Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: velcomrob on July 20, 2009, 09:52:22 PM

Title: weird problem
Post by: velcomrob on July 20, 2009, 09:52:22 PM

I am a newibe to CNCing and having some problem I can't seem to figure out after reaching mach3 documentation a couple times.

I have a part drawn out in Solidworks and GCode generated with Solidcam.

The size being cut via mach3 isn't the same size as what's been sketched in Solidworks.

For example one line would be 2.28" and when cut it would only cut 1.5" (estimated, I didn't do a precise measurement because it was way off).

Im using a Sherline 2000 Mill with stepper motors and have the Sherline profile (Inch) loaded into Mach3. 

Title: Re: weird problem
Post by: Hood on July 21, 2009, 01:35:47 AM

Check to see if the scaling at the side of the DROs are all set to 1.
Hood

Title: Re: weird problem
Post by: velcomrob on July 21, 2009, 02:01:18 AM

Hello

All scales are already set to 1

Same prob

Title: Re: weird problem
Post by: Hood on July 21, 2009, 02:46:26 AM

Ok so if you zero and axis then go to MDI and command a G0X1 does the X axis move 1 inch?
 If it does then it would seem your code may be the problem, if it doesnt then looks like your steps per unit may be the issue.
Hood

Title: Re: weird problem
Post by: velcomrob on July 21, 2009, 11:55:17 PM

do you mean move 1 inch including the diameter of the tool?

Im using a .125 end mill and the bit moves to 0.75 of an inch

so im assuming if you add 2 offsets since i started at 0.125   Does the offset start at the right of the tool or left?   Im moving right on the X Axis for the test.

All DRO's say 0 so in essence if I moved to 1 inch and I measured the distance with a square, would the tool need to be at 1.125 ?  when im measuring the distance im measure from the starting point on left side of the tool to the left side again of the tool at the end.  is that correct?

maybe its my gcode or setup.  thats what im trying to figure out.  

Title: Re: weird problem
Post by: HimyKabibble on July 22, 2009, 12:05:14 AM

If you command a 1" move, it should move 1".  Zero the DROs, and type "G0 X1 Y1" into the MDI line.  The X axis should move 1" to the right, the Y axis should move 1" to the rear.  If they don't, you need to change your steps/inch settings.

Regards,
Ray L.

Title: Re: weird problem
Post by: velcomrob on July 22, 2009, 12:45:40 AM

So I should be measuring to the right of the tool ? and that should be 1" ?

For example:

*---------------------------*
^                           ^
Start Point               End. 

I would measure tothe right of * and it should be 1" and then for Y axis I would measure to the rear of the tool to get 1" on Y Axis.  is that correct?

Title: Re: weird problem
Post by: Chip on July 22, 2009, 01:48:23 AM

Hi, Velcomrob

       *---------------------------*
 |**^**|                       |**^**| ,"Tool Center" 1\2 tool dia. or leading edge to leading edge, or trail edge to trail edge
Start Point                           End.  

Chip

Title: Re: weird problem
Post by: velcomrob on July 22, 2009, 01:53:58 AM

Ah ok.  then I am off.

My step per is correct.    I did calculations based on TPI and it seems to be correct.  do I need to play with velocity and acceleratio to get correct measurements?

I was playing with the step per to see what would happen.  Is it fairly easy to damage these motors?   I bumped my steps per to 32000 and wondering if that would cause damage?  My normal setting is 16000 which is already available in the sherline profile and based on calculations I came to same number. 



thanks.

Title: Re: weird problem
Post by: Chip on July 22, 2009, 02:09:10 AM

Hi, Velcomrob

You can't really damage any thing, Steps Pre is the only way to calibrate your machine's accuracy.

Chip

Title: Re: weird problem
Post by: velcomrob on July 22, 2009, 09:00:25 AM

Ok.

Much appreciated ill try messing with steps per