Like Nick says, the boring op works well for making small holes with, it’s the CNC version of drilling.
I messed it up a few times;
but after Vince, Nick and others pointed some things out I changed what I was doing to;
- A 1 degree ramp angle (in a boring op I think it is depth per revolution)
- A bit that was sufficiently smaller than the hole I was making, 3.125mm for 4.2mm hole was OK, 4mm bit for 4.2mm hole gave me trouble getting the chips out
- Backing off the feed speed far enough based on that handy formula from Haas
It worked out OK.
As you’re only going through 2mm of material you shouldn’t have too much trouble with chip evacuation, these are not deep holes…
I’d suggest making sure your workholding allows you to cut through the bottom of the stock if necessary, i.e. don’t use a hard metal as the workholding base, use a plastic, a sheet of MDF or something like that.
I’d also suggest that you set your work co-ordinate system in the Fusion job setup to be the base of the workpiece, that is, the top of your workholding base. If you do this then it’s much easier to machine accurately to the bottom and not leave a skin you have to trim out.