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Carbide Motion manual Gcode Over travel and Observations

Posted: Fri Jul 24, 2015 1:57 am
Hi All,
This afternoon I was attempting to try and calibrate my SO3 for belt stretch. Instead of milling a bunch of pockets and measuring them, I came up with an idea of using 123 blocks and a small precision end mill blank that came with my Precise Bits collet package (Highly recommend) and sending the commands manually. Before I got to that however, I was playing around with the Gcode sender in Carbide Motion. My router was inside having measurements taken for an upcoming dust shoe; which is why it is missing in the video.
When I was putting in various G0 commands, the machine was not acting like I thought it should. Here are a few of my observations:
• - The machine was over traveling by a significant margin - see video
- If I Typed G0 X50 [Enter] The machine would move
- If I followed again this again with an [Enter] Or Send command, the machine would just sit
- G20 and G21 did not appear to do anything, I was expecting that the (mm) would change between mm/in by toggling either G20/G21
I have had my machine put together for almost 2 months. I have ran jobs successfully, so I know the machine works. Has anyone else experienced something similar, or have any ideas on what could be done to resolve this situation?
\$100, \$101, and \$102 are all set to 20 mm
I tried powering everything down, unplugging it and starting over to no change.

Any and all help is greatly appreciated!
Thanks,
Dave

Re: Carbide Motion manual Gcode Over travel and Observations

Posted: Fri Jul 24, 2015 8:13 pm
Hi Dave,

A couple of things to note here

1.) Issuing G0 X50 (initially) should move your machine 50mm (units) in the positive direction, if your machine began at X=0
2.) Once you move to X=50, sending another G0 X50 command will not move your machine. Why? Because it's already at 50 Remember that the numbers you're sending to the machine are telling it to move to an absolute coordinate.
3.) After issuing the G0 X50 command, if you were to issue G0 X0, your machine would in fact move 50mm in the negative direction. Why? Because you're sending it to X=0.

It's an un-intuitive 'feature' of running in the standard absolute coordinate mode of gcode. There is another mode called 'incremental' which would make the machine act as you were originally expecting, but in most cases we run the machine in absolute mode.

Regarding the other issue of distance: Copy and paste your GRBl settings to the board and we'll see what we can figure out. They should match these settings. (assuming your DIP switches are all set accordingly)

Re: Carbide Motion manual Gcode Over travel and Observations

Posted: Tue Jul 28, 2015 5:06 pm
edwardrford wrote:Hi Dave,

A couple of things to note here

1.) Issuing G0 X50 (initially) should move your machine 50mm (units) in the positive direction, if your machine began at X=0
2.) Once you move to X=50, sending another G0 X50 command will not move your machine. Why? Because it's already at 50 Remember that the numbers you're sending to the machine are telling it to move to an absolute coordinate.
3.) After issuing the G0 X50 command, if you were to issue G0 X0, your machine would in fact move 50mm in the negative direction. Why? Because you're sending it to X=0.

It's an un-intuitive 'feature' of running in the standard absolute coordinate mode of gcode. There is another mode called 'incremental' which would make the machine act as you were originally expecting, but in most cases we run the machine in absolute mode.

Regarding the other issue of distance: Copy and paste your GRBl settings to the board and we'll see what we can figure out. They should match these settings. (assuming your DIP switches are all set accordingly)
Edward,
Thanks for getting back to me. I've been meaning to get back and let you know how this turned out.
As I suspected, the issue was how I was misunderstanding how the gcode should be behaving. I went back and tried it on my machine, and the commands and movements appear to be making much more sense. When measured, the distances are right where they should be. I still need to account for belt stretch and fine tune the axes, but progress!
There is still one issue that I am seeing or possibly not understanding. Upon start up of the machine. 0X,0Y,0Z appears to be taken as whatever state the the machine is in as it starts up. Issuing a G0 X50 command will move the gantry 50 mm in the X. Then issuing a G0 X0 command, the machine moves back to where it originated.
Now, What I have tried doing, is going into the manual machine move / jog mode and moving the gantry to a new locations, and zero all the axes. If I then issue a G0 X50 command again, the machine will go migrate over the the same spot as before, like the zeroing had no effect. If I then issue a G0 X0 command, it brings the machine back to the original start-up location, instead of the spot where I had zeroed out all the axes, like I anticipated.
Am I doing something wrong with my commands/work flow? Is there a way to a new zero and issue manual commands from that zero?

I will post my grbl settings when I get home from work.

Thanks again for all of your help!
Dave

Re: Carbide Motion manual Gcode Over travel and Observations

Posted: Tue Jul 28, 2015 9:22 pm
Hi Dave,

Sounds like you're getting the hang of it. For clarity, this is how I run a job:

1.) Turn the power off on your machine and make sure your spindle is off.
3.) With the power still off, move your machine (just drag it with your hands) to where you want 0,0,0 to be (lets just say the bottom left corner of your material).
4.) Holding The spindle down so the bit is pressing against the workpiece (so the springs don't pull it back up) , turn the power on.
5.) Once the power is on, your machine should stay in place and you can let go of the z-axis.
7.) Go to jog in carbide motion and zero everything - X, Y, and Z should all read 0.00
9.) Quit the jog feature and go back to Load your g-code file
11.) Breath.
12.) Click Run Job!
13.) Dominate World.

-Edward

Re: Carbide Motion manual Gcode Over travel and Observations

Posted: Tue Aug 04, 2015 4:16 am
edwardrford wrote:Hi Dave,

Sounds like you're getting the hang of it. For clarity, this is how I run a job:

1.) Turn the power off on your machine and make sure your spindle is off.
3.) With the power still off, move your machine (just drag it with your hands) to where you want 0,0,0 to be (lets just say the bottom left corner of your material).
4.) Holding The spindle down so the bit is pressing against the workpiece (so the springs don't pull it back up) , turn the power on.
5.) Once the power is on, your machine should stay in place and you can let go of the z-axis.
7.) Go to jog in carbide motion and zero everything - X, Y, and Z should all read 0.00
9.) Quit the jog feature and go back to Load your g-code file
11.) Breath.
12.) Click Run Job!
13.) Dominate World.

-Edward
Hi Edward,
Thanks!
This definitely makes sense. For the most part I do follow the steps you outlined for my work flow as well. When following these steps when processing a job I haven't run into any problems.
However, when manually jogging the machine around by manually entering gcode commands, I am having some questions. You answered the biggest one I had earlier - namely, that I was misunderstanding the G0 command.

Now I am observing that the home (X0,Y0,Z0) Position cannot be changed from when initially starting the machine up, even after re-zeroing all axes.
Essentially, If I start up the machine with it positioned about centered in the x and y directions over the effective cutting area of the machine, then issue a G0 X20 command. The machine will move in the positive X 20 mm. Then if I follow this up with a G0 X0 command, the machine will move back to the home position, or move 20 mm in the negative x direction.
At this point, all is expected.

Now, I exit out of the Manual gcode sender and enter machine jog mode and move the machine to a new x,y location from when it was started up and zero all axes.
From here, if I then go back into the MDI and enter in G0 X20 command, the machine will move to the same point as after the machine initially turned on (In the x axis at least) I would expect that the machine would move 20 mm in the positive x from what I believe to be the "new" home or 0X,0Y,0Z of the machine. I can further realize that this is not the case by sending G0 X0 to the machine, and it will move to the starting position of the machine as it was first turned on, and not where I zeroed all axes. Does this make sense? Are there other gcode commands that I am missing in my workflow that I need to execute to get the results I desire? I can create a video that may make this a little more clear if needed.
Thanks,
Dave