On 1/11/2020 10:23 AM, Bob La Londe wrote:
As most of you know by now I make molds for a pretty small niche market.
Â*Most of those molds are two piece (sometimes with inserts and other
things) that are placed together and held with clamping screws (or bar
clamps).

I also make some for gravity casting that are hinged with handles.Â* For
the most part they are small enough I can drill the holes or spiral
interpolate for hinge pins on one of the CNC machines.Â* Once in a while
I make one that is to big to set under a drill on any of the machines
except the drill press.Â* My drill press is NOT a precision machine.Â* I
made a steel jig that fits over the hinge boss of those molds.Â* It gets
clamped in place, and a hand held drill is used to drill the hinge pin
holes.Â* Its not great, but its better than the "big" drill press in the
shop.Â* I know I need a decent drill press (or preferrably a taller
mill), but for now that's the solution.Â* It has worked, and I don't have
to do it very often.Â* Not often enough to spend the money on a better
quality drill press or bigger milling machine.

Well.... I have another tall hinged mold on the mill right now.Â* 18.5
inches.Â* I'm actually roughing the blank on one machine, and machining
the cavity on another due to speed and envelope limitations.Â* It
actually took me a little while to get happy with my order of
operations, and I still have to hand drill the damned hinge pin holes. I
sure would like a better process for that.

Than I had an "aha" moment.Â* My thoughts about gun drilling on the lathe
hold the answer.Â* I have an MT4 adapter sleeve for the spindle, and an
MT4 ER32 collet chuck.Â* Its time to develop my method for holding and
positioning stock on the carriage.Â* For a one off I can probably just
use some of my assortment of right angle plates.

Bob,

So, I was 3/4 way through reading your second paragraph. I started
to envision mounting your thingie in a lathe and drilling horizontally.
Then I got to your last paragraph and a smile came across my face. :-)

The one challenge is dialing in the elevation. But, I am guessing
you got that worked out with something in your shop.

Fun read!!! Thanks!!

Have a good rest of the weekend.

Les'