Hello Guest it is October 14, 2019, 12:21:06 PM

Author Topic: Alright fellow campers...a frankenstein moment!!  (Read 6439 times)

0 Members and 1 Guest are viewing this topic.

Re: Alright fellow campers...a frankenstein moment!!
« Reply #10 on: November 14, 2017, 03:16:28 AM »
As I mentioned earlier, that the 4th axis lathe which is controlled by mach 3, comes on when the spindle spins up even though the spindle is independent of mach 3 and is manually turned on when it is being used.  
 
Now I tried an experiment earlier.  I disconnected the power cable from the inverter to the spindle at the spindle end of the cable... then turned on inverter... the lathe still would come on!
If I reconnnected the cable to the spindle end and disconnected it from the inverter end, and turned the inverter on—then the 4th axis lathe (a-axis) does not come on.  So I figured it had to be the cable itself as it was not shielded and so I felt that was the problem.  So I bought a shielded cable and put that on... that worked for an hour and then the problem re-occurred.  So this time I did the same procedure of disconnecting the cable at one end and then the other... and the 4th axis lathe did not spin up either way... so that’s an improvement... but if I connect the spindle, and turn the spindle on, the the lathe activates and starts grinding along.  Does this trigger any thoughts about what might actually be happening?
Re: Alright fellow campers...a frankenstein moment!!
« Reply #11 on: November 14, 2017, 03:24:41 AM »
Hi,
there are a number of mechanisms that will allow electromagnetic noise in one circuit interfere with another. The radiated 'transmitter/receiver'
idea is reasonably well understood. Another is conducted noise.

If you have a VFD plugged into a 230V socket and have another power supply also plugged into that same socket the noise 'referred to the input' of one
device can propagate to the output of another device.

As an experiment supply your VFD from a remote socket with an extension lead. Does it make any difference?

Craig
My wife left with my best friend...
     and I miss him!

Offline Chaoticone

*
  • *
  •  5,604 5,604
  • Precision Chaos
    • View Profile
Re: Alright fellow campers...a frankenstein moment!!
« Reply #12 on: November 14, 2017, 06:30:29 AM »
This triggers lots of thoughts in my mind but none that have not been covered by previous replies or links in those replies. You're just gonna have to dig into it (following the previous replies) and experiment until you can remove and repeat the problem at will. When you can do that you can be pretty confident you know what to do to eliminate at least one of the problems (you may have several).

Separate wires (put some distance between them), change ends the shields are grounded on, float or bond commons, etc.

The best tools to use to fight noise issues are detailed wiring schematics and component layout drawings. Those 2 are the first steps in mitigating noise issues. Assuming they match the machine exactly you can use them to check for ground loops, star ground, proximity of components, etc. Without those the best anyone can do is make educated guesses. That route usually ends being way too much wasted effort and time to guess down problems that should have never existed in the first place. Not a game most will take time to play.
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Tweakie.CNC

*
  • *
  •  7,945 7,945
  • Super Kitty
    • View Profile
    • Tweakie.CNC
Re: Alright fellow campers...a frankenstein moment!!
« Reply #13 on: November 14, 2017, 06:54:47 AM »
Hi Halfmill,

It’s an illusive problem and no one solution cures all. When I fitted my VFD the manufacturer’s instructions regarding grounding were well over the top of what was actually required but the fitting of an RFI mains filter and shielded cable between the VFD and spindle also VFD and controller (shields only grounded at one single point and at one end only) was essential.
A couple of years back I did a basic wiring tutorial (for beginners) and this may be what Chaoticone was referring to (a couple of posts back). If it’s of any assistance it is here: https://openbuilds.com/threads/electronics-101.693/

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Alright fellow campers...a frankenstein moment!!
« Reply #14 on: November 14, 2017, 11:25:43 AM »
Hey Guys,  thank you again for the suggestion above... I will slowly work through this.

bob

Offline Chaoticone

*
  • *
  •  5,604 5,604
  • Precision Chaos
    • View Profile
Re: Alright fellow campers...a frankenstein moment!!
« Reply #15 on: November 14, 2017, 11:44:43 AM »
One thought I had is "How close is the drive that is picking up noise to the other drives? Are the step and direction durations set the same for all the motors in motor tuning".........
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Alright fellow campers...a frankenstein moment!!
« Reply #16 on: November 14, 2017, 12:28:35 PM »
Chaoticone Hi,

The stepper driver is right next to all the other drivers.  See attached photo.  There is three feet distance from the inverter to the box that houses the stepper drivers and power supplies.  But usually its five feet as its stored under the work table.

I will go into mach 3 and check your other suggestions...

bob

Re: Alright fellow campers...a frankenstein moment!!
« Reply #17 on: November 14, 2017, 01:09:40 PM »
One thing to consider is fitting some resistors across the input pins of the drive board if this isn't already done. This will drop the input impedance of the board and help dissipate any spurious signals while allowing the more powerful signals from the PC to get through uninterrupted. The resistor value depends how much current you can get through from the paralell port or controller board. Equally you can fit pullup resistors to pins that are grounded to activate, reducing their susceptibility to spikes and noise and of course coolant leakage. Gotta keep them angry pixies in check.  

Edit: If all this is in a wooden box you may want to consider a metal one, this will help a lot.

Be scrupulous when grounding things, bring everything back to a single point, no loops.
« Last Edit: November 14, 2017, 01:12:05 PM by BluePinnacle »

Offline RICH

*
  • *
  •  7,367 7,367
    • View Profile
Re: Alright fellow campers...a frankenstein moment!!
« Reply #18 on: November 14, 2017, 01:20:02 PM »
You just received a PM from me.

RICH

Offline Tweakie.CNC

*
  • *
  •  7,945 7,945
  • Super Kitty
    • View Profile
    • Tweakie.CNC
Re: Alright fellow campers...a frankenstein moment!!
« Reply #19 on: November 15, 2017, 02:45:31 AM »
Just a suggestion...

I think you need to sort out some of your wiring - each drives supply (+ & -) should be wired directly back to the PSU and not a star and daisy chain as you have at present.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.