On Tue, 7 Jan 2020 00:26:50 +0000, David Billington
wrote:

On 06/01/2020 21:46, wrote:
On Mon, 6 Jan 2020 13:15:59 -0700, Bob La Londe
wrote:

On 1/5/2020 10:50 AM, Bob La Londe wrote:
Ok, my previous deep drilling operations went off pretty well. Carbide
3 flute drills worse used on a couple of them. One to start holes for a
hand ground split point, and the smaller hole with just a carbide jobber
drill. Both actually met up in the middle close enough. One for a
hinge pin and the smaller one for an injection cavity feature. They
worked. Didn't actually do any gun drilling.

Now I am looking at an application that will need to drill straight
(size is not highly critical), for from 20 to 28 inches for a water
jacket.
The only machine i have I think would be suitable for it is the 14x40
engine lathe. Throwing a 20x30 inch piece of plate on the chuck is
obviously not the answer. LOL. I was thinking to use some sort of tool
holder in the spindle, and make a mount and support for the plate on the
carriage. After doing a bit of reading gun drilling does not just use
hydraulic pressurized oil. It is also done with pneumatic air mist
under pressure. Now the trick I think is to figure out how to
pressurize a spinning gun drill inside a lathe spindle. I have some
ideas, but they are kind of vague at this point.

The thought of buying and setting up a dedicated machine down the road
is not out of the question. Right now I am looking for the shade tree
get it done short term solution.
I think I have most of it figured out if using the lathe is the answer.
Just the details of the actual fluid delivery and recovery to work out,
and you guys have given quite a lot of information to help figure that
out.

I figure I can mount a big right angle plate (I have one) in place of
the compound, stand the plate on edge, and clamp it to it. I can stack
blocks to get height if needed, and adjust with the cross slide. By
putting the plate on edge it will virtually eliminate any material sag
(a concern at 30 inches long) from over hang as long as the clamps do
not slip.

The whole thing gives me ideas for solving some of my other deep
drilling issues as well. Making them easier. Next is a stop switch on
the carriage, so I can walk away for a minute without fear of a crash
because I got distracted. I think the same kind of roller micro switch
as is on the chuck safety cover. Maybe with a mag lock mount for rapid
positioning. Allow it to over travel as it comes to a stop of course.

If only I could easily automate peck drilling with it. LOL.
I just set up an air cylinder to release the half nut on the carriage.
I used a proximity switch to sense the carriage and thereby close a
relay which powers a solenoid air valve. It works very well and allows
overtravel of the carriage past the switch. The system repeats within
.003"
Eric

An interesting modification but I wonder how fail safe it is in the case
of power failure, the lathe would coast to a halt so I guess it depends
how close the stop point is to the chuck. The reason I mention it is
that a guy I used to work with mentioned operating a lathe with an air
chuck and* they had a power failure and the air supply turned off and
jettisoned the part narrowly missing the guy, they fitted a UPS to that
circuit shortly afterwards.


Thats why a reserve air tank before the work holding is critically
important. You can use any old air compressor tank as a reserve. Just
a heads up.

Gunner
__

"Journalists are extremely rare and shouldn’t be harmed, but propagandists are everywhere and should be hunted for sport"

Yeah..with no bag limit.