Need Help! Mach 4 and ESS Limit/Homing Configuration


Results 1 to 7 of 7

Thread: Mach 4 and ESS Limit/Homing Configuration

  1. #1
    Member
    Join Date
    Feb 2012
    Location
    Australia
    Posts
    11
    Downloads
    0
    Uploads
    0

    Default Mach 4 and ESS Limit/Homing Configuration

    G'day all,

    When setting up the Limits and Homing, specifically soft limits in Mach 3, I had the last 25mm before "0" home, travelling at 20% of nominal speed.

    How do I achieve the same in Mach 4 with the ESS? I've had a look at the Limits/Home tab in the ESS plug in, but am not sure about the values to enter regarding the "unit/minute" column. They are set to "1" at the moment. Is that that "1mm/minute" and for how many mm preceding "home" would it be activated?

    Thanks

    Ray

    Similar Threads:


  2. #2
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Mach 4 and ESS Limit/Homing Configuration

    Hi,

    They are set to "1" at the moment. Is that that "1mm/minute" and for how many mm preceding "home" would it be activated?
    That is the homing speed, it does not go fast until it gets close and then slow down. When you think about it....it can't. If it knew where
    the home switch is and slowed down 25mm before it got there then why are you bothering to reference your machine?.
    The whole point of referencing is to inform Mach of it location relative to the home switches. Thereafter and for the remainder of the session Mach
    knows where it is by cumulative motion.

    The setting in the ESS is the speed the axis will travel when executing a home command. It does not have a fast phase. Note that you approach
    at one speed but can back off at another.

    Thus you might approach the home switch at 300mm/min, a bit quick for repeatable accuracy, but you can back off until the home switch deactivates
    at a much lower and therefore accurate rate of 50 mm/min.

    Craig



  3. #3
    Registered
    Join Date
    Feb 2018
    Location
    United States
    Posts
    10
    Downloads
    0
    Uploads
    0

    Default

    I'm working on building my 2nd machine, and I have been looking for pretty much the same thing.

    What I have found so far suggests that it can be done using a custom stript for the homing button. But if it IS possible. You will likely need extra limit switches to let mach know it's close to home and needs to slow down. I would love to be able to rapid home and slow to a crawl for the last half inch of travel! If I figure it out here. I'll let you know what I came up with.

    "What I DO have is a GED and a Give 'em Hell attitude, and I'll figure it out" -Dean Winchester


  4. #4
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Mach 4 and ESS Limit/Homing Configuration

    Hi,

    You will likely need extra limit switches to let mach know it's close to home and needs to slow down.
    Some industrial machines have just exactly that arrangement....extra switches called pre-limit switches to inform the controller that a hard
    limit is approaching and to reduce speed to avoid crashing into it.

    Another possibility is to use the latest generation AC servos with multi-turn absolute encoders.

    For example DMM have introduced a new encoder, a 32 bit absolute, arranged as 16 bits (65536) turns from home and 16 bits
    (1/65536 th) within that one turn. These positions are battery backed so that if you turn your machine off and come back later and turn
    it on it remembers where it was and can start from there without having to do the whole home/reference thing. Very nice but probably
    an expensive way to get out of homing your machine. Is it really that painful/slow/arduous?

    Craig



  5. #5
    Member ger21's Avatar
    Join Date
    Mar 2003
    Location
    Shelby Township
    Posts
    35538
    Downloads
    1
    Uploads
    0

    Default Re: Mach 4 and ESS Limit/Homing Configuration

    Another possibility is to use the latest generation AC servos with multi-turn absolute encoders.

    For example DMM have introduced a new encoder, a 32 bit absolute, arranged as 16 bits (65536) turns from home and 16 bits
    (1/65536 th) within that one turn. These positions are battery backed so that if you turn your machine off and come back later and turn
    it on it remembers where it was and can start from there without having to do the whole home/reference thing. Very nice but probably
    an expensive way to get out of homing your machine. Is it really that painful/slow/arduous?
    The servo drive may know where it is, but how do you tell Mach where it is?

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  6. #6
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Mach 4 and ESS Limit/Homing Configuration

    Hi Gerry,
    good question, I don't know, I don't have such a servo to experiment with.

    I presume that once the servo drive is powered up the position is reported and held by the drive. The position can be read by Mach.

    Inducing Mach to overwrite its machine coordinates is not trivial. I would attempt to have Mach 'home in place' but apply the home offset as provided
    by the drives..

    Craig



  7. #7
    Member
    Join Date
    Oct 2016
    Location
    Sweden
    Posts
    10
    Downloads
    0
    Uploads
    0

    Default Re: Mach 4 and ESS Limit/Homing Configuration

    Quote Originally Posted by nr0x View Post
    I'm working on building my 2nd machine, and I have been looking for pretty much the same thing.

    What I have found so far suggests that it can be done using a custom stript for the homing button. But if it IS possible. You will likely need extra limit switches to let mach know it's close to home and needs to slow down. I would love to be able to rapid home and slow to a crawl for the last half inch of travel! If I figure it out here. I'll let you know what I came up with.
    I don't know what the homing routine on the ESS looks like but I have solved this differently on my 3040 which use limit switches for homing. I use the Darwin parallel port plug-in and it has no options for back-off.

    I made a custom script for the homing button that performs a first rapid homing according to homing speeds in control config. This speed is as high as I dare to run without crashing into the switches. It's far from accurately homed.
    Then I back-off enough to clear the limit switches and programmatically change the homing speeds to a much lower speed and perform a second accurate homing.
    Finally I programmatically restore the homing speeds to the high speeds I started with.
    The script has not been tested with any other controller but if you are interested in trying it or get some inspiration for a similar solution you can have a look at it at https://github.com/perhof/Mach4-scripts

    A different option could be a script that reverse the homing direction in the settings to home backwards after a first high speed homing but it would also need to invert the switch levels to make them activate when they open again and I haven't looked into those settings so I don't know if it can be done.
    Besides, I prefer to change as few settings as possible because I'm afraid of what would happen to my settings if the application would crash while running with the temporary settings.
    The worst thing that could happen with my script now is that I would get stuck with very low homing speeds which at least is safe.



Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

Mach 4 and ESS Limit/Homing Configuration

Mach 4 and ESS Limit/Homing Configuration