MACHINING ALLOWANCES
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Minimum OD and ID stock allowances for DOM tubing
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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 |
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Up to 1.500
|
0.015
|
0.020
|
0.025
|
0.025
|
—
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Over 1.500 to 3.000
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0.020
|
0.025
|
0.030
|
0.030
|
—
|
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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
|
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Over 6.000 to 7.000
|
0.035
|
0.040
|
0.045
|
0.045
|
0.050
|
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Over 7.000 to 8.000
|
0.035
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0.043
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0.048
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0.048
|
0.053
|
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Over 8.000 to 10.500
|
0.035
|
0.045
|
0.050
|
0.050
|
0.055
|
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Over 10.500 to 12.500
|
—
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0.045
|
0.055
|
0.055
|
0.060
|
|
Over 12.500 to 14.000
|
—
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0.045
|
0.055
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0.055
|
0.060
|
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Over 14.000 to 15.000
|
—
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0.045
|
0.055
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0.055
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0.060
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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.