First time poster on this forum.  Apologies if this question has been addressed.  I looked in the FAQ's and poked around a bit.

I'm starting my mill file in Autocad, importing to Lazycam and then opening the g-code in mach 3.

My file in Lazycam looks great.  It looks exactly as I drafted it in CAD.  However, when I open the g-code in Mach 3 I lose a lot of the integrity of the original drawing.  For example, some arcs will become giant circles, or if I have two lines ending close to each other Mach 3 will connect them, much to my dismay.  I've had to do all these work-arounds, actually changing my CAD file through trial and error to get Mach 3 to perform as I originally intended it to with my CAD drawing.

Is there a setting or tolerance I need to adjust in either Lazy cam or mach 3?  Is there a thread about something similar someone can point me to?  I have a pretty good feeling this is all user error, but I'd like to learn how to fix it.

Thank you.

The circles for sure are caused by you having the wrong IJ mode, so either call it at the start of your code (best practice) or change it by going to the Config Menu then General Config.

Dont use LazyCAM I am afraid so cant help with the other problem
Hood

two lines ending close to each other Mach 3 will connect them

Yes there is a tolerance setting that you can set. Tolerance is defined on Page 16 of the Manual which you will find in the Members Docs.
I may add, you do a drawing in CAD ...but....your drawing should reflect how you want to machine the part. All explained in the manual.

Hood answered the other question. Occasionaly you may get an unwanted circle even though Mach's settings are correct, and just delete it.
You should always check  / step thru the gcode before deleting it.

RICH

Mach3 does exactly what the g-code tells it to.

And your CAD drawing should be exactly what you want it to be.

Which points to LazyCAM, or the LazyCAM operator.

You might want to look at a different CAM program. Vectric's Cut2D is probably the easiest to use by a large margin, and s also quite powerful.

It was my tolerance setting in lazy cam.  Set it to .001 and all is well. Thanks for the help.

While I'm here, I've set my motor steps per unit to get a 1:1 ratio on the table. However my x is spot on while my y is off by about a half inch. I cannot figure out why. X and y motors have the same settings an I don't have any scaling applied to the y axis. Any thoughts?

Its out by 1/2 an inch you say but over what distance? Does that increase to 1 inch if you double the distance moved?
Are the microstep settings of the drive the same? Do you have different gearing between motors and screw? Are the screw pitches the same?
Hood