Last updated 10 August 2026
Cut it to .3279 / .3311 on pitch diameter for a coat of .0002 to .0005 per side. That is the class 2A band of .3287 / .3331 moved down by four times the coating, not twice.
This is the whole job in two steps and it is worth seeing them separately, because each has its own way of going wrong. The first step is a lookup that people usually get right. The second is the four times factor, which people miss because they have already doubled for sidedness and have no reason to expect another factor of two.
Notice what the plating range does on top of that. The window is .0003 wide, and on a thread it costs four times that upstream, so .0012 of a .0044 tolerance is gone before the machinist has touched the part. Better than a quarter of the band, spent on not knowing what the plater will actually deposit.
That is the argument for asking the plater what they hold rather than accepting what the specification permits, and it is sharper on threads than anywhere else on the part.
| On the print | .3287 / .3331 in |
|---|---|
| Process | Plating |
| The feature | thread, both surfaces in the process |
| Per side | 0.0002 to 0.0005 in |
| The dimension moves | larger at this operation |
| Shift per unit of per-side effect | 4 times |
| Hold before the process | .3279 / .3311 in |
Open this case in the calculator, and change the numbers.
Computed by ctrlPlanner. MIL-STD-870, Federal Screw Thread Specification H28.
This is one characteristic. A real part has forty of them through five operations, and every one needs the same walk when the drawing revises. That is what ctrlPlanner does from a ballooned print.
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