Chamfer call out on a threaded hole, where is it measured from?
Chamfer call out on a threaded hole, where is it measured from?
(OP)
Is the chamfer call out .015 x 45 (degree symbol)on an internal threaded hole measured from the diameter of the cylindrical hole feature or the major diameter of the thread?
Example: I have a 3/8-24 UNF-2B threaded hole and I want a .015+/-.005 chamfer on the edges of the letter Q (.332) hole. Please note that I am aware that the .357-.372 diameter chamfer is not an appropriate lead in for the tap but is required for other reasons.
Example: I have a 3/8-24 UNF-2B threaded hole and I want a .015+/-.005 chamfer on the edges of the letter Q (.332) hole. Please note that I am aware that the .357-.372 diameter chamfer is not an appropriate lead in for the tap but is required for other reasons.





RE: Chamfer call out on a threaded hole, where is it measured from?
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Chamfer call out on a threaded hole, where is it measured from?
RE: Chamfer call out on a threaded hole, where is it measured from?
Chris
SolidWorks 11
ctopher's home
SolidWorks Legion
RE: Chamfer call out on a threaded hole, where is it measured from?
So, there's nothing to measure.
So, linear dimension and angle is just a silly way to specify the chamfer on a threaded hole.
You could specify the chamfer that way, to be measured when it still exists, after chamfering but before tapping. ... but you can't know after tapping what that dimension was before tapping.
So, it makes much more sense to specify by angle and diameter of the intersection of the chamfer with the normal surface.
Mike Halloran
Pembroke Pines, FL, USA
RE: Chamfer call out on a threaded hole, where is it measured from?
RE: Chamfer call out on a threaded hole, where is it measured from?
So the dimension is to a 'theoretical sharp corner' in circular form.
Since it's all but impossible to measure, the requirement is stupid.
Mike Halloran
Pembroke Pines, FL, USA
RE: Chamfer call out on a threaded hole, where is it measured from?
"Know the rules well, so you can break them effectively."
-Dalai Lama XIV
RE: Chamfer call out on a threaded hole, where is it measured from?
I agree and apologize to you and Mike. Effectively the part is blanked on a lathe and the edge that gets this chamfer is there only to remove the burr left from the cutoff process. It is not intended to provide your typical thread lead in as the design intent is to have no chamfer after threading at all. Having the chamfer call out on the drawing is intended only to prompt the machinist to include this step in his/her programming steps. I could have placed a note to "break edge MAX .372 dia) but there simply wasn't enough room on the drawing to fit that. The machinist interpreted it as starting from the major diameter of the thread and face and bet me a pizza that they were right. Not wanting to pass up on a free meal I was hoping to get a consensus from others as to the definition of the start point (cross section of the hole to the face), not when to measure it, or if the design intent is "silly" or "stupid" as Mike put it.
RE: Chamfer call out on a threaded hole, where is it measured from?
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Chamfer call out on a threaded hole, where is it measured from?
RE: Chamfer call out on a threaded hole, where is it measured from?
Least awful way to specify, I think, is "CSK 90deg to .372in max dia" or similar, but it should be on the process sheet if there is one, or on a raw/intermediate "make from this" drawing, since the feature doesn't appear on the finished part in an inspectable form.
Mike Halloran
Pembroke Pines, FL, USA
RE: Chamfer call out on a threaded hole, where is it measured from?
RE: Chamfer call out on a threaded hole, where is it measured from?
This being the case I'd buy the machinist the pizza just to buy the good will
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