Re: Dumb question on the drilling of holes

--- In CAD_CAM_EDM_DRO@y..., alan@s... wrote:

> Forgive me this seemingly dumb question, but how does a

person "drill"

> accurately placed holes under CNC control without first center-

punching

> them.
>

Alan: I have used both methods in a manual mill setup with a DRO. I
draw the part in CAD and have it display the XY cooridinates in the
print. Because twist drills will "walk" prior to making penetration
I start the hole with a 1/4" diameter NC peck drill, then switch over
to the real drill and drill the hole. I have talked to several guys
that just use the CNC table to peck drill all of the through holes
then they drill them on a conventional drill press. I am converting
my large Gorton to CNC and I plan to continue to first peck drill
then go back and finish drill the final hole. On thicker material
(> .375) I will probably manually drill the final hole so I can back
the drills out and clear the chips. I find that using the DRO and
first drilling a locator hole is faster and more accurate than center
punching and drilling (they way I used to do it prior to the purchase
of my DRO).