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Circle is not a Circle
« on: February 05, 2018, 03:54:21 AM »
Hello.

First, sorry for my english. I post this to find some help because I dont find anything similiar in the forum/web.
I paint a simple piece (a circle with a drill in the center) in Solidworks 2011 and make the machining with MasterCam X5, the simulation is fine. Then I export the G-Code and load to mach3 but the preview of the piece is not a circle, it looks like a diamond. Then when I start the machine, its make a diamond. I dont understand what is happen. Anyone can help me please?
I attach some photos.
Thank you in advance.
Re: Circle is not a Circle
« Reply #1 on: February 05, 2018, 04:14:04 AM »
There is a another photo of the piece in the machine, it cut fine but this piece is not that I desing in solidworks. My machine is a chinese CNC 3020T with parallel port under windows 7 32 bits. I configure it as the vendor said me, and it look that the configuration is OK because it make all the movements that I programmed in MasterCAM X5 but this is not my piece. I dont know what more to do, can anybody help me please?
Thank You.

Online Tweakie.CNC

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Re: Circle is not a Circle
« Reply #2 on: February 05, 2018, 04:35:05 AM »
Hi Mesp,

Try this Gcode file.

Tweakie.

EDIT  Just spotted the problem...

In Config / General Config change the IJ Mode to Inc. then Regen Toolpath.
In general all Gcode files containg arcs should include the G90.1 or G91.1 (as appropriate). For your Gcode file add G91.1 on a seperate line at the start of the code - your circles will then become round.  ;)

« Last Edit: February 05, 2018, 05:00:58 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Circle is not a Circle
« Reply #3 on: February 05, 2018, 06:06:36 AM »
Hello Tweakie.

I appreciate very much your help. I test the G-Code that you send me and I attach a photo of them. There is a perfect circle with smile.
I check that my software Solidworks, mastercam and mach 3 are in metric (mm) and they are correct.
Thank you so much for the help, I going to test the solution that you say me.
 
Re: Circle is not a Circle
« Reply #4 on: February 05, 2018, 06:57:24 AM »
Hello Tweakie.CNC.

THANK YOU VERY MUCH. Is just Config / General Config change the IJ Mode to Inc. and then Regen Toolpath. Now my circle is a circle :) . If this is in the mach3 configuration, I dont need write the G91.1 line in my file, really?

Thank you again.

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Re: Circle is not a Circle
« Reply #5 on: February 05, 2018, 07:54:13 AM »
Hi Mesp,

Some CAD/CAM software's create arcs in Incremental Mode whilst other create arcs in Absolute mode ( you would need to Google it but the difference is basically the positioning of the centre of the arc ).
The IJ Mode setting within Mach3 is Modal so to be sure of the correct outcome all Gcode files containing arcs should specify the Mode (G90.1 / G91.1) as appropriate. This way you can run Gcode that has been created with any CAD/CAM software without encountering the problem you had discovered. Look at the Gcode of the smiley, it contains G91.1 so I knew it would run OK on your setup.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Circle is not a Circle
« Reply #6 on: February 05, 2018, 08:03:35 AM »
Ok. Thank you so much for the help again. :) :)

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Re: Circle is not a Circle
« Reply #7 on: February 05, 2018, 10:21:19 AM »
I am pleased that you have resolved the problem.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.