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Author Topic: G2/G3 codes and CV.  (Read 12461 times)

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Offline Hood

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Re: G2/G3 codes and CV.
« Reply #10 on: July 25, 2008, 02:35:47 AM »
Well using your xml and your snippet of cde CV stays on. If you just use the snippet that you posted does CV turn off? Do you actually see the CV LED turning off or is there another reason you believe it is turning off?

Hood

Offline wyama

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Re: G2/G3 codes and CV.
« Reply #11 on: July 25, 2008, 02:42:39 AM »
Yes, using the code supplied the CV light is on.  That's not the issue.  Changing the code from G64 to G61 will turn CV off which the CV light goes out on the Mach screen as well.

Either way, the code as is when it run on my machine will "whine" down to a stop and then whine back up when starting the next line of code.  "Whine" is the sound of both the X,Y steppers making music.

I made a simple straight line with two segments.  Just moving X on the X,Y plane the CV on or off changes the machine behaviour.  Changing it to add Z as well also behaves correctly with and without CV mode.

These are G1 linear move commands.  G2, G3 are circular move commands and based on what I'm seeing it appears CV is not implemented on circular moves.

Wayne

Offline Hood

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Re: G2/G3 codes and CV.
« Reply #12 on: July 25, 2008, 02:54:04 AM »
CV in a G2/G3 move will sound like its winding down to a stop because one axis has to come to a stop as it reaches the cardinal point, it then reverses and goes the other way. Same when you get to the next cardinal point, the other axis will wind down and stop then reverse. With constant velocity the axis should not have a significant delay but it will stop as it is impossible for an axis to reverse without stopping. Your motor tuning will make a  big difference to what you see/hear. A machine with fast acelleration you wil hardly notice the slow down, one with a slower acelleration will be quite noticeable.
 If you put G61 in you will, or should notice a more significat slow down/stop.

Hood

Offline wyama

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Re: G2/G3 codes and CV.
« Reply #13 on: July 25, 2008, 03:01:27 AM »
Cool, that makes a lot of sense.

Still, It doesn't seem correct why it whines down off cardinal.  Where it ends up stopping is say 20 degrees off top dead center.  Also, the initial transition into the circle from the straight line it whines down and ends up stopping way past the start point of the circle.  Maybe, there is an offset from where it transitioned into the start of the circle and now is shifted.

It's not in CV mode if the head slows down and stops is it?  that's what is happening.

It seems to behave the same on this particular code with CV on or off.

Wayne

Offline Hood

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Re: G2/G3 codes and CV.
« Reply #14 on: July 25, 2008, 03:03:11 AM »
Can you take a video of it and put it on the Mach group You Tube page, that will give us a better idea of what you are meaning.
Hood

Offline wyama

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Re: G2/G3 codes and CV.
« Reply #15 on: July 25, 2008, 03:12:14 AM »
Ha!!!  Just what I was thinking.  Give me a second.  Uploading.

Offline wyama

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Re: G2/G3 codes and CV.
« Reply #16 on: July 25, 2008, 03:23:00 AM »

Offline wyama

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Re: G2/G3 codes and CV.
« Reply #17 on: July 25, 2008, 03:44:48 AM »
Here's a longer video of a section of code for threadmilling.

I've loaded a drill into the spindle to help visually see the head move.  The CV light was on in the Mach screen.

http://www.youtube.com/watch?v=p_9rU5cmEf8

The associated code:

Code: [Select]
M6 T5 (TOOL CHANGE TM-1875) (MSG, LOAD TOOL # 5)
S2500
M01
G0 G54 X0.4737 Y0.4156
Z1.0
M01
 Z0.1
G1   Z0.0391  F9.0
 X0.4909  Y0.3984   F4.5
G2 X0.4972 Y0.375 Z0.037  R0.0469
X0.385 Y0.2628 Z0.0277  R0.1122 F9.0
X0.2728 Y0.375 Z0.0185  R0.1122
X0.385 Y0.4872 Z0.0092  R0.1122
X0.4972 Y0.375 Z0.  R0.1122
X0.385 Y0.2628 Z-0.0092  R0.1122
X0.2728 Y0.375 Z-0.0185  R0.1122
X0.385 Y0.4872 Z-0.0277  R0.1122
X0.4972 Y0.375 Z-0.037  R0.1122
X0.385 Y0.2628 Z-0.0462  R0.1122
X0.2728 Y0.375 Z-0.0555  R0.1122
X0.385 Y0.4872 Z-0.0648  R0.1122
X0.4972 Y0.375 Z-0.074  R0.1122
X0.385 Y0.2628 Z-0.0832  R0.1122
X0.2728 Y0.375 Z-0.0925  R0.1122
X0.385 Y0.4872 Z-0.1017  R0.1122
X0.4972 Y0.375 Z-0.111  R0.1122
X0.385 Y0.2628 Z-0.1203  R0.1122
X0.2728 Y0.375 Z-0.1295  R0.1122
X0.385 Y0.4872 Z-0.1387  R0.1122
X0.4972 Y0.375 Z-0.148  R0.1122
X0.385 Y0.2628 Z-0.1573  R0.1122
X0.2728 Y0.375 Z-0.1665  R0.1122
X0.385 Y0.4872 Z-0.1758  R0.1122
X0.4972 Y0.375 Z-0.185  R0.1122
X0.385 Y0.2628 Z-0.1943  R0.1122
X0.2728 Y0.375 Z-0.2035  R0.1122
X0.385 Y0.4872 Z-0.2127  R0.1122
X0.4972 Y0.375 Z-0.222  R0.1122
X0.385 Y0.2628 Z-0.2313  R0.1122
X0.2728 Y0.375 Z-0.2405  R0.1122
X0.385 Y0.4872 Z-0.2498  R0.1122
X0.4972 Y0.375 Z-0.259  R0.1122
X0.385 Y0.2628 Z-0.2682  R0.1122
X0.2728 Y0.375 Z-0.2775  R0.1122

Offline Hood

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Re: G2/G3 codes and CV.
« Reply #18 on: July 25, 2008, 03:48:22 AM »
Thats certainly not looking very good, can you post the full code as a file and I will see what my mill runs like with it.
Hood

Offline wyama

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Re: G2/G3 codes and CV.
« Reply #19 on: July 25, 2008, 03:51:49 AM »
Hood, Thanks for replying.

I was beginning to believe pilot error.

I started running at tool change 5.  That's the bottom section of the file.

Wayne