Thread Mill How-To Guide
Radius Offset (RPRG)
RPRG is the reference value of tool radius offset. Conventionally, the tool radius was entered during setup as a parameter of the NC system, which was corrected by checking the thread with a gauge. However, it has become possible to reduce the checking and correction simply by entering the RPRG value indicated on the tool shank.
NOTES: 1. RPRG are reference values. Determine optimal values after trial cutting as values depend on machining environment. 2.RPRG values are optimally established to achieve ISO:5H (formerly Grade 1) internal thread limits for metric threads and ANSI:3B internal thread limits for unified threads. RPRG values established for taper pipes (R/Rc) are effective when using the thread milling NC code generator software ThreadPro available on our website. 3. For diameters of thread mills, RPRG values are calculated based on the minimum cutting bore diameter (the minimum cutting internal thread size of the tool diameter). To cut other diameters, it is necessary to use a smaller value than RPRG.
+0.150
Example • Tool diameter:φ7.5; Pitch: 1; Minimum cutting bore diameter: 10 (EDP: 8304721) • Internal thread size: M10 × 1 • Tolerance for pitch diameter: 0 to +0.118 (ISO-5H) , 0 to +0.150 (ISO-6H)
+0.118
Entered value of RPRG: 3.681
Radius
Pitch Dia. 0
RPRG=3.681
Entered value of Radius: 3.75
ThreadPro (Thread Milling NC Code Generator Software)
www.osgtool.com/threadpro
• A vailable in 12 different languages • Supports 8 NC programming languages • Incorporates RPRG* value to further simplify process
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* RPRG = reference value of tool radius offset
Threading Technical
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