CNC a dome/bowl without CAM software?

[NotDylan]

I am wanting to make a small bowl without using a CAM system, is it possilbe? My school recently got Gibbs Cam, however no one here is trained on it yet and we have no way of exporting the NC code. Is there any kind of canned cycle available? I searched through our programming manuals for our mills (Bridgeport) and found nothing.

[dpuch]

Use trig to figure out the radius and height for circles around the sphere. See The Unit Circle here Then using a ball mill do a bunch of circles with changing Z level and radius. Make you programed sphere radius larger then the target sphere by the radius of the ball end mill, then offset the program down by the ball mill radius.

I just re read, and saw you wanted a bowel. In that case your target sphere is SMALLER, and move your program UP.

A backplot of the code from the spindle view is a bunch of concentric rings.
Hope that is enough for you to visualize what I mean.

[dpuch]

Ok, this got me interested. I wrote a fanuc macro to machine this. If you don't have fanuc macro B or some of the system variables used, you will have to modify it. I did not test run this either, so use a bit of caution trying it out.

O8001(Spherical bowel macro)
(for Fanuc macro B)
(cut half spherical pocket)
(#24=X Sphere center)
(#25=Y Sphere center)
(#26=Z Sphere center)
(#6=K Sphere radius)
(#9=F Feed rate)
(#21=U Ball mill radius)
(#18=Q maximum step over)
(#17=R Rapid plane)

IF[#4010EQ98] THEN #17=#5043 (set R to current Z Initial point return)
IF[#4003NE90] THEN #3000=90(Must be in absolute mode)
#2=#4001 (store G01-G03 mode)
#3=FUP[[.5*3.1416*#6]/#18] (number of layer cuts)
#4=90/#3 (angle for each step)
#5=0 (current angle)
#7=0 (zero out current radius)
#8=#26-#21 (current Z)

G0 X#24 Y#25
G0 Z#17
G1 Z#8 F#9 (Ball center at sphere center)
WHILE [#5LT90] DO 1
#7=COS[#5]*[#6-#21]
#8=[#26-#21]-[SIN[#5]*#7]
G1 X[#24+#7] (move to current radius)
Z#8 (move to current Z)
G3 X[#24+#7] Y#25 I-#7 J0 (I J set to inc. center point value)
#5=#5+#4
END 1

G1 X#24
Z[#26-#6]
G0 Z#17

G#2
M99

And since it isn't much different, the external ball version

O8002(Spherical ball macro)
(for Fanuc macro B)
(cut half spherical ball)
(#24=X Sphere center)
(#25=Y Sphere center)
(#26=Z Sphere center)
(#6=K Sphere radius)
(#9=F Feed rate)
(#21=U Ball mill radius)
(#18=Q maximum step over)
(#17=R Rapid plane)

IF[#4010EQ98] THEN #17=#5043 (set R to current Z Initial point return)
IF[#4003NE90] THEN #3000=90(Must be in absolute mode)
#2=#4001 (store G01-G03 mode)
#3=FUP[[.5*3.1416*#6]/#18] (number of layer cuts)
#4=90/#3 (angle for each step)
#5=90-#4 (current angle)
#7=0 (zero out current radius)
#8=#26+#21+#6 (current Z)

G0 X#24 Y#25
G0 Z#17
G1 Z#8 F#9 (Ball center at sphere X Y center and Z top)
WHILE [#5GE0] DO 1
#7=COS[#5]*[#6+#21]
#8=[#26-#21]+SIN[#5]*#7
G1 X[#24+#7] (move to current radius)
Z#8 (move to current Z)
G2 X[#24+#7] Y#25 I-#7 J0 (I J set to inc. center point value)
#5=#5-#4
END 1

G0 Z#17

G#2 (reset movement mode)
M99