Programing a large "countersink" in aluminum Disk

I am pretty new to this, been doing it about a months. I have figured out all the normal things, like pockets and contours. But the part I am working on now need a large “countersink” inside of an aluminum disk. The disk measures about 4" wide, with a 1.75" hole, and is about 1/2" thick. I need to mill a countersink in the holes, all the way around. I am trying to learn meshcam, since I figured this is the type of cut it is for.

Any other suggestions of how to do it?

Not sure it applies to your need but here’s a recent discussion on using contour toolpaths to do chamfers

(that thread was about wood though)

I don’t think you need 3D toolpaths “just” for countersinking a set of holes, chances are a set of 2D circular contours with appropriate stepdown should work. What tool are you going to use ?

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Or indeed 2D contours with a 45degree cutter at constant depth but with horizontal stepover to progressively open out the chamfer.

In Fusion 360 I use a boring operation with a ball end mill to do custom countersink type things.

What tool should I/would you use?

The angle is actually 82 degrees, so I cant use 45 (I thought of this) Does anyone know if a 82 degree countersink can cut along its edge?

You dont happen to know of a tutorial for this? I am trying to set aside time to learn fusion.


Sorry, I don’t. I would recommend learning to model in Fusion before trying to do anything in the CAM side of Fusion.

For reference, here is my order of operations for a countersink:

  1. Bore the hole using the appropriate square endmill
  2. Rough bore the countersink using the same square endmill
  3. Bore the countersink using the appropriate size ball endmill

The tool Neil suggested would also work. I just tend to use the tools I already have on hand unless I am trying to do a lot of something that would benefit from buying a new tool.


As Nick says, there’s quite a steep learning curve to Fusion.

If you want to spend the time, Lars Christensen has excellent introductory videos on YT and NYCCNC have very good specific ‘how to do this thing’ content once you have the basics down.

You can also do a scallop operation with a ball end mill. Just make sure to rough it first, and you’ll get a functional countersink.

I am trying to find time; I use Solidworks for work, so its been hard to find time to learn fusion too!

You’ll pick up Fusion quickly.

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Or just continue to use Solidworks. You can use a CAM add in, like SolidWorks Cam, HSM Works, MasterCam ect. Or, you can import your model into Fusion360, which essentially includes HSM Works, to program machine operations. Fusion360 is a handy piece of kit, and the default integration of cam is quite convenient. I think most would agree, SW is better.

All of those add ins cost a decent amount of money? Which one is the best for the money?

Also, it looks like autodesk removed the import function for the hobby version.

They are not cheap. You mentioned you used it at work, so I wasn’t sure what kind of access you might have to a seat.

If its just for hobby/fun, I’d recommend designing in SW, then importing into Fusion360 for CAM. The hobby license will essentially give you HSM Works for zero dollars. I kept my personal use account, and still use it for 3D printing projects and various non work related junk. You can most certainly import STEP files, as well as another 11 or 12 file types.

I prefer SolidWorks, but use Fusion360 because paid seat is CHEAP. And its perfectly acceptable for the things I do daily. The cloud aspect is of no benefit to me, and is a bit of an annoyance on rare occasions. But, its cheap. Having integrated CAM is great.

First, thansk to everyone for the info! I pushed my self an mostly figured it out!

The only question: I am starting with premachined disks; how do I tell fusion it does not have to cut out the 1.75" inside, since its already cut out?

Right now I just run the program and speed it up until ti gets to where I need!

You can model your stock if you need to. You shouldn’t need to though. The CAM in Fusion has a lot of controls.

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