3D carvings producing gouging.

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3D carvings producing gouging.

Postby 86bg » Fri Feb 28, 2020 7:29 pm

It seems every 3D carving program that I produce using fusion 360 produces one or two gouges in the final product that are rather small.

My searches tell me that it could be a precision issue but I am using the default constant velocity settings installed on a millimeter machine and my g-code is it all in millimeter.

When I visualize the g code using third-party applications I cannot find any error in the g-code that would produce these results. I'm currently not at my machine but I can follow up with the settings.

Can someone contribute settings they typically use in the fusion 360 p post processor as well as their CV settings? 4x8 machine that you could compare to the one made by CNC Router Parts/Avid. Even tried using the latest version of the software and get the same results. Will follow up with photos later
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Re: 3D carvings producing gouging.

Postby 86bg » Sat Feb 29, 2020 12:07 am

Version 1.2113

It seems the common denominator on the gougings are at lead-ins. Or lead outs. Could this be an issue with how it interprets arcs?


Again, machine is set for metric. Code posted in metric. Are these settings too high?
IMG_20200228_153309.jpg


IMG_20200228_153043.jpg


IMG_20200228_153049.jpg
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Re: 3D carvings producing gouging.

Postby ger21 » Sat Feb 29, 2020 12:10 pm

I don't think that any CV settings should be able to cause gouging like that.
You need to post the g-code for anyone to be able to help, preferably isolated down to just the code causing the gouging.
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Re: 3D carvings producing gouging.

Postby cncdrive » Sat Feb 29, 2020 12:41 pm

No, the CV settings can't cause that, because you said you working in millimeters and you set tolerances of 0.03 and 0.03mm is small tolerance and would not be that visible as on your workpiece.

How are the leadins and leadouts, the gouges are where the Z axis moves up and down?
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Re: 3D carvings producing gouging.

Postby 86bg » Mon Mar 02, 2020 4:20 am

Upper Left Cabinet Door.zip
(242.15 KiB) Downloaded 526 times


I suspected the settings because I can't spot the stray line in the 2 gcode visualizers I used. Nor is it visible as a gouge in fusion 360 Simulate in comparison mode. (shows red colors in parts where the part is gouged.)

The gouge happens in the second tool (1/8" ball mill") but where, I don't know because I wasn't around to see it happen. I mirrored the toolpaths across the door vertically and horizontally. However, this gouging was spotted in other carvings. That one I can probably replay back and catch the moment where it happens. The roughing operation where it's happening isn't hours long like this cabinet door finishing operation I am attaching.

NEMA 34 with Gecko drivers with high amperage settings. There's no way the motors are stalling. Repeating the parts repeats the results in the exact same place.
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Re: 3D carvings producing gouging.

Postby 86bg » Sat Mar 14, 2020 11:47 pm

On an identically shaped door part (but with different height and widths) and using copy pasted fusion 360 Setup and toolpaths I forced all rapids (G0) to instead be high feed rate G01 moves and the gouging went away. Obviously this part isn't exactly the same toolpaths so it's not an apples to apples comparison but I am curious if that could be what was causing the gouging? I've been told by someone that some machines treat rapid moves differently so that's why I gave it a shot. Any thoughts?
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Re: 3D carvings producing gouging.

Postby ger21 » Sun Mar 15, 2020 11:01 am

You might want to check for mechanical issues on the Z axis, like a loose coupling or bearing.
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Re: 3D carvings producing gouging.

Postby 86bg » Sat Mar 21, 2020 4:33 am

That logic doesn't follow considering repeating the toolpath that is 3 hours long produces the exact same gouges in the exact same place
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Re: 3D carvings producing gouging.

Postby 86bg » Fri Apr 10, 2020 2:47 pm

I'm still getting rogue toolpaths, and this time it happened in an area not clouded by other toolpaths. The toolpath plotter doesn't even show the move. I'm going to recreate this with the offending section of gcode with a camera set up watching to find the exact offending gcode. If it's not visible in the plotter on the screen I hesitate to say but am beginning to believe it is a bug. I recently got the latest version of uccnc to see if I can rid myself of these rogue toolpaths to no avail. Thank goodness that I'm cutting a forgivable material else I might put the full power of nema 34 motors right into the spindle bearings.


This was a 3h50m program that besides this one rogue toolpath the part came out perfectly. No steps were missed by the steppers.


IMG_20200409_184032.jpg


IMG_20200409_184057.jpg


IMG_20200320_181655.jpg
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Re: 3D carvings producing gouging.

Postby cncdrive » Fri Apr 10, 2020 8:50 pm

Is this gauge always happens like on your first picture? I mean is it always a bump downwards along the Z-axis? If so then I would check the mechanical backlash on the Z-axis.
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