Fusion 360: Rest Machining Between Setups

If you consistently read my blog, it doesn't take long to notice that there is a large cross-section of material covered.  That is influenced by my job, but it is also related to my drive to constantly learn new skills.  Similarly, Autodesk keeps expanding its offering, and one of their current areas of development is CAM.  Consequently, I have been spending some of my time picking up some CAM skills.  Recently, I was talking to one of our customers that does CNC machining.  He had an interesting question that lead me to a really cool workflow that I thought was worth sharing.

The Scenario:
The customer had a part that required machining on more than one side.  Also, he preferred to include the vise in the model to make sure he didn't have any issues with the tool contacting his workholding.  He wasn't exactly sure how to approach the multiple setups, but his biggest question was how could he get the stock for the Setup 2 to be the shape that was left after the operations of Setup 1.

The Answer:
I knew Fusion 360 was capable of all of this, but it had been a long time since I had worked with Fusion 360's ability to export a setup's remaining stock.  Also, Fusion 360 had changed so much since the last time I had done it and I wasn't confident that it worked the same way, as the last time I used it.  So I had to do a little bit of research to refresh my memory. 

During my research, I found two important pieces of information.  First, a reminder for where the command was to export stock from a setup.  Secondly, there was a feature preview that allows a user to use the previous setup's remaining stock as the stock for a setup.  However, I tried this a few times and I was never able to get it to work.  It is only a preview feature and that typically means that Autodesk is not quite done with it.  So I wasn't too disappointed.

The first part of what this user was trying to do was easy.  Fusion 360 allows for multiple setups with different coordinate systems, fixture identification, and stock definitions.  The coordinate system is the critical part because the tool for milling operations always comes from the Z-axis.

The vise portion of the workflow isn't difficult either, it is possible to have multiple instances of the same vise in the model.  Then it is just a matter of using the necessary Joint definition to orient each vise appropriately.  Then the user can toggle the visibility of the vises as needed.  

When it comes to the initial CAM setup, if you are going to place and constrain your part in a  workholding, you will also need to model the stock for Setup 1 as a body or component.  This is because you will need selectable geometry for the Joint between the stock and vise.  The stock generated by the software for the setup will only be seen while you are in the Manufacture workspace, where you will be unable to make the joint.  I will admit it is possible to create offsets in the joint to get the jaws to the necessary positions.  However, that creates a disconnect between the defined stock and the jaw placements.

Setup 1

Setup 2

The process of getting the result of one setup to be the stock for another setup is not that complicated.  However, if you plan on including your workholding, there are some intricacies that you will need to account for.  The process of exporting the solid is just a matter of simulating the setup, then playing the complete simulation or jumping to the end.  Then the command to save the stock is in the right-click menu.

The remaining stock will be saved as an STL file on your local machine.  At this point, it could be brought back into the same design file.  The one exception to this is if you want to place it in a vise.  This is because the STL is a mesh file and in my testing, I was unable to select the mesh faces and edges while defining the joint to place the stock in the vise.  

It is possible to convert the mesh into a solid, but that is best done in a separate file.  For the Mesh to Brep command to be available, you have to disable the setting for Capture Design History.  So my process in this case is:

1. Start a new design file
2. Insert mesh file, scaling if necessary
3. Disable setting for Capture Design History
4. Use Mesh to BRep to convert the mesh to a solid model
5. Save the design
6. Return to original design
7. Place and ground the stock for the next setup

Because the origin of the original design and the imported mesh are the same, it worked out that the new stock landed on the original model.  This may not be the case for you so you might want to check this and move bodies as needed.

The last step in the process above is to ground the stock.  The reason for that is when you create the joints to hold the stock in the vise, the stock is likely to move away from the original design.  This is not ideal and the easiest fix is to just ground the newly imported stock.

At this point, the new stock should be located over the original model, and you may or may not have it placed in a vise.  Now you can return to the Manufacture workspace and begin creating your new setup.  This time, when picking stock, you will use the From Solid option and pick the imported stock model.  I like to do this by picking it from the browser, that way I don't get the wrong body, especially because the model and the stock are overlapping.  

Then you should return to the Setup tab to define a coordinate system that matches the part origin and orientation for this setup.

I do want to remind you that this is an export and import process.  So if the operations in Setup 1 change enough that the remaining stock will change, you will need to perform the export and import processes again.

Here is a YouTube video that demonstrates the process.

I don't CNC program for a living, but I feel pretty confident that this would be my process if I did.  I think this process gives you a truer representation of what is happening and will likely lead to more efficient programs.