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Discussion in 'CNC Mills/Routers' started by Paul Stoller, Sep 22, 2019.
I am building a Sphinx 55 from the bones of my old C-Beam machine. Rising from the ashes so to speak.
Paul Stoller published a new build:
Read more about this build...
Hey Paul, looking forward to following along looks like it will be a fun Build!
I still have more pictures to add, and descriptions for a few things, but thought I would add this for now
I had gotten around to installing limit switches on my first machine so I never really got into the whole homing processing until now.
I've gone through the Grbl settings and believe I have it configured correctly but wanted to post a demo video of the homing and return to zero process to be sure the machine is behaving as is expected for those operations.
If anyone can confirm if it looks correct that would be great.
Another note, I just tried the same sequence again without changing any settings and now I'm having the Z axis move in the wrong direction when attempting to return to zero so it's hitting the limit switch almost immediately during that operation.
I'm not not able to get the return to zero option working without the Z axis repeatedly hitting the limit switch.
Here is a video of the failure along with grbl settings.
$0=10 ;Step pulse time, microseconds
[16:42:40] [ $$ ] $1=255 ;Step idle delay, milliseconds
[16:42:40] [ $$ ] $2=0 ;Step pulse invert, mask
[16:42:40] [ $$ ] $3=4 ;Step direction invert, mask
[16:42:40] [ $$ ] $4=1 ;Invert step enable pin, boolean
[16:42:40] [ $$ ] $5=0 ;Invert limit pins, boolean
[16:42:40] [ $$ ] $6=0 ;Invert probe pin, boolean
[16:42:40] [ $$ ] $10=1 ;Status report options, mask
[16:42:40] [ $$ ] $11=0.020 ;Junction deviation, millimeters
[16:42:40] [ $$ ] $12=0.002 ;Arc tolerance, millimeters
[16:42:40] [ $$ ] $13=0 ;Report in inches, boolean
[16:42:40] [ $$ ] $20=0 ;Soft limits enable, boolean
[16:42:40] [ $$ ] $21=1 ;Hard limits enable, boolean
[16:42:40] [ $$ ] $22=1 ;Homing cycle enable, boolean
[16:42:40] [ $$ ] $23=3 ;Homing direction invert, mask
[16:42:40] [ $$ ] $24=100.000 ;Homing locate feed rate, mm/min
[16:42:40] [ $$ ] $25=1000.000 ;Homing search seek rate, mm/min
[16:42:40] [ $$ ] $26=250 ;Homing switch debounce delay, milliseconds
[16:42:40] [ $$ ] $27=5.000 ;Homing switch pull-off distance, millimeters
[16:42:40] [ $$ ] $30=1000 ;Maximum spindle speed, RPM
[16:42:40] [ $$ ] $31=0 ;Minimum spindle speed, RPM
[16:42:40] [ $$ ] $32=0 ;Laser-mode enable, boolean
[16:42:40] [ $$ ] $100=199.100 ;X-axis steps per millimeter
[16:42:40] [ $$ ] $101=199.100 ;Y-axis steps per millimeter
[16:42:40] [ $$ ] $102=199.100 ;Z-axis steps per millimeter
[16:42:40] [ $$ ] $110=2500.000 ;X-axis maximum rate, mm/min
[16:42:40] [ $$ ] $111=2500.000 ;Y-axis maximum rate, mm/min
[16:42:40] [ $$ ] $112=2500.000 ;Z-axis maximum rate, mm/min
[16:42:40] [ $$ ] $120=150.000 ;X-axis acceleration, mm/sec^2
[16:42:40] [ $$ ] $121=150.000 ;Y-axis acceleration, mm/sec^2
[16:42:40] [ $$ ] $122=150.000 ;Z-axis acceleration, mm/sec^2
[16:42:40] [ $$ ] $130=333.000 ;X-axis maximum travel, millimeters
[16:42:40] [ $$ ] $131=315.000 ;Y-axis maximum travel, millimeters
[16:42:40] [ $$ ] $132=85.000 ;Z-axis maximum travel, millimeters
After having turned off the blackbox and reconnected I am now able to complete the homing cycle and goto zero without triggering the Z alarm. I had been changing settings I wonder if I didn't save something.
Now I just need to be sure it's behaving as expected.
I know I've got something off in my setup, tried running an air cut of hello world and it's crashing at the positive end of the X axis.
I'm still not sure what my issue is, but I've added limit switches to both the positive and negative end of each axis now. I thought I had seen a setting to tell the software you had dual limits, but I'm not finding it now.
Did you remember to SETZERO where the aircut stock's origin is? (bottom left, and a little up in the air)
I could have missed this, being too focused looking through the grbl settings, I'll give this a try again.
One thing I'm trying to figure out now is how to re position the limit switches on the Z axis, having two switches on there has really restricted my Z movement. Maybe I should just use a single switch for Z.
Tried setting zero in the bottom left but that didn't stop it from crashing again, I must still have something else that is off.
Zeroed left, but crashed at far right... Hmm, calibrated steps per mm?
I need to try again, but I believe it was zeroed left and crashing left.
X-Positive is rightwards: Cartesian coordinate system - Wikipedia
So: Grbl Settings, Invert Direction: Flip the X switch
Upon revisiting the right hand rule I see I had remembered it incorrectly. That seemed to have helped but now homing is acting odd. I think I need to start from scratch and start over.
Probably best, but in terms of homing there is also a Invert Homing Dir just flip X too
I reset the values back to factory to start over, but I think I made a mistake doing that, I thought they would revert back to the machine defaults but they look to be grbl defaults. Is there an easy way to reapply the machine defaults.
Grbl Settings > Select Machine > save
Lol, I should have guessed it would be that simple. Thank you
When the homing operation is successfully complete where should the X, Y and Z end up for the machine?
Anywhere (; HOME and ORIGIN are two different things (unlike the 3D printing world where Homing switches set the Origin - which is wrong in gcode standards)
Homing sets the Machine coordinates (usually 3rd quadrant: See gnea/grbl) and SETZERO sets the Work Coordinates (Space in which your gcode moves)
Most people use switches just as safeties, homing is not needed, for most jobs you mount the stock, jog to where the origin should be, hit setzero and run the job.
Homing only becomes useful in batch jobs (shutdown for the day, come in tomorrow, rehome to reestablish where the machine and work coordinates are, then run more of the same job)
Okay, I was just wanting to be certain I had gotten all of the setting correct. Currently if I complete the homing operation it's ending up with the X and Y in the upper left and Z at the top.
I can now perform SETZERO and aircut the hello world job without any crashes.
So I'm thinking I've got things mostly correct. And knowing that a lot of the homing stuff isn't necessarily right or wrong depending on what one wants, just wanted to make sure I was following best practices.
Thanks for the help through this.
Perfect - read the Grbl FAQ section linked earlier
Here is a nice long boring video of the machine running through an aircut of hello world.
I wanted to take from the opposite side of the machine but I need to get a USB extension cable to move the camera to the other side of the bench.