Richard J Kinch wrote:
Jim Stewart writes:

Is this right?

No. Here is the thread data from my softwa

Ned got me pointed in the right direction
and the problem is solved. Is your software
available for download?




0.875"-20 T H R E A D D A T A

0.8750 D Basic diameter (in)
0.0500 P Pitch (in)
0.029 Ideal measuring wire size (in)
0.029 W First practical measuring wire size (in)
0.0437 Subtract from first wire measurement for actual pitch diameter (in)
0.032 W Second practical measuring wire size (in)
0.0527 Subtract from second wire measurement for actual pitch diameter (in)
NOTE: interpolated fundamental deviation
INTERP: 1.2700 on [1.0000,1.5000] onto [0.0260,0.0320] -- 0.0292
0.0012 EI Fundamental deviation (allowance), internal thread (in)
-0.0012 es Fundamental deviation (allowance), external thread (in)
INTERP: 1.2700 on [1.0000,1.5000] onto [0.1600,0.1900] -- 0.1762
NOTE: ext thread pitch dia tolerance above max pitch in table
INTERP: 1.2700 on [0.0000,1.0000] onto [0.0000,0.1180] -- 0.1499
0.0069 TD2 Internal thread pitch diameter tolerance (in)
0.0059 Td2 External thread pitch diameter tolerance (in)
INTERP: 1.2700 on [1.0000,1.5000] onto [0.1800,0.2360] -- 0.2102
INTERP: 1.2700 on [1.0000,1.5000] onto [0.2360,0.3000] -- 0.2706
0.0083 Td External thread major diameter tolerance (in)
0.0107 TD1 Internal thread minor diameter tolerance (in)

EXTERNAL:
0.8738 dmax Major dia, max (in)
0.8656 dmin Major dia, min (in)
0.8197 d1max Minor dia, max (in)
0.8047 d1min Minor dia, min (in)
0.8414 d2max Pitch dia, max (in)
0.8355 d2min Pitch dia, min (in)

INTERNAL:
0.8903 Dmax Major dia, max (in)
0.8762 Dmin Major dia, min (in)
0.8327 D1max Minor dia, max (in)
0.8220 D1min Minor dia, min (in)
0.8506 D2max Pitch dia, max (in)
0.8437 D2min Pitch dia, min (in)

EXTERNAL THREAD PRACTICAL DATA:

0.8656-0.8738 MAJOR DIAMETER RANGE
0.8792-0.8851 PITCH DIAMETER MEASUREMENT RANGE ON 0.0290 WIRES
0.033-0.039 SHARP-TOOL MINIMUM INFEED (decrease by tool tip blunting)

INTERNAL THREAD PRACTICAL DATA:

0.823-0.833 BORE
0.033 SHARP-TOOL MINIMUM OUTFEED (decrease by tool tip blunting)