Unexpected gcode output

[drksky1056]

I'm new to Fusion and CNC in general.  I'm trying to do a simple drilling toolpath on just a rectangular piece of stock.

I start a sketch and draw a 2-point rectangle with the origin at the bottom left, then extrude that rectangle up in Z to represent the stock piece.  Then I select the top face and start a new sketch there to lay out points where I want the holes drilled.  First weird thing is that when I enter that second sketch, the coordinates for x and y are not negative.

I create a drill path using the points on the top surface then output gcode using the grbl post processor...but all my x and y moves are negative moves.  So if I set my machine to its home at the lower left, the gcode immediately sends it to the limit switches at the lower left.  I'm driving myself nuts trying to figure out why this is happening and just can't find the problem.  Yes.  It's entirely possible I have something set in Fusion wrong, but I can't find what that might be.  Any help??

[jhackney1972]

You need to attach your model.  It is probable you have your Manufacturing Origin in any upside down position but we cannot tell since we do not have your model to see your setup.  If you do not know how to attach your model, open it in Fusion360, select the File menu and then choose Export and save the .F3D file to your hard drive. Then use the Attachments section of a reply forum post to attach it.

[drksky1056]

I've attached a simple example of what I'm trying to do, the project file as well as the output gcode from the grpl post processor.  Thanks

[engineguy · Accepted solution]

@drksky1056 

You have your Design Origin set to bottom left corner and yout Manufacture Origin to the middle of your stock, they must both be the same for it to work correctly in your example. A tip, always use the Top of your stock in the lower left corner for your Origin because that is likely where you will be "touching off" (Probing) for your Part Zero at the Machine. What you do at the machine should be matched in Fusion.

If you use the Lower Left corner as your Origin then Coordinates will be as follows :-

Go Right and Up = +X and +Y

Go Right and Down = +X and -Y

Go Left and Up = -X and +Y

Go Left and Down = -X and -Y

So in your example all the Hole coordinates will be positive if you have set the Origin correctly in your Manufacturing Setup to the Lower Left corner.

As they are with the Origin in the middle of the stock then you have the holes in the Lower Left quadrant so they will be Minus in both the X and Y.

With Negative values then your CNC will try to move to the minus positions, that is the issue there.

Unless you have set your Stock to that physical position on your CNC then you will need to input the G54 values of your Part Zero into your grbl control, as you can see from the code the first holes position in the X5 Y5mm so if you have placed your stock say in the middle of your CNC table the the G54 will need to be the actual position of the stock relative to the Machine Zero. I assume that you already know how to do that so not going to go through that here 🙂 🙂 🙂

File attached.

Stay Safe

Regards

Rob

[drksky1056]

Thanks.  That helps a lot.  Truthfully, I didn't even notice that the origin had moved in the manufacturing tab.