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Strange toolpath !
« on: March 15, 2007, 05:31:49 PM »
Hello Brian,
two pictures to show my problem.
Why this strange toolpath with the wizard shape DB9 ?

Tool diameter: 2.5mm

You can see the result on the part!

I forgot some things?

Mach3 V2.0.54
NewFangled V2.72

Thank you
Francis


« Last Edit: March 15, 2007, 05:34:04 PM by ftissera »
Re: Strange toolpath !
« Reply #1 on: March 16, 2007, 09:23:54 PM »
Can you tell me more about how you ran this one- the x and y position, were any of the mirror or rotate functions selected? I assume you selected mm? Can you post the Gcode generated by the wizard?

thanks,

ron ginger
Re: Strange toolpath !
« Reply #2 on: March 16, 2007, 10:23:31 PM »
Hello Ron thank you for the reply

program start to x0 y0 (center of DB9)
No mirror and no rotate selected (same problem with rotate)
My machine's metric, unit's mm

The problem occurs line 33 of this Gcode:

(Program Posted for Aluminum )
G0 G49 G40.1 G17
G80 G50 G90 G98 
G21 (mm)
(****DB 9 Pin****)
M6 T25(TOOL DIA. 2.5)
 G43 H25
M03 S4000
M8
G0  X0 Y3.5154
X0 Y3.5154 Z1
G1 X0 Y3.5154 Z-1.5 F20.3
G41  P1.25 X0.442 Y5.2019 F40.6
G3  X-0.7315 Y5.4991 R2.46126
G1 X-8.001 Y5.4991
G3  X-10 Y3.5001 R1.99898
G1 X-10 Y1.6002
X-12.3977 Y1.6002
G3  X-13.9979 Y0 R1.6002
X-12.3977 Y-1.6002 R1.6002
G1 X-10 Y-1.6002
X-10 Y-3.5001
G3  X-8.001 Y-5.4991 R1.99898
G1 X8.001 Y-5.4991
G3  X10 Y-3.5001 R1.99898
G1 X10 Y-1.6002
X12.3977 Y-1.6002
G3  X13.9979 Y0 R1.6002
X12.3977 Y1.6002 R1.6002
G1 X10 Y1.6002
X10 Y3.5001
G3  X8.001 Y5.4991 R1.99898
G1 X-3.2715 Y5.4991
G3  X-4.445 Y5.2019 R2.46126   <----- a circle instead of an arc
G1  G40 X-4.003 Y3.5154
G0  X-4.003 Y3.5154 Z1
M5 M9
M30

Thank you
Francis

Offline ger21

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Re: Strange toolpath !
« Reply #3 on: March 16, 2007, 10:59:59 PM »
We get those on our router at work from time to time. If you use IJ arcs instead of R arcs they'll probably go away.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Strange toolpath !
« Reply #4 on: March 17, 2007, 04:47:38 AM »
We get those on our router at work from time to time. If you use IJ arcs instead of R arcs they'll probably go away.

Hello Gerry,
This Gcode is produced by Nefangled wizard.  In the configuration of Mach3, IJ i's incremental. 

Thank you Francis

Offline Graham Waterworth

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Re: Strange toolpath !
« Reply #5 on: March 17, 2007, 05:55:25 AM »
I don't use the NFS programs so I can't check it but it looks like a cutter compensation error to me, can you change the lead in/out options.

Graham.
Without engineers the world stops

Offline ger21

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Re: Strange toolpath !
« Reply #6 on: March 17, 2007, 09:30:08 AM »
Change the line at the end with the G40 in it to just G40 and it will work fine. I didn't see the comp was in there.


G3  X-4.445 Y5.2019 R2.46126
G40                                         <----------------- Change this line to this
G0  X-4.003 Y3.5154 Z1
M5 M9
M30

Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Strange toolpath !
« Reply #7 on: March 17, 2007, 02:41:32 PM »
Change the line at the end with the G40 in it to just G40 and it will work fine. I didn't see the comp was in there.


G3  X-4.445 Y5.2019 R2.46126
G40                                         <----------------- Change this line to this
G0  X-4.003 Y3.5154 Z1
M5 M9
M30


Hello all, It is correct with this modification. 
I also replaced the G0 last by G1 to up the tool slowly.

Thank you for the assistance.
Francis
Re: Strange toolpath !
« Reply #8 on: March 17, 2007, 08:51:32 PM »
Ok, I have looked at the code and it is a cutter comp error. If you use a 2mm tool it works OK, anything larger cause an increasing gouge. it looks like the lead-out arc specified in the shapes file is to short. The R format arc may be part of the problem.

I'm not sure how I'm going to fix this one, I'm still working on it. But for now you seem to have a fix.

damn, I hate cutter comp !!!

ron ginger
Re: Strange toolpath !
« Reply #9 on: March 18, 2007, 06:23:26 AM »
Ok, I have looked at the code and it is a cutter comp error. If you use a 2mm tool it works OK, anything larger cause an increasing gouge. it looks like the lead-out arc specified in the shapes file is to short. The R format arc may be part of the problem.

I'm not sure how I'm going to fix this one, I'm still working on it. But for now you seem to have a fix.

damn, I hate cutter comp !!!

ron ginger

Ron,
Thank you for the explanations and the fix.
Do not waste any more time with that it is not a big problem. Essentially cosmetic.

Francis