4th Axis rotary
19 Feb 2011 16:57 #7317
by judedude
4th Axis rotary was created by judedude
I just added a 4th axis rotary. It runs well but I am having issues with the G code feed rates. I am using V Carve and got the post from the Vcarve website. During parts of the rotary milling the feed rate is 1546 at select points the rotary milling drops to 21.8. Can anyone shed light on the program. Is the post written incorrectly? What can i do to correct? Any help would be appreciated. I attached the G code to help.
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19 Feb 2011 20:26 #7319
by BigJohnT
Replied by BigJohnT on topic Re:4th Axis rotary
Most of the program is using a feed rate of F20.
John
John
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19 Feb 2011 21:00 #7320
by judedude
Replied by judedude on topic Re:4th Axis rotary
Yes. Just need to understand why the rotary speed drops from 1546 to 21.8 at lines 746 and 1197. Should the post be specifiying the feed rate differently. Does EMC drop the defult feed rate after so many lines?
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19 Feb 2011 21:42 #7321
by BigJohnT
Replied by BigJohnT on topic Re:4th Axis rotary
No, EMC attempts to maintain the programmed feed rate if the acceleration rate and distance allows. You can program any feed rate you want but the machine can only do so fast in a certain distance based on the acceleration of each axis. When more than one axis is moving at the same time the rate of all axis is reduced to allow all the axis to meet up at the programmed point. So if one axis is slow it will drag the others down to it's level.
John
John
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20 Feb 2011 11:32 #7323
by Rick G
Replied by Rick G on topic Re:4th Axis rotary
Hello,
You may want to look here
www.linuxcnc.org/docview/html/gcode_main.html#sub:G93,-G94:-Set
As I understand it and John pointed out.
With the g code and a linear & rotary move the rotary axis will try to keep up with the speed of the move based on the linear move speed.
But
If there is no linear move the speed with be based on the rotary speed.
A F20 linear speed move and a F20 rotary speed move are very different things.
Rick G
You may want to look here
www.linuxcnc.org/docview/html/gcode_main.html#sub:G93,-G94:-Set
As I understand it and John pointed out.
With the g code and a linear & rotary move the rotary axis will try to keep up with the speed of the move based on the linear move speed.
But
If there is no linear move the speed with be based on the rotary speed.
A F20 linear speed move and a F20 rotary speed move are very different things.
Rick G
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20 Feb 2011 12:39 #7324
by BigJohnT
Replied by BigJohnT on topic Re:4th Axis rotary
Rick,
Good catch... and it is as clear as mud here:
www.linuxcnc.org/docview/html/common_mac...r.html#sub:Feed-Rate
that makes my head hurt reading it even though it is sure to be exactly correct...
John
Good catch... and it is as clear as mud here:
www.linuxcnc.org/docview/html/common_mac...r.html#sub:Feed-Rate
that makes my head hurt reading it even though it is sure to be exactly correct...
John
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21 Feb 2011 10:24 #7344
by Rick G
Replied by Rick G on topic Re:4th Axis rotary
John,
Yep, there it is, clear as mud, not even sure if it is in English.
I did however help a friend with this on his machine so knowing the outcome and reading it again it starts to make sense.
Rick
Yep, there it is, clear as mud, not even sure if it is in English.
I did however help a friend with this on his machine so knowing the outcome and reading it again it starts to make sense.
Rick
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21 Feb 2011 11:26 #7347
by BigJohnT
Replied by BigJohnT on topic Re:4th Axis rotary
Hi Rick,
If you can come up with a plain English way to describe that I'm all ears. At least you have the advantage of understanding from experience. Most of my work on the docs has been from experience and trying to do something...
John
If you can come up with a plain English way to describe that I'm all ears. At least you have the advantage of understanding from experience. Most of my work on the docs has been from experience and trying to do something...
John
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21 Feb 2011 17:59 #7352
by judedude
Replied by judedude on topic Re:4th Axis rotary
Big John T
Thanks for the insight. I am not the best at G code but I think I understand the basic concept. I guess I could modify the feedrate in the program for these rotary only moves to a higher F # but this is very manual and time consuming. Do most post processors take rotary feed rates into account and make the adjustment or specify the feeds automatically? If I am way out in left field let me know.
Thanks for the insight. I am not the best at G code but I think I understand the basic concept. I guess I could modify the feedrate in the program for these rotary only moves to a higher F # but this is very manual and time consuming. Do most post processors take rotary feed rates into account and make the adjustment or specify the feeds automatically? If I am way out in left field let me know.
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21 Feb 2011 18:31 - 21 Feb 2011 18:32 #7354
by BigJohnT
Replied by BigJohnT on topic Re:4th Axis rotary
Well, I've never worked with a rotary yet and have only used a few post processors... so I'm at a loss about it. I do know that all the post processors I've worked with allow you to configure most things. Some are better than others and some try and hide things from you.
John
John
Last edit: 21 Feb 2011 18:32 by BigJohnT.
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