Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: moxy on October 09, 2012, 06:41:38 PM

Title: mpg
Post by: moxy on October 09, 2012, 06:41:38 PM

Hi AllI am using a 1000 line encoder in a home built MPG which works fine except.......when I stop moving the handwheel the axis starts tiny jog movements back and forth ans you can hear the stepper "singing to itself" I have tried 2 other encoders with the same result. Anyone have suggestions to fix?
Many thanks
Moxy

Title: Re: mpg
Post by: Hood on October 10, 2012, 02:54:00 AM

Sounds like the issue is the encoder is stopping on a state change of the pulse and  jumping back and forth between states. MPG's usually have indents which hold the  wheel in a fixed position when stationary and that position will be away from a state change of the pulse.
Hood

Title: Re: mpg
Post by: moxy on October 10, 2012, 10:49:40 AM

Hi Hood, Thats what I thought too so I tried a different mpg and got the same result. I'm using and old stepper with an encoder on it and the only detent I have is the normal magnetic one  of the motor. Many thanks
Les

Title: Re: mpg
Post by: Hood on October 10, 2012, 01:12:11 PM

Problem with the stepper may be it has 200 indents per rev the encoder is 100 pulse per rev. So if you line up the encoder so its half way on a pulse with an indent then the next indent will make it on the edge of a pulse.
Hood

Title: Re: mpg
Post by: moxy on October 10, 2012, 04:21:02 PM

I think you are right so I'll see if I can move the glass scale a bit and see if that helps.
Les

Title: Re: mpg
Post by: moxy on October 11, 2012, 01:42:13 PM

I finally found the cause.........I had connected the mpg to the controller 5v instgead of the usb 5v. Swapped irt around and it's working sweetly.
Les

Title: Re: mpg
Post by: Hood on October 11, 2012, 04:39:37 PM

Good to hear :)
Hood