Lost or Extra Steps!

Just one of the many tortures waiting for you in CNC Hell!
 
 (The following info comes from my personal experiences while working with other people caught in CNC Hell! )

 

1.Make sure you run your DOS program in DOS!  It will jog the motors in a DOS window under Windows 95-98 but you will get lost steps.  Have Windows reboot in MSDOS mode.  It is there on your shut down screen.

2. Losing steps with homemade controller.  Did you add a .01uf cap across the 7474s or other chips used to count the steps. These are called deglitch cap. Most FREE Internet circuits don't show these!  Don't add one big cap across the 5 volt line. You need a cap across each IC chip. Between the Plus five and Ground pins.

3. Motors jump back and forth during jogging. Slow them down, if they still jump back and forth your phases are wired wrong.  This happens with 6 wire motors alot. They may also seem to run smoother in one direction  than the other.

4. Running the motors fast with nothing hooked to them, they pop and lose steps.  Slow them down! "Motor Spinner" and put a load on them. You know a load! Like hooking them into a real machine!

5. When hooked into the machine, you hear them lose steps while jogging back and forth. Slow down the jog rate. Go into the program and adjust the Ramp-up and Ramp-down. Some software calls this acceleration-deacceleration. Make sure the machine is not binding!

6. Motors jog fine but when a GCode is run the motors loses steps.  In the GCode add a F6 to some of the lines and try again.  Without putting a F6 (feedrate of 6 inches per minute) the machine will defalt to its fastest speed set in the software.  Sometimes it just goes flatout leaving the motors twitching. (F7 is seven inches)  (F8 is eight inches) etc.

7. Here is my favorite!  You make lots of GCodes with a text editor. Everything is fine for months.   Then you start using a CAD program and the GCodes made from your DXF files go crazy. Using your text editor add some F6 commands and look for  G00  commands.  When you convert a DXF file using ACE or other converters.  The G00 commands are added between cuts. The files you made using a text editor only had G01 G02 and maybe a few others commands. When you convert a DXF to GCode G00 commands show up. These are rapid movents.  You can convert these to G01 or  you will have to slow down the maximum speed of your machine VIA the software. G00 is the fastest speed your machine can travel at without losing steps. Make sure you keep your machine lightly oiled. Intermittent binding happens at faster speed.

8. The polarity of your step signal. What the HELL is that? The DOORBELL on you house is off right now, RIGHT?  When someone presses the button it rings, RIGHT!  What if you wired it so it rang all the time and when someone pressed it, it went OFF!  The polarity of the step signal is the same way. Some controllers need the signal to sit a five volts.(HIGH)  Each step of the motor is caused by the signal going to ground. (LOW)  If you have your polarity backwards all kinds of nasty things happen. Yes! your motors will jog. But when you run certain GCodes problems show up. You don't want a step signal to come while the motor is changing direction or you will lose a step. Make sure you have your polarity set right.  My PIKER likes a Step signal that sits low and goes high for each step.

9. Lets talk extra steps! During the time a step signal goes from High to Low or Low to High a noise spike can get in and cause an extra step. Running a Dremel tool on the same line as the controller can cause this. Arc welders cause all kinds of problems around controllers.  Plasma controllers are a nightmare!  Try putting the controller on a different leg of your electric system. A UPS unit will sometimes fix things.

10. Compatibility problems.  All simple hobby controllers work with CNCPro-KCam-TurboCNC and DeskNC. You just need to make some adjustments.  The top end software and controllers are a different story. I won't name names but if you are having a problem, good luck!  Try a second computer. If that fails, ask the controller guy which software to use. Also ask the software guy which controller to use.  Talk to people who got the two systems working together. Now that you have spent over $1000 I hope you get it working!
 

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