On 8/20/2013 7:57 AM, Joe AutoDrill wrote:
So I promised to post some of our challenges here...

We do simple drilling in most cases. No CNC, no feed calculations, just
an air stroked automatic drilling machine with a supplemental hydraulic
feed control that is manually adjustable. You look at the chips and
determine whether you need to go faster or slower, etc. RPM rates are
usually conservative but slightly adjustable. It's a purpose built
machine for most people.

So... I've got a return customer who loves our product. We were
initially nervous about selling to this guy because of the difficulty of
this projects, but it turns out he implemented drill bushings and all
other types of stabilization that made it a huge success. ...And we
were transparent with him about our concerns from day #1 but he admitted
that after many calls, we were the people who would actually work with
him and provide a custom solution for an affordable cost.

Anyhow... He calls me a few days ago with a new challenge. He needs to
drill six holes in one stroke. 7/8" diameter in ductile cast iron.
Nothing fancy, just needs thru holes for mounting a flange-type part.

Problem is, the largest machine I have is a 3 HP unit (sometimes 5 HP on
special jobs). It can only create 1000 lbs. of thrust at 100 psi shop
air and we really don't like pushing it with more air because the
components inside have not been tested under heaver loads in a
production atmosphere. We've run as high as 1600 lbs. of thrust for a
number of tests, but tests are different than real life, day in and day
out use...

So, after the standard "Well, you know we need to really think this
through because it's once again a uniquely challenging application."
statements, we dig into it.

His cycle time isn't critical but being able to press a button and walk
away is.

We came up with a staggered length head design that we believe will work
for him. In essence, the machine will only see the load of two holes at
a time as the "bits" will pass thru the part before the next two engage,
etc.

We are likely quoting a 6" stroke machine with a full 6" of hydraulic
feed control. Air stroked at 120 PSI shop air. Drill bushings. Guide
rods to further stabilize the heavy multispindle drill head (maybe
spring loaded to decrease some of the weight load too). ER40 style
spindles and collets - maybe ASA. 3 HP with a gear reduction system
running around 375 RPM (conservative). Pneumatic stroke controller (FRL,
start button, tubes, fittings, starter bottle of oil - Press the button
and the drill will stroke forward to a limit switch and then retract and
wait for the button to be pressed again.) 3 phase motor - panel and
additional controls by the customer.

If he needed a faster cycle time, we would have face mounted the
multiple spindle head onto a motor and gear reducer combination and
suggested he have someone build him a hydraulic slide mechanism... We've
done that many times successfully but prefer to avoid making the slides
themselves. Those big slide jobs excite me as I really enjoy the larger
drilling devices. ...But they are rare these days.

...Still working on the details with this customer, but it is just
another example of what gets placed in front of us on a daily basis.
Cost is still reasonable since there isn't much customization going on
here, just some creativity...

Any random comments, questions or critiques?





I've read all the responses so far and I'm surprised that nobody
mentioned using core drills to reduce HP HP and pressure requirements.
Of course, I don't know the ups and downs of it, I just came to mind.

I'll have to send you a pic of a "multi-drilling machine" we put
together to drill two screw pilot holes in a block. I took a small B&D
hobby drill press and bolted a Harbor Freight 3/8" $20 hand drill on the
side. Truly inspired!