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Thread: Continious feedrate during splines

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    Question Continious feedrate during splines

    I am running Camsoft Lite and when my machine runs splines it accelerates and decelerates from point to point. I know that it does it because I have decelstop programmed into my G1,G2,G3 commands in the gcode.fil. The G2 and G3 commands work great like this. But if I take it out of the G1 my machine jerks at the beginning and end of each move, and especially when changing direction. What I want it to do is be able to run a continuous feedrate and slow down at the end just a little if possible. I have even tried using the VT and IT native galil commands with no luck. And the G08 and G10 commands seem to act just the same as having the decelstop command in the G1.

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    Last edited by johnwaa; 01-15-2010 at 01:25 PM.


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    I have got to the point where I can make a G08 work on splines smoothly at high feedrates the only problem is when the machine takes off it does not ramp accelerate before reaching full feedrate speed. The machine will try to take off so hard that it shuts the amps down. Is there anyway I could program some accel ramp time into my G1 in camsoft?



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    Lower your acceleration value in setup



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    I tried lowering the accel in setup and it makes no difference. When I program the machine to move at feedrates in excess of 50 IPM it shuts down on the initial G1 move trying to go to full feedrate instantly. If I manually turn the feedrate down to like 5 IPM and run my program the machine jerks very hard on take off and then I can manually turn the feed speed up and it will move just fine throughout the rest of the spline and even decelerate on the last move. Is there be any sort of accel ramp time on G1 moves.



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    [QUOTE=johnwaa;721515]I tried lowering the accel in setup and it makes no difference. ... QUOTE]

    You've still got all the symtems of too high acceleration. Try reducing by a factor of 10 or even 50. The machine should be sluggish.

    If this don't change anything, search for use of the ACCEL command someplace. This command is used to chage accleration. maybe your .cbk is changing it back.

    As a final check, you could read out the current acceleration off the Galil card. Enter these commands:

    COMMAND MG_ACA
    RESPONSE \55
    MESSAGE \55

    Karl



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    The response for \55 is 23552 which is where I have it set. I have tried using the accel command in my G1 and in the startup.fil, I had the accel and decel at 1000 and the machine could not even reach full rapid travel in around 100 inches which is really slow accel and decel and the machine still jerks on takeoff, is this normal for the machine or should it accel a bit. I have even contacted Galil and they have been trying to give some commands that might work but no luck there either. It does not seem as if accel is to be used during the G1.



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    Quote Originally Posted by lizvern View Post
    The response for \55 is 23552 which is where I have it set. I have tried using the accel command in my G1 and in the startup.fil, I had the accel and decel at 1000 and the machine could not even reach full rapid travel in around 100 inches which is really slow accel and decel and the machine still jerks on takeoff, is this normal for the machine or should it accel a bit. I have even contacted Galil and they have been trying to give some commands that might work but no luck there either. It does not seem as if accel is to be used during the G1.
    You've proved its not ACCEL. But, I'm guessing from here. I'd next try adjusting your PID parameters. I'd try redcuing all three paramter by 10% and 20% just to see if your'e barking up the right tree. if this bears fruit, look into proper servo tuning.

    Karl



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    I have tried reducing parameters in the PID so low that the motion would stop on normal G00 rapid commands and this also made no changes in my problem. We are also still working with Galil tech support on the tuning issue. When I use a G08 and follow it with L2 or L20 what is really the difference?
    And is the syntax G08L20 correct? I have seen the G08 work but at the end even if I program G09 the machine takes off really hard to the next move its almost as if it is trying to move to positions that are further down in the code than it should be. I am still not convinced that its not a tuning issue so we will keep working on it until we can cross that one off the list.



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    Quote Originally Posted by johnwaa View Post
    ...And is the syntax G08L20 correct? ...
    This little bugger got you pissed off yet???

    If you're comfortable with native Galil commands, I'd try moving the machine with a short native program in Galil's command editor. Prove to yourself its in tuning and not in Camsoft. Or vice versa.

    Have you tried using other default Camsoft .cbk and only enter the tuning PID; then move the machine? Far easier than above and helps you look for trouble within your own .cbk

    I've not seen G08 with an L parameter. Would you post a copy of your G08 and G09 Gcodes?

    Karl



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