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feed rates different?

Discussion in 'SketchUcam Help' started by frankrcfc, Dec 26, 2008.

  1. frankrcfc

    frankrcfc New Member

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    Not sure if this is the right area. I didn't realize that after getting the gcode out of sketchup that my feed rate on the Y axis is consistently 500 X is at 250 along with Z. If I release a build I can only assume that will make other printers haul a** am I correct?. Only thing I can think of is the fact that my X is set at 38, Y is set at 8 and Z is set at 6 for feed rates. This is really getting interesting as I "stumble" along with learning the details as opposed to just plowing out a build and thinking all is good for other peoples machines. Here is a short sample of my latest. How will this correlate to other peoples machines if they want to cut this build out? Oh yes, this is with the latest Phlatscript build installed on v6 of Sketchup.

    %
    G90
    G20
    G49
    M3 S15000
    G0 Z 0.050
    X 9.561 Y 4.976 F 500
    G1 Z -0.125 F 250
    G0 Y 5.351 F 500
    Z 0.050
    X 4.049 Y 10.040
    G1 Z -0.237 F 250
    G0 Y 20.727 F 500
    Z 0.050
     
    frankrcfc, Dec 26, 2008
    #1
  2. Crash

    Crash Moderator Staff Member

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    If I understand your question...

    The gCode is simply coordinate data - basically machine "instruction". The speed at which that data is processed is soley dependent on the machine settings for the particular machine on which the data is being cut.

    Let's say a file processes quickly on your machine, but I load it on my machine that may be set at lower speeds, it will process slower.

    When feedrates differ on the X and Y axis, and the code calls out for both axes to be used (like in the case of a 45 degree cut where both X and Y must move), the total feedrate is dropped to match the speed of the maximum rate that the slowest of the two motors can travel.

    For example, if X can travel at 100 ipm and Y can travel at 50 ipm, then when both axes are expected to travel (like in the case of a 45 degree cut), then the total feedrate is reduced to 50 ipm the max speed of the slowest motor). If MY machine can run both the X and Y at 100 ipm, then a total feedrate will be 100 ipm across the entire process.

    This is just a simple example. Of course, if you are cutting a path where the slower Y is not required to travel a long distance (like in an angle cut not as steep as a 45 degree), then you may see a faster total feedrate.

    I hope that this answers your question! :D
     
    Crash, Dec 26, 2008
    #2
  3. dangre

    dangre New Member

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    What Frank and I were postulating was, if there was an issue with the g-code saying 500ipm and your motion software (Mach) slowing things down to your max settings at say 8ipm, would there be any issues with acceration or such? Probably not, but I was just questioning why Franks g-code contained feed rates of 500ipm to begin with. Also Mach will always interpolate the motion corelating the speed of slowest axis settings. From the Mach manual:

    "5.5.3.3 Why You Want To Avoid a Big Servo Error
    Most moves made in a part program are coordinated with two, or more, axes moving together. Thus, in a move from (X=0, Y=0) to (X=2, Y=1), Mach3 will move the X axis at twice the speed of the Y axis.
    It not only co-ordinates the movements at constant speed, but also ensures that the speed-required relationship applies during acceleration and deceleration by accelerating all motions at a speed determined by the “slowest” axis."

    Just trying to get Frank's PP up to speed.
    Happy Holiday Mike!
     
    dangre, Dec 26, 2008
    #3
  4. frankrcfc

    frankrcfc New Member

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    Darn it Dan you beat me to the reply :lol: wow. Thanks Mike. I appreciate your reply sir. That pretty much explains it for me. It's just something that I never considered before. Makes sense. So each machine handles whatever setup it's dealt with. Sweet! I have a few planes to put out now. ;)
     
    frankrcfc, Dec 26, 2008
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