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Author Topic: Understanding Tool offsets G41  (Read 3409 times)

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Offline Sage

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Understanding Tool offsets G41
« on: January 24, 2013, 08:33:44 PM »
I have some code that mills a small cam shape about .25 inches in diameter.
I have a huge tangent lead in line several inches long at the moment. The code runs fine.
In order to understand tool (wear) offsets I added a G41 P0.05 at the beginning of the code just after the default pre-amble G40.
When the code loads I get a  "tool radius greater than approach".
So Where does Mach get it's information about what tool I'm using? I have NO tools programmed and there is nothing in the code to indicate a tool size.
So the tool radius is certainly NOT larger than the several inch long lead-in line.

I have also attempted to add a tool T1, selected it in the code and go into the tool table and assign it a value of 0.5" diameter. Mach still complains with the same error.

What am I missing here?


Offline ger21

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Re: Understanding Tool offsets G41
« Reply #1 on: January 24, 2013, 09:08:38 PM »
P0.05 means you're using a tool with a diameter of 0.1
P is the tool radius.

There are three ways to specify the tool radius with cutter comp.
G41 Px.xx uses x.xx as the tool radius
G41 D2 will use the radius of tool #2 in the tool table
G41 by itself will use the radius in the tooltable of the current tool.

You need to show us your code to if you want to know why it doesn't work.
« Last Edit: January 24, 2013, 09:10:26 PM by ger21 »

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Offline Sage

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Re: Understanding Tool offsets G41
« Reply #2 on: January 24, 2013, 09:21:45 PM »
Wel I think you've pointed out the problem for me.
 I was using the P figure as an offset i.e how much I want the tool to be offset from the programmed path.
I thought that's how Smids described it in his book. G41 stay to the left of the line G42 to the right of the line by the amount specified in the P value. (may have the directions wrong).
I guess I read it wrong.

So if my gcode specifies the tool path center line i.e the tool diameter has already been figured into the code, how do I adjust the path slightly for a worn tool?

Code is attached

« Last Edit: January 24, 2013, 09:35:36 PM by Sage »

Offline Sage

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Re: Understanding Tool offsets G41
« Reply #3 on: January 24, 2013, 10:25:44 PM »
Well, you can pretty much ignore everything I posted earlier including the code I attached.
I was working from a poor memory.
I went back briefly and read the book again and I wasn't even close to using the G41 properly.
I'll go back and read the book more after a nights sleep.
if I still have a problem I'll let you know.

Sorry to bother you.

Thanks for your help Gerry.