TMX 5-618-140 1-1/4in MT3 4-Flute HSS Counterbore
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The TMX 5-618-140 is a new 1-1/4 in (31.75 mm) diameter, 4-flute high-speed steel counterbore with a #3 Morse Taper (MT3) shank, designed for producing flat-bottomed recesses to seat socket-head cap screws and similar fasteners in ferrous and non-ferrous workpieces. The 4-flute geometry provides a smooth surface finish in the counterbored recess and offers increased rigidity compared to 3-flute designs, making it well-suited for use in drill presses, milling machines, and other spindle-driven equipment fitted with an MT3 socket or adaptor. The tool features a black oxide surface treatment visible in the photos, which provides mild corrosion resistance and reduces galling; the pilot hole (for a standard interchangeable pilot) centers the tool over the existing through-hole to ensure concentricity. TMX (Travers Tool Co. house brand) manufactures this counterbore to standard inch dimensions consistent with ANSI B94.2 counterbore geometry.
Product Specifications
| Brand | TMX |
| MPN | 5-618-140 |
| Counterbore Diameter | 1-1/4 in (31.75 mm) |
| Shank Type | Morse Taper #3 (MT3) |
| Number of Flutes | 4 |
| Material | High-Speed Steel (HSS) |
| Surface Treatment | Black Oxide |
| Pilot Type | Interchangeable (removable pilot) |
| Bottom Style | Flat bottom |
| Condition | New |