Hide the Menu in Mach3 with Ultimate Screen G-Code Axis Spindle Setup - Mach3 Regenerative Resistors Restoring XML Mach3 Restore Mach3 Spindle Pulley Setup for. Hi, I am writing some new software for my CNC router and am adding a G-code command interpreter. G-Code Ripper is a g-code reading and manipulation program written in python. The root features of the program were written from scratch. The Graphic User Interface (GUI) is based heavily on the GUIs I wrote for F-Engrave and Dmap2Gcode. G-Code Ripper is a free open source program released under the GNU General Public License (GPL) Version 3. Mar 27, 2013 P a g e 9 MachMotion Version 1.01 1.13 Tool Table Zero or one tool is assigned to each slot in the tool table. 1.14 Tool Change Mach3 allows you to implement a procedure for implementing automatic tool changes using macros or to change the tools by hand when required.
A relocation of the positions of linear axes into curved tool motions is known as circular interpolation. It’s alternative definition is that the commands of circular interpolation are utilized to implement the tool’s motion along a circular arc to the pre-set end position. In short, it is the circular movement of the tool, which could be a complete circular motion or less than that.
Circular interpolation needs 5 components or pieces of details, namely: a center, a feed rate, a radius, an endpoint, and a direction of the tool movement.
However, in this article, we will deal with the two methods that relate to G02 and G03 G codes.
What is Circular Interpolation in CNC programming ?
As we read above, circular interpolation is the movement of the machine tool along a curved arc. Apart from the fair and exotic capability to follow a “NURBS” path, almost every G code controller supports only 2 types of motions: linear and circular motions.
Circular interpolation is comparatively more demanding on CNC machines as 2 axes have to be coordinated with high precision and accuracy. Making the outline of a complete circle not only includes the coordinated motion, but also the direction of reversal of the points of all the 4 quadrants. The degrees to which the machine motion will take place correspond to 0°, 90°, 180°, and 270°. Therefore, if the machine experiences a backlash ever, then it will be definitely at the reversal of those angles as an error will be there in the cut there.
Circular motion is the mode of the CNC machine which is initiated through G02 and G03 codes. It is similar to linear motion, which is started by using G00 and G01 codes.
G02 code is responsible for commanding the machine to move in clockwise circular arcs. G03 initiates a mode which moves the machine in a counterclockwise circular arc.
What are G02 and G03?
G02 and G03 are the two G codes which are applied in the CNC machine programming to instruct what movements shall the machine implement. These two program codes turn the machine along a curved or circular arc, in contrast to G00 as well as G01 (which move the machine tool in a rectilinear motion), respectively.
G02 executes circular motion of the machine, but in a clockwise arc. Whereas, G03 moves the machine tool along a reverse arc (i.e., in anticlockwise direction).
In order to utilize the above mentioned G codes for circular interpolation, you must set the coordinates following which the CNC machine will operate.
The radius of the arc or the offsets to the arc’s centre and the extra turns that the machine will optionally make during the motion of the tool. These movements’ speed is also termed by the F-word meaning feed rate.
How to Use R Method and I, J, K Method for Circular Interpolation ?
G02 G code indicates clockwise arc movement at feed rate.
G03 G code implies movement of the arc in the anticlockwise direction at feed rate.
The clockwise direction is figured out by observing the arc to the arc plane from the positive portion of a vector normal.
Similar to the G01 code, G02 and G03 alsi need a feed rate (F) and distance (or destination coordinates (like X, Y, and/or Z). If the feed rate is commanded earlier in the program, then it will continue to serve as the default value to the current feed rate. For complete circles, all the three coordinates– X, Y and Z could be removed (check out the I, J, K Method given below for clearer understanding).
The arc must be aligned with a plane as defined by the 2 axes of the CNC machine motion. The plane should be enabled in the header of the program by G7, G18, G19.
There are 2 types of ways or methods to program G02 or G03 code for circular interpolation:
1. I, J, K Method
This is the only method that can be used to program a complete circle. It can be used any time the R method could be used, but it is a little more complicated.
Any two of I, J, and K will be utilized. The selection of any two amongst these three will be based on the type of arc plane that is selected (see below: G7, G18, G19).
If the arc plane chosen is:
G17 – utilize I and J
Solid edge v20 64 bit download. G18 – utilize I and K
G19 – utilize J and K
The arguments– I, J and K indicate the respective distances between the arc’s starting point to the arc’s center point. Notice the arc’s starting point is neither included in the G02 nor the G03 command. The start point of the arc is figured out by the cutter’s location while the command is executed. Plus, the center point of the arc is never directly mentioned in the command. In case the geometry of the circle is not possible (to within 0.0001), then it is usually followed by a glitch.
Example 1: I, J, K Method
Suppose that machine is presently set at X0.0 Y0.0, and G90 and G17 codes are permitted in the header.
G01 Y1.0 F8.0;
G02 X1.2803 Y1.5303 I.750;
Will produce the following toolpath. Notice the value for J (the distance in the Y axis) would be zero, it can be omitted:
Note: The i’s value is set to 0.75 because it indicates the distance from the starting point of the arc, and not because it’s the distance from Y-axis.
Example 2: I, J, K Method
In order to develop a programming for a full circle, the ending point is removed from the G02 code. Also, suppose that the machine is presently set at X0.0 Y0.0, and G90 and G17 G codes are set up in the header:
G01 Y1.0 F8.0;
G02 I.750;
2. R Method
The R Method could be only utilized for arcs that are not more 360 degrees. For your information, the letter R is used to address and specify the arc’s radius.
Example 1: R Method
Suppose the CNC machine is presently set at the following coordinates X0.0 Y0.0, and G17 and G90 are implemented in the header.
Mach3 G Code Samples
G01 Y1.0 F8.0;
G02 X1.2803 Y1.5303 R.750;
Example 2: R Method
Mach3 G Code Examples - Evillasopa
Note that other than the arc mentioned in the above instance, there is another arc which too satisfies the same criteria. This arc has the same radius but a longer arc length. The arc too has the same start and end points as the one in the previous example.
In case you want to utilize the arc with longer length, you should use a -R value (as -R address doesn’t have a solid meaning).
G01 Y1.0 F8.0;
G02 X1.2803 Y1.5303 R-0.750;
Conclusion
Well, that’s all about G02 and G03 G codes and their application in circular interpolation in CNC programming. If you are new to this topic of CNC, then hopefully this article will help you to get sufficient knowledge of G code programming for circular interpolation.
If you know a bit about the speeds and feeds, or if you have ever gone through any tooling catalogues, you must have a bit of an idea about surface speed. It is basically the quantity that is used for defining the speed at which the tip of the tool is able to move over the workpiece. It is more convenient compared to spindle RPM as it is not dependent on the diameter. The surface speed ends up changing at each distance from the central point, for any particular RPM.
Both G96 and G97 represent constant surface speed codes in CNC machining. These are the two modes that you can select when you are trying to control the rotational speed of your component. The G96 is for constant cutting surface speed and the G97 is for constant spindle surface speed.
What is the G97 Code?
For controlling the spindle’s RPM, you can directly use the G97 code for constant spindle speed commands. For most of the controls, you get to just enter the G96 code for telling the machine to go at a constant surface speed. G97 is used for cancelling G96 and returning to the normal RPM modes on the spindle. It is useful in a number of situations, such as the ones that need central line work, like tapping and drilling.
Format
G97 S—- M–
Example
G97 S2000 M03
Here, G97 is the constant spindle speed command, S has the RPM of the work piece or the spindle, and M03 represents the direction of the spindle.
What is the g96 code?
The G96 code is utilized when you need a constant cutting speed or surface speed. It is the speed that shows the distance to which the tool is able to move along the component surface each minute. Thus, when you choose G96 is chosen, the spindle speed gets changed automatically using the machine controls. This makes sure that the speed of the surface of the material remains constant even as the diameter varies at the time of machining operations.
This cutting speed gets determined by the chucking method, the components shape, the cutting tool, and the material. When the tool goes near the central line of the part, spindle speed starts increasing till it hits the maximum possible spindle speed of the machine. It is usually not a good idea because, at that speed, the centrifugal force might make the chick unable to hold the workpiece securely.
For setting a maximum speed that you want the machine to attain as the part’s diameter decreases, you will have to resort to a G50 command. The speed will be clamped as directed by the G50 command.
Format
The typical G96 blocks usually look somewhat like this: G96 S— M–
Example
G96 S200 M03 (or, M04)
G96 refers to the constant surface speed code, S refers to the cutting speed in meters per minute, and M04 or M03 denotes the direction of the spindle rotation.
Given below is the best practice for using G96 and G97 that you should follow:
- Utilize the regular RPM mode, i.e. G97, till the tool gets positioned for beginning a path
- Make the switch to G96 at this point and make your pass
- Switch it back again to G97 before you reposition for your next pass
- Do not utilize G96 for each cut. Put it to use when the end and the starting of the cut will be significantly different in diameter
- Set up the right RPM limit depending on the particular case for each use of the code G96.
Summing up
It is important to define a particular spindle speed when you are alternating from G96 to G97. Because the command G50 is not able to go with G97, you need to take care and make sure that the lowest possible speed of the fixture and the chuck is not overstepped.