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Author Topic: Radius Circle is generated as Ellipse.  (Read 1603 times)

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Radius Circle is generated as Ellipse.
« on: January 19, 2017, 03:21:02 PM »
Hi Guys,

I just noticed that when using R(radius) from Fusion360 post processor the circles in Mach3 are not round. I am cutting a 10mm outer diameter with 3mm end mill, the zero is in the center. The GCode is 100% correct, so it is not an issue from Fusion360.


So i took a closer look at the generated path in Mach3 to find out the following:
On the Y axis Top and Bottom points on the circle are correct at 6.500mm and -6.500, but on the X axis left and right are -6.420 and +6.420. it is basically generating an elipse with 6.5mm and 6.42mm radii.

When using I J all works fine. So i was wondering if anyone else can reproduce this problem. It costed me a couple of hours to figure out that the issue is not with the CNC machine...



Thanks

Not working:
G3 X-6.456 Y0.748 R0.449
G2 X6.456 Y-0.748 R6.5
X-6.456 Y0.748 R6.5
G0 Z15.

Working fine:
G3 X-6.456 Y0.748 I-0.163 J0.418
G2 X6.456 Y-0.748 I6.456 J-0.748
X-6.456 Y0.748 I-6.456 J0.748
G0 Z15.
« Last Edit: January 19, 2017, 03:26:10 PM by Mandrake »
Re: Radius Circle is generated as Ellipse.
« Reply #1 on: January 19, 2017, 03:46:37 PM »
Why not try :-

G00 X6.5 Y6.5
G03 I-6.5 F100.
G00 Z15.

Pud
Re: Radius Circle is generated as Ellipse.
« Reply #2 on: February 05, 2017, 09:27:11 AM »
Out of curiosity is R an allowable way to define a circular motion in Mach3. While it sort of works I don't remember if it is "approved"


Mike
We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.

Offline Tweakie.CNC

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Re: Radius Circle is generated as Ellipse.
« Reply #3 on: February 06, 2017, 01:52:40 AM »
Hi Mike,

Radius (R) is a Mach3 approved method - Newfangled Wizards use R for circular pocketing.

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

Offline RICH

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Re: Radius Circle is generated as Ellipse.
« Reply #4 on: February 06, 2017, 06:16:37 AM »
Can't answer you question.
May be something in the post processor for Fusion that you are using. If you export the drawing out for the circle see if it is a true  circle
in CAD. I have just started playing around with Fusion ..............

RICH