Carbide Drill Feed & Speed Starting Guide

Use this guide as a starting point for solid carbide drill feeds and speeds. Drill settings vary by drill diameter, material, spindle speed, machine rigidity, runout, backing material, peck drilling method, and hole quality requirements.

Important: These values are conservative starting points only. Small carbide drills are easy to break if there is spindle runout, poor material support, excessive feed pressure, or inadequate chip clearing. Always test on scrap material first.

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Enter the drill diameter in decimal inches. Example: enter 0.03125 for a 1/32" drill, or 0.125 for a 1/8" drill.

Enter the highest RPM your spindle, drill press, CNC router, or machine can realistically run. The guide estimates a material-based RPM, then uses the lower of that value or your machine’s maximum RPM.

Select your material, drill diameter, and machine max RPM, then click Calculate.

How the Drill Guide Works

The guide estimates a spindle RPM from the selected material and drill diameter, then limits that RPM to your machine’s maximum RPM. It also estimates a conservative drill feed rate using a diameter-adjusted chip load per revolution.

RPM = 3.82 × SFM / Drill Diameter
Feed Rate (IPM) = Chip Load per Revolution × RPM Used

For very small carbide drills, setup quality matters as much as the calculated values. Excessive runout, flex, poor backing support, or chips packed in the hole can break drills even if the RPM and feed look reasonable.

Material Notes

Material Starting Note
FR-4 / PCB Laminate Abrasive PCB laminate; use backing material, dust extraction, and a rigid setup.
G10 / Fiberglass Laminate Very abrasive; keep feed conservative and clear dust/chips well.
Lexan / Acrylic Use sharp drills and avoid excessive heat or chip packing.
General Plastic Avoid melting; use steady feed and clear chips from the hole.
Wood / MDF Use backing support to reduce breakout; reduce feed if the drill wanders.
Aluminum Use lubrication or chip clearing when appropriate; avoid chip welding and packed holes.
General / Unknown Use conservative settings and test first. Reduce feed if the drill squeals, wanders, or loads up.

These drill values are starting points only. Reduce feed rate, improve support, or use lighter peck cycles if you see drill deflection, poor hole quality, chip packing, squealing, overheating, or broken drills.

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