---
title: "G73 vs G83: Chip Break vs Full Retract Peck Drilling"
description: "G73 snaps the chip with a tiny back-off and stays in the hole; G83 pulls out to the R plane every peck. Depth, chip type and coolant decide which to run."
url: https://gcodepractice.com/journal/g73-vs-g83-peck-drilling-chip-break-vs-full-retract/
canonical: https://gcodepractice.com/journal/g73-vs-g83-peck-drilling-chip-break-vs-full-retract/
author: "Lawrence Arya"
authorUrl: https://www.linkedin.com/in/vibecoding/
published: 2026-10-02
updated: 2026-10-02
category: "Code reference"
tags: ["g73", "g83", "peck-drilling", "canned-cycles", "drilling", "chip-control"]
lang: en
---

# G73 vs G83: Chip Break vs Full Retract Peck Drilling

> **TL;DR** G73 is high-speed peck drilling: after each Q-depth peck the drill backs off a small controller-set distance to break the chip, then continues, never leaving the hole. G83 is deep hole peck drilling: after each peck the drill rapids all the way out to the R plane to clear chips, then rapids back to just above the last depth. Run G73 on holes up to about three or four diameters deep with stringy chips; run G83 when the hole is deeper, chips pack, or coolant cannot reach the tip.

G73 and G83 look almost identical on the page. Both take X, Y, Z, R, Q and F, both sit in the same canned cycle family as G81, and both drill in steps instead of one plunge. The difference is what happens between the steps. G73 backs the drill off a hair to snap the chip and keeps going. G83 pulls the drill all the way out to the R plane to empty the flutes, then comes back. One is fast and trusts the chip to break; the other is slower and trusts nothing. Knowing which one a hole needs is a daily decision on any machining center, and getting it wrong is one of the most common ways to snap a drill.

## Why peck at all

A drill makes chips at the tip and has to move them up the flutes and out of the hole. In a shallow hole that happens on its own. As the hole gets deeper, three things go wrong: the chips get longer, coolant struggles to reach the tip, and the flutes start to fill. A long stringy chip wraps around the drill, a packed flute raises torque, and a dry tip overheats. The [Wikipedia article on drilling](https://en.wikipedia.org/wiki/Drilling) describes the same chip evacuation problem from the process side.

Pecking solves it in steps. Each peck drills a set depth, Q, and then interrupts the cut. The two cycles differ only in how big that interruption is. If you have not yet met the plain drilling cycle, [G81 vs G83 drilling canned cycles](/journal/g81-vs-g83-drilling-canned-cycles/) covers the single plunge cycle and why deep holes need something more.

## What G73 does, move by move

G73 is usually called high-speed peck drilling or chip breaking drilling. A typical Fanuc-style line reads:

`G98 G73 X25. Y40. Z-18. R2. Q3. F150`

The machine rapids to X25 Y40, rapids down to the R plane at Z2, and feeds down 3 mm. Then it retracts a small distance, set by a controller parameter rather than in the line, typically a fraction of a millimetre. That back-off is enough to snap the chip. It feeds down again, 3 mm past the previous depth, backs off again, and repeats until it reaches Z-18. Then it rapids out to the initial plane (because of G98) or the R plane (with G99).

The drill never leaves the hole until the end. That is why G73 is fast: there is almost no air cutting. The [LinuxCNC G73 reference](https://linuxcnc.org/docs/html/gcode/g-code.html#gcode:g73) describes the same motion as a drilling cycle with chip breaking, with a small fixed retract after each increment.

## What G83 does, move by move

G83 is the deep hole peck drilling cycle. The line is the same shape:

`G98 G83 X25. Y40. Z-60. R2. Q5. F150`

The machine rapids to position and down to R2, then feeds 5 mm. Now it rapids all the way back up to the R plane. That full retract lets the chips fall out of the flutes and lets coolant flood the hole. Then it rapids back down to a small clearance above the previous depth, feeds another 5 mm, and repeats.

Each peck costs two rapid strokes of the full hole depth so far, so the cycle gets slower as the hole gets deeper. The [LinuxCNC G83 reference](https://linuxcnc.org/docs/html/gcode/g-code.html#gcode:g83) describes the same full retract after every increment.

## G73 vs G83 side by side

| Feature | G73 chip break | G83 full retract |
| --- | --- | --- |
| Retract after each peck | Small, set by a controller parameter | All the way to the R plane |
| Drill leaves the hole between pecks | No | Yes |
| Main job | Break long stringy chips | Clear packed chips and let coolant in |
| Typical depth range | Up to about 3 to 4 times drill diameter | About 4 times diameter and deeper |
| Cycle time | Short, little air cutting | Longer, grows with depth |
| Best chip types | Long, stringy: aluminium, mild steel, many plastics | Packing or powdery: cast iron, deep holes in anything |
| Main risk | Packed flutes in deep holes, snapped drill | Lost time, extra wear on the R plane approach |
| Words in the line | X Y Z R Q F | X Y Z R Q F |

The words are identical, so nothing in the line warns you if you picked the wrong one. The decision sits entirely in knowing the hole and the material.

## How to choose between them

Start with depth over diameter. A 6 mm drill going 15 mm deep is a 2.5 times diameter hole, and almost any peck strategy works; many shops would run plain G81 there. The same drill going 40 mm deep is nearly 7 times diameter, and chips will pack unless they are cleared, so G83 is the default.

Then look at the chip. Aluminium and low carbon steel tend to make long, ribbon-like [swarf](https://en.wikipedia.org/wiki/Swarf) that wraps around the drill. Breaking it is the main need, so G73 shines. Cast iron and brass tend to make short or powdery chips that do not wrap but do pack, so breaking them is pointless and clearing them is everything: G83.

Finally, consider coolant. A drill with through-spindle coolant pushes chips out on its own, and many shops run those with G81 or a shallow G73 even at depth. A drill relying on flood coolant only gets fresh coolant at the tip when it leaves the hole, which favours G83 once the hole is deep.

A useful shop rule: G73 up to three or four diameters with stringy chips, G83 beyond that or whenever chips pack. Then adjust on the machine by watching and listening.

## Setting Q sensibly

Q is the peck depth in both cycles, and it is always a positive incremental value. Too small a Q wastes time with endless pecks; too large a Q defeats the purpose.

As a starting point, many machinists use a Q of about one drill diameter for G73 in free-cutting materials, and a smaller Q, half to one diameter, for G83 in deep holes where packing is the risk. Some controls also support a variable peck that starts deep and shrinks as the hole goes deeper, which suits G83 well. Check whether your control supports it before relying on it.

On most Fanuc-style controls, the decimal point matters. `Q3.` is 3 mm in metric mode, while `Q3` without a point may be read as 0.003 mm, giving a cycle that pecks thousands of times. If your G73 or G83 suddenly runs forever, look at the decimal on Q first.

## G98 and G99 with peck cycles

Both cycles end with a retract to either the initial Z level or the R plane, chosen by G98 or G99. With G99 the drill stays at R between holes, which saves time on flat parts. With G98 it climbs back to the initial level, which clears clamps and bosses. The choice is the same for both peck cycles and is covered in [G98 vs G99 canned cycle return plane](/journal/g98-vs-g99-canned-cycle-return-plane/).

One interaction is worth knowing. With G83, the per-peck retract always goes to the R plane, regardless of G98 or G99, so a careless R value close to a clamp height is tested on every peck, not just at the end.

## Cancelling the cycle

Both G73 and G83 are modal. Once active, every following X or Y position drills another hole until the cycle is cancelled with G80. Forgetting G80 is a classic crash: the next positioning move after the last hole quietly drills a hole where none was wanted. Ending each drilling block with G80 on its own line is a cheap habit that prevents it, and a [safety line with G80](/journal/safety-line-g-code-safe-start-block-explained/) at the start of each tool catches a cycle left over from an interrupted run. The same modal logic is explained more broadly in [modal vs non-modal G-codes](/journal/modal-vs-non-modal-g-codes/).

## What CAM output looks like

Most CAM systems offer both cycles under names like "chip breaking" and "deep drilling" or "full retract", and post them as G73 and G83 on Fanuc-style machines. Some posts expand the cycle into long runs of G01 and G00 moves instead, for controls without the canned cycle or when the programmer asks for it. An expanded G83 is easy to recognise: a feed down, a rapid all the way up to the same Z each time, a rapid back down to just above the last depth. An expanded G73 shows a feed down followed by a tiny rapid back-off of a fraction of a millimetre. Reading the expanded form is good practice, because it shows exactly what the canned cycle hides in one line, and it helps you spot a post that chose the wrong strategy for the hole.

## Common mistakes with peck drilling

- Running G73 in a deep hole because it is faster, and snapping the drill when the flutes pack.
- Running G83 on shallow aluminium holes, adding minutes of air cutting to a large batch.
- Writing Q without a decimal on a control that needs one.
- Setting R so close to the surface that chips on the top face get dragged back into the hole.
- Forgetting G80 after the last hole.
- Assuming the G73 retract is the same on every machine. It is a parameter, and it varies.

## Practising the decision

Peck drilling rewards fast recall more than deep theory: you need to see a hole callout and know the cycle and Q without looking anything up. A good drill is to take ten hole callouts from a real print, note depth over diameter and material for each, and write the cycle and Q you would use. Then compare with what the shop actually runs. The codes themselves are worth drilling to reflex alongside the rest of the canned cycle family on the [G-code practice](/g-code-practice/) page.

## Bottom line: break it or clear it

G73 breaks the chip with a tiny back-off and keeps the drill in the hole; G83 clears the chip by retracting to the R plane every peck. G73 is faster and right for shallower holes with stringy chips. G83 is slower and right for deep holes, packing chips and flood coolant. The lines look identical, so the choice lives in your head, not on the screen.

## Frequently asked questions

### What is the difference between G73 and G83?

Both are peck drilling cycles. G73 breaks the chip by backing off a tiny distance after each peck and keeps the drill in the hole. G83 clears the chip by retracting all the way to the R plane after each peck, then rapids back down. G73 is faster; G83 is safer once chips start packing in a deep hole.

### When should I use G73 instead of G83?

Use G73 for holes up to roughly three or four diameters deep in materials that make long, stringy chips, such as aluminium and mild steel, where breaking the chip is the problem. Switch to G83 when the hole is deeper than that, when chips pack rather than string, or when coolant cannot reach the tip.

### How far does G73 retract between pecks?

Only a small, controller-set distance, typically a fraction of a millimetre. On Fanuc-style controls it is set by a parameter rather than in the program line, and LinuxCNC uses a fixed small retract. Check your machine's manual, because that one value decides whether the chip actually breaks.

### What is the best way to remember which peck cycle is which?

Tie each code to its motion: G73 is the short twitch that snaps the chip, G83 is the full trip out that empties the flutes. Then drill the pair until recall is instant. A free app like G-Code Sprint quizzes canned cycle codes in timed rounds and repeats the ones you miss.

### When is G73 not a good choice?

In deep holes, in materials that make powdery or packing chips such as cast iron, and with drills that lack through-spindle coolant. In those cases the chip is never evacuated, it packs in the flutes, torque rises, and the drill can snap. G83 costs cycle time but removes that risk.

## Sources

- [LinuxCNC G-code reference: G73](https://linuxcnc.org/docs/html/gcode/g-code.html#gcode:g73)
- [LinuxCNC G-code reference: G83](https://linuxcnc.org/docs/html/gcode/g-code.html#gcode:g83)
- [Wikipedia: Drilling](https://en.wikipedia.org/wiki/Drilling)
- [Wikipedia: Swarf](https://en.wikipedia.org/wiki/Swarf)
- [Wikipedia: G-code](https://en.wikipedia.org/wiki/G-code)

---

Source: https://gcodepractice.com/journal/g73-vs-g83-peck-drilling-chip-break-vs-full-retract/
Author: Lawrence Arya — https://www.linkedin.com/in/vibecoding/