THCAD-300 and Hypertherm (65)
17 Feb 2020 02:48 #157552
by phillc54
Replied by phillc54 on topic THCAD-300 and Hypertherm (65)
Only the
PlasmaC User Guide
and scattered bits of info on this forum
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17 Feb 2020 03:03 - 17 Feb 2020 03:03 #157554
by rodw
Can you change your Joint settings for velocity and acceleration to agree with your AXIS_Z settings as shown above?
I think your Joint settings will be limiting your velocity and accelerations here
This is a but messy but basically we cheat the external offsets feature here becasue THC and Gcode/Jogging are mutually exclusive. External offsets (eg. the THC) require a percentage of velocity and acceleration to be reserved for external adjustments. SO what we do is double the Z axis joint velocity and acceleration settings and use
to give external offsets (the THC) 100% of the available velocity and acceleration. (eg by giving it 50% of the inflated values). You can blame me for working that out!
Re settings: with a 5mm pitch ball screw and 269 oz/on NEMA 23 stepper I am using velocity of 60mm/sec and acceleration of 700 mm/sec/sec actual (not inflated values). Thats with a Mesa board, not sure how you will go with a par port.
Replied by rodw on topic THCAD-300 and Hypertherm (65)
I did forget to mention that the Height Per Volt setting is only used by Void Lock which doesn't work too well so it won't affect anything else.
This is really good to know. I did ask Rod here as well, but are there any more documents that cover the rest of the THC settings in the config tab? threshold, PID, VAD, Void override, etc?
[JOINT_3]
MAX_VELOCITY = 3.66666666666
MAX_ACCELERATION = 60.0Can you change your Joint settings for velocity and acceleration to agree with your AXIS_Z settings as shown above?
I think your Joint settings will be limiting your velocity and accelerations here
This is a but messy but basically we cheat the external offsets feature here becasue THC and Gcode/Jogging are mutually exclusive. External offsets (eg. the THC) require a percentage of velocity and acceleration to be reserved for external adjustments. SO what we do is double the Z axis joint velocity and acceleration settings and use
OFFSET_AV_RATIO = 0.5Re settings: with a 5mm pitch ball screw and 269 oz/on NEMA 23 stepper I am using velocity of 60mm/sec and acceleration of 700 mm/sec/sec actual (not inflated values). Thats with a Mesa board, not sure how you will go with a par port.
Last edit: 17 Feb 2020 03:03 by rodw.
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17 Feb 2020 03:05 #157555
by rodw
Phill has done a really good job of harvesting all that info and merging it into plasmac and supporting docs. Its been a long journey for some of us who started well before Plasmac was conceived...
Replied by rodw on topic THCAD-300 and Hypertherm (65)
Only the PlasmaC User Guide and scattered bits of info on this forum
Phill has done a really good job of harvesting all that info and merging it into plasmac and supporting docs. Its been a long journey for some of us who started well before Plasmac was conceived...
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17 Feb 2020 11:45 #157586
by snowgoer540
Ok, I think I am following. I just want to be sure. Currently in [AXIS_Z] my MAX_VELOCITY = 3.666 and MAX_ACCEL = 60. You want me to make the corresponding [JOINT_3] values match? Or do you want me to make the [JOINT_3] values 3.666 and 60, and then double them in [AXIS_Z].
It sounds like the [AXIS_Z] values are for the THC and the [JOINT_3] values are for jogging around, etc? Wont making them match take my max velocity from 110in/min to 220in/min at all times?
I am making a new Z axis with a 4mm pitch ball screw. So when I do, I expect my velocity to go much higher. At that time, should I still make [JOINT_3] and [AXIS_Z] match?
I am running a MESA card as well, and a similarly sized NEMA 23. The problem is right now I have a 3/8-12 ACME Screw. so it takes a bazillion turns to get it moving anywhere. Maybe some of my problem, not sure.
Replied by snowgoer540 on topic THCAD-300 and Hypertherm (65)
I did forget to mention that the Height Per Volt setting is only used by Void Lock which doesn't work too well so it won't affect anything else.
This is really good to know. I did ask Rod here as well, but are there any more documents that cover the rest of the THC settings in the config tab? threshold, PID, VAD, Void override, etc?
[JOINT_3] MAX_VELOCITY = 3.66666666666 MAX_ACCELERATION = 60.0
Can you change your Joint settings for velocity and acceleration to agree with your AXIS_Z settings as shown above?
I think your Joint settings will be limiting your velocity and accelerations here
This is a but messy but basically we cheat the external offsets feature here becasue THC and Gcode/Jogging are mutually exclusive. External offsets (eg. the THC) require a percentage of velocity and acceleration to be reserved for external adjustments. SO what we do is double the Z axis joint velocity and acceleration settings and use
to give external offsets (the THC) 100% of the available velocity and acceleration. (eg by giving it 50% of the inflated values). You can blame me for working that out!OFFSET_AV_RATIO = 0.5
Re settings: with a 5mm pitch ball screw and 269 oz/on NEMA 23 stepper I am using velocity of 60mm/sec and acceleration of 700 mm/sec/sec actual (not inflated values). Thats with a Mesa board, not sure how you will go with a par port.
Ok, I think I am following. I just want to be sure. Currently in [AXIS_Z] my MAX_VELOCITY = 3.666 and MAX_ACCEL = 60. You want me to make the corresponding [JOINT_3] values match? Or do you want me to make the [JOINT_3] values 3.666 and 60, and then double them in [AXIS_Z].
It sounds like the [AXIS_Z] values are for the THC and the [JOINT_3] values are for jogging around, etc? Wont making them match take my max velocity from 110in/min to 220in/min at all times?
I am making a new Z axis with a 4mm pitch ball screw. So when I do, I expect my velocity to go much higher. At that time, should I still make [JOINT_3] and [AXIS_Z] match?
I am running a MESA card as well, and a similarly sized NEMA 23. The problem is right now I have a 3/8-12 ACME Screw. so it takes a bazillion turns to get it moving anywhere. Maybe some of my problem, not sure.
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17 Feb 2020 11:48 #157588
by snowgoer540
I agree, the amount of work that has gone into making Plasmac what it is, is impressive! I am grateful for those who have contributed along the way to get it where it is. I am trying to wrap my head around everything, so that I can hopefully one day understand, and then make meaningful contributions to the project. Unfortunately it means i have to go through the n00b stage for a bit! Thanks for taking the time to answer my questions, I really appreciate it!
Replied by snowgoer540 on topic THCAD-300 and Hypertherm (65)
Only the PlasmaC User Guide and scattered bits of info on this forum
Phill has done a really good job of harvesting all that info and merging it into plasmac and supporting docs. Its been a long journey for some of us who started well before Plasmac was conceived...
I agree, the amount of work that has gone into making Plasmac what it is, is impressive! I am grateful for those who have contributed along the way to get it where it is. I am trying to wrap my head around everything, so that I can hopefully one day understand, and then make meaningful contributions to the project. Unfortunately it means i have to go through the n00b stage for a bit! Thanks for taking the time to answer my questions, I really appreciate it!
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17 Feb 2020 13:01 #157596
by rodw
Replied by rodw on topic THCAD-300 and Hypertherm (65)
Leave your axis values as they are and make the joint agree with them. I think that is why you are too slow. eg. The joint can't deliver what the axis has asked of it ATM so they both need to be the same.
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17 Feb 2020 13:05 #157599
by snowgoer540
I thought I had a light bulb moment just then, but then it went off pretty quick. Isn't the OFFSET_AV_RATIO = 0.5 taking it back to the same value as the Joint?
I don't know what I don't know, so I apologize for being obtuse.
Replied by snowgoer540 on topic THCAD-300 and Hypertherm (65)
Leave your axis values as they are and make the joint agree with them. I think that is why you are too slow. eg. The joint can't deliver what the axis has asked of it ATM so they both need to be the same.
I thought I had a light bulb moment just then, but then it went off pretty quick. Isn't the OFFSET_AV_RATIO = 0.5 taking it back to the same value as the Joint?
I don't know what I don't know, so I apologize for being obtuse.
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17 Feb 2020 20:02 #157654
by rodw
Replied by rodw on topic THCAD-300 and Hypertherm (65)
NO what I think will happen is the lowest setting will be what is adopted so it will be 50% of that or half what you expect. I have always made sure the Joints and Axis settings are the same (eg double the actual)
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17 Feb 2020 22:38 - 17 Feb 2020 22:39 #157660
by phillc54
My impression was:
The [JOINT] values were set to whatever was calculated/tested as best for the machine.
Then [AXIS] values were then set to double the [JOINT] values and the ratio was set to 0.5.
This then shares the [AXIS] value equally between the [JOINT] and the axis offset.
We may need to seek come clarification on this.
Replied by phillc54 on topic THCAD-300 and Hypertherm (65)
This has me thinking now...NO what I think will happen is the lowest setting will be what is adopted so it will be 50% of that or half what you expect. I have always made sure the Joints and Axis settings are the same (eg double the actual)
My impression was:
The [JOINT] values were set to whatever was calculated/tested as best for the machine.
Then [AXIS] values were then set to double the [JOINT] values and the ratio was set to 0.5.
This then shares the [AXIS] value equally between the [JOINT] and the axis offset.
We may need to seek come clarification on this.
Last edit: 17 Feb 2020 22:39 by phillc54.
The following user(s) said Thank You: Clive S
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17 Feb 2020 23:39 - 17 Feb 2020 23:40 #157665
by rodw
Phil, I was playing with external offsets back in August 2017 when it was still an experimental branch under the guidance of Dewey Garret who wrote the eoffset code..
Using OFFSET_AV_RATIO = 0.5 and inflating the velocity and acceleration was never intended use by the external offsets branch but it was something I devised to give the THC maximum velocity and acceleration rather than just a percentage of whats available. I came up with this becasue I knew velocity and acceleration are king when it comes to plasma.
Ignoring external offsets for a minute, My understanding was its perfectly valid to reduce the Axis settings below the joint settings (eg. for example you might not want to use 800 inches per minute that a joint can deliver on a small machine). I think that if the axis asks for more than what the joint can deliver, the velocity and acceleration will be capped by the joint settings. So I doubt that external offsets changes this behaviour.
You'd need to test this by some halscope plots of velocity and acceleration to confirm.
Bear in mind my suggestion was written to a user who was finding that his Z axis velocity and acceleration settings were too slow, so making that small change and seeing if it helps his problem would be worthwhile. If I'm right, he is only using 50% of whats available. There is not really any reason why Plasmac is adjusting the torch height too slowly that I could think of....
Replied by rodw on topic THCAD-300 and Hypertherm (65)
This has me thinking now...
My impression was:
The [JOINT] values were set to whatever was calculated/tested as best for the machine.
Then [AXIS] values were then set to double the [JOINT] values and the ratio was set to 0.5.
This then shares the [AXIS] value equally between the [JOINT] and the axis offset.
We may need to seek come clarification on this.
Phil, I was playing with external offsets back in August 2017 when it was still an experimental branch under the guidance of Dewey Garret who wrote the eoffset code..
Using OFFSET_AV_RATIO = 0.5 and inflating the velocity and acceleration was never intended use by the external offsets branch but it was something I devised to give the THC maximum velocity and acceleration rather than just a percentage of whats available. I came up with this becasue I knew velocity and acceleration are king when it comes to plasma.
Ignoring external offsets for a minute, My understanding was its perfectly valid to reduce the Axis settings below the joint settings (eg. for example you might not want to use 800 inches per minute that a joint can deliver on a small machine). I think that if the axis asks for more than what the joint can deliver, the velocity and acceleration will be capped by the joint settings. So I doubt that external offsets changes this behaviour.
You'd need to test this by some halscope plots of velocity and acceleration to confirm.
Bear in mind my suggestion was written to a user who was finding that his Z axis velocity and acceleration settings were too slow, so making that small change and seeing if it helps his problem would be worthwhile. If I'm right, he is only using 50% of whats available. There is not really any reason why Plasmac is adjusting the torch height too slowly that I could think of....
Last edit: 17 Feb 2020 23:40 by rodw.
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