How do I electrically disconnect my Z axis limit switches - Page 2


Page 2 of 4 FirstFirst 1234 LastLast
Results 13 to 24 of 42

Thread: How do I electrically disconnect my Z axis limit switches

  1. #13
    Registered
    Join Date
    Jan 2007
    Location
    USA
    Posts
    54
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    A better approach would be to suppress the EMI at the source. I would first try a shielded power cable from the VFD to the motor.


    Sent from my iPhone using Tapatalk



  2. #14
    Gold Member
    Join Date
    Jun 2006
    Location
    Suffolk, UK
    Posts
    2472
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Quote Originally Posted by lens42 View Post
    A better approach would be to suppress the EMI at the source. I would first try a shielded power cable from the VFD to the motor.


    Sent from my iPhone using Tapatalk
    Thanks for the input Lens42, but as I said I think I have already done all I can with the spindle and dedicated VFD. This includes a shielded cable from the VFD to the motor, as short as possible and grounded at both ends.

    Phil



  3. #15
    Gold Member
    Join Date
    Jun 2006
    Location
    Suffolk, UK
    Posts
    2472
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Quote Originally Posted by CNCMAN172 View Post
    Philbur,

    You can isolate the limit switch inputs to the breakout board using opto isolators or relays. Here is a diagram so you can understand. This will stop the ESTOP issue you are seeing. If you are using the LIMITS as HOME sensors as well you will need one per AXIS.

    Russ
    Thanks for the diagram, I'm not sure I understand VCC or the second 2 in 2K2.

    Phil



  4. #16
    Registered john-100's Avatar
    Join Date
    Mar 2007
    Location
    uk
    Posts
    1365
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Hi Phil
    VCC is the positive supply to the switch
    the resistor is 2200 ohms = 2.2K = 2K2
    ( the K is very often put in place of the decimal point so its not lost in poor copies of the diagram or stray spots taken as decimal points )

    I would re-arrange the circuit to put the limit switch in the ground connection to the opto-isolator
    so you can't short circuit the + 12V or 24V supply

    How do I electrically disconnect my Z axis limit switches-12v-24v-logic-jpg

    John



  5. #17
    Gold Member
    Join Date
    Jun 2006
    Location
    Suffolk, UK
    Posts
    2472
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    My limit switches are currently wired as normally closed, can I stick with this or do I need to wire them normally open, or something else.

    Phil



  6. #18
    Gold Member
    Join Date
    Jun 2006
    Location
    USA
    Posts
    2775
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Phil - is this problem on your original PCNC 1100? My S/N 119 1100 was giving me intermittent limit switch E-stops which went away when Tormach sent me a ferrite that looks something like this one to install on the parallel port cable.

    Laird Technologies - HFA150068-0A2 - High Freq 275 Ohms @300MHz 0.266In Max I.D. EMI Ferrite Split Snap-On Core - Allied Electronics

    Tormach sells one here:

    https://www.tormach.com/store/index....show&ref=30749



  7. #19
    Gold Member
    Join Date
    Jun 2006
    Location
    Suffolk, UK
    Posts
    2472
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Quote Originally Posted by MichaelHenry View Post
    Phil - is this problem on your original PCNC 1100? My S/N 119 1100 was giving me intermittent limit switch E-stops which went away when Tormach sent me a ferrite that looks something like this one to install on the parallel port cable.

    Laird Technologies - HFA150068-0A2 - High Freq 275 Ohms @300MHz 0.266In Max I.D. EMI Ferrite Split Snap-On Core - Allied Electronics

    Tormach sells one here:

    https://www.tormach.com/store/index....show&ref=30749
    Hi Michael thanks for the info it is much appreciated. I was starting to wonder about the printer cable. There seems to be a wide range of impedance and frequencies for ferrite cores. Is the Laird one you list the same spec as the one supplied by Tormach.

    Phil

    PS: yes it is on my original PCNC1100 serial number #037. which end of the cable did you install it?



  8. #20
    Registered
    Join Date
    Aug 2016
    Posts
    7
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Quote Originally Posted by philbur View Post
    Is there anyway to determine which axis is the culprit?
    I just went through this same VFD noise problem. To isolate which limit switch that was falesly tripping, I moved all 3 axis well away from the limit switches. Then I went into the Mach3 Config screen and disabled the limit switches one at a time until the problem went away. On my setup, the noise was coming from the Z-axis limit switches. I guess it's expected as they sit close to the spindle. I'm running with an ethernet Smootstepper and to fix the issue, I added some noise filtering to the limits on the ethernet Smoothstepper config screen.

    One other thing I noticed that helped with the noise is adjusting the carrier frequency on the VFD. There seemed to be sweet spots wrt minimizing the noise. I checked it with an oscilloscope and for me, 9KHz was the best.



  9. #21
    Registered
    Join Date
    Aug 2016
    Posts
    7
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    FYI -This is the relay circuit I used to do the voltage conversion on the limit switches:

    How do I electrically disconnect my Z axis limit switches-limitswitchcircuit-jpg

    Using a relay allowed me to use normally closed (NC) switches but still use the normally open (NO) inputs on the BOB.



  10. #22
    Gold Member
    Join Date
    Jun 2006
    Location
    USA
    Posts
    2775
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Quote Originally Posted by philbur View Post
    Hi Michael thanks for the info it is much appreciated. I was starting to wonder about the printer cable. There seems to be a wide range of impedance and frequencies for ferrite cores. Is the Laird one you list the same spec as the one supplied by Tormach.

    Phil

    PS: yes it is on my original PCNC1100 serial number #037. which end of the cable did you install it?
    No, the Laird was just a quick page grab to show the general idea. I don't recall any special instructions, but mine is located a foot away or so from the PC connector. It slides around pretty easily. The only markings I can see are "Fair-Rite V0" and it looks like Figure 2 on this page:

    Round Cable Snap-Its Archives - Fair Rite

    On edit: Mine measures about 1.25" long (C) x 0.42" high (D) which might narrow it down a bit. I didn't measure directly but it looks like the hole diameter is between 0.4 and 0.5 in. The PC cable is about 0.4-in OD and the ferrite slides easily on the cable.

    Last edited by MichaelHenry; 01-10-2017 at 11:01 PM.


  11. #23
    Registered john-100's Avatar
    Join Date
    Mar 2007
    Location
    uk
    Posts
    1365
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Hi Phil

    I'd stick with normally closed switches
    I expect its more likely for a cable to go open circuit than go short circuit

    using an opto-isolator as in post 16 you don't need to change the mach3 config

    have a look at any extra earth wires you have added and check they don't add parallel earth paths to the original wiring
    its possible they have caused ground loops that could of added to your problems

    John

    Last edited by john-100; 01-11-2017 at 04:57 AM.


  12. #24
    Gold Member
    Join Date
    Jun 2006
    Location
    Suffolk, UK
    Posts
    2472
    Downloads
    0
    Uploads
    0

    Default Re: How do I electrically disconnect my Z axis limit switches

    Quote Originally Posted by mill808 View Post
    I Then I went into the Mach3 Config screen and disabled the limit switches one at a time until the problem went away.
    Hi mill808, thanks for the input it is very much appreciated. Unfortunately I need to be spoon fed on these types of issue. Under the Mach3 Config drop down menu there are a number of alternative screens. I assumed you meant the homing/limits screen however I can't see an option to disable the limit switches on this screen. Please could you give me directions to the relevant screen.

    Phil



Page 2 of 4 FirstFirst 1234 LastLast

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

How do I electrically disconnect my Z axis limit switches
How do I electrically disconnect my Z axis limit switches