Thread: G68 command

1. G68 command

Hi All,

I understand that the coordinate system is rotated.

Refering to sketch attached it is clearly visible that the Program (executed by commanding G68) overtravels the Machine Table & can collide with the Column on which Z axis is built up.

Than how it works & how G68 command takes care of it?

Need Help

Ash

2. So if you are going to rotate the program you need to move the part on the table so it stays inside the travels.

3. I believe you can rotate your program using G68 to any point on the part. You have the lower left in your drawing. You could just as easily have rotated it on the upper right corner, or the middle of the part. Then it's just a case of locating the part so no tool path goes off grid.

BTW, it's a great way to work on a part that's longer than your X travel.

4. Hi ALL

In the sketch drawn I just showed you a example.

But if we have a machine size ( 1000* 500 ) & we have to machine a part 900 * 440 & if we use G68 command (to rotate the coordinate system), then what.

I understand that the coordinate system is rotated, but I predict that it will overtravel & all collide with the Z-axis Column.

Thanks

Ash

• Originally Posted by Ashish B
In the sketch drawn I just showed you a example.

But if we have a machine size ( 1000* 500 ) & we have to machine a part 900 * 440 & if we use G68 command (to rotate the coordinate system), then what.

I understand that the coordinate system is rotated, but I predict that it will overtravel & all collide with the Z-axis Column.

Thanks

Ash
If you have a part that just barely fits in your machine travels then why are you rotating anything?
The only reason to rotate the entire program would be if your 900 * 440 part were programmed with its 900 dimension along the 500 axis of the machine, or some such thing. Then you would put the part on the machine in such a way that it fits and rotate the program to match the part.

• If you use:

G68X0Y0A5.0

(I don't remember which "word" to use for degree of rotation, so I used A)

your part rotates from its origin as you have drawn.

If you use:

G68X900.0Y440.0A5.0

It will rotate from the upper right corner, so that the origin is lower and less left.

If you use:

G68X450.0Y220.0A5.0

It should rotate about the center of the blank, upper right is now more upper, less right and lower left is more lower, less left.

I hope I understand your query.

• Hi

Hi

G68 is commanded when using with probes as that avoids alignment of part. Just touch two points on the face & the whole coordinate system is rotated.

Actually my question was that if Coordinate system rotation is commanded & suppose for eg. if the toolpath crosses the table size by 3 mm (because G68 is commanded ), then wl it show overtravel ?

I am specfically not addressing about rotation centre ( as Beege told ), I am concern about above mentioned scenario....

Thnks,
Ash

About CNCzone.com

We are the largest and most active discussion forum from DIY CNC Machines to the Cad/Cam software to run them. The site is 100% free to join and use, so join today!

Follow us on

Search Engine Friendly URLs by vBSEO ©2011, Crawlability, Inc.