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Reamer Speeds and Feeds
Guide · Updated October 27, 2026
Reaming gives size and finish to a drilled hole. Most reaming problems come from too much speed, too little feed, or the wrong stock allowance.
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Step by step
- Drill undersize: Leave about 0.008–0.015 in of stock on the diameter for 1/4–1/2 in holes. Leave less for small holes.
- Set the speed: Run about half to two-thirds of the drilling SFM for the material.
- Set the feed: Use more feed per rev than drilling, often 2–3×, so the reamer cuts and doesn't rub.
- Use coolant: Flood it or use cutting oil, and don't dwell at the bottom.
- Check size: Check the hole with pin gages, go and no-go.
Problems
- Oversize holes: runout, too little stock, or a worn guide.
- Chatter: speed too high or feed too low.
- Bell mouth: misalignment, so use a floating holder.
Related: drilling speeds and feeds, pin gages.
Worked example: reaming a 0.500 in hole in 1018 steel
A common rule is to run a reamer at about one-half to two-thirds of the drilling speed and twice the drill feed. If you would drill 1018 with HSS at about 80 SFM, ream at 40 to 50 SFM. For a 0.500 in reamer, RPM = 3.82 × 45 ÷ 0.500 ≈ 344 RPM. Feed about 0.004 to 0.008 in per revolution, roughly 1.4 to 2.8 in/min at that speed.
Leave the right stock: about 0.010 to 0.015 in on diameter for a 1/2 in reamer, so pre-drill with a 31/64 in (0.484 in) drill, which leaves 0.016 in. Too little stock makes the reamer rub and glaze; too much overloads it. Do not stop the spindle in the hole or reverse it, and use cutting oil. Check the hole with a 0.500 in pin gage set: a GO pin should enter and a NO-GO pin at the upper limit should not; for H7 at 1/2 in (12.7 mm) the band is +0.018 mm, so NO-GO is about 0.5007 in.
Aluminum allows much higher speeds, often 100 to 150 SFM with HSS; stainless needs lower speeds, around 20 to 30 SFM, and a steady feed so the reamer cuts instead of rubbing and work-hardening the bore.
FAQ
How fast do you run a reamer?
Roughly half to two-thirds of the drill speed for the same material.
How much stock should I leave?
About 0.008–0.015 in on the diameter for medium holes.
Why is my reamed hole oversize?
Runout, too little stock or a built-up edge.
How do I check reamed holes?
Pin gages, checked against gage blocks. Build any reference size free with the Gage Block Calculator at gageblockcalc.com.
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General shop information only — follow your gage manufacturer's instructions and your quality system.