Welcome to Our Community

Some features disabled for guests. Register Today.

Probe vs Machine Max Travel

Discussion in 'General Talk' started by Andy C, May 6, 2022.

  1. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    Hi All,

    I'm hoping you can help me with a similar issue. When I use the probe with my laptop it zeros with no issues however when I set up my interface it will not zero and gives a "target exceeds machine travel" error. See screenshot attached. I can jog with the interface with no issues as well, just the probe causing grief at the moment. Any help/advice would be appreciated.

    thanks
    Andy
     

    Attached Files:

  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    A) make sure you Homed to set Machine Coordinates
    B) make sure you arent trying to probe to outside the allowed machine envelope (too far down, to far to one side etc)
     
  3. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    Hi Peter,

    All axis were homed prior to using the probe. The router bit was then jogged over the hole in the probe as per procedure. I ran the exact same sequence with the computer attached without issue so I am very well inside the machine envelope. Once I tried with the interface then I started getting this issue.....I went through all the documentation and can't see anything I missed. One question I have is, how does the interface know what machine I'm using? Is it pulling this info from the black box? I didn't see a step to set up the interface with those parameters like the computer setup.

    thanks
    Andy
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    Yes, Grbl stores all that info. Its also Grbl telling you the probe operation will violate a soft limit. Its not an Interface issue. Interface just sends the move, Grbl threw the error
     
  5. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    Peter, thanks for the reply.

    Fair enough.....what do you suggest trying next to solve the problem given it works with the laptop attached but not with the interface?

    thanks
    Andy
     
  6. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    Rethink your workflow - jogged to a different spot, stock mounted a little differently - something is different between the two times
    Custom probe on CONTROL and default probe on Interface?
     
  7. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    Peter,

    After playing around with this for the last few hours with very little headway, I got the same message when I used the laptop again but it had a little more text that read "this error may be a symptom of an earlier event".....I thought this was the Grbl settings remembering the event from the interface. Either way, I had a brainfart while doing this and decided to zero out when I homed the machine. Low and behold the laptop probed with zero issues. This prompted me to do the same with the interface and again.....success with the probe. So long story short this whole issue may have been me with my head up my arse because looking at setting once it probed and then trying to probe again, I'm asking the machine to travel from a negative positions........Either way I now know to zero when I home, and then use the probe......problem solved.

    Thanks for patience with me on this issue.
    Andy
     
  8. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    Peter,

    The issue came back and I spent a significant amount of time troubleshooting again which was super frustrating since I thought it was solved. This time no matter what I did I could not get the probe to work neither with the interface nor the laptop. So I got desperate and went to the internet......which told me to disable the home cycle. Well, I thought this to be not very good advice at all however short of getting in the fetal position I was willing to try anything. Well it solved the problem....I repeated the test about 50 times to make sure I wasn't getting excited about nothing and it worked every time without issue. It didn't matter if I used the interface or the laptop. It didn't care where the router was when I started. It just worked.

    Have you heard of there being a conflict with the homing faction enabled? Is there anybody out there using the probe with the homing function enabled?

    thanks
    Andy
     
  9. Alex Chambers

    Alex Chambers Master
    Moderator Builder

    Joined:
    Nov 1, 2018
    Messages:
    2,681
    Likes Received:
    1,321
    If you disable the homing cycle the MACHINE co-ordinate system zero will be set at the position its in when you power on.
    If you re-enable the homing cycle, home the machine and then jog to the extreme front, left position - note what the dro says the MACHINE co-ordinates for X and Y are and compare that with your maximum travel settings. Let us know if there is any difference.
    Alex.
     
  10. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    That jus confirms my above suggestions:

    - homing sets machine coordinates
    - Soft limits keeps machine inside machine coordinates
    - Machine Coordinates are defined by Homing and Max Travel values in Grbl
    - Probing routing moves in Work Coordinates, but Grbl will always protect the machine from violating Soft Limits (in Machine coordinates from 0,0,0 to -xmax,-ymax,-zmax)
    - Where you are probing, will violate soft limits thus the error

    So either you are placing stock too far front, and too far left (not leaving room for probe routines to move around the probe) or your Max Travel values are set incorrectly

    Disabling Soft Limits (not homing) will stop the error but if Max Travel was set correctly that will result in crashing into one of the sides (instead of soft limits error stopping that from happening) so also not a good suggestion.

    So, rather, rethink what you are trying to do, move it inward on the bed so there is space to move around the probe safely
     
  11. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    When I home the machine, its already at the front left position. Did you mean the front right?

    thanks
    Andy
     
  12. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    Peter,

    Here are some pictures of where the probe is in relation to the limits of the machine. If they were too close to the limit switches for the probing cycle then wouldn't they activate when I probe with the homing cycle disabled?

    thanks
    Andy
     

    Attached Files:

  13. Alex Chambers

    Alex Chambers Master
    Moderator Builder

    Joined:
    Nov 1, 2018
    Messages:
    2,681
    Likes Received:
    1,321
    I should have asked where your homing switches are, but homing sets the MACHINE co-ordinate system back, right, up corner as zero, so front, left in the MACHINE co-ordinate system should be the same as the your maximum travel settings for X and Y. As @Peter Van Der Walt explained above, one possible cause of your issues would be if your maximum travel settings are not set correctly.
    Alex.
     
  14. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    Alex,

    I followed the build video for Lead 1515 and at 13:07 min it shows the X limit switch being installed at the front left and at 14:28 min it shows that the Y limit switch being installed at the front right. Is this incorrect?

    I also have tested the max travel limits after homing and the software recognizes the travel and throws an error and prevents a crash.

    I have tried the probe in the middle of the bed and I get the same error. This error isn't me trying to be too close to the limit switches or trying to travel outside of the max area.

    thanks
    Andy
     
  15. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    Switches can be where-ever = Machine:0,0,0 are at axis maxima Frequently Asked Questions · gnea/grbl Wiki
    Switches in front is fine and from our videos... and already corrected in our machine profiles by setting $23=3. It's just a convenience thing to move them there - but keep in mind internally Grbl thinks as the back/right/top as Machine:0,0,0
    You then set Work:0,0,0 using probes and Setzero so you have both Machine Coordinates and Work Coordinates set

    From your photo fine, you are not near what the machine should think is a soft-limit in XY (if you remember to Home prior to setting up for probing of course)

    But, you also have a Z axis that you could be asking to move outside that boundary...

    If it homes to the Top, but you have Z Max travel set to say 100mm (just example) But 100mm away from the Z limit switch still has the endmill up in the air by 10mm, you can't move it down lower without violatig a soft limit - XYZ probing brings the bit down to touch the sides of the probe too, and your subsequent Gcode job will too. If moving down lower hits a soft limit before the endmill got to the spoilboard - Max travel was set less than you have on the machine

    Thus my advice to CHECK you Max Travel values in Grbl. And to then correct it, if you have something just a little different from our stock build

    (For example, mounted router a little higher in the mount, shorter endmill, etc. We know you turned on Soft Limits that's not from our default profiles - so we know you made some changes already - question is just what else. )

    1) Home
    2) Jog around in all axes and explore the working envelope - see where the soft limits trigger (Check Z too)
    3) Soft limits is the distance of Max Travel Grbl v1.1 Configuration · gnea/grbl Wiki away from the switches - if you have more space left, fix the Max Travel values
     
    Alex Chambers likes this.
  16. Andy C

    Andy C New
    Builder

    Joined:
    Apr 28, 2022
    Messages:
    21
    Likes Received:
    6
    Peter,

    Yep you were right all along. The z axis was set to allow the bit to cut into the spoil board however this was enough to cause the error. I believe it seemed to be solved and then came back because I was using 3/4" material and then moved to 1/2" material.....at any rate I increased the z axis max travel and it solved the issue.

    Again thanks for your patience with this issue.
    Andy
     
  17. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    Probe routines command a distance to move, regardless off where it will hit (to deal with sometime parking bit a bit higher etc) - Z has to allow for that too, set Z axis max travel to what the actuator can move, to prevent damage to the machine, rather than "just enough" - someday you fit a stubby endmill or very shallow stock, different spoilboard, a job where you want to intentionally cut into spoilboard etc
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice