Runout, HSS drills and dowel holes

Hello

Thank you for reading

I was taught that minimizing run-out is essential for successful drilling
I can see machinists making dowel holes with HSS drills in collets, and sometimes these drills run even more than 0.1mm out, on steel and aluminium.
I know the spot drill defines the position of the holes, however drilling with a drill which runs more than 0.1 out, I would not use it even to make a normal tapped hole for a high precision job
What’s your experience about run out

Thank you in advance for your support

Relative to the job - 0.1mm is fine for a hole that is to be tapped, for dowel holes, they must be reamed to fit.

Drills are only ever treated as a way to get an approximate sized hole, the accuracy is added later by machining or reaming or boring etc.

If the spot-drill is used correctly then the drill can be quite bad and still drill in the correct place.

Collets come in different tolerances. If your vender does not mention tolerance you can probably assume they are from the cheap end of the pile :very_drunk: