Aluminum Machining Tutorial
Using CAM Tools
In order to machine parts first you must design your tool path using CAM (Computer Aided Manufacturing) Tools. In this tutorial we will show how to create toolpaths in Autodesk Fusion and export the Gcode for milling.
1. First, go to the file icon at the top menu and select 'New Design from File'. You must select a .stp format file. Once the file is selected on the left of the ribbon a tab should say 'sculpt'. Click the tab and scroll down to select 'CAM'. Just to the right of CAM is the 'setup' option. Click setup and a box should appear that says 'model orientation':
2. Click model orientation and select the axis you wish to adjust. Set the stock material within the file to match the way the stock will be placed on your milling machine. Then go to origin and choose selected point. This allows you to select a universal origin for your part. All tools and toolpaths will reference this origin.
3. Next, go select the drilling option. Drilling must always be performed first. Once the menu appears, near Tool click 'select' and choose the proper drill size. All parts for the ASL-Robot use three hole sizes, 2mm, 2.5mm, and 4mm diameter holes.
4. Once the tool has been selected click the geometry tab in the drilling menu and set the tool orientation to match that of your milling machine. Next click the 'heights' tab to the right of the geometry box and go to 'bottom height'. You will see small check box for 'drill through bottom'. Select the check box and the distance you wish to pierce through your material. This ensures that the drill goes all the way through your material. Then, BEFORE you close the drilling menu, make sure all boxes are unchecked and click the holes you wish to drill on your design. It will create a drilling path as shown below:
5. Once you've selected all the holes you wish to drill click 'okay' and close the drill menu box. At the top where you selected drilling you can see an 'action' panel with three options. The left most option is the simulation. Simply click the simulation option and the play button at the bottom of the screen to see a simulation of the drilling operation. You should always simulate first to make sure the operation is as desired. Once you have confirmed the operation is as desired click the 'post process' option to the right of the simulation option. This will export the operation as a gcode file. NOTE: Make sure to choose the proper file extension for your milling machine. In our case we use generic linux (.ngc). Once the file is exported it can used on a milling machine.
6. For our parts there are two other required operations, boring and milling. Both operations use a mill. Clear the drilling operation from the file by deleting it under the setup folder. Then at the top there is a tab for '2D', from here you can now select a boring or milling operation. The milling operation we use is 2D Contour:
7. Both operations use the same tool, a milling bit. For our parts we used a 1/4 inch bit. Once the tool orientation has been set under the geometry tab, the tool path can be selected. For the Bore path simply choose a large hole you wish to bore out. For the 2D Contour CAREFULLY choose the perimeter you want to mill around. Make sure you are reaching to the bottom of your stock material if you wish to remove the piece completely. Below are examples of the Bore (top) and 2D Contour (bottom) Tool Paths:
8. Make sure to export each operation as a single gcode file. Once you have all three of your gcode files you are ready to begin milling.
Using Linux CNC
1. After starting Linux CNC, select file, open and choose the gcode file you wish to use. You should ALWAYS start with the drilling file first. Then the bore file, then the mill file. Note the edit option in this same location:
2. Once the file is open, you may see a yellow streak on the screen. This is the previous tool path. If you move the tool while linux CNC is on it will create a path that follows the tool. To clear the path click the brush icon at the top right.
3. We now move our actual CNC drill/mill to the point of origin on our stock material. Make sure that this is exactly where you want to start the operation based off the CAM file made in Autodesk Fusion. When running the gcode it will complete the operation assuming this as the point of origin. Once your drill/mill is placed properly once more clear the yellow path in Linux CNC.
4. Once your piece is centered, we must now home the location. Click the 'touch off' button to set the current location to 0. The once it's zero'd click the 'home axis' button to home the point. You may have to do this multiple times to 0 the axis. This must be done for all 3 axis, x, y, and z.
5. Once all axis are zero'd check your gcode to make sure its as desired. Sometimes your gcode requires manual edits. In our case, the Z0 in the image shown below needs to be Z12. That parameter controls how far the tool is raised before moving when not performing an operation. With it set to 0 the tool will scrape across the metal as it moves. To manually edit gcode select the 'edit' option from the file tab on the top as described in step 1. This will bring a popup text box where you can edit your gcode. Once edit make sure to save the file and refresh the linux cnc page. If successful the change in the gcode should appear in the bottom code on the linux cnc page.
7. Finally, turn OFF the milling machine and run your simulation by clicking the blue arrow as shown below. Make sure your simulation runs as desired on Linux CNC before running the actual machine. Once everything checks out you can begin milling the part.
Using the Mill
When using the mill follow the following steps. The entire process is explained and demonstrated in the video found here: Aluminum Machining Tutorial
1. Put on a pair of safety goggles. THIS IS THE MOST IMPORTANT STEP.
2. Securely fasten your stock material to a piece of wood on the milling surface. Make sure it is tightly fastened and try to plan so the toolpath does not intersect the mounts.
3. Begin the drilling operation. Make sure to keep the drill well oiled and to stop the operation if the drill is heading towards a mount.
4. Once the holes are drilled use wood screws to lock the piece securely to the block of wood. Then move the mounts so the milling tool can follow the entire milling path without intersecting the mounts.
5. Run the bore operation first. Make sure to keep the speed of descent slow so the mill does not jam, it is not well designed for boring operations.
6. Finally run the milling operations. Make sure to keep the tool path well oiled so the mill easily slice through the material. Keep a vaccum handy to prevent metal shards from flying all over the lab. Wearing gloves is highly recommended.
7. When the piece is fully cut out, clean off the metal shards and wood with a cloth or paper towel.
8. Next we use a chamfer on the drill press to deburrow and finish the holes. This is shown in the video above.
9. Finally we sand the piece to smooth the edges and give it a nice finish. This whole process can take anywhere from 30 minutes to an hour depending on the piece.
10. Lastly, if the piece needs to be bent, use a breaker to slowly bend the piece. Be careful of the pieces thickness and the fragility of the material. Bending applies a lot of force and can easily break most pieces.