Perpendicularity to a pitch diameter
Perpendicularity to a pitch diameter
(OP)
I need some info on how to measure this properly. The feature is a spot-face with a M14 x 1.5 -6H Rolled thread (oil drain plug) The feature control frame Perp. 0.15 to Datum D is on the spot face. It is also a critical characteristic requiring SPC. D is the pitch diameter of the thread. Do I need an optical comparator to measure this or is there a way to do it on our CMM.
Thanks, Randy
Thanks, Randy





RE: Perpendicularity to a pitch diameter
It seems backward to me; I would have located the pitch diameter relative to the spotface, but what do I know?
Sorry this doesn't really help with your problem.
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Perpendicularity to a pitch diameter
I am not familiar with all CMM methods, but I imagine there is a way for the CMM probe to calculate a pitch diameter with the equivalence of an "over wires" measurement. You could use a thread gage inserted into the hole and measure against it. I would contact thread gaging specialists for this:
http://www.johnsongage.com/
http://www.greensladeandcompany.com/
RE: Perpendicularity to a pitch diameter
RE: Perpendicularity to a pitch diameter
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Perpendicularity to a pitch diameter
RE: Perpendicularity to a pitch diameter
What I consider to be a large disconnect in GD&T is caused, in part, I believe, by this kind of wink wink well maybe "they just don't know what they are doing" if it is not politically popular with whomever you are speaking with. It seems reasonable, to me, that these applications want what is specified, whether it is popular or easy to check.
My trainer used to say if you measure a football field does it matter which end you start with? If you want to turn it around go ahead but don't say he doesn't want what he wants
Do you know how hard it is to find these final numbers, or how lucky we are to finally have this kind of information?
Do we really care which comes first, in the end, is that what you believe down deep?
I know lots of people don't know what they are doing, to so quickly undercut the ones that seem reasonable undercuts the progress we have made.
Frank