Problem generating toolpath...please help

[Anonymous]

Hello,

I ve just finished my first design and G code preparation from fushion 360. Everything is really nice, but i have a strange problem after exporting gcode. I am using newest version of Mach3 as a controling program for my 3 axis CNC machine so i selected Mach3Mill.cps - Generic Mach3Mill as post processor. I am quite sure, that my setup and toolpaths are right, i followed a step by step tutorial, also the simulation looks like it should. Also my orientation and stock point is selected in a right way. But after exporting Gcode and importing it in Mach 3, there are some very strange paths inside the file which should not be there. The toolpaths as in simulation are there too, but there is a strange super deep path for Z axis, which goes as a first movement and also some strange X axis path going way far from the workpiece. Because of this i cant even start the job, because i am forced to emergency stop the process because of the strange Z axis movement in the beginning to prevent machine damage. Axis reference points in the mach 3 are set right. Toolpath screen is showing the original path with the strange ones, i f i use some onlin egcode viewer there are none of the strange paths.

Can anybody please help locate the problem? I am quite new to fushion 360 but this is very strange i think this can be caused during the export process, but i am not sure maybe I am just missing something.

Thank you very much for any suggestions i am attaching my Gcode and fushion screenshot for better example. Also i am attaching screenshot of the path from mach3 after import where you can see the strange paths (the red ones going deep) which should not be there please note that the view is rotated.

Ondrej CZ

[HughesTooling]

This looks like the question that comes up every couple of weeks and is down to G28 moves. So does your machine have limit switches and have you homed the machine. The G28 moves take the machine to the home\limit switch and if you don't have them it's going to move to a random place.

Mark

[daniel_lyall]

@Anonymous it's as Mark says it's this part of the code 

G28 G91 Z0.  this is go to machine home 
G28 X0. Y0.   this is go to machine home as well 
M30

if I home at the same places as work 0,0 your pick and what I have on screen is the same.

you need to home the machine first, machine Zero/machine home

then you set the top of the part as work zero.

Mach3 is a dumb system it will do what you make it do, don't use the newest version of Mach3 use the one ending with 62. 

this is a link to the Mach3 manual it has all the info you need in it  http://www.machsupport.com/wp-content/uploads/2013/02/Mach3Mill_Install_Config.pdf

[Anonymous]

Hello,

thank you guys for reply i wasnt aware of what the G28 is, now i know. I found this very usefull topic for everybody with the same problem (link bellow). I have decided to just turn of the G28 in fusion post processing preferences, this solved the problem right away since i dont have mohe swithes on my machine. Anyway thank you very much for guideing me what to look for.

Ondrej CZ