Rounded Corners / MAX_FEED_OVERRIDE
28 Oct 2016 11:53 - 28 Oct 2016 11:57 #82173
by TomAux
Rounded Corners / MAX_FEED_OVERRIDE was created by TomAux
Hi!
I currently have some issues with the AXIS GUI. My CAM doesn't know wood so gives me a little lower speeds than I would want. I thought I could compensate by using the Override > 100% but when i adjust the MAX_FEED_OVERRIDE in the .ini File, all Corners of the paths are coming out extremely rounded - that is with the actual Feed Override still set at 100%.
This looks like a bug to me, how can the maximum of a slider affect the path?
Maybe however I don't understand how Feed Override works?
Btw. I observed this using the "Splash Screen" LinuxCNC G Code.
I currently have some issues with the AXIS GUI. My CAM doesn't know wood so gives me a little lower speeds than I would want. I thought I could compensate by using the Override > 100% but when i adjust the MAX_FEED_OVERRIDE in the .ini File, all Corners of the paths are coming out extremely rounded - that is with the actual Feed Override still set at 100%.
This looks like a bug to me, how can the maximum of a slider affect the path?
Maybe however I don't understand how Feed Override works?
Btw. I observed this using the "Splash Screen" LinuxCNC G Code.
Last edit: 28 Oct 2016 11:57 by TomAux.
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28 Oct 2016 12:02 #82174
by andypugh
Replied by andypugh on topic Rounded Corners / MAX_FEED_OVERRIDE
When setting up your configuration you will have defined some maximum acceleration values.
These values define the minimum radius that the machine is capable of at a given speed. (this is physics, not software)
As the speed increases, so does the minimum radius.
If the acceleration numbers that you chose were based on guesses rather than on experiment then you should try to increase them.
if the values are accurate, then you will have to sacrifice some speed around corners for path accuracy. Take a look at the linuxcnc.org/docs/2.7/html/user/user-con...rajectory_controlG61 and G64 settings.
These values define the minimum radius that the machine is capable of at a given speed. (this is physics, not software)
As the speed increases, so does the minimum radius.
If the acceleration numbers that you chose were based on guesses rather than on experiment then you should try to increase them.
if the values are accurate, then you will have to sacrifice some speed around corners for path accuracy. Take a look at the linuxcnc.org/docs/2.7/html/user/user-con...rajectory_controlG61 and G64 settings.
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28 Oct 2016 12:11 #82176
by TomAux
Replied by TomAux on topic Rounded Corners / MAX_FEED_OVERRIDE
Thank you for your answer. That is not the issue though.
I have two otherwise identical .ini files, one with MAX_FEED_OVERRIDE at 1.2, one with 3.0
When running the same G Code on both "machines" at Feed Override at 100% (same speed on both!) the one with the higher MAX_FEED_OVERRIDE rounds over the corners as if G64 was active with high tolerance.
I have two otherwise identical .ini files, one with MAX_FEED_OVERRIDE at 1.2, one with 3.0
When running the same G Code on both "machines" at Feed Override at 100% (same speed on both!) the one with the higher MAX_FEED_OVERRIDE rounds over the corners as if G64 was active with high tolerance.
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28 Oct 2016 12:17 #82177
by TomAux
Replied by TomAux on topic Rounded Corners / MAX_FEED_OVERRIDE
P.S.: To reproduce, change MAX_FEED_OVERRIDE to 3.0 in .ini file, run axis.ngc, exit, switch back to 1.2, restart, run axis.ngc again.
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28 Oct 2016 12:21 - 28 Oct 2016 12:21 #82178
by TomAux
Replied by TomAux on topic Rounded Corners / MAX_FEED_OVERRIDE
Last edit: 28 Oct 2016 12:21 by TomAux.
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28 Oct 2016 12:33 #82180
by andypugh
Replied by andypugh on topic Rounded Corners / MAX_FEED_OVERRIDE
I have a vague memory about this...
The part of the planner that creates the trajectory creates all the moves in advance. It has to leave enough leeway in the path shape to allow for max-override when the path is actually being cut.
The part of the planner that creates the trajectory creates all the moves in advance. It has to leave enough leeway in the path shape to allow for max-override when the path is actually being cut.
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28 Oct 2016 12:46 #82181
by TomAux
Replied by TomAux on topic Rounded Corners / MAX_FEED_OVERRIDE
That sound like a reasonable explanation, thank you! Guess I'll have to look a little further into how control is done for CNC machines. Coming from industrial robotics I'm used to Hand Override not affecting the path geometry.
Will the path also be affected by override settings between 0 and 100% ?
Will the path also be affected by override settings between 0 and 100% ?
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28 Oct 2016 13:29 #82184
by andypugh
Replied by andypugh on topic Rounded Corners / MAX_FEED_OVERRIDE
I think that the path is exactly the same regardless of override, but is always a path that can be followed at max override.
Your simplest fix will be to set a G64 tolerance.
The best fix would be to make sure the machine acceleration limits are accurate, and to see if you can edit a setting in the CAM software to allow faster feeds.
If not, a rather hacky-fix would be to use feed/10 in the CAM and then have an input filter for LinuxCNC that miltiplies all F-words by a factor of 10.
Your simplest fix will be to set a G64 tolerance.
The best fix would be to make sure the machine acceleration limits are accurate, and to see if you can edit a setting in the CAM software to allow faster feeds.
If not, a rather hacky-fix would be to use feed/10 in the CAM and then have an input filter for LinuxCNC that miltiplies all F-words by a factor of 10.
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22 Dec 2016 02:38 #84535
by OT-CNC
Replied by OT-CNC on topic Rounded Corners / MAX_FEED_OVERRIDE
I ran into a similar issue on my lathe recently. During rapids the path was rounded and quite noticeably. I turned my rapids down from 300ipm to 100ipm and the same rounding occurred. I then looked into trajectory control and added G64 P.002. Oddly nothing changed. I then looked at my code and changed any numbers that didn't carry the decimal. I had few Z1. instead Z1.0000. Once that change was made, the rounding disappeared.
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22 Dec 2016 03:08 #84537
by andypugh
That is a surprise. I thought that all G-code numbers were float by default.
Replied by andypugh on topic Rounded Corners / MAX_FEED_OVERRIDE
I had few Z1. instead Z1.0000. Once that change was made, the rounding disappeared.
That is a surprise. I thought that all G-code numbers were float by default.
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