# Programming Efficient Peck Drilling Cycle

June 2, 2012, 9:18 amArticle Summary

Eldar Gerfanov

June 2, 2012, 9:18 am

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Eldar Gerfanov

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Using Peck Cycle is often needed when drilling deep holes.

When using proper feed and speed no peck is required at depths of up to 3xDia for regular or 5xDia for High-Performance Parabolic drills.

At depths up to 10x, up to 5 pecks are required for regular drills and up to 3 for Parabolic.

Anything over 10x Dia requires constant pecking of 0.5-1x Dia for regular drills and 1.5-2 Dia for Parabolic.

Since for programming you need a peck amount. Here are the numbers:

3x-10x: 1xDia Peck

over 10x:.75xDia Peck

over 15x:.5xDia Peck

5x-10x: 2xDia Peck

over 10x: 1.5xDia Peck

Of course our HSMAdvisor Speed and Feed Calculator suggests not only the Speeds and Feeds but also the proper peck depth for various drill types and depths of the hole.

It in fact was the first machinist calculator to do so. This feature was much later borrowed by our competition.

And here is a pretty image showing Peck VS Hole Depth for regular twist drill:

This not only means that peck amount should be different for different styles of drills and depths of holes.

But also that peck distance should be different for different stages of drilling the same hole.

Ideally we should start the hole with large pecks, that continually reduce as the hole gets deeper and deeper.

Let's find out how we can apply this knowledge when programming our toolpaths.

This is format for normal Pecking:

G83 X Y L R Q P F

- X Y : Location of the hole
- L : Number of holes to repeat is G91 (incremental mode) is used
- R : Position of the R plane
- Q : Peck amount
- P : Dwell at the last peck in seconds
- F : Feed Rate
- Z : Target depth

(T15 7/32 HiHelix DRL DEEP a 3.5" Hole)

(Tool # 15 Drill: .21875 )

T15 M6

S6400 M3

G90 G0 X-0.5 Y-1.0

M8

G43 Z0.5 H15

G83 X-0.5 Y-1.0 Z-3.5 Q0.375 R0.1 F48.

G80 G0 Z0.5

...

Many machine manufacturers have variable peck drilling cycle.

This allows programmer to use deep pecks in the top of the hole and shallow pecks at the bottom.

Using this feature prolongs tool life and greatly reduces cycle time, this also makes programming proper peck easier.

Format for Variable Pecking

G83 X Y L R I J K P F

- X Y : Location of the hole
- L : Number of holes to repeat is G91 (incremental mode) is used
- R : Position of the R plane
- I : First Peck amount
- J : Peck Reduction per pass
- K : Minimum Peck amount
- P : Dwell at the last peck in seconds
- F : Feed Rate
- Z : Target depth

(T15 7/32 DRL DEEP a 3.5" Hole)

(Tool # 15 Drill: .21875 )

T15 M6

S6400 M3

G90 G0 X-0.5 Y-1.0

M8

G43 Z0.5 H15

G83 X-0.5 Y-1.0 Z-3.5 I1.125 J0.1875 K0.375 R0.1 F48.

G80 G0 Z0.5

...

The sample code above was posted with Surfcam's MPost processor.

Here is the nessesary modifications to the cycle

PECK # Pecking canned/manual cycle I=First Peck, J=Peck reduction, K=Min peck

G83 G98 X[H] Y[V] Z[D] I[VBite]*3 J[VBite] K[VBite] F[FRate] R[VCLear]

end cancel

...

Using this modification programmer only needs to program a single peck value and the post will automatically calculate the I and J values.

Regardless of how you get the variable pecking set up in your post, you should definitely make sure you are using this feature. As this allows you to make sure you don't only get the proper peck for the depth, but also that is is done as efficiently as possible.

In my particular case drilling thousands of deep holes in large moulds time savings were between 50% and 70% versus the regular pecking cycle.

--Eldar Gerfanov

## By Tom

Excellent explanation of the G83 function!

## By Miguel

There is some reference for the depth in the different materials?

## By Eldar Gerfanov

The graph is true for most materials. With the exception of the exotics and tough ones, where you need to start pecking almost right away.