is there something wrong with my machine?

[Geo Girl]

Hi Gang,

confused, i can machine radii on my emco's no problem, but I have a machine with a fanuc oimb controller and i cannot make work.

its a simple profile. I even used mastercam to create a program and its the same i was trying to use, but it doesn't work.

its a 1/2 ball. 1.968 dia material. radius starts at xozo and its a rad of .984 and the end point is x1.968 Z-.984. can't be simpler.

it should be written
G00 X0 Z0
G03 X1.968 Z-.984 R.984 (i've tried I-.984 or K-.984 or i.984 or k.984) The radius (if works) ends up at too small a diameter.

please help

[littlerob]

Originally Posted by Geo Girl Hi Gang, confused, i can machine radii on my emco's no problem, but I have a machine with a fanuc oimb controller and i cannot make work. its a simple profile. I even used mastercam to create a program and its the same i was trying to use, but it doesn't work. its a 1/2 ball. 1.968 dia material. radius starts at xozo and its a rad of .984 and the end point is x1.968 Z-.984. can't be simpler.

It can always be simpler, IMO

Originally Posted by Geo Girl it should be written G00 X0 Z0 G03 X1.968 Z-.984 R.984 (i've tried I-.984 or K-.984 or i.984 or k.984) The radius (if works) ends up at too small a diameter. please help

If the radius is coming out too small with those same numbers in the code, I would guess that a G42 (cutter comp right) is active, and has the wrong value in the offset page. IE if you are programming from M.C. with a .0156 R tool, with comp. at the computer, and the G42 is active at the control, with a .0312 Radius in the offset page, it'll come out smaller. It needs to be cancelled(G40). Other than that it should work

Robert

[Geo Girl]

thanks for the reply.

i made sure the cutter comp is off and ran it again. the tool radius is set at .020 so thats fine. still the same problem. I'm sure i'm doing something wrong.

the program i ran is
G03 x1.969 Z-.984 I0.0 K-.984 (the OD ends up at aprox .984 dia)

if I run it with
G03 x1.969 Z-.984 I0.0 K-1.968 the OD is aprox 1.703

and both look egg shaped.

heeelpppp!!!! please

[sinha_nsit]

Is this a lathe or a milling machine?

[Geo Girl]

Lathe

[CNCRim]

Originally Posted by Geo Girl thanks for the reply. i made sure the cutter comp is off and ran it again. the tool radius is set at .020 so thats fine. still the same problem. I'm sure i'm doing something wrong. the program i ran is G03 x1.969 Z-.984 I0.0 K-.984 (the OD ends up at aprox .984 dia) if I run it with G03 x1.969 Z-.984 I0.0 K-1.968 the OD is aprox 1.703 and both look egg shaped. heeelpppp!!!! please

Egg shape cause by angle change..... program it for center of the tool that way tool will tangent to the surface.

[Geo Girl]

But its also not turning it to the correct dia, not even close.
How would you write a radii program?

[CNCRim]

Post the program on here since it's lathe.

[CNCRim]

Originally Posted by Geo Girl But its also not turning it to the correct dia, not even close. How would you write a radii program?

I have a feeling you program is not right and second thing is the ball endmill you put in the machine is not parallel to the axis that is cutting that's why it 's small.

[sinha_nsit]

G00 X0 Z0;
G03 X1.968 Z-.984 R.984 ;
should work provided you have diameter programming on your machine.
With radius programming, it should be
G03 X.984 Z-.984 R.984;
You can choose between diameter/radius programming with a parameter.

[dcoupar]

Sounds like maybe you're not accounting for the virtual tip?

Try the attached code.

[ImanCarrot]

Hang on a sec...

Assuming your cutting clockwise surely you should set X0 Z0 at the vertex of your sphere? you should then go from X 0.984, Z 0.984 to X0, Z0. That's the way I would do it.

No need to machine right over the vertex.

If the resulting "sphere" is "M" shaped your tool is not to centre, if it's an inverted "V" shape, like a cone, your tool's past centre- jog your X0 accordingly. You can make a steel gauge by cutting a concave radius into a flat piece if steel, place it over the sphere and look for the profile (like using a steel rule to check a flat).

I do this regularly except to a very high accuracy and use a Talysurf to check the form of the sphere.