Smith Tool 311-51-217 1-1/16" ACME Tension & Compression Tap Holder

The Smith Tool 311-51-217 is a new tension and compression (floating) tap holder designed for ACME thread tapping, accepting a 1-1/16" square shank (SH) tap drive. The "ACTH" designation confirms this is an ACME-series tap holder from Smith Tool's 311-series floating tap holder line; the "51" sub-series identifies the body/spindle size class, and "217" encodes the specific tap shank size and drive configuration. The tension and compression float mechanism allows the holder to extend and compress axially as the tap advances and retracts, compensating for minor feed-rate mismatches between the machine spindle and the tap, which is critical for ACME thread forms that require precise lead control and generates high axial loads. The tool body features a knurled lock ring for float adjustment, a hardened and black-oxide finished steel construction, and a quick-change collet-style front end with bayonet-lock pins visible at the nose for fast tap changes. Manufactured in the USA, this holder is used in CNC machining centers, turret lathes, and NC drill/tap machines where ACME lead screws, nuts, or jack-screw components are produced at scale. Product Specifications Brand Smith Tool MPN 311-51-217 Series ACTH (ACME Tap Holder) Tap Shank Size 1-1/16 in Square Thread Form ACME Drive Type Square Shank (SH) Holder Type Tension & Compression (Floating) Country of Origin USA Finish Black Oxide Body Material Hardened Steel