Router cutting circles too big

[terry1956]

hi chaps i have a fault which i just dont understand. i have drawn a part in solidworks and then formed the g code in vcarve pro. my machine as been calibrated before the start of the job. all goes well until it comes to cutting the 22mm dia circles, the machine cuts then 49mm. I have ran the g code in a sim and all is ok. the router is using a CS-LABS MIO/IP-M motion controller. Anyone know whats going on here. thanks

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[dillonfitz]

hi chaps i have a fault which i just dont understand. i have drawn a part in solidworks and then formed the g code in vcarve pro. my machine as been calibrated before the start of the job. all goes well until it comes to cutting the 22mm dia circles, the machine cuts then 49mm. I have ran the g code in a sim and all is ok. the router is using a CS-LABS MIO/IP-M motion controller. Anyone know whats going on here. thanks

Settings for IJ code. Incremental vs absolute.


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[terry1956]

Sorry, I have no idea what you mean,what is IJ code incremental vs absolute

[ger21]

How are you programming the circles in V Carve Pro?
Should be either a pocket, or a profile Inside.

[terry1956]

I am using pocket in vcarve. After reading posts on other forums it looks like mach3 needs a g91.1 line adding to the start of the code run. Someplace and for gods know why reason mach3 will not follow the original G code for circles if the line above is not added.

[dillonfitz]

I am using pocket in vcarve. After reading posts on other forums it looks like mach3 needs a g91.1 line adding to the start of the code run. Someplace and for gods know why reason mach3 will not follow the original G code for circles if the line above is not added.

Go into the Mach 3 setting and look for I-J

Under that it will have an option for INC or ABS.


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[ger21]

The Vectric post should be adding the G91.1.
Are you sure you have the tool diameter specified correctly?

[terry1956]

Hi, yes the cutter is correct. The fault looks to lay within mach3. I will be playing around today to reset the I’m setting.

[terry1956]

OK, update. today I did the following. in steps. first just added G91.1 to the g code after G90. result same big circles. 2nd step went into mach3 set up and changed the IJ setting from absolute to incremental still keeping the G91.1 in the g code. Mach3 would not run the g code. 3rd step. removed the G91.1 from the G code. mach3 ran but made the circle 39mm not 22mm. the cutter is correct and it shows it at 6mm in the G code as 6mm. I have zeroed all the machine settings before starting the job. so what is going wrong here.

[routalot]

Have you checked that the original circle size is correct?You wouldn't be the first person to input the dimension as a radius rather than a diameter-not that I'm admitting anything you understand....

Could you copy and paste the actual G code you were running?

[dragon_sa]

Are the circles actually closed...is it possible it is cutting inside the circle then finds a gap and follows the line outside the circle as well?

[he1957]

As mentioned, post the G-code generated.

Is Mach-3 showing it has the correct tool number selected?
Is that tool number set up correctly (diameter, length etc) in the tools database?

[terry1956]

Hi, at the moment I have switched from vcarve pro to fusion360 and the circles came out find. I have been told that vcarve needs g91.1 in a line alone after the g90 input. I will be checking if that works tomorrow.

[he1957]

Ok. What about tool selection and parameters in vCarve Pro?

Not a user of it yet but noted it has separate tool databases for metric and imperial.

Would be worth comparing the G-code produced by Fusion and vCarve too.