Circularity of Holes
Circularity of Holes
(OP)
After reading so much gd&t stuff, it has become apparent that no vendor is capable of accurately drilling a straight hole with a single diameter, what are commonly held tolerances to be applied to holes that are:
drilled
drilled and reamed
made with an endmill
Or is it only for pocketed recesses in turned parts.
And does circularity also apply to tapped holes?
drilled
drilled and reamed
made with an endmill
Or is it only for pocketed recesses in turned parts.
And does circularity also apply to tapped holes?
Fox Manufacturing Group http://foxmfggroup.com/Home.html





RE: Circularity of Holes
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Circularity of Holes
If I just want a drilled hole, what tolerance should be called out. I ask, because in the past, I would have just dimensioned a hole of size with a given +-, and did not use circularity, assuming some common value for the process. If I wanted it tighter, or with a better finish, I would have made the size tighter and assumed reaming, but still no circularity. But with gd&, I feel bullied into using circularity, but don't know how to tolerance it or rather by how much.
Obviously a super precise application for a feature would dictate the circularity, but I'm at a loss when it comes to specifying it for common features made by simple standard processes.
Fox Manufacturing Group http://foxmfggroup.com/Home.html
RE: Circularity of Holes
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Circularity of Holes
"If I just want a drilled hole, what tolerance should be called out."
What you really want is a hole. It should not matter how it gets there. Function should determine tolerance and the machine shop determines how to put the hole in based on the tolerance and other specifications.
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II