Error when using circular interpolation on lathe

Been trying to get a handle on circular interpolation and it doesn't seem EMC is playing fair with a newb! It doesn't seem to matter how I structure the G3 statement I always get a "radius to end of arc differs from radius to start:" error.

I have plotted the radius of the surface in Autocad and a drawing is attached. I am trying to learn how to use this statement and cryptic errors aren't making it easy!

Thanks,

Justin B.

justinbowser wrote:

It doesn't seem to matter how I structure the G3 statement I always get a "radius to end of arc differs from radius to start:" error.

Are you using relative or absolute coordinates for the arc centre? (This is set using G90.1 or G91.1) www.linuxcnc.org/docview/html/gcode_main.html#sec:G90.1,-G91.1

Do you have the correct plane selected?
Typically G17 for a mill(XY) and G18 for a lathe(XZ)
Also, on a lathe radius/diameter mode can confuse matters. (G7, G8)

As I understand it there is only so much room in the error message to put text so that is why I elaborated about the error in the 2.5 manual.

linuxcnc.org/docview/2.5/html/gcode/gcod...#_center_format_arcs

From the 2.5 manual.

When programming arcs an error due to rounding can result from using a precision of less than 4 decimal places (0.0000) for inch and less than 3 decimal places (0.000) for millimeters.

and I found a typo in the manual by cutting a pasting

Deciphering the Error message Radius to end of arc differs from radius to start:

start - the current position

center - the center position as calculated using the i,j or k words

end - the programmed end point

r1 - radius from the start position to the center

r2 - radius from the end position to the center

Can you post the relevant lines of code?

John

Also, on front tooling lathes you have to lie on the floor and look up to get the right direction for your arcs.

So far I've been unable to open your file.

John

This is the .dxf image image missing http://www.linuxcnc.org/media/kunena/attachments/legacy/images/Selection_009.png

Thanks for the replies and suggestions. Here is the code snippet I just tried:

g18 g8 g90.1
f3
g01 x1.2815 z-.0376
g03 x0 z0 i0 k-5.1354

This results in the following error:

radius to end of arc differs from radius to start:
start =(Z-0.376, X1.2815) center=(Z-5.1354, X0.0000)
end=(Z0.0000, X0.0000) r1=5.2564 r2=5.1354


I really appreciate the help. I've been using EMC for a couple of years but nothing fancier than linear moves!