Page 2 of 2 FirstFirst 12
  1. #11
    In your original pic of the cut parts the notch where the depth changes is a classic sign of machine flexure. I had the same thing with my machine till I beefed it up. If I were a betting man, I'd say your gantry sides are flexing and also the z axis is either flexing itself or flexing where its attached. I suggest that you examine each park in turn while cutting and identify the problem. As JAZZ mentioned, check the couplings too.

  2. #12
    Quote Originally Posted by JAZZCNC View Post
    This won't be copied software or Mach3 fault. It will be one of 5 things.
    #1 Mechanical issue so slipping coupler or something.
    #2 Electrical noise from spindle affecting signals.
    #3 Incorrect setup of Steps per milimeter
    #4 Pulse signal is set wrong in drive so changing on wrong side so losing 1 step on every directiuon change.
    #5 Low power parallel port voltage so not enough voltage differential between high and low signal causing lost steps.

    My suggestion is first check all mechanical connections and wire connections. Then identify if noise by running G-code in air without spindle running. Measure starting height and check when finished.
    If ok then check the Active edge set in the drive.
    I have already check all the couplings, they seem to be good. How do i check if pulse signal is set wrong in drive? Yes there is some noise while running in air, some strange noise like clicking. Starting point is not the same, its like 3-4 mm deeper when the program finished. What does active edge means, what is it used for?
    Thanks for your help.

  3. #13
    Quote Originally Posted by masinecc View Post
    How do i check if pulse signal is set wrong in drive?
    Depending on your drive it will have either a switch to change the Active edge or software setting. If not then it will be fixed and the documentation should state the rising or falling edge.

    Quote Originally Posted by masinecc View Post
    Yes there is some noise while running in air, some strange noise like clicking. Starting point is not the same, its like 3-4 mm deeper when the program finished.
    I don't mean noise has in sound.! . . . I mean Electrical interference noise EMF from other components around like Spindles etc. Looking at the condition of your wiring with motor wires unshielded and probably poorly grounded control box then it's a Huge chance this is your problem.!

    Quote Originally Posted by masinecc View Post
    What does active edge means, what is it used for?
    This means the point when the drive issues the Step signal. It can be the rising or the falling edge of the signal Pulse. (also some controllers look for the Step on certain edge.)
    If your drive issues the Step pulse on the falling edge of the pulse and your controller is expecting seeing it on the rising edge you'll have timing issues. Often when active edge is wrong you'll loose 1 step or micro step for every direction change.

    One common mistake made is that people will wire the motor phases wrong. ie: Put A+ to A- on the drive connection. Then when the motor spins in wrong direction they just change the Active hi-low state in Mach motor outputs and it spins in correct direction.!! . . . BUT this now means the control (mach3) is looking for the Step pulse on a different edge and if this edge is the opposite edge to drive then you could have timing issues resulting in loosing position.
    The correct way to change an axis direction if needed is using the Reverse option in Home and Limits.

    If you wire the motor phases correctly to the drive. ie: A+ on motor to A+ on drive then 99% of time the motors will spin in correct direction and will match the Active edge set in the drive. This is often the rising edge but some drives like the Geckos do use the falling edge in which case if the motor phases are set correct then you would set the Active step edge in motor tuning to match. ie Step low active ticked.

    Another common cause of positional lose with parallel port revolves around timing issues and the Kernal speed set in Mach3.?
    The pulses created only have a certain time interval between changing state and the higher you have the Kernal speed the shorter interval. So if you set the Kernal speed high you shorten this time interval so combined with high motor tunign it's very easy to lose Steps. This is why it's recommended with parallel port to keep Kernal speed set at 25Khz for most stable performance. Every change up in Kernal speed increases chance of unstable system.

Page 2 of 2 FirstFirst 12

Similar Threads

  1. 1mm position accuracy for timing belt
    By motomage in forum Belt Drive, Pulleys & Timing
    Replies: 3
    Last Post: 01-02-2015, 01:46 PM
  2. Tool diameter accuracy
    By Neale in forum Tool & Tooling Technology
    Replies: 15
    Last Post: 05-03-2014, 11:18 PM
  3. Accuracy Problem
    By richie00boy in forum Machine Discussion
    Replies: 12
    Last Post: 09-09-2013, 11:24 AM
  4. Machine bed accuracy
    By Colin Barron in forum Gantry/Router Machines & Building
    Replies: 1
    Last Post: 03-11-2010, 11:24 AM
  5. Ball Screw Accuracy V Price
    By Wobblybootie in forum Lead Screws, Nuts & Supports
    Replies: 5
    Last Post: 02-01-2010, 11:55 AM

Bookmarks

Posting Permissions

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