Hello CNC Snapmakers , Can I ask some advise 
I have some problems with the accuracy / precision from Fusion 360 post processs to Snapmaker. I,m trying to rework some existing aluminium project were I want to cut out the outher sides , as shown in the pictures. I made a drawing in fusion and setup the carving specs and selected the snapmaker artisan tool. When running the simulation it seems working as planned. However when post processed / uploaded the file to snapmaker It does not follow the exact line from the centerpoint ( have aligned the aluminium rework exactly and select the centerpoint exactly)., it does follow the programmed line but not exaclty from the middle point I have selected , I have try’d to select other starting points but every time it seems to go inside the work tomuch and the other side go off to much the aluminium rework. Can there be something wrong with configuration between snapmaker and fusion 360 post process ??. Probably when I go few mm offset from the centerpoint I,m getting close but then it,s never precise. Search for days but can’t understand why this go wrong ! I have selected the post processing snapmaker.cnc
It’s a bit difficult to diagnose without more information and how exactly you are setting up the tool on the ali part.
That said, from your second photo, it looks like the centre of a circle is not on the axis 0,0
It also appears from your first photo that you are using the lines on the bed to set it up, that can’t be a good thing?
I have selected the centerpoint, however on the picture it looks slightly offset I have checked this several times , yes on the first picture i have used the lines to center but measured with a caliber so can’t be far off. when running the snapmaker miling just above the part it,s atleast more then 3-5 mm off compared left to right 
The only way to be sure is to set up with tool contact to the part.
But, with your current set up, if still locked in place, you can check the periphery is the same in -X,+X,-Y,+Y.
Got to 0,0. Move the tool in X or Y only, to outside the part, lower in Z, bring back to contact tool with the part using calibration card or paper. Note X or Y offset. Repeat 3 more times and compare.
If that’s all OK I would check your rails.
Thanks Boxkite !!
I have changed the setup and moved the tool against the part with the calibration card , but possible the entry point is not correct. Need to find out how to change this ? .
One more question, I believe I found the problem, when I tough the outside of the part and then bring ~ 1,6 mm in ( diameter mill 3,175 mm ) then it follows the correct path. In the program it doesn’t say that I need to add the radius of the milling tool. Can I add this somewhere in the config 2D contour ??
It already knows the tool radius if you chose it for the setup of the toolpath.
I,m struggeling to find the correct setting, when selecting the correct tool " snapmaker 3.175mm " and rpm speed 12000 it start at 18000 and still the tool will off half of the tool diameter from my part. Can there be something wrong in the config ?
This process will only tell you if your ali part is centred on your WORK coordinates. If you have any differences between your -/+ X or Y when you do this, your ali part is not centred. If not, you will then have to repeat it from one side of the X or Y by touching with paper again, then ‘Set X origin’ to zero (or Y, which ever you are doing) and then move the head (after raising in Z!) a total of tool-radius+part radius+paper-thickness towards the centre. When you get there you will need to ‘Set X origin’ to zero (or Y, which ever you are doing) again. Do the other axis too if necessary. Then check again as in the post above. Tedious I know!
(Note: I am fairly new to CNC and Fusion 360, but have 35 years of CAD.)