Cleveland Thread Forming Tap #4-40 1.88 in 0 Flutes Bottoming Bright

Thread Forming Tap for #4-40 UNC Threads

This Cleveland C59194 thread forming tap creates internal #4-40 UNC threads in ductile materials by displacing metal rather than cutting it. The bright, uncoated high-speed steel tool suits general-purpose threading tasks where chip removal is difficult. Right-hand threading and a 2B class of fit cover standard fastening requirements. The H3 thread limit provides a precise tolerance band for consistent results.

Capacity and Headroom for Thread Forming

The tap measures 1.88 in overall length with a .31 in thread length, limiting reach to shallow holes. A 75 percent thread drill size of 1.95 mm prepares the correct hole for full thread engagement. Zero flutes mean no chip evacuation path, so the tool works best in through-holes or blind holes with ample clearance at the bottom. Hard or brittle materials exceed the forming capability of this uncoated HSS design.

Practical Limits of the Forming Process

Thread forming requires ductile workpiece material; cast iron, hardened steel or glass-filled plastics will cause premature wear or tap breakage. The absence of flutes prevents lubricant flow to the forming zone, increasing torque and heat in deeper holes. Bright finish offers no wear resistance coating, so tool life drops quickly in abrasive alloys. Users needing higher production rates or harder materials should consider coated cutting taps instead.