IJ mode is Absolute?

[battenberg]

Hi, Complete newbie here...

I dont like flashing warnings without knowing what they are

What does 'IJ Mode is Absolute' mean??

please can someone explain for me?

[grg12]

IJ coordinates in G02 and G03 command could be "relative" or "absolute" - if your programm uses wrong mode results may be intresing (in most cases - very big circles and arcs)

[beege]

Absolute means that the circle center is described in coordinates relative to the work origin (0,0), where incremental means the circle center is described in terms coordinates relative to the arc start point.

[battenberg]

Originally Posted by beege Absolute means that the circle center is described in coordinates relative to the work origin (0,0), where incremental means the circle center is described in terms coordinates relative to the arc start point.

Ok, many thanks... so it is only relavent to circle cutting?

The learning curve now goes circlular... !!!!!

So can you sum up the cause and effect easily for me?

I now understand that: the circle center is either referenced from the original zero/zero position, or the circle centre is referenced from the start of the arc point. In both cases the circle centre coordinates are specified, so how can one produce radical differences from the other?

And how should Mach3 be setup by default?

[ger21]

Originally Posted by battenberg Ok, many thanks... so it is only relavent to circle cutting?

Circles and arcs, or, more specifically, G2 and G3 moves.

So can you sum up the cause and effect easily for me?

I think your original post about "flashing warnings" was referring to the most ill conceived "feature" in Mach3, the Abnormal Condition warning.

Typically, the flashing warning doesn't indicate anything "Abnormal", but just different from the default.

In both cases the circle centre coordinates are specified, so how can one produce radical differences from the other?

Because Mach3 is drawing a circle (or arc) with a center point that is different from the intended center point. The difference between locations can be substantial (hundreds of units).

And how should Mach3 be setup by default?

It should be set the way you or your CAM program writes the code. Most CAM software uses Incremental IJ mode. I believe the default in Mach3 is Absolute, and some Mach3 Wizards use Absolute IJ Mode for your code.

The best thing to do is to specify the mode in your g-code.
G90.1 = Absolute IJ, and G91.1 = Incremental IJ.

Placing the code at the start of your program will put Mach3 into the correct mode when you run the code, and it won't matter what the default mode is set to.

And I believe that the code is modal, meaning that if it's changed by the g-code, whatever it's changed to will remain in effect until either you change it, or another g-code command changes it.

Here's how I do it.
G20 G40 G90
G91.1
M3
G0 Z0.250
G0 X2.000 Y3.000 Z0.250
G1 X2.000 Y3.000 Z-0.010 F50
G2 X2.000 Y3.000 Z-0.010 I0.000 J-1.000 F100
G0 X2.000 Y3.000 Z0.250
G0 Z1
M5
M30

[battenberg]

Gerry, many thanks for such a clear answer.

and just to let you know...
I cut my first shape last night, what an achievement!

Build and configure the machine
Learn to draw in Autocad
Learn how to toolpath and generate gcode in CAM
Learn how to setup the job on the machine.
CUT.!!!!




What a feeling, such a steep learning curve, but to watch it cut your first ever bespoke peice was truly a great buzz!!!

I hope you can remember that feeling?

Cheers