Circle and arc problems

[antoinedrouin]

Hello,
I am new here and a total beginner at G-code. I am using a CNC Aerotech 3200 and it is working as expected for regular straight translations in XYZ axis. I tried programming circles and I am running into issues.

I can do circles in the XY plane without specifying an end point by using "G2 I5 F20". I can also do "G2 X0 I5 F20" or "G2 Y2 I5 F20" but weirdly, when I do "G2 X0 Y2 I5 F20" as some online tutorials suggest, there is an error at the "X0" part. The same thing happens (only one end coordinate working) when I use the R method for circles.

Other problem, circles only work in the XY plane. When I try to do it in the XZ or YZ plane by using G18 and G19 ("G18 G2 K5 F20"), only the X or Y axis oscillates. There is no movement along the Z axis. I can move it manually with buttons in the gui while the circle is happening but not in a programed, controlled way.

Any help regarding those problems is greatly appreciated,
Thanks

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[Jim Dawson]

I have never seen a G2 or G3 move without either I and J or an R. Not sure how you could derive the radius and sweep without the I, J, and an X, Y end point. The start point is normally the current position. The X or Y and the I or J could be modal so would then be implied.

The X0 may be confusing the controller, try X0.0001 and see what happens. Arcs that end on exactly 180 or 360 can sometimes cause problems in the math in the controller.

[sinha_nsit]

If an arc end point is not specified, the start point is taken as the end point and a complete arc (circle) is made.
If the end point is being specified, make sure that the arc is mathematically possible. The center of the circle must lie on the perpendicular bisector of the line joining the start and the end points, within a parameter-defined tolerance.

[antoinedrouin]

I tried the X0.00001 instead of X0 and it does work as in the tutorials I found. Thanks!

Now regarding the other problem, I noticed that when using G18 (XZ plane) and trying to make a circle using "G2 X0 Z0 K10", the software tells me that the Z axis is not in the right plane. If I omit the Z and put "G2 K10", it will work but only the X axis oscillates (as stated in the original post). Our setup also mentions a YY axis (for a total of 4) although there is no motion associated with it. I noticed that when I use "G18 G2 X0 YY0 K10", it works. It is as if the G18 plane was a X-YY plane. How could I change which axis is in which plane?

[Jim Dawson]

I tried the X0.00001 instead of X0 and it does work as in the tutorials I found. Thanks!

Now regarding the other problem, I noticed that when using G18 (XZ plane) and trying to make a circle using "G2 X0 Z0 K10", the software tells me that the Z axis is not in the right plane. If I omit the Z and put "G2 K10", it will work but only the X axis oscillates (as stated in the original post). Our setup also mentions a YY axis (for a total of 4) although there is no motion associated with it. I noticed that when I use "G18 G2 X0 YY0 K10", it works. It is as if the G18 plane was a X-YY plane. How could I change which axis is in which plane?

Happy to hear that worked.

The other problem sounds like your controller does not recognize a G18 command. Not sure how to fix that one. To get true 3D machining, it may be necessary to output arcs as line segments. That should allow full 3D profiling. Many controllers won't handle 3 (or more) axis profiling.

[antoinedrouin]

I am fairly sure it recognizes the G17, G18 and G19 commands because I get an error when specifying the end point out of the correct plane. It's just that G17 is X-Y, G18 is X-YY and G19 is Y-YY. In the end it's only names. The axis I use are actually WSX, WSY, WSZ, WSYY. I feel I could just assign the two axis to the plane I want but I have absolutely no idea how all of this works deep down.

edit: I really don't care about losing the YY axis functionality so I don't need more than 3 axis at once.

[Jim Dawson]

I just briefly looked at the AeroTech 3200 specs & features. It looks like you can get into the guts of the system and do anything you want. Completely user programmable using the built in command set, and/or the .net API. But I have no idea how to do it at this point. If you can program or learn to program, it should be fun to play with.

Any idea what a 6 axis AeroTech 3200 costs? If the cost isn't crazy, I might get interested.

[antoinedrouin]

My guess is a lot of money but how it compares to others I don't know at all. I just took a look at the website and this is exactly what I see in the software:
https://www.aerotech.com/product-cat...-software.aspx

From the "jog pad" right in the middle, it seems my YY axis is their A axis which I think is a rotational axis from what I've read. Now why and how G18 could be linked to this kind of axis, I have no idea...

[Jim Dawson]

What happens when you click on the Configure button? Anything in there that you can change? Like maybe reassigning axes or something? I guess the other question is what kind of a machine are you running with this?

[antoinedrouin]

Finally found the answer! The G16 command assigns the axes to the planes.

I use "G16 X Y Z" so that G17 is X-Y plane, G18 is X-Z and G19 is Y-Z. One could use "G16 A B C" so that G17 is A-B plane, G18 is A-C, etc.

Thank you again for your help!

[Jim Dawson]

I'm happy to hear you found the answer.

Not sure I was all that much help, but I try to do what I can.