Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: saintr on July 24, 2009, 10:14:02 AM

Title: Coordinates are wrong
Post by: saintr on July 24, 2009, 10:14:02 AM
Hi everyone,

I saw a previous post asking about Mach3 sowing "massively wrong" coordinates but there were no replies that adequately answered the question. I have built a 60" x 48" x 9" CNC router, got through the first two tutorials, set units to inches, entered in all the motor tuning information according to the correct motor-leadscrew ratio (1000 SPI, 126 IPM, 90 accel). When I jog the router I get coordinates appx 6x the amount actually traveled. Please let this newbie know what he's doing wrong.

Much appreciated
Title: Re: Coordinates are wrong
Post by: Hood on July 24, 2009, 10:26:33 AM
What is the pitch of the screws? Do you have any gearing between motors and screws? What type of drives or what is the microstepping of them.
Hood
Title: Re: Coordinates are wrong
Post by: vmax549 on July 24, 2009, 10:28:15 AM
You r math for the SPI is off by 6x. List your setup and we can help do the math.

(;-) TP
Title: Re: Coordinates are wrong
Post by: saintr on July 24, 2009, 10:31:09 AM
Screws are:

3/8-10, 2 start for Y and Z axes
1/2-10, 2 start for X axis

They are all driven by Xylotex 425 oz.in. steppers at 200 SPR with no gearing, they're all 1:1 pulley-belts.

Thanks
Title: Re: Coordinates are wrong
Post by: Hood on July 24, 2009, 10:38:43 AM
Do xylotex have microstepping?
Hood
Title: Re: Coordinates are wrong
Post by: HimyKabibble on July 24, 2009, 10:46:07 AM
Do xylotex have microstepping?
Hood

Yes - 1X, 2X, 4X or 8X, jumper selectable.  If he's really getting the DROs to show 6X the actual travel, I'd guess he has Mach moving in mm, and the Xylotex set for 4X microstepping.  That would give him almost exactly 6X.

Regards,
Ray L.
Title: Re: Coordinates are wrong
Post by: saintr on July 24, 2009, 10:49:18 AM
I haven't set it to any microstepping. I will check with Xylotex on that. As far as setting it to mm, I have set the default units to inches nearly a dozen times now.

Thanks
Title: Re: Coordinates are wrong
Post by: ger21 on July 24, 2009, 11:26:07 AM
It's 1/8 by default, so 1600 steps/rev, x 5 turns per inch. Should be 8000 steps/inch.