Choosing an internal grooving tool for a small bore is mostly an exercise in respecting limits: the bore diameter sets the shank, the groove sets the width, and the tool that ignores either one will break or scrap the part. This guide walks through the six decisions that matter.<br><br>1. Start from the minimum bore diameter (DMIN)<br>DMIN is the smallest bore the tool can enter without the body touching the wall. For example, the Cutoutil R/LSC4.G050.2009 enters a bore from Ø2 mm on a Ø4 mm shank, while the R/LSC4.G100.4215 needs Ø4.2 mm. Always leave 0.2-0.5 mm of clearance between the bore and the tool body for chip evacuation and coolant.<br><br>2. Match the cutting width to the groove drawing<br>Cutting width (CW) is ground, not adjusted. Order the exact width: 0.5 mm, 0.78 mm for circlips, 1 mm for general seal grooves. If a groove is toleranced at ±0.02 mm, specify a ground tool with a width tolerance rather than a pressed insert.<br><br>3. Check usable length against groove position<br>Usable length (LU) is how far the cutting edge can reach into the bore. A tool with LU 9 mm will not cut a groove 15 mm deep. Longer reach means more overhang, so take the shortest LU that reaches the groove.<br><br>4. Respect maximum groove depth (CDX)<br>CDX is the deepest groove the geometry allows in one pass. Cutting deeper overloads the neck of the tool. For deeper grooves, plan two passes with a small stepover instead of one deep plunge.<br><br>5. Choose the grade for the work material<br>TA61 with the M6 PVD coating covers steel and stainless; TD61 covers cast iron, non-ferrous and high-temperature alloys. Running a steel grade in aluminium causes built-up edge, and running an aluminium-polished grade in hardened steel wears the edge fast.<br><br>6. Plan for chips<br>In a blind bore, the chip has one way out: back past the tool. Use a chip-breaker geometry for stringy materials, apply through-tool coolant where the holder allows it, and peck the groove in two or three steps rather than one continuous plunge.<br><br>Practical checklist<br>Confirm DMIN, CW, LU, CDX and shank diameter on the drawing before ordering; verify that the holder bore matches the shank, ISO tolerance h6 preferred; start at 60-70% of the recommended feed on the first part; and measure the second part before releasing the batch.<br><br>If you are replacing a Sandvik Coromant or Horn tool, send the order number. The Cutoutil SC series is dimensionally interchangeable, so the swap does not require new offsets.
R/LSC4.G050.2009, R/LSC4.G100.4215, R/LSC4.G078.4215
