MACHINING ALLOWANCES

Minimum OD and ID stock allowances for DOM tubing
Finished OD
Inch
0.187
and
Under
Over
0.187
0.230
Over
0.230
0.360
Over
0.360
0.460
Over
0.460
0.580
Up to 1.500
0.015
0.020
0.025
0.025
—
Over 1.500 to 3.000
0.020
0.025
0.030
0.030
—
Over 3.000 to 4.750
0.025
0.030
0.035
0.035
0.040
Over 4.750 to 6.000
0.030
0.035
0.040
0.040
0.045
Over 6.000 to 7.000
0.035
0.040
0.045
0.045
0.050
Over 7.000 to 8.000
0.035
0.043
0.048
0.048
0.053
Over 8.000 to 10.500
0.035
0.045
0.050
0.050
0.055
Over 10.500 to 12.500
—
0.045
0.055
0.055
0.060
Over 12.500 to 14.000
—
0.045
0.055
0.055
0.060
Over 14.000 to 15.000
—
0.045
0.055
0.055
0.060

NOTE: These allowances plus normal size tolerances must be considered in calculating the size to be ordered.

 


Example: Customer wants a tube to finish 3.250 in O.D. x 3.000 inches I.D. x 26 inches long.
3.250 inch O.D.
3.000 inch I.D.
+ .025 inch O.D. Allow
-.025 inch I.D. Allow
+ 0.02 inch Camber
-.020 inch Camber
3.295 inch
2.955 inch
+.010 inch O.D. Tolerance
-.010 inch. I.D. Tolerance

Ordered size will be 3.295″ OD + .010″ -.000″ x 2.955″ ID + .000″ – .010″

Drawn O.D. and I.D. tolerance is .010 inch total for this size and gage.

These calculations are based on conventional chucking procedures.