How to use this calculator
- Enter drill geometry. Set drill diameter, full-diameter hole depth and point angle.
- Set feed and RPM. Use spindle speed and feed per revolution from your speeds-and-feeds choice.
- Choose peck settings. Enter max peck depth, clearance plane, return clearance, chip-break retract and dwell.
- Set machine rapid. Use a conservative effective rapid rate if acceleration dominates short moves.
- Compare cycle types. Use full-retract and chip-break time to plan the drilling cycle and batch time.
How it works
Peck drilling starts with the same axial feed relation as ordinary drilling:
Vf = fn x n
where fn is feed per revolution and n is spindle RPM.
Blind-hole programming often needs the conical point allowance,
Lp = (D/2) / tan(A/2). The programmed depth is
Z = H + Lp, and the peck count is
Np = ceil(Z / Q), where Q is the maximum peck depth.
The full-retract estimate adds a clearance-plane retract and rapid return for each intermediate peck. The chip-break estimate adds short up/down chip-break retracts between pecks plus one final retract to clearance. For deep-hole G83/G73 planning, use the deep-hole peck cycle calculator search page.
Worked example
Verified against the live calculator
A 1/4 in drill making a 1.000 in full-depth
blind hole with a 118 deg point adds about
0.0751 in of point allowance, so programmed depth is
1.0751 in.
With 0.250 in pecks, the job needs ceil(1.0751 / 0.250) = 5
pecks. At 2500 rpm and 0.004 in/rev, feed rate is
10 in/min and cutting feed time is about 6.45 s per hole
before retracts and dwell.
Frequently asked questions
How do you calculate peck drilling depth?
Add the drill point allowance to the required full-diameter depth, then divide by the maximum peck depth: pecks = ceil((H + Lp) / Q). The last peck is the remaining depth after the earlier full pecks.
What is the drill point allowance?
For a conical drill point, point allowance is Lp = (D/2) / tan(A/2), where D is drill diameter and A is the included point angle. Add it when a blind hole must be full diameter at the bottom.
What is the difference between full-retract and chip-break peck drilling?
A full-retract cycle is a G83-style approximation that retracts to the clearance plane between pecks. A chip-break cycle is a G73-style approximation that uses a short retract between pecks and one final retract to clearance.
Does this match my CNC control exactly?
No. It is a planning model. Canned-cycle parameters, acceleration, feed overrides, retract modes, dwell behavior, coolant, spot drilling, pilot holes and tool changes can all change actual cycle time.
How should I choose peck depth?
Use the drill or toolmaker recommendation for material, hole depth ratio, coolant and chip evacuation. If the setup is uncertain, compare several peck depths and verify on the machine before committing production time.
Why does peck drilling add so much time?
The cutting feed time can be small compared with repeated retract and return moves. Full-retract cycles clear chips well but can add more rapid travel than chip-break cycles, especially on deep holes or large hole counts.
Method & assumptions
- Internal math uses length in mm, feed and rapid rate in mm/min, and time in seconds.
- Full-retract timing approximates a G83-style cycle, not a specific controller implementation.
- Chip-break timing approximates a G73-style cycle with a short retract between intermediate pecks.
- Rapid moves use the entered effective rapid rate; acceleration, jerk limits and feed overrides are not modeled.
- Does not include tool changes, spot drilling, pilot drilling, coolant-through drill guidance, chip packing, tool wear, runout, hole tolerance or inspection requirements.