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tool offset problems
« on: September 06, 2006, 11:57:21 AM »
Hi
This problem might have been asked severel times before, but i could not fin any threads answering my question.

I am a total newbie to cnc and G-codes.

When i For example try to cut a circle drawn in Autocad and stored as dxf, and the import it to Mach3 it cuts, no problem, but the problem appears when i want to set the tool offset.
I hav tried to manually put in G41 at the top of the code list and it cuts outher an G42 for inner (correct me if I am wrong)

The problem is that the tool stats atthe startpostion in the lower Z pos and then moves out to the offsetdiameter of the circle
i dont know if you guys understand what i mean, but in short the piece that i want in the middle (circle) gets a mark of half the tool with

Sorry, ill try to post a picture of it if you guys dont understand my messy explenation.

Can somebody tell me how and where to write th G41 and G42 codes in the g-code table?

Cory
Re: tool offset problems
« Reply #1 on: September 06, 2006, 04:08:03 PM »
here is the g-codes as i run them, and it would be nice if someone could take their time to run them on their mill, simulation or in live

(File maal )
(Sunday, November 05, 2006)
G90G80g49G41
G0 Z2.0000
g090.1
S1000
G0 Z2.0000
g0 X44.1386 Y925.7701
M3
F50.000 G1 Z0.0000
f700G2 X44.1386 Y925.7701 I94.1386 j925.7701
G0 Z2.0000
G0 X236.1920 Y911.8317
F50.000G1 Z0.0000
F700.000G1 X236.1920 Y961.8317
G1 X286.1920 Y961.8317
G1 X286.1920 Y911.8317
G1 X236.1920 Y911.8317
M5
G0 Z2.0000
G0 X44 Y920
M5M30


Cory

Offline Chip

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Re: tool offset problems
« Reply #2 on: September 07, 2006, 10:20:58 PM »
Hi, Cory

What ver of Mach are you using, post your dxf file

What post processor are you using.

Thank's Chip

Offline ger21

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Re: tool offset problems
« Reply #3 on: September 08, 2006, 09:34:07 PM »
You need a lead-in move, and you need to specify the tool by using P and the radius or D and the tool # in the tool table, ie

G42 P0.25
or
G42 D1

Here's an example:

G40
G0 Z0.13
G0 X0.00 Y2.50 Z0.13
G42P0.25
G1 X0.00 Y3.00 Z0.00 F150
G2 X0.00 Y3.00 Z-0.25 I0.00 J-3.00
G2 X0.00 Y3.00 Z-0.25 I0.00 J-3.00
G0 X0.00 Y3.00 Z0.13

This thread has an explanation that might help.
http://machsupport.com/forum/index.php?topic=1109.0

If you're using AutoCAD 2002 or newer, I wrote a macro that will create your g-code from within AutoCAD, including G41/G42 (automatic lead-ins on circles).

http://mywebpages.comcast.net/cncwoodworker/acad/downloads/AC2GCv039.zip
Gerry

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