[cOmmOnjOe]

I want to take a 1.0" ball nose end mill and make a bowl shape: For example, 4.5" diameter and 1.0 deep. I used to know the arithmetic formula to hand write the g-code for this but that was way back in 1996. I know there's software to do this but my shop needs me to do this by hand.
Any solutions out there?

[txcncman]

1.0 inch deep with how many step downs?

[cOmmOnjOe]

.010" to .020" step down I think would make a good blend. But since I want to run it at around 1 min...I think I should go .050"
I'm cutting plastic (polystyrene I think) with solid carbide tooling at 80 ipm feed. So spiraling down even at .020 would be fast.

[txcncman]

Like this?

[cOmmOnjOe]

Yes, that's it.
Just want to remember how to write the g-code for it. Right now I've programmed a diameter and then step it down -.1 while bringing it in -.1 but I want to avoid this scalloping effect by ramping the two movements together.

Also, what type of machining do you call this? It's not helical. Is it concave path milling?

[txcncman]

Done in MasterCam with Flowline. Not "efficient" in the code. Lots of lines. "Efficient" in that it is done.

[cOmmOnjOe]

Yea that's what I figured.
But I used to do it years ago by hand, if only I could remember the algorithm I used to generate the math.

Oh well. Thanks a lot bro and have a good weekend.

[txcncman]

It is arc to arc tangent trig and the point on arc to arc center trig. Machinery's Handbook has trig examples.

[txcncman]

Does this help?

[cOmmOnjOe]

No, I don't have access to cam.
But I think I'll poke around on the wed for "arc to arc tangent trig and the point on arc to arc center trig" and see if I can figure it out.

[firecat69]

Here is a macro we used a while back(8YRS) for a job. It worked on a i-80 Yasnac control. I have not tried it on one of our Fanucs. May need to be tweeked. You can change values depending on size of sphere needed. good luck.

O1234(MACRO FOR MILLING SPHERICAL RAD)
(DEPRESSION SPERICAL)
(1/4 BALL EM)
N100 T01 M06
G00G90G54X.85Y0S10000M3
G43Z.1H1M08
#100=5.8(RADIUS)
#101=5.727(DISTANCE FROM TOP OF PART TO CENTER)
#102=.005(STEP SIZE)
#103=.25(CUTTER DIAMETER)
#104=#100-#101(DISTANCE FROM TOP OF PART TO BOTTOM OF RADIUS)
#105=#100-[#103/2] (NEW RADIUS)
#106=#105-#104(DISTANCE FROM TOP OF PART TO CENTER OF NEW RADIUS)
#107=SQRT[[#104*[[2*#105]-#104]]](STARTING X AT Z0)
#108=0
WHILE[#107GE0]DO1
G01X#107Z#108F100.0(A NEGATIVE IN FRONT OF Z WILL CREATE AN UPWARDS SPHERE)
G03I-#107
#107=#107-#102
#108=#106-SQRT[#105*#105-#107*#107]
END1
G0G90Z1.0
G91G28Y0
M30

[cOmmOnjOe]

Thanks bro. I'll give this a try.