Re: CNC drilling

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Ron Ginger <ronginger@...> wrote:

>
> I just finished a new Jet mill conversion. In the past I have always
> been afraid to drill under CNC control- Ive let the program single step
> to location, then I operate the quill by hand.
>
> What feed rates are used for CNC drilling? Do you calculate chip load
> like you would for an end-mill? What is a reasonable chip load for a
> drill? I suppose that varies by drill diameter?
>
> ron ginger
>

Ron,

I see you got the tables and calculations.

here is a bit of advise.

use cutting fluid.

drops of cutting oil, spray mist, flood cooling. ANYTHNG.

I went from a broken drill in as few as 10 holes and and many as 35
holes. now, I have not broken a drill in under 100 holes. I did
break a drill in just under 200 holes but that was because I got lazy
or forgetful and did not replace/sharpen the drill after 100 holes.

I raise to home before the hole, then touch the material on the first
peck. raise to the release point, then peck to my per-peck depth, then
rapid to my release point, rapid back to about 0.005" over the last
hole and start to feed.

the last peck is preceeded with a home of the Z.

I think there are many ways to do it. I went from 4 pecks to 2 pecks
on some material. but the one thing that changed things 100% was
cutting fluid.

Dave