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Discussion Starter · #1 ·
Help. I was 9 hours into a 18 hour cut and came home from breakfast and spindle had stopped. Limit switch tripped. Cleared switch and hit restart and now I am cutting air until it gets back to wood. Unit is a probotix nebula using aspire 9.0. my question is when a switch is tripped and you clear it how can you restart from where it stopped and not cut air again. This is the first time it has happened to me. Thanks in advance
 

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In linuxCNC the G-code scrolls by in a window at the bottom of the screen. Typically for me the current line hangs out 3rd from the bottom of the visible list. So when a job is stopped by a limit switch that 3rd or 4th line up was the last line run. If you right click on any line you'll get an option to "run from here". I usually scroll up the list to find the last Z move, make sure the bit is in the air not in the wood, restart the spindle then "run from here" on that line. Depending on the job finding the best line to restart on can be tricky. Always worth the effort over starting from the beginning on a long run.

Also in the configurator you can download from Probotix's wiki page there is an option for "Soft Limits". Choosing soft limits in a configuration will let a job run within the machine cutting limits without stopping for any incidental limit switch error. That feature alone has made our limit error prone Nebula into a reliable machine again.

4D
 

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Power up the software again. You may have to override the limit switch. Jog the spindle up. If a move is to another x/y/z location when you restart the bit will usually just travel diagonally from wherever it is to that location then continue as usual.

As the only time the bit automatically starts spinning is at the beginning of files you absolutely have to restart it yourself after a limit error and before resuming a job.

4D
 

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Discussion Starter · #6 ·
I did have to override the switch. I tried to restart the spindle and it would not so I restarted the whole file. I will print these tips and hopefully never use them again. I will go onto the website and try and find the soft limit and download that.
 

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Discussion Starter · #7 ·
4d will o download the soft limit on a thumb drive and then download it onto the Linux computer or into the aspire program. So far most of my cutting had been vcarve signs. The few 3d stuff I have done has been shared files or bought or downloaded from aspire so I have not programmed a lot of 3d stuff. My machine was on storage for a year while the new house was being built. I have cut 9 signs just to get used to the machine again with no problems. What I did notice was when I came back this am the dust hose had come off. Maybe I had a static electricity problem. It still would have Been nice to come back to a machine running just a lot of sawdust.
 

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I’ve seen this issue more than once , and was wondering why it happens in the first place. Is the gantry or carriage not actually/physically at the limit switch when it’s saying it’s tripped?
 

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Mark,

You have a spindle correct? When you click on the icon to start the spindle (manually), you will also have to click on the + icon until you get the spindle up to the correct rpm. Another option to start the spindle is to go into the MDI tab and type in M3 S16000 and hit enter (make sure bit is not in the wood as it will start as soon as you hit enter). The M3 is the spindle start command, the numbers behind the S are the rpm (so enter what ever you need there). Then go back to the Manual tab and do the run from selected line option.

Definitely worth using the 'run from selected line" option that 4D directed you to, rather than starting over.

Dave
 

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I’ve seen this issue more than once , and was wondering why it happens in the first place. Is the gantry or carriage not actually/physically at the limit switch when it’s saying it’s tripped?
There is enough flex in their gantry beam/Z axis that vibration can make the switch contacts bounce open. Once open that will stop the machine in its tracks. The long beam of the Asteroid and Nebula are where this is most likely to happen.

Probotix knows about this and have come up with a much stiffer beam design using a 60mm x 60mm extrusion rather than the current 60mm wide by 30mm tall extrusion.

They also now have an option you can select in the configuration app to select "soft limits". One set all the limit switches are used for is to home the machine. Once the machine knows its actual limits it ignores open limit switches unless they are tripped when somehow the machine has moved past a programmed software limit.

4D
 

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I did some looking on the Probotix Wiki and I think I have your answer Edison Auto. You need to configure LinuxCNC to use soft limits. This allows the machine to use the limit switches for the initial homing and then use soft limits while cutting. This keeps you from having intermittent limit switch errors that could be caused by static electricity or even a heavy cut that could vibrate the switch. To set the soft limits you'll need to follow the instructions on the Wiki for loading the NEW LinuxCNC configuration. The configuration options are pretty obvious but on step 9b you'll need to mike the Z-puck for an accurate thickness. Here is the link to the Wiki instructions. Good luck, Mark. It should help stop limit switch errors on future projects.

NEW LinuxCNC Configuration - PROBOTIX :: wiki

Jay
 

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Rick
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There is enough flex in their gantry beam/Z axis that vibration can make the switch contacts bounce open. Once open that will stop the machine in its tracks. The long beam of the Asteroid and Nebula are where this is most likely to happen.

Probotix knows about this and have come up with a much stiffer beam design using a 60mm x 60mm extrusion rather than the current 60mm wide by 30mm tall extrusion.

They also now have an option you can select in the configuration app to select "soft limits". One set all the limit switches are used for is to home the machine. Once the machine knows its actual limits it ignores open limit switches unless they are tripped when somehow the machine has moved past a programmed software limit.

4D
Makes perfect sense now . Thanks ;)
 

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Discussion Starter · #13 ·
Thanks everyone. Still cutting air for about another 25 minutes and then should start cutting wood again. I will download the update after this is through cutting.
4d do you know if the updated gantry can be installed on the older(2 years) in December nebula?
 

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Discussion Starter · #14 ·
Jay I went to the link and it looks confusing. I am going to call them on Monday as I was going to update to the zpuck for my Christmas present any how and see if the beam is available for upgrade and see if they can send me a configured thumb drive.
 

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Discussion Starter · #20 ·
Thanks for the help from everybody especially Dave and Jay. Limit switches get setting and when I restarted it started cutting to deep. Dave helped me reset z and run 3 tests before z came back to top of board. Started and it buried bit. Going to run updated program to eliminate soft switch problems,install another chunk of wood and try a different program before wasting another 24x24 piece of wood and 18 hours.?
 
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