Size tolerances on drilled and punched holes
Size tolerances on drilled and punched holes
(OP)
Guys-
I'm a design engineer and am looking for an authoritative source for run-of-the-mill size tolerances on drilled and punched holes. I've spoken to three machinists and each have given me different ideas on what "the standard" is.
One source, Engineers Edge(www.engineersedge.com/drill_sizes.htm) gives the following diameter ranges and tolerances:
.0135-/125: +.004/-.001
.126-.250: +.005/-.001
.251-.500: +.006/-.001
.501-.750: +.008/-.001
.751-1.000: +.010/-.001
1.001-2.000: +.012/-.001
but they provide no rationale or data to substantiate the tolerances!
Thanks!
I'm a design engineer and am looking for an authoritative source for run-of-the-mill size tolerances on drilled and punched holes. I've spoken to three machinists and each have given me different ideas on what "the standard" is.
One source, Engineers Edge(www.engineersedge.com/drill_sizes.htm) gives the following diameter ranges and tolerances:
.0135-/125: +.004/-.001
.126-.250: +.005/-.001
.251-.500: +.006/-.001
.501-.750: +.008/-.001
.751-1.000: +.010/-.001
1.001-2.000: +.012/-.001
but they provide no rationale or data to substantiate the tolerances!
Thanks!
Tunalover





RE: Size tolerances on drilled and punched holes
"The following formulas give the amount of hole oversize to be expected in normal drilling operations within .001 inch for drills of 1/8 to 1 inch diameter:
Maximum Oversize = .005 + .005D
Minimum Oversize = .001 + .003D
where D is the nominal drill diameter in inches."
I don't see this as being a standard, just a helpful rule of thumb.
Manufacturing Freeware and Shareware
http://mrainey.freeservers.com
RE: Size tolerances on drilled and punched holes
The rationale behind the tolerances is based on experience. A normally sharpened drill will produce the hole sizes listed from some sort of study or they were plagarized from someone else's standards book. The Allis Chalmer shop practice guide shows the following tolerances for drilled or the top of punched holes:
0 to .125 -.002/+.005
.125 to .250 -.002/+.006
.250 to .500 -.002/+.008
.500 to .750 -.002/+.009
.750 to 1.000 -.002/+.010
1.000 to 2.000 -.002/+.016
2.000 to 3.500 -.005/+.025
Breakout for Allis Chalmers follows:
Thickness Oversize at bottom
0 to .015 .006
.015 to .040 .008
.040 to .125 .02
.125 to .250 .03
.250 to .500 .04
.500 to .750 .05
I won't publish the Cat standards as they are still in business and may show releasing this info as a violation of their copyright.