Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Joshblaze6 on April 01, 2013, 09:02:58 PM

Title: Part diameter shrinking .003 every part
Post by: Joshblaze6 on April 01, 2013, 09:02:58 PM

I am running a Sherline 4000 lathe using mach3 for controls. I have a 200 step motor i think...400 step with Sherline 1/2 stepping?
I have my Z axis steps set at 16000 and my X axis set at 8000. My Z axis has no problem holding its position but every part i run my O.D. shrinks by .003. I have tried calling Sherline support but since I'm controlling it with mach3 they said they cant help me. i have my accel and velocity both set around 17 in motor tuning. I have tried 1-5 on step pulse and dir pulse with no luck.
Any help would be much appreciated!
Thanks, Josh

Title: Re: Part diameter shrinking .003 every part
Post by: Joshblaze6 on April 02, 2013, 01:06:41 PM

    Is my stepper motor skipping steps? Would skipping steps make the diameter get smaller every cut?

Title: Re: Part diameter shrinking .003 every part
Post by: BR549 on April 02, 2013, 01:11:34 PM

Could BE , Try reducing the accel values by 1/2 and retest.

Just a thought, (;-) TP

Title: Re: Part diameter shrinking .003 every part
Post by: Hood on April 02, 2013, 01:33:28 PM

Few other things you can try if reducing the accel doesnt help.
Enable Sherline mode
Change the active state of the Step pulse for the X axis.
Hood

Title: Re: Part diameter shrinking .003 every part
Post by: Joshblaze6 on April 02, 2013, 01:49:21 PM

How do i go about changing the active state of the step pulse? And what should i change it to? I do have the sherline mode checked.
Thanks

Title: Re: Part diameter shrinking .003 every part
Post by: Hood on April 02, 2013, 01:57:49 PM

Config menu, Ports and Pins, Motor Outputs.
You can only select it to be active low or not active low (ie active High)
Hood

Title: Re: Part diameter shrinking .003 every part
Post by: RICH on April 02, 2013, 04:59:49 PM

How much backlash does the X axis have?

RICH

Title: Re: Part diameter shrinking .003 every part
Post by: Joshblaze6 on April 02, 2013, 05:27:17 PM

   Not sure which one worked since I changed both the velocity and the state of the step pulse at the same time, but thanks to both of you for your help! It is now running perfectly consistant with no fluctuations at all!! I get to sleep tonight...finally