G68 and G68.2 difference

[MazatrolMatrix]

Hi,

I'm wondering what the difference between those two is? The manual describe that G68 rotate the coordinate system through a new workpiece origin described using XYZ and then rotated around one of those using ijk with a given R value, to define a plane for the purposes of easy of programming. When I read Haas article about this for example, they describe it more like figure rotation around a given point. So I find it confusing.

Then when I read G68.2, it describes.. basically the same thing?
Is the difference that G68.2 is used along with G53.1 to align a B axis for example to be perpendicular with a given plane? And that G68 is rotating the coordinate system but is not used to align this plane necessarily with a swivel head? It's purpose is more about figure rotation?

But what if I rotate the coordinate system using G68, and then tilt B-axis to align with this plane, then what is the difference between it and 68.2?

Using an Integrex in my case.

 

[DouglasJRizzo]

Things are a bit different in Mazatrol land, even with the G code function.
When I taught the MX/SMX classes at Doosan, G68 was "Balance Cutting Mode" - ie, using two turrets to cut a part, even on the multi tasking MX/SMX which is similar to your Integrex.
G68.1 would rotate the coordinate system, without swiveling the B, G368 would swivel the B and rotate the coordinate system, but G400, would do all of that with a much simpler line of code.

I'm wondering if the G68 and G68.2 are similar in your case.

 

[MazatrolMatrix]

Things are a bit different in Mazatrol land, even with the G code function.
When I taught the MX/SMX classes at Doosan, G68 was "Balance Cutting Mode" - ie, using two turrets to cut a part, even on the multi tasking MX/SMX which is similar to your Integrex.
G68.1 would rotate the coordinate system, without swiveling the B, G368 would swivel the B and rotate the coordinate system, but G400, would do all of that with a much simpler line of code.

I'm wondering if the G68 and G68.2 are similar in your case.

Seems that way with a lot of things.

Yes, that's my understanding of it. The G68.2 using for example Euler angles along with a G53.1 will define the plane rotated around all three axis in one line of code, and then automatically calculate the positions of both Rotary axis to align perpendicular to the plane defined.

But the same should be possible with G68(.1 in your example), just that you would need more lines of code if the plane is rotated through more axis and align rotary axis manually with the plane. But if that is correct then a more advanced version of it isn't really necessary, although more convenient I suppose.

Or the other way around, it makes G68 obsolete. Or it could still be used to rotate shapes of course or in conjunction with a probe maybe, but there is already other G-codes for rotating figures and mirror them and what not so..

 

[LockNut]

There is quite a bit of difference between G68 and G68.2.
G68 rotates around the current work offset, in the case of X0Y0Z0, or another point relative to the work offset. It does not follow the kinematics or COR of the two rotaries. It also works on machines without rotaries at all such as when using a right angle head or adjustable head.

G68.2 rotates around the current work offset while keeping track of the machine COR using the kinematics parameters. The part zero can also be temporarily moved according to the X, Y, Z component of G68.2.

The two have totally different uses.

 

[MazatrolMatrix]

There is quite a bit of difference between G68 and G68.2.
G68 rotates around the current work offset, in the case of X0Y0Z0, or another point relative to the work offset. It does not follow the kinematics or COR of the two rotaries. It also works on machines without rotaries at all such as when using a right angle head or adjustable head.

G68.2 rotates around the current work offset while keeping track of the machine COR using the kinematics parameters. The part zero can also be temporarily moved according to the X, Y, Z component of G68.2.

The two have totally different uses.

I see.
But if I use G52, G68, and then manually align the rotary axis to pe perpendicular to this plane, I have replicated the mechanics of the G68.2 code as I understand it?

 

[LockNut]

Yes, with an emphasis on "manually align". And G68 is oblivious to the COR. In my opinion G68 should not be used on a 5 axis machine only because G68.2 is a better option. G68 is tied to the part. G68.2 is tied to the machine.