[MadMax]

You risk a few things with your drill press arrangement:

If you're not using a crosslide travel (i.e. freehand with guide/fence)

Bit catching the workpiece and pulling it with the cutter. Cutting edge digs into wp and pulls it in tangent to the cutter progressively pulling it through the cutter. This results in a very poor finish and can cause damage to the wp or cutter. You can imagine what happens if you don't let go of the wp and it drags your hand in.

This kind of progressive bite and drag happens with a fence because the fence backs the workpiece against the cutter but allows it to be pulled in direction of the cutter tangent.

It could be safer to push the wp against the direction of the cutter as the cutter would push your hand away from the cutter if it grabs. Unfortunately you could still damage the part or get the wp spat into your face.

Chuck falls off spindle

This is actualy pretty likely with a drill press. They're definitely not designed for sidecutting. I used to maintain the students workshop for an engineering design class. Every year, I had to replace chucks or drillpresses because students tried to use the drillpress for sidecutting. They typically worked wood or styrofoam and attempted sidecuts with drill bits which don't have the right cutting faces for that. Once the chuck falls off from sidecutting load, you tend to scratch the spindle because it's still spinning while you're dragging the wp against the chuck. Once the spindle is scratched, it doesn't register to the chuck so well and it falls off more easily.

Hand drills have a screw which keeps the chuck pulled on because they tend to get sideloaded because the user tends to not be very well aligned. Sideloading is expected in hand drills but not drillpresses.


Unfortunately there aren't many options you can easily go with if you want a professional looking deep sidecut with common tools. I sometimes use a hacksaw to remove the bulk of material before milling. My mill isn't all that stiff so it helps to do bulk removal. Saves me some patience so I can take more light cuts within the capacity of my machine.

If you don't mind a more hand finished look, you could saw off the bulk of mat'l and finish to the desired shape with a single cut file (parallel straight edges, not "diamond" faces made by two edges). Aluminum is a bit cloggy, get a file card to brush out the file regularly.