Machsupport Forum
G-Code, CAD, and CAM => G-Code, CAD, and CAM discussions => Topic started by: kyle_vk on December 05, 2011, 01:40:03 PM
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Hey all,
Forgive me for my ignorance as this is all pretty new to me. I've been in the process of trying to figure out a way to produce 4 axis gcode for the hotwire cutter i've built. After having trouble finding any program that could do this (that wasn't only for doing wings for rc planes), I used the grasshopper plugin for Rhino and made a definition that produced a GCode for a 4 axis shape. Essentially it just reads the two different paths for each tower of the hotwire cutter. My problem is that when I load the GCode into Mach3 it doesn't seem to actually "do" what the gcode is telling it to do. Like if it says to move to point "x" it just keeps going. I've been confused with this because its obviously reading the gcode and responding to it somehow, but i can't tell where i'm going wrong. One thing i've questioned is that the gcode that i get form grasshopper has only one command style (i.e. all the lines are G1 x,y,a,b..etc.), so i didn't know if this would affect what the machine is doing or not. If anyone can give me some advice or direction, or if anyone knows of any software that is capable of 4 axis GCode that would be greatly appreciated.
Here is a small sample of the Gcode that i get from grasshopper...
G01 X15.035 Y12.440 A20.758 B7.212
G01 X15.085 Y12.503 A21.517 B8.179
G01 X15.125 Y12.573 A22.126 B9.248
G01 X15.154 Y12.648 A22.569 B10.394
G01 X15.171 Y12.726 A22.839 B11.594
G01 X15.177 Y12.806 A22.928 B12.820
thank you,
Kyle
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I have never seen a G01 command. G0 is a rapid move and G1 is a move at feed rate but G01 is new to me.
Try setting the feed rate to 10 and then edit your code to be all G1. It should move slow and perform the code.
F10.00
G1 X15.035 Y12.440 A20.758 B7.212
G1 X15.085 Y12.503 A21.517 B8.179
G1 X15.125 Y12.573 A22.126 B9.248
G1 X15.154 Y12.648 A22.569 B10.394
G1 X15.171 Y12.726 A22.839 B11.594
G1 X15.177 Y12.806 A22.928 B12.820
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HIYA Steve The G0/G00 G1/G01 are interchangeable so that mach can comply with both type of coding.
Same with teh rest of the single digit Gcodes
G4/G04 etc.
Kyle your idea of 4 axis code and the rest of the world will differ (;-) Hotwire machines running parralell axis' are special things.
I will look into what you are seeing BUT if you can give a little more detail it would help. I assume your A and B axis are parralell to XY as pairs and the A/B are linear axis as well?
Can you post a picture of what shape it is suppose to be cutting
(;-) TP
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thanks, i've figured out one problem and discovered another. I tried out foamworks 4.0 for creating the GCode and it reads the codes correctly now. Unfortunately....I'm now having an issue figuring out why my motors are running like crap when i run the code. I've been trying to research all the things that could cause this and am having trouble pinning down any one thing that makes it better. The stepper motors are calibrated and move true (enough) to how far i tell them to go, they jog fine and sound fine when jogging, but when it goes to run the code the get loud and stutter and its just no good. Any pointers as to things I should be checking out? Sorry for for the 21 questions, i'm new but i am trying to problem solve on my own.
Again, thank you for your help so far.
Kyle
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It sounds as if the g-code is in small line segments, turn on the constant velocity mode and see if that helps.
Graham
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the gcode is in smaller line segments, unfortunately i've tried that (still have it on) , i've got it on sherline mode, Distance mode = absolute, IJ Mode = Inc, Shuttle Accel = .001,
Steps Per = 3250
Velocity = 6.7 in/min
Acceleration = 5 in/sec/sec
Step Pulse = 5
Dir. Pulse = 0
i'm not sure what else is relevant...
thanks again and i'll keep at it, if theres any other information that you need please let me know, i've attached the gcode that i'm trying to test the machine with.
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Heres a couple screen shots to avoid confusion, not sure if this is helpful but i'm just trying to provide more info on what settings i have and what may be wrong.
(http://i799.photobucket.com/albums/yy276/kyle_vanklompenberg/Hotwire%20Cutter/GeneralConfig.jpg)
(http://i799.photobucket.com/albums/yy276/kyle_vanklompenberg/Hotwire%20Cutter/MotorTuning.jpg)
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I've also been looking into possible PC issues causing pulse interference? This is still all very confusing to me but sounds like it could be a factor....
I've ran the driver test and this is the result (tried to capture about the worst point, it would go from roughly flat to this and back agina...)
(http://i799.photobucket.com/albums/yy276/kyle_vanklompenberg/Hotwire%20Cutter/DriverTest.jpg)
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HIYA Steve The G0/G00 G1/G01 are interchangeable so that mach can comply with both type of coding.
Same with teh rest of the single digit Gcodes
Well that doesn't make me much help then does it. Learn something new every day.
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Is that the fastest your machine will go, 6.7"/min is very slow looking, I would have expected figures 10 times that for the velocity or have you limited it to this for a reason?
Graham
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its definitely capable of faster, i just assumed that being a hotwire cutter, it won't physically be able to cut faster than that, but the machine itself is capable of faster speeds. Could its velocity being set low have to do with it running poorly during a code but jogging smoothly?
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well i've been messing around with a lot of stuff and its gotten a little better...my feed was set at 6.7 and after upping that alot it seemed to run a little better. I think i might have to tweak the acceleration or something because it will go from sounding pretty rough to smooth and back to rough again...it seems to be smoothest going around arcs/circles and then when i have a straight line/diagnal line it runs kind of cruddy again. Any pointers? I'm slowly learning! :)
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Heres a video (low quality phone video), you can here it smooth out/speed up going through the sharper curves and then get rough again....
edit: still working on embedding the video..
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You need to tune the velocity to the maximum reliable speed it will move along with the fastest acceleration with out skipping steps, then the cutting speed is controlled with the F command in the g-code.
This way you have maximum rapid moves with the smoothest feed moves as the acceleration is not ramping up and down between moves.
Graham
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is this tested by jogging or do i have to change the velocity/acceleration then run the code and repeat? Because it jogs smooth and fluid...