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How to Center Drill and Spot Drill
Guide · Updated October 28, 2026
A twist drill wanders if it starts on a flat face. Spotting first gives it a cone to follow so the hole starts on location. Center drills and spot drills both do this, but they aren't the same tool.
Lay out and check locations
Check hole positions with a height gage set on gage blocks; build stacks with the free Gage Block Calculator.
Step by step
- Pick the tool: Use a spot drill on the mill for holes; use a center drill to make 60° center holes for lathe centers.
- Match the angle: A 90° spot is common for chamfered holes; a 118° or 120° spot matches standard drill points; 140° for 135° drills.
- Locate: Find the hole location with an edge finder, DRO or layout.
- Set speed: Spot drills are stubby and rigid; run near the drill speed for that diameter, and slow a center drill because the small pilot breaks easily.
- Spot: Peck in just until the spot is slightly smaller than the drill diameter (or larger for a chamfer).
- Drill: Change to the drill without moving the table and drill the hole.
- Check: Check hole location and add a chamfer or deburr.
Center drill or spot drill?
A center drill (combined drill and countersink) is made for 60° lathe center holes. Its small pilot is fragile and it isn't ideal for spotting on a mill. A spot drill is short, stiff and point-only, made for starting holes.
Worked example
For a 1/4 in hole with a 118° drill, use a 120° spot drill and go about 0.10 in deep so the spot is around 0.23 in across. With a 90° spot, depth for a given diameter is half the diameter: a 0.28 in spot that leaves a small chamfer needs 0.14 in depth.
Lathe centers
For work between centers or with a tailstock, pick a center drill size from a chart by work diameter and drill until the 60° cone is about two-thirds formed. Oil the dead center or use a live center.
Tips
- Use the right speed; see drilling speeds and feeds.
- Find location with an edge finder or transfer punch.
- For a countersunk hole, a 90° spot can double as the chamfer; see countersinks.
- Deep holes after spotting: see peck drilling.
FAQ
What is the difference between a center drill and a spot drill?
A center drill makes 60° center holes for lathe centers and has a fragile pilot. A spot drill is short and rigid with a single point and is made to start holes on a mill.
What angle spot drill should I use?
Match or slightly exceed the drill point angle, 120° for 118° drills, or use 90° to leave a chamfer.
How deep should I spot drill?
Until the spot diameter is just under the drill diameter, or a little larger if you want a chamfer.
Do I need to spot drill with a CNC?
Often yes for long or small drills; short stub carbide drills may not need it.
Why does my center drill break?
Usually too much feed, too slow RPM, no peck to clear chips, or misalignment with the tailstock.
Related guides and calculators
- Drilling Speeds and Feeds
- Peck Drilling Basics
- Countersink and Counterbore Basics
- Edge Finder Basics
- How to Use a Transfer Punch Set
- Tap Drill Chart Explained
- Layout Dye and Scribing Basics
- How to Use a Bench Center
- How to Face on a Lathe
- How to Ream a Hole
- Chamfer Mill Basics
- How to Drill on a Mill
- How to Sharpen a Drill Bit
- How to Counterbore on a Mill
- How to Use a Steady Rest
- How to Tap on a Mill
- How to Turn Between Centers With a Lathe Dog
- How to Use a Live Center
- How to Use a Dead Center
- How to Use a Center Finder
- How to Use a Center Punch and Prick Punch
- How to Use a V-Block for Drilling Round Stock
- How to Use a Cathead on a Lathe
- How to Transfer Hole Locations
- How to Use a Rotary Broach
- All free machinist calculators
- How to Use a Wiggler
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