CamBam or Mach3 Scaling/Shrinking Drawings?!

[catabolic]

I cannot figure out how my drawings are being scaled down before milling. In autodesk/autocad mech. the units are set correctly and they match up in cambam /mach3 as well. But upon cutting on my machine everything is being scaled down by a factor of ~11/32. In other words a drawing that is 8 inches wide in cad/cam comes out 2.75 inches after cutting. I jog the g-code drawing and the machine coord's/units are correct as well in mach3...I see "scale" next to mach3's machine coord's, should this be edited?

Is it because my power settings are set at 1/2 step, 75% current settings? I'm checking units/ and measuring, but am drawing a blank. Hopefully it's something small I've overlooked. Advice? Thanks

[ger21]

Post some sample g code for a simple 6" square.

[catabolic]

I can edit scale on the machine coord's, but want it to show cutting to real time scale. Scaling up would take the machines movements off the boundaries of my table?

[catabolic]

will do, one moment

[catabolic]

( Made using CamBam - CamBam CNC Software )
( samplesquare 7/11/2011 6:51:51 PM )
( T0 : 0.0 )
G20 G90 G64 G40
G0 Z0.0
( T0 : 0.0 )
T0 M6
( Engrave1 )
G17
M3 S1000
G0 X-3.0 Y-3.0
G1 F10.0 Z-0.01
G1 F30.0 X3.0
G1 Y3.0
G1 X-3.0
G1 Y-3.0
G0 Z0.0
M5
M30

[catabolic]

No cutting, just as if the bit was replaced with a pen tip.

[ger21]

Mach3 problem.

What are your Default Units?
If they are inches, then you're steps/unit are probably wrong.

[catabolic]

yeah, my native units are in inches...what is the fix/problem? Thanks

[ger21]

What kind of screws are you using, and what are your steps/unit set to in motor tuning?

[catabolic]

I think I see it now that you mention it... 12 tpi acme screws, 1600 steps 79.98 vel./ 40acc on x axis. I spent so much time trying to decrease stepper noise/running smoothly that I didn't pay attention to scale (as I have fairly small parts that I am trying to mill and engrave). So I'm going to have to go full step power setting and 200 steps/per for tuning and just deal with the noise (I posted about this issue in another forum thread recently)? Or is there a better way that you can suggest...

[ger21]

Should be 4800, not 1600.
12 * 2 * 200 = 4800

[catabolic]

sorry, you're dealing with a new guy here... I did put 4800 at one point, but I guess I got confused with power settings/noise from the stepper. So dialing in 4800 should fix it?