[Paul_radonc]

Hi,

I have just joined the forum, thank you.
I work in the field of radiotherapy, the repair and maintenance of linear accelerators.

I have recently completed building a 3 axis mill which i intend to use to make pcb's.
I am using Eagle PCB to do the plots, then pcb-Gode to generate the Gcode.
To drive the mill I am using LinexEMC
I have tried to set it up and so far I can communicate with the mill and drive all the axis's- all good there

I have a problem however in running the programme with the gcode loaded.
I am sure its a problem with my initial setup...just cant work it out.
Using the "touch off" command for x&y I have placed the job within the red perimeter of the work screen....Is that the correct method?
I can jog the steppers X,Y &Z with the keyboard

When I run the programme the error messages below are generated. I have tried to sort it out but I very confused and lost in it all. I have disabled the home switches for the moment and set up the mill so that I can do no damage.

"Program exceeds machine minimum on axis z" & "Program exceeds machine maximum on axis z"

If I choose to ignore the error and run it just sits there - no movement
I did at one stage get the x & Y steppers to run then it stopped at line 30: G00 Z0.5000

Thank you for any assistance

regards,
Paul

[elfrench]

Check the settings in Eagle/pcb-Code to see where the Z height of the board is set. You may be able to change it to match your mill.
In LinuxCNC, you can set the Z-axis travel to one of the following using the Step Config wizard:
0 to (mill's max Z travel)
(mill's max Z travel) to 0
-(mill's max Z travel)/2 to +(mill's max Z travel)/2 (actually anywhere between the mill's min and mill's max travel.)

Also open the generated gCode file to find the min and max Z settings. This will indicate how you need to set up LinuxCNC (or change in Eagle/pcb-Code).

[blinkenlight]

In the CNC milling world, there are generally two types of coordinate systems: work coordinates (which you may re-zero arbitrarily using touch-off whenever you want) and machine coordinates, that are supposed to be absolute, and used by the machine controller to know its own limits and avoid hitting the end of the axes. These are not supposed to be changed - you configure them once in your LinuxCNC config file (sorry, forgot which one exactly), and the machine is supposed to find / verify them using your home switches whenever you tell it to "home". With home switches disabled / unused your machine very likely has the wrong idea about where it actually is, and it clearly thinks it would hit the end if it moved the Z axis - what you can do is make sure you configured the actual z-travel you have in the appropriate config file (as advised above), then check the _machine coordinates_ LinuxCNC displays and make sure it actually is within the z-interval you configured...

EDIT: sorry, just noticed you are able to move even Z by jogging - if you can get it to move that way to the height you would expect to mill at, your machine coordinates are OK. However, you still need to tell the machine where you want to be when milling - a.k.a. touch off the Z-axis as well, normally to read zero when the tool touches the top of your workpiece (PCB surface, in this case).

[Paul_radonc]

In the CNC milling world, there are generally two types of coordinate systems: work coordinates (which you may re-zero arbitrarily using touch-off whenever you want) and machine coordinates, that are supposed to be absolute, and used by the machine controller to know its own limits and avoid hitting the end of the axes. These are not supposed to be changed - you configure them once in your LinuxCNC config file (sorry, forgot which one exactly), and the machine is supposed to find / verify them using your home switches whenever you tell it to "home". With home switches disabled / unused your machine very likely has the wrong idea about where it actually is, and it clearly thinks it would hit the end if it moved the Z axis - what you can do is make sure you configured the actual z-travel you have in the appropriate config file (as advised above), then check the _machine coordinates_ LinuxCNC displays and make sure it actually is within the z-interval you configured...

EDIT: sorry, just noticed you are able to move even Z by jogging - if you can get it to move that way to the height you would expect to mill at, your machine coordinates are OK. However, you still need to tell the machine where you want to be when milling - a.k.a. touch off the Z-axis as well, normally to read zero when the tool touches the top of your workpiece (PCB surface, in this case).

Hi and thank you for your replies.

I did have some success late yesterday. I got mill to work in a fashion and all appears to be ok with the mill and its operation with EMC.

I have to work out the setup of the stepconfig file and try to get my head around the setup.
I have noticed that the x axis is going to right hand endstop despite the job being located centrally in the red bordered work space.??

I have installed microswitches in the extreme ends of travel in the X & Y motions which simply disable the motor drive to prevent any real damage. There also home microswitches in place in the X & Y motions but for now are disabled in software until I sort the other issues out.

So I changed the table travel (X) from 0 to 4 to 4 to 0. Then the red border disappeared in that plane. That leads me to think its a setup problem.
Not sure how to set up the work space perimeter correctly and the motions all go in the correct direction.

I appreciate your help. Thank you

- - - Updated - - -

Hi and thank you for your replies.

I did have some success late yesterday. I got mill to work in a fashion and all appears to be ok with the mill and its operation with EMC.

I have to work out the setup of the stepconfig file and try to get my head around the setup.
I have noticed that the x axis is going to right hand endstop despite the job being located centrally in the red bordered work space.??

I have installed microswitches in the extreme ends of travel in the X & Y motions which simply disable the motor drive to prevent any real damage. There also home microswitches in place in the X & Y motions but for now are disabled in software until I sort the other issues out.

So I changed the table travel (X) from 0 to 4 to 4 to 0. Then the red border disappeared in that plane. That leads me to think its a setup problem.
Not sure how to set up the work space perimeter correctly and the motions all go in the correct direction.

I appreciate your help. Thank you

[elfrench]

You probably need to invert the X axis direction in the Step Configuration Wizard in order for X0 to be at the left side. While you're in the wizard, check the travel, both direction and distance, to make sure they are correct for each axis. The Step Configuration Wizard also allows you to set the speeds and acceleration for each axis.

[Paul_radonc]

Hi again. It looks as though I have sorted it all out with your help. I have made a small pcb in Eagle, generated the Gcode, loaded it into EMC and I can see that it all looks ok. I have not got the bits for routing the board so I have used a pencil attached to the Z axis. thanks again
regards,
Paul