Trying to interpolate X and A axis.

[Konstantin]

Hello everybody.
I have been playing with my 4 axis router and was able to route an octagonal stick. Now I want to cut the octagonal stick helix´ed 0.125 turns or 45 deg.
My stock piece of wood is a cylinder 10.5 mm dia, 20mm long.
I have tried something like

X0 Y0 A0
G02 X20 A45 R5.25

And X and A was moving but Y was moving as well.

Is G02/03 appropriate for the job I intend to cut?

My A axis in on X.
Thanks for any advice.
Konstantin.

[ajl6549]

Try using G1 instead of G2. Use the appropriate feed and start/stop points on X and A axis

[HuFlungDung]

What kind of controller (software) are you using?

What mode (G90 absolute, or G91 incremental) are you running your program in?

I would think you want to index the A axis all by itself with a command on a line by itself:
G00 A45.

G02/G03 is likely confusing the controller as it is not possible to coordinate a circular interpolation move between X and A. By default, XY is the default plane (G17) for circular interpolation in most controllers, unless you change it deliberately with a G18 or a G19 which, I would think, is not your intention in this case.

[Konstantin]

Yes, linear interpolation seems the right choice. I am using Mach3.
One thing is unclear to me, if I go from X0Y0A0 and G01X20A45 will the X and A stop moving at the end point? Is there any chance that one axis will finish sooner than the other?

Also, is it possible to use incremental G91 mode only on one of the axis? For example I want to use incremental on A axis only while going absolute coordinates on XYZ.
Konstantin.

[Switcher]

I'm thinking something like this:

______________________________________________________________________________________________________

%
(Code to send to start of workpiece)
G91
G01 X20 A360 F10
(code to bring X-axis back to zero/start position, rotate A-axis another 45deg. repeat above code, 3 times)
(Send Home)
M30
%
______________________________________________________________________________________________________














.

[Switcher]

The X & A axis should stop at the same time.
If they are on the same line.


.

[ajl6549]

Originally Posted by Konstantin Yes, linear interpolation seems the right choice. I am using Mach3. One thing is unclear to me, if I go from X0Y0A0 and G01X20A45 will the X and A stop moving at the end point? Is there any chance that one axis will finish sooner than the other?

The axis will/should stop at the same time (at A20 A45). Try running it with the tool above the work to avoid scraping the work piece

[Konstantin]

Thanks for the help.
I wrote a little program to do it and ran it and here is the result.
I wanted to go with incremental positioning for the A axis while keeping XYZ in abs (don't know if its at all possible or practical), but decided to go absolute and later will experiment with incremental.

;Cutting an octagon rotated 45 degrees



;Position at the workpiece with safe hight
G1X0Y0Z1A0
M3
F160



;---------------------------XY iteration #1  0 deg
G1 Z-0.35 ;plunge
G1 X0 Y-1.45
G1 X29 A45 ;first pass
G0 Z1        ;save Z

G0 X0 Y0 A0  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A45 ;second pass
G0 Z1        ;save Z

G0 X0 Y1.45 A0  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A45 ;third pass
G0 Z1        ;save Z
G0 X0 Y-1.45 ;Return to the workpiece start
;-------------------------END 


;---------------------------XY iteration #2  45 deg
G1 Z-0.35 ;plunge
G1 X0 Y-1.45
G1 X29 A90 ;first pass
G0 Z1        ;save Z

G0 X0 Y0 A45  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A90 ;second pass
G0 Z1        ;save Z

G0 X0 Y1.45 A45  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A90 ;third pass
G0 Z1        ;save Z
G0 X0 Y-1.45 ;Return to the workpiece start
;-------------------------END 

;---------------------------XY iteration #3  90 deg
G1 Z-0.35 ;plunge
G1 X0 Y-1.45
G1 X29 A135 ;first pass
G0 Z1        ;save Z

G0 X0 Y0 A90  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A135 ;second pass
G0 Z1        ;save Z

G0 X0 Y1.45 A90  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A135 ;third pass
G0 Z1        ;save Z
G0 X0 Y-1.45 ;Return to the workpiece start
;-------------------------END 

;---------------------------XY iteration #4  135 deg
G1 Z-0.35 ;plunge
G1 X0 Y-1.45
G1 X29 A180 ;first pass
G0 Z1        ;save Z

G0 X0 Y0 A135  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A180 ;second pass
G0 Z1        ;save Z

G0 X0 Y1.45 A135  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A180 ;third pass
G0 Z1        ;save Z
G0 X0 Y-1.45 ;Return to the workpiece start
;-------------------------END 

;---------------------------XY iteration #5  180 deg
G1 Z-0.35 ;plunge
G1 X0 Y-1.45
G1 X29 A225 ;first pass
G0 Z1        ;save Z

G0 X0 Y0 A180  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A225 ;second pass
G0 Z1        ;save Z

G0 X0 Y1.45 A180  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A225 ;third pass
G0 Z1        ;save Z
G0 X0 Y-1.45 ;Return to the workpiece start
;-------------------------END 

;---------------------------XY iteration #6  225 deg
G1 Z-0.35 ;plunge
G1 X0 Y-1.45
G1 X29 A270 ;first pass
G0 Z1        ;save Z

G0 X0 Y0 A225  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A270 ;second pass
G0 Z1        ;save Z

G0 X0 Y1.45 A225  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A270 ;third pass
G0 Z1        ;save Z
G0 X0 Y-1.45 ;Return to the workpiece start
;-------------------------END 

;---------------------------XY iteration #7  270 deg
G1 Z-0.35 ;plunge
G1 X0 Y-1.45
G1 X29 A315 ;first pass
G0 Z1        ;save Z

G0 X0 Y0 A270  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A315 ;second pass
G0 Z1        ;save Z

G0 X0 Y1.45 A270  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A315 ;third pass
G0 Z1        ;save Z
G0 X0 Y-1.45 ;Return to the workpiece start
;-------------------------END 

;---------------------------XY iteration #8  315 deg
G1 Z-0.35 ;plunge
G1 X0 Y-1.45
G1 X29 A360 ;first pass
G0 Z1        ;save Z

G0 X0 Y0 A315  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A360 ;second pass
G0 Z1        ;save Z

G0 X0 Y1.45 A315  ;next point 
G1 Z-0.35 ;plunge
G1 X29 A360 ;third pass
G0 Z1        ;save Z
G0 X0 Y-1.45 ;Return to the workpiece start
;-------------------------END 


G0 Z1
G0 X0 Y0 
M5