View Full Version : Some general questions. Drilling and pocketing.

14-02-2014, 06:36 PM
A bit of a general and elementary question here, but there's probably a 'right' way of doing this that I don't know about.

Consider this piece of 'free cutting' brass stock:



The way I'd approach this job would be to spot then drill the 4mm hole first, then pocket the 6.5mm - here come the dumb questions:

1. I take it I'm better off using a drill bit specifically for brass, but how about spindle rpm's and peck/depth settings? Where's a good place to start? I have one of the 2.2kw Chinese spindles - will dropping the rpm kill the torque enough to prevent it from drilling? Something tells me that I really don't want to send a drill in at 12000 rpm...

2. What end-mill would you recommend using to pocket the 6.5mm hole? A 6mm? Or stay small and go with a 4mm? 2 flute carbide intended for alu going to be okay?

Apologies for the basic nature of these questions, but I'd sooner start with half a chance of getting it right rather than waste stock/bits...



14-02-2014, 11:05 PM
It depends on various factors.
Drilling is the quickest way to remove metal, however you need to make sure you're spindle is capable of the required torque.
With limited torque, you may find spiral milling will work better with your spindle.
Best bet is try some figures at FSWizard - Free Advanced CNC Speed and Feed Calculator (http://zero-divide.net/?page=fswizard) and see what will work with your spindle/available tools.