G-code basics

[loo7]

Hi,

I have a very basic question about how g-code is generated.
Let's say that i have some simple design that i want to engrave on a piece of wood, and let's say that at the begining the wood is a cube.
I understand that the g-code is the path of each end point that the bit will travel to it. Right?!
How the machine knows where to begin engraving and how it will track the physical possition of the bit? what will happen if it stuck/slow in the middle?

Regards,
Louay

[ger21]

The g-code specifies the exact coordinates of where the tool is. From start to finish. If the machine stops or slows for any reason, then the part will usually be ruined.

[Al_The_Man]

There are different methods of specifying the start of the cut, usually rather than using the machine coordinates, a work coordinate is set up say, to state zero as being the corner of the sheet of material being cut etc.
The machine can be re-referenced in this way using codes G54 to G59 and are called Work Coordinate System 1 to 6.
With steppers there is no feedback or tracking of the tool, it relies on the machine following the commanded postion, as opposed to a servo, which will provide feedback to the motor controlling element.
Al.

[loo7]

So the machine gets the pulses for the motors hopefuly everything will be OK!

If my design is smaller than the cube, and the gcode defines each start/finish points of the desing, how the other extra parts (of the begining sheet) will be removed till the tool reachss the specific possition?

Or can i get a very basic and simple explanation of how the gcode works?
I'll give an example of what i mean.
The cube is 100mmx100mmx100mm
My desing (smaller cube) begins at x=10mm, y=10mm z=10mm, my tool is set to begin at 0,0,0. What will the gcode look like?

Louay

[ger21]

If you need to change the size of your cube, you 'll need g-code to do that before cutting your design.

[loo7]

no, not exactly.
Let me ask it in a different way.
If i start from a cube, and my design is any shape with curves (of course smaller than the cube), so if we substract the desing from the cube we will get the extra areas that should be removed, Right!! In other words the gcode should describe these areas, RIGHT!!. Who should take care of the gcode of these areas, since i have only a definition of my design.

Louay

[ger21]

Originally Posted by loo7 no, not exactly. Let me ask it in a different way. If i start from a cube, and my design is any shape with curves (of course smaller than the cube), so if we substract the desing from the cube we will get the extra areas that should be removed, Right!! In other words the gcode should describe these areas, RIGHT!!. Who should take care of the gcode of these areas, since i have only a definition of my design. Louay

Right. If you are writing the g-code, than you need to take care of it. If you use a CAM program, then that will remove the material first.

[loo7]

Thank you Gerry for the help.
I appreciate that.

Louay