Re: EMC and Drilling

David L Anderson wrote:

> From: David L Anderson <daveland@...>
>
> Hello again
>
> Just got a question for all the EMC and CNC Experts.
>
> I want to drill holes at very precise (+/- .002) locations in 3/16"
> thick steel locomotive frames. To get the two frames to align to one
> another I stack them ( with small screws to hold them together) before I
> drill. This makes both sides identical even if I am off a bit. What I
> was thinking of was an aluminum tooling plate that I could fasten the
> "blanks" too with cap screws. I would align the plate to the ways and
> then machine a reference edge (similar to a fence on a wood planer) to
> set the frames straigth. Then the cap screws would hold it down. I see
> two problems:
>
> 1) How do I set the reference position to my part when the fixture can
> on hold the part in "Y" and does not control "x". Any ideas?

I made an alignment jig that has a long (~ 28") straight bar, with a couple of
holes in it, and a small piece of aluminum plate that bolts onto the end, which
is milled square to the long edge of the bar. The bar is clamped to the table
and set parallel to the X axis, and the plate that overhangs the end is the
X=0 reference edge. The bar, itself, is the Y=0 reference edge.

>
> 2) how do I program a drill cycle in EMC.

This is in the EMC documentation. It pretty much follows the AB/Fanuc/etc.
standards on canned drilling cycles. The docs I have show :
G73 Deep hole peck drilling with dwell
G81 simple Drilling
G82 Drilling with dwell
G83 Deep hole peck drilling
G80 Cancel fixed cycles
Fred Proctor changed some of these functions to make them more likely
to be useful. The R word sets a Z axis height to which the tool retracts
after the cycle completes. I haven't used this, yet, so I'm not too sure
which parameter words are implemented.

Jon