Countersunk Holes?

I want to make counter sunk holes in wood and aluminum, what endmill would you use for this? I have a changer cutter and thought doing multiple stepdowns would work but I assume there is a better option. I saw that center drills have this ability but I’ve never seen someone use one on a Shapeoko.

What do you do?

I would chamfer around the hole using a 90 degree endmill — wish there was a readily available 82 degree V endmill in carbide for Imperial hardware.


Depending on how many holes you need to CS sometimes it’s easier/quicker by hand or on a drill press with the depth set. Or maybe an 82 degree chamfer mill?


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I make my C’Sunk holes two ways…fast and dirty (CC Wood) and slow and precise (F360 Metal)…

In Carbide Create I make an offset hole (EDIT: Using a V-Bit of the desired angle), based upon the Angle and Diameter I need, but first I trig out the math.

In Fusion 360, I model the C’Sink and typically use a Ball End Mill to 3D mill it.

Hope this helps.


I use Estlcam for pretty much all my drilling and countersinking ops.

You can use both a Vee bit to chamfer, or if you are lazy (I fall into this category) and want to save on tool changes, you can just use a regular flat end mill - cutting a series of mini steps.
Check out this video - specifically, watch from 2:22 to 4:05 and he covers both of the above scenarios.

If you have a bunch of identical holes to drill and chamfer, you just set out the details on one, then copy and paste onto the others. Very quick and easy.

I also like it because you can use the helical drill function with just a regular end mill - works fantastic into Aluminium plate. And of course, you then just chamfer using the same bit no tool change required.

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In another thread people were discussing a US source for endmills in Oregon (EDIT RogueSystems @Griff ) that would take orders for specialty endmill. Maybe if there is enough demand, they could make an 82deg X .5in V bit with a .250in shank designed for countersunk holes.


I need to be making more brass hardware for that to be something I could justify (but my next major project is looking as if I’m going to need to make some custom hardware), so yeah, put me down for 3 on that order.

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I’ll add this to a list I’m compiling for Bill at RogueSystems as we speak.

Any other suggestions? PM me. Oh, please don’t ask for mills they already make :crazy_face:, check their listing first.


@WillAdams - That makes sense. I thought @DanoInTx suggestions about using the 82 deg chamfer mill sounded good. I saw sound and thought it might work.

@RichCournoyer - Oh really? A ball endmill to do it in aluminum? That makes sense, it would have scallop heights but I could still try it before buying a special chamfer mill if I want to do it a lot.

@3DGG - That makes sense. I will try this strategy with what I have and see how it works. Thanks for the video!

@luc.onthego - That’s a good thought!

Cool! You saw my suggestions from the other thread so I don’t have any other ideas currently.

I would PREFER a chamfer (V) cutter, but because the Z motor is quite weak (18 lbs of downforce) a ball end mill is the safe cutter choice. Scallop (They are called Cusps in the CNC world) height is manageable with F360. Meaning you pick the height. ((I typically use 0.004-0.005")


Great, I’ll give it a try!

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