"jon_banquer" wrote in message
...

On Feb 15, 8:20 pm, jon_banquer wrote:
snip

"Would spot drilling, drilling, and reaming be just as good? Any
better ideas?"

For what you're doing, in I guess a manual Bridgeport, I'd use a 135
degree split point screw machine drill and then ream the hole.

If you need more positioning accuracy than say .005 you should spot
drill first.

If you are using a CNC, I'd would interpolate the hole with an
endmill. I see no reason to use a single point tool for what you are
doing.


The drawing calls for a diameter of .251 +/- .001 and spacing between the 2
holes is 6.375 +/- .002, I'm hoping to do a little better than that. I'll
be doing this on a low hours Enco "Bridgeport" style mill.

While at my shop last week, I turned on my CNC control (Anilam Crusader II)
and it doesn't look good, display (7-segment LED's) was dim with various
numbers, didn't respond to a reset... So it's probably upgrade opportunity
time. The old control had a 1000 line memory with no drip feed, ok for hand
entered code but very limiting for computer generated code. So the
EMC/LinuxCNC conversion should be a big improvement, plus I can add a
spindle drive to run on single phase plus have speed control.

Thanks for the info!

RogerN