Error when using circular interpolation on lathe

More
04 Feb 2012 02:47 - 04 Feb 2012 02:49 #17375 by justinbowser
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.

File Attachment:

File Name: 25_128.dxf
File Size:39 KB
Attachments:
Last edit: 04 Feb 2012 02:49 by justinbowser.

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 08:36 - 04 Feb 2012 08:38 #17384 by andypugh
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)
Last edit: 04 Feb 2012 08:38 by andypugh.

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 12:22 #17388 by BigJohnT
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

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 12:31 - 04 Feb 2012 12:32 #17390 by BigJohnT
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
Last edit: 04 Feb 2012 12:32 by BigJohnT.

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 16:05 #17398 by ArcEye
This is the .dxf image
Attachments:

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 17:41 #17399 by justinbowser
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!

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 17:56 #17400 by BigJohnT
I assume your trying to cut the radius in the lower right hand corner? What is the orientation of the cut as far as X and Z are concerned?

John

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 18:07 #17401 by justinbowser
Yes, the cutting would be in the lower R/H quadrant with the tool moving in a CCW direction as viewed from the top. This snippet assumes that the rod has already been faced off and Z touched off on the face and that it has been turned down from 1.5" to 1.2815"

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 18:09 #17402 by BigJohnT
The Z part does not make sense to me... when I lay it out it is 0.1626 difference between start Z and end Z.

John

Please Log in or Create an account to join the conversation.

More
04 Feb 2012 18:17 #17403 by justinbowser
Oopa! I made a typo in my error message.. It should have read:

start =(Z-0.0376, X1.2815) center=(Z-5.1354, X0.0000)

Please Log in or Create an account to join the conversation.

Time to create page: 0.467 seconds
Powered by Kunena Forum