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Author Topic: Engrave/V-Carve Toolpaths overcutting corners  (Read 154 times)

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Engrave/V-Carve Toolpaths overcutting corners
« on: February 04, 2019, 08:53:24 PM »
Hi All I am running a CNCRouterparts 5x10, it's my second cnc router. I am trying to do an engrave toolpath inside a square with a 1/2" 60 degree V-bit but when the bit comes to do the corner pass where it drags up to square the corner it is slightly over cutting the corner which gives me a little flare on the profile. I have tried slowing the feeds, zeroing on top and at the bottom of the wprkpiece, lowering the acceleration curves of the motors, playing with CV on/off and different CV angles as well as outputting g-code from Fusion360 and Vectric. The F360 files were slightly less pronounced but still happened. Does anyone know what might be causing this? I am at a loss.
Re: Engrave/V-Carve Toolpaths overcutting corners
« Reply #1 on: February 05, 2019, 12:47:04 AM »
Hi,
I don't know if there is a specific answer for your situation but:

Quote
lowering the acceleration curves of the motors,

is exactly wrong. The best and most accurate tool path following is achieved with the HIGHEST POSSIBLE
acceleration, not the lowest.

Craig
My wife left with my best friend...
     and I miss him!
Re: Engrave/V-Carve Toolpaths overcutting corners
« Reply #2 on: February 05, 2019, 12:53:34 AM »
Thanks Craig, I will up the curves tomorrow and see what happens.
Re: Engrave/V-Carve Toolpaths overcutting corners
« Reply #3 on: February 05, 2019, 04:49:14 PM »
Well increasing motor acceleration helped up until the table started shaking (damn you extrusion) along with lowering the feed rate. I am still getting some small ears but they are much reduced. Seems a bit strange though I have done lots of engraving on my much cheaper ballscrew machine and haven't noticed anything like this before.
Re: Engrave/V-Carve Toolpaths overcutting corners
« Reply #4 on: February 05, 2019, 05:37:36 PM »
Hi,
I suspect it's the ratio of acceleration to velocity. The higher the acceleration allows the spindle to follow the tool path
at a given speed. Increasing the acceleration OR reducing the feed rate achieve the same result.

Craig
My wife left with my best friend...
     and I miss him!