Feeds & Speeds Chart for Counterbores 
Feeds & Speeds Chart for Drills, Reamers, Mills and Saws 

Machinist tooling tips

As you work a piece you may see certain problems arise. Hopefully this trouble shooting chart will help you to troubleshoot your machining problem or even help you to develop methods on how to use your lathe, mill (milling machine) or even you drill press.

Problem Solving Guide for machining when you are using carbide tipped tools. MILLING PROBLEMS || DRILLING PROBLEMS || REAMING PROBLEMS Always wear safety glasses MILLING PROBLEMS POSSIBLE CAUSES POSSIBLE SOLUTIONS 1. ROUGH FINISH Dull cutting edge Wrong feeds & speeds Re-sharpen to original tool geometry. Increase speed - also try reduced feed. 2. EXCESSIVE CUTTING EDGE WEAR Wrong feeds & speeds Rough cutting edge Insufficient coolant Increase feed (should always be over .001" per tooth) - especially when machining ductile or free machining materials. - Also try reduced speed. Lightly hone cutting edge with fine grit diamond hone. Increase coolant flow - review type of coolant. 3. CHIPPED CUTTING EDGE Poor chip removal Recutting work hardened chips Vibration Incorrect carbide grade Use tool with larger flute space - larger diameter or fewer flutes. Increase coolant flow. Increase rigidity of set-up, especially worn tool holders. Change to tougher carbide grade. 4. CHATTER MARKS Insufficient machine horsepower Vibration Drive belt loose Use tool with fewer flutes as correct speeds & feeds must be maintained. Consider climb milling. Use larger diameter cutter. Re-sharpen tool with more clearance. Re-tension your drive belts 5. GLAZED FINISH Feed too light Dull cutting edge Insufficient clearance Increase feed. Resharpen tool to original geometry. Resharpen tool with more clearance. 6. POOR TOOL LIFE Excessive cratering Milling abrasive material Milling hard material Insufficient chip room Milling surface scale Delayed resharpening Thermal cracked carbide Increase speed or decrease feed. Change to harder grade of carbide. Decrease speed and increase feed. Increase coolant flow. Climb milling better than conventional milling. Reduced speed - rigidity very important. Use larger diameter tool. Conventional milling better than climb milling. Prompt resharpening to original geometry will increase total tool life. Increase coolant flow at all times. Climb milling is cooler than conventional milling. DRILLING PROBLEMS POSSIBLE CAUSES POSSIBLE SOLUTIONS 1. CHIPPED CUTTING EDGE Excessive feed Excessive lip relief Vibration Thermal cracking carbide Reduce feed. Reduce lip relief to provide smaller chisel angle. Frequently a worn drill bushing - REPLACE. Maintain adequate coolant flow at all times to avoid thermal shocking carbide. 2. SHORT TOOL LIFE Drill Dwelling Only one lip cutting Maintain adequate feed at all times. Regrind with equal lip heights and chisel in center. 3. DRILL WALKS OR DRIFTS Unequal lip heights Worn drill bushing Regrind with equal lip heights and chisel in center. Replace drill bushing. 4. OVERSIZE HOLES Unequal lip heights Excessive lip relief Worn drill bushing Regrind with equal lip heights and chisel in center. Reduce lip relief to provide smaller chisel angle. Replace drill bushing. 5. ROUGH FINISH Dull cutting edge Inadequate coolant Regrind with fine grit diamond wheel. Review type of coolant and maintain adequate flow. REAMING PROBLEMS POSSIBLE CAUSES POSSIBLE SOLUTIONS 1. POOR FINISH Unequal chamfers Incorrect margins Excessive spindle runout Chatter Regrind reamer with equal chamfer angle. Regrind reamer with narrow margins for reaming lower tensile materials. Increase reamer back taper (will lose size faster). Reduce speed and increase feed rate. Use power feed unless material is hard. Use right or left spiral fluted reamer. Grind secondary lead angle immediately back of 45° chamfer. 2. OVERSIZE HOLE TAPER HOLE BELL MOUTH HOLE POOR FINISH Misalignment Insufficient cutting action Use bushing - .0002"/.0003" over reamer diameter. If hole location varies, use floating reamer holder. Increase reamer back taper (will lose size faster). Specify reamer with positive radial rake to reduce cutting pressure - may produce slightly larger diameter holes. 3. EXCESSIVE TOOL WEAR Insufficient stock for removal Excessive reaming pressure Misalignment Decrease previous operation drill size to allow more material for removal by reamer - leave about 3% of hole diameter for cast iron and more stock for non-ferrous materials. Increase feed rate. Reduce stock to be removed by increasing previous operation drill size - leave about 3% of the hole diameter. See problem #2 above. 4. CROOKED HOLES Not drilled straight Correct previous drilling operation - reamer will follow the drilled hole. Increase reamer attack angle (chamfer) to 120°/180° included angle. 5. TOOL BREAKAGE Excessive reaming pressure Misalignment Reduce stock to be removed - see problem #3 above. See problem #2 above.

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