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Author Topic: Motor "Sometimes" goes in Wrong Direction while Tuning  (Read 8816 times)

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Motor "Sometimes" goes in Wrong Direction while Tuning
« on: March 13, 2009, 09:10:34 AM »
Made some serious headway tuning the motors last night. NOW the direction is possessed and none of the 3 ways in the MACH3 Manual seem to fix it. While tuning, the UP ARROW Key should make the motors turn + and the DOWN ARROW Key should move the Motors -.

This is the case only 50% of the time. It is unreliable at best

A sample would be like below:

UP ARROW - Moves the motor +

DOWN ARROW - Moves the Motor -

UP ARROW - Moves the Motor +

DOWN ARROW - CONTINUES TO MOVE THE MOTOR +

They sometimes move in the direction they should, however after 3-4 movements in the correct direction, the motors WILL ALWAYS move in the WRONG direction when the opposite ARROW is prressed.

Any ideas?

Offline Hood

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #1 on: March 13, 2009, 09:24:37 AM »
Sounds like for some reason your direction signal is not getting through. Check the wiring and if that seems fine then maybe change the active state to the opposite of what you have at the moment.
Hood
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #2 on: March 13, 2009, 04:16:06 PM »
I recently resolved a similar problem with my CNC.  I have two motors on my Z axis, and one would quit turning one direction, so that even when I changed directions, one motor would obey, and the other would not.  The result was an instantly racked gantry.  

The problem is slightly different, in that the motor in question is NOT turning in one direction.  In your case its turning in the WRONG direction.  Be sure that is the case.  In my case I had to disengage the motor from its rack gear to clearly see the direction of the pinon gear.  

In my case a motor winding was not getting voltage, which ended up being a bad connection at the Gecko driver for that motor.  When I pushed on the connector I got the motor to work correctly, but only intemittently. I replaced the Gecko and installed new connectors and its been working fine.

But I have to add that I probably BLEW the Gecko by prodding around at the connector when I was troubleshooting.  It sparked once, and then quit working altogether.   I guess that made the repair easier, but more expensive.  

If you are using Geckos, try swapping out both the Gecko and the connectors.  I now keep a spare Gecko driver so I can do this.  

Good luck, and don't get too frustrated.  It'll fix.  

Wayne from White Salmon

Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #3 on: March 17, 2009, 11:44:41 AM »
I have tried the above fixes and no dice this is happening on all 3 axis's the drives were just returned from gecko with a clean bill of health any more thoughts

thanks

Jamie

Offline Tweakie.CNC

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #4 on: March 17, 2009, 12:36:15 PM »
It could be that the direction signals are somehow getting corrupted. You are not using and active BOB (with opto isolators) prior to your Gecko connection are you ?.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #5 on: March 17, 2009, 02:03:24 PM »
i do not know what an active bob is so probably not unless it is built into the software and can be checked as a box

i can take some pics if it would help

thanks for your time

jamie

Offline Tweakie.CNC

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #6 on: March 18, 2009, 03:33:08 AM »
Hi Jamie,

Sorry I just assumed you would know.
A breakout board (BOB) is where the LPT connection from the computer joins with the machine. Some BOB's are 'active' in so far as they incorporate opto isolators and are powered 5 Volts. The Gecko controller already incorporates opto isolators on its inputs and sometimes behaves oddly if active BOB's are used. For Gecko operation a passive BOB is usually used.
Hope this explains what I was getting at and once again sorry for posting a reply that was not fully explained.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #7 on: March 18, 2009, 07:23:09 AM »
Tweakie I appreciate your time and thoughts the BOB I have doesn't seem to be active it looks like a plain circuit board with no electronics on it at all.

any other ideas

thanks

Jamie

Offline Tweakie.CNC

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #8 on: March 18, 2009, 07:34:54 AM »
Hi Jamie,

As Hood said earlier have you tried changing the direction signals from active high to active low (or visa versa) ?. This is under Configuration, Ports & Pins, Motor Outputs.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #9 on: March 18, 2009, 08:04:53 AM »
yes i have tried that with low settings on acceleration and velocity that seems to give the motors the power to get going without it they don't even turn at all

but with higher settings on accelleration and velocity it doesn't seem to make any difference

thanks

Jamie