CNC Milling G Code List For Beginners

Download and print this nice large print CNC Milling G Code List

Download CNC Milling G Code List PDF

I always begin my training sessions by telling my students not to remember anything I say.

This sounds completely stupid and my excuse is it wasn’t my idea to say it.

About ten years ago I worked in France. After about a year and it seemed obvious that I would need to speak to people to order “Fish n Chips” and stuff like that.

Anyway I got these CD’s to teach me French and the bloke (can’t remember his name) started off by telling you not to remember anything he told you.

I think there is a bit of reverse psychology going on but the main idea is that you understand not remember. It didn’t work for me because I still managed to completely fuck up the language. Not realizing French Canadians speak differently to native Frenchmen (I was working for Bombardier) . Anyway I asked this bloke, in French, to “come with me”. I can’t remember what it is in French and after all the bloke on the CD had specifically told me not to remember.

Anyway turns out this had a sexual connotation and made me the complete laughing stock everywhere I went from then on. (I’ll let you do the maths on that one.)

When it comes to CNC Programming the idea of not remembering loads of G Codes is really important. Truth is you only need a few and it’s all about understanding what they do.

For Example I want to drill a hole.

You completed a training course at the CNC Training Centre. You understood it all and you practiced with you free simulation software that you get with the course.

You start writing a program to drill some holes.

From your training you know that there is a cycle that drills holes.

You understand how the cycle feeds the tool down to a depth and then it rapids out ready to do another.

Quick Fix G81 Video

You also know that if you keep adding more positions (X50. Y50.) it will keep drilling holes.

And… when you are sick of drilling holes there’s another G code to stops it.

What Are These G Codes?

So you just look em up on your CNC Milling G Code List.

G81 Drilling Canned Cycle
G80 Cancel Canned Cycle

Then you think “mmm I’m sure there’s one that pecks the material out and breaks it up”

“Let me see… Ah this looks like the one

G73                 Peck Drilling

Type up or print this list in nice big letters and stick it to the side of your machine

Download CNC Milling G Code List PDF

CNC Milling G Code List

G00                 Move at Rapid speed
G01                 Feed in a Straight Line
G02                 Clockwise Arc
G03                 Counter Clockwise Arc

G04                 Time Dwell
G28                 Return Axis to Home

G41                 Cutter Compensation Left
G42                 Cutter Compensation Right
G40                 Cancel Cutter Compensation

G43                 Apply Tool Length Offset
G54 to G59     Work Offsets

G81                 Drilling Cycle
G73                 Peck Drilling
G83                 Deep Hole Drilling Cycle
G84                 Tapping Cycle
G80                 Cancel All Canned Cycles

G90                 Absolute Programming
G91                 Incremental Programming

Download CNC Milling G Code List PDF

G82 Drilling Program Example

G82 Drilling Program Example

G82 Drilling Program Example, this simple part has four M12 holes drilled countersunk and tapped.

The datum is the centre of the part so the holes positions are.

X55. Y55.
X-55. Y55.
X-55. Y-55.
X55. Y-55.

Here is the CNC code

The machine first moves to X-55. Y-55. and rapids the Z axis to 3mm above the part.

It then rapids the Z axis down to 1mm above the part R1.

The G82 Cycle instructs it to drill a hole 6mm deep (Z-6.) at a feed of 200mm per minute (F200.)

When it gets to depth the P3000 tells it to dwell for 3000 milliseconds which is 3 seconds. No decimal point allowed. (Varies on controls)

When the hole is done it rapids back to the initial point (Z3.) This was in the line

This is because of the G98.

If it were G99 it would return to 1mm above the job (R1.)

See explanation of G98 and G99

Once the cycle is active each time it sees a position it repeats the drilling process.

When the G80 is programmed it no longer drills holes.

Now watch the video to see it all in action.

G82 Drilling Program Example

Haas G82 example

It’s been great fun writing this article for you but to be totally honest i think this cycle is a complete waste of time. Whenever I have put a dwell in a spot drilling cycle it always seems to chatter.

However if you do use this cycle please let me know if you have success with it.

Thanks

If you have been affected by any of the issues in this post or need CNC Counselling then contact me.

If you want to learn to program CNC Milling Machines

Look no further Contact CNC Training Centre

G73 Peck Drilling Example (Canned Cycle)

G73 Peck Drilling Example

G73 is a peck drilling canned cycle.

This cycle drills holes and breaks up the chips as it goes. It does not fully retract from the hole.

It retracts just enough to break the chips up.

This simple part has four M12 holes drilled countersunk and tapped. The datum is the centre of the part so the holes positions are.

X55. Y55.
X-55. Y55.
X-55. Y-55.
X55. Y-55.

Here is the CNC code (G73 Peck Drilling Example)

The machine first moves to X-55. Y-55. and rapids the Z axis to 3mm above the part.

It then rapids the Z axis down to 1mm above the part R1.

The G73 Cycle instructs it to drill a hole 17.5mm deep (Z-17.5) at a feed of 200mm per minute (F200.) 

The Q2. tells the machine to drill the hole in 2mm steps. After each step it retracts a small amount to break up the chips from the drilling.

As it drills the depth increases by 2mm each time.

When the hole is done it rapids back to the initial point (Z3.) This was in the line

This is because of the G98.

If it were G99 it would return to 1mm above the job (R1.)

See explanation of G98 and G99

Once the cycle is active each time it sees a position it repeats the drilling process.

When the G80 is programmed it no longer drills holes.

Now watch the video to see it all in action (G73 Peck Drilling Example)

G73 Drilling Example

Haas G73 example

Thanks

If you have been affected by any of the issues in this post or need CNC Counselling then contact me.

If you want to learn to program CNC Milling Machines

Look no further Contact CNC Training Centre