Widia Gtd
Widia Gtd VTSFT-TC5156 Spiral Flute Tap 3/8"-24 Bottoming 2 Flutes UNJF
A spiral-flute tap cuts 3/8"-24 UNJF threads to a 3B fit with a 3/4-inch thread length and H3 limit
- 3/8"-24 UNJF thread size fits precise applications
- Spiral flute design evacuates chips efficiently
- Bottoming chamfer cuts threads near blind-hole bottom
- Two flutes balance strength and chip clearance
- High-speed steel with black oxide resists wear
Spiral Flute Tap 3/8"-24 UNJF
The Widia Gtd VTSFT-TC5156 is a high-speed steel spiral flute tap designed for cutting UNJF threads in blind holes. Its bottoming chamfer and right-hand thread direction suit machinists and maintenance technicians who need precise internal threads in aerospace or automotive components. The black oxide finish adds wear resistance during repeated use.
Practical Limits Of The UNJF Standard
The UNJF thread form features a controlled root radius that reduces stress concentration but requires a larger minor diameter than standard UNF threads. This tap produces a class 3B fit with an H3 thread limit, demanding accurate hole preparation using the specified 8.50 mm drill size. The 75 percent thread depth target balances strength with tapping torque in tough materials.
Upgrading From Straight Flute Taps
Switching from a straight flute tap to this spiral flute geometry improves chip evacuation in blind holes, reducing the risk of tap breakage and damaged threads. The upgrade is worth it when threading deeper blind holes or working with ductile materials that produce long, stringy chips. It does not replace the need for proper lubrication or correct alignment during the tapping operation.
Highlights
- 3/8"-24 UNJF thread size fits precise applications
- Spiral flute design evacuates chips efficiently
- Bottoming chamfer cuts threads near blind-hole bottom
- Two flutes balance strength and chip clearance
- High-speed steel with black oxide resists wear
Specifications
| Brand | WIDIA |
|---|
Questions about this item
Which thread size and pitch does this tap cut?
The tap cuts a 3/8"-24 UNJF thread, matching the size and pitch in the product name.
What does the H3 thread limit mean for the finished hole?
H3 sets the pitch-diameter tolerance to a 3B class of fit, giving a tighter allowance than standard 2B taps.
What drill size should I use before tapping?
Use an 8.50 mm drill to produce the recommended 75 percent thread engagement for this tap.
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