |
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RE: Suggested concentricity tolerances
Barry1961
RE: Suggested concentricity tolerances
In most cases, when folks specify concentricity, they are actually thinking and measuring runout.
Concentricity in its true form is difficult to measure, and requires measuring size, roundness, and position of two surfaces.
Runout is what you measure by rotating a part clamped on one cylindrical surface with a dial indicator on another. Much easier, and in most cases more than adequate.
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RE: Suggested concentricity tolerances
RE: Suggested concentricity tolerances
If your concern is strictly "concentricity tolerance", then you are concerned primarily with assembly fits. Any level of tolerance (concentricity or run-out) can be achieved in a given part or assembly. It's just a matter of what you are willing to pay to get it. And any geometric or dimensional tolerance you may specify can only be inspected under static conditions.
But if your concern is really "rotating elements at various speeds", then what you should be concerned about is dynamic imbalance. So I would recommend that you determine what is the maximum unbalance moment that you can accept for a given part/assembly, and develop a procedure to dynamically balance that part/assembly within that limit. It's a common practice with high performance race cranks, flywheels, clutches, etc. like those used in NASCAR.
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RE: Suggested concentricity tolerances
http://www.me.metu.edu.tr/me114/tolerancing.htm
I have always used the Basic Hole Class of Fits chart in the back of my drafting book. I considered it took into account the part sizes, the runout of manufacturing and the assembly relationship etc.... The main thing is to learn what the classes are by trial & error and cautious reading. I have never had an error from using them. The 2 links above.
Other help:
Balancing act: http://www.mpta.org/MPTABalancingPrimer.pdf
Reference, excellent: ht
Related: http://www.mmsonline.com/articles/049602.html
Related: ht
Related Services: http://www.onsitemachining.com/tolerances.html
Related Specs: Concentricity tolerance (DIN ISO 1101)
Reference: http://www.datamyte.com/PDF/Concentricity.pdf
Reference info, halfway down: http://www.mitutoyo.com/pdf/4192-211.pdf
Just for sh*ts and giggles: http://www.dstan.mod.uk/data/02/304/01000200.pdf
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RE: Suggested concentricity tolerances
Thank you all for the very helpful feedback.
I found an alternative to calling out concentricity in Lowell Foster's "Geometrics II" page 296 in which he suggests as an alternative to concentricity, calling out positional tolerance regardless of features size and referencing the same datum [you] would reference in the concentricity callout - with the datum too regardless of feature size.
cheers!
RE: Suggested concentricity tolerances