On 8/19/2011 9:25 AM, jim wrote:


Tom Gardner wrote:

I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need.005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together
and drill all four plates at once in the mill using the DRO to position
the plates and have the top plate and the bottom plate be within .005"?


In other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

You can do that easily if the mill head is true. Not sure why you would
spot the holes with
combination drill countersink. or do you mean center drill?

The Bridgeport is as perfect as any can be with very low hours, trammed
to perfection. I guess it's worth some test holes.

Yes, a "Center Drill"! Us old people have had many arguments over the
years about the official name of the tool. Had I typed "center drill" I
certainly would have gotten flack from other old people.