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Author Topic: Rounding the corners  (Read 1600 times)

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Rounding the corners
« on: July 05, 2016, 08:20:10 AM »
Hi,
I have a problema persistent, when i make a square o rectangle a high speed i get radius greater at radius of the tool, if i increases the velocity then the raius is greater still.

My aceleration is 200mm/s2
Velocity is 2800mm/min
With Constant velocity.

Only know two solutions, put a exact stop, but no serve for work of molds, and increase the aceleration but my servodrive work good with 200, if increase a 400mm/s2 shock vibration begin a occur. Some other configuration can i make for decrement the rounding in the corners?

regards
Renato
Re: Rounding the corners
« Reply #1 on: July 05, 2016, 02:12:59 PM »
What feedrate is the machine actually running at (is 2800 the maximum axis velocity, ie g00, or is it your feedrate... ie g01, g02 or g03?)

At 2800mm/min, your velocity is approximately 46.6mm/sec, so with an acceleration of 200 mm/s/s, it would take 0.23 of a second for motion to go from 46.6mm/sec to zero or visa versa.

Hence the distance traveled would be 5.25mm....

Hence you either need higher acceleration or a lower feedrate.... as your acceleration is normally fixed.... I'd suggest lowering your feedrate in the corners via the post-processor or whatever software you are using to create your gcode.
Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”
Re: Rounding the corners
« Reply #2 on: July 05, 2016, 04:28:56 PM »
Yes g0 is 2800mm/min, the corners begin a be seen from 500mm/min, a 2800 the excess of radius is of 1 a 2mm.
When the tool is small and i do letter little at velocity of 1500 mm/min, this change the type of letter.
It seem i only have option of slow velocity.

Renato
Re: Rounding the corners
« Reply #3 on: July 05, 2016, 05:48:24 PM »
I know anything about servo drives, but with a stepper motor you could increase the voltage to the drive and it would improve the velocity and acceleration.

The other thing is feedrate is dictated by the tool you are using.... how many cutting edges it has.... hence if you are using a 4 tooth cutting tool....if you change to a two tooth cutting tool, you can half the velocity.... but this won't improve your cutting time.... but may allow you to do a slower finishing cut?

Others will be able to advise too....give them time to review and respond as I am not an expert here.
Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”
Re: Rounding the corners
« Reply #4 on: July 05, 2016, 05:53:01 PM »
It may also be possible to increase the acceleration if you decrease the maximum velocity...

What is your fastest g1, g2 and g3 feedrate?

Reduce your maximum velocity to a little above this and try to tune your acceleration upwards....this may work a little given the acceleration is linear (normally.... I think you can adjust the acceleration with a kflop controller to be different a little... but not with mach3 or mach4)
Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”