I just finished a job where I drilled 700 holes .468 diameter 1.600
long in 4340. I used one drill that had already been used at least a
little. The drill was a .468 split point stub length cobalt HSS drill.
So this tool drilled through 93 feet of material removing 61 cubic
inches of 4340 in the process. I'm pretty impressed. I ran the drill
at 650 RPM at .006 IPR feed. Actually the drill fed while the part
spun. The drill is still in good enough shape to run at least another
100 parts.
Eric

On Wednesday, July 8, 2015 at 2:35:05 PM UTC-4, wrote:
I just finished a job where I drilled 700 holes .468 diameter 1.600
long in 4340. I used one drill that had already been used at least a
little. The drill was a .468 split point stub length cobalt HSS drill.
So this tool drilled through 93 feet of material removing 61 cubic
inches of 4340 in the process. I'm pretty impressed. I ran the drill
at 650 RPM at .006 IPR feed. Actually the drill fed while the part
spun. The drill is still in good enough shape to run at least another
100 parts.
Eric

And the drill was made by ...........................? And bought from......................?

I recently bought an annular cutter off ebay. Due to circumstances beyond my control, I have not used it for real work. But I think it will be the bees knees for drilling largish holes.

Dan

On Wed, 8 Jul 2015 14:07:49 -0700 (PDT), "
wrote:

On Wednesday, July 8, 2015 at 2:35:05 PM UTC-4, wrote:
I just finished a job where I drilled 700 holes .468 diameter 1.600
long in 4340. I used one drill that had already been used at least a
little. The drill was a .468 split point stub length cobalt HSS drill.
So this tool drilled through 93 feet of material removing 61 cubic
inches of 4340 in the process. I'm pretty impressed. I ran the drill
at 650 RPM at .006 IPR feed. Actually the drill fed while the part
spun. The drill is still in good enough shape to run at least another
100 parts.
Eric

And the drill was made by ...........................? And bought from......................?

I recently bought an annular cutter off ebay. Due to circumstances beyond my control, I have not used it for real work. But I think it will be the bees knees for drilling largish holes.

Dan
Whoops! Precision Twist Drill. Available from all the usual suspects.

" fired this volley in
:

I recently bought an annular cutter off ebay. Due to circumstances
beyond my control, I have not used it for real work. But I think it
will be the bees knees for drilling largish holes.

When did 0.468" become a "largish" hole? What we want to know is the make
and model of the drill bit. That's an extraordinarily good life for a
'common' twist drill... split point or not.

Lloyd

fired this volley in
news
Whoops! Precision Twist Drill. Available from all the usual suspects.

Thanks. Will investigate (meaning will buy some, and see what works!)

Lloyd

On Wednesday, July 8, 2015 at 6:36:37 PM UTC-4, Lloyd E. Sponenburgh wrote:


When did 0.468" become a "largish" hole? What we want to know is the make
and model of the drill bit. That's an extraordinarily good life for a
'common' twist drill... split point or not.

Lloyd

..458 is not a largish hole. But the annular cutter I bought is a 20 mm drill. Not all that large, but big enough that I would drill a pilot hole if using a regular drill.

Dan

wrote in message
news
On Wed, 8 Jul 2015 14:07:49 -0700 (PDT), "
wrote:

On Wednesday, July 8, 2015 at 2:35:05 PM UTC-4,
wrote:
I just finished a job where I drilled 700 holes .468 diameter
1.600
long in 4340. I used one drill that had already been used at least
a
little. The drill was a .468 split point stub length cobalt HSS
drill.
So this tool drilled through 93 feet of material removing 61 cubic
inches of 4340 in the process. I'm pretty impressed. I ran the
drill
at 650 RPM at .006 IPR feed. Actually the drill fed while the part
spun. The drill is still in good enough shape to run at least
another
100 parts.
Eric

And the drill was made by ...........................? And bought
from......................?

I recently bought an annular cutter off ebay. Due to circumstances
beyond my control, I have not used it for real work. But I think it
will be the bees knees for drilling largish holes.

Dan
Whoops! Precision Twist Drill. Available from all the usual
suspects.

Dry? coolant? cutting oil?

" fired this volley in
:

Not all that large, but big enough that I would drill a pilot hole if
using a regular drill.

I might 'pip' the hole to make sure it started without any vibrations, but
pilot? (I assume you mean full-depth) With THAT small of a bit?

If my machines can't hold center better than that, I'd better quit or
rebuild their spindles! G

Lloyd

On Wed, 8 Jul 2015 16:39:16 -0700 (PDT), "
wrote:

On Wednesday, July 8, 2015 at 6:36:37 PM UTC-4, Lloyd E. Sponenburgh wrote:


When did 0.468" become a "largish" hole? What we want to know is the make
and model of the drill bit. That's an extraordinarily good life for a
'common' twist drill... split point or not.

Lloyd

.458 is not a largish hole. But the annular cutter I bought is a 20 mm drill. Not all that large, but big enough that I would drill a pilot hole if using a regular drill.

Dan
My son was working at a boat builder and they were having a terrible
time drilling a 1 inch hole through a 3/4 inch thick 304SS plate. He
suggested that they let me try. So I got out a small drill, 5/16 I
think, and drilled through pretty fast. Then I put the 1 inch drill in
the machine and slowed it way down. My son was surprised about the low
RPM of the drill. I told him it was the correct RPM. I then proceeded
to drill through the plate with a heavy feed. So the whole thing took
about 5 minutes. Drilling a hole to provide clearance for the web of a
larger drill can really speed things up. On the other hand it is not
always necessary. I have a repeat job where I drill a 7/8 hole 2
inches deep in 6061 aluminum in 1.6 seconds. The part is spinning 3000
RPM and the drill is fed at .016 IPR. Well, really, the CNC lathe is
doing the drilling. The spade drill I use has high pressure coolant
through. If someone turns off the coolant for some reason and presses
the start button the spade drill and part are destroyed. I know this
because an employee twice forgot to turn the coolant back on after
turning it off for some reason. GRRR.
Eric

fired this volley in
:


doing the drilling. The spade drill I use has high pressure coolant
through. If someone turns off the coolant for some reason and presses
the start button the spade drill and part are destroyed. I know this
because an employee twice forgot to turn the coolant back on after
turning it off for some reason. GRRR.


Ayup, and yes.

And a twist drill can do that all day long, too, so long as the spindle
is rigid and the coolant is keep on.

Lloyd

On Wednesday, July 8, 2015 at 8:34:26 PM UTC-4, Lloyd E. Sponenburgh wrote:
" fired this volley in
:

Not all that large, but big enough that I would drill a pilot hole if
using a regular drill.

I might 'pip' the hole to make sure it started without any vibrations, but
pilot? (I assume you mean full-depth) With THAT small of a bit?

If my machines can't hold center better than that, I'd better quit or
rebuild their spindles! G

Lloyd

The pilot hole is not to make sure that the machines hold the center . It is to eliminate the pressure needed to have a decent feed rate. On stainess as Eric describes it in his message, it makes a huge difference with normal hobby grade drill presses. If you do not do that , you end up work hardening the stainless and or stalling the drill press.

Sure if I buy an industrial grade drill press, it is not necessary. But this lets me use a cheap ( less than $600 ) drill press. I just can not justify spending more for a drill press since I do not do production work.

Dan

Dan

" fired this volley in
:

I just can not justify spending more for a drill press since I do not
do production work.

Yeah... I guess my Solberga (with power down-feed) would be overkill for
that, huh? G

Lloyd

On Wednesday, July 8, 2015 at 10:09:17 PM UTC-4, Lloyd E. Sponenburgh wrote:


Yeah... I guess my Solberga (with power down-feed) would be overkill for
that, huh? G

Lloyd

I wish you lived close enough that I could visit when I want to drill big holes.

Dan

On Wed, 8 Jul 2015 18:40:46 -0700 (PDT), "
wrote:

On Wednesday, July 8, 2015 at 8:34:26 PM UTC-4, Lloyd E. Sponenburgh wrote:
" fired this volley in
:

Not all that large, but big enough that I would drill a pilot hole if
using a regular drill.

I might 'pip' the hole to make sure it started without any vibrations, but
pilot? (I assume you mean full-depth) With THAT small of a bit?

If my machines can't hold center better than that, I'd better quit or
rebuild their spindles! G

Lloyd

The pilot hole is not to make sure that the machines hold the center . It is to eliminate the pressure needed to have a decent feed rate. On stainess as Eric describes it in his message, it makes a huge difference with normal hobby grade drill presses. If you do not do that , you end up work hardening the stainless and or stalling the drill press.

Sure if I buy an industrial grade drill press, it is not necessary. But this lets me use a cheap ( less than $600 ) drill press. I just can not justify spending more for a drill press since I do not do production work.

Dan

Dan
Greetings Dan,
If I was drilling the same hole in one of the CNC machines with a
twist drill I would still drill a pilot hole just because it would put
the hole in faster. With a coolant through spade drill and the 15 HP
CNC lathe I would probably drill a 1 inch hole in one shot. But I did
a job where I had to put a large hole in several 17-4 PH SS parts and
even though I used a coolant through spade drill the hole was so large
that I drilled a pilot hole. I was able to then nearly triple the
spade drill feed compared to using the spade drill to remove all the
material.
Eric

If we look at the surface being drilled - the center of the drill
the cross point helps on the drill or spade - the surface speed is all
but zero and the drill is pushing itself through. Further out there is
cutting because surface speed is reasonable.

Martin

On 7/9/2015 11:16 AM, wrote:
On Wed, 8 Jul 2015 18:40:46 -0700 (PDT), "
wrote:

On Wednesday, July 8, 2015 at 8:34:26 PM UTC-4, Lloyd E. Sponenburgh wrote:
" fired this volley in
:

Not all that large, but big enough that I would drill a pilot hole if
using a regular drill.

I might 'pip' the hole to make sure it started without any vibrations, but
pilot? (I assume you mean full-depth) With THAT small of a bit?

If my machines can't hold center better than that, I'd better quit or
rebuild their spindles! G

Lloyd

The pilot hole is not to make sure that the machines hold the center .

It is to eliminate the pressure needed to have a decent feed rate.

On stainess as Eric describes it in his message, it makes a huge

difference with normal hobby grade drill presses. If you do not do that ,

you end up work hardening the stainless and or stalling the drill press.

Sure if I buy an industrial grade drill press, it is not necessary. B

ut this lets me use a cheap ( less than $600 ) drill press.

I just can not justify spending more for a drill press since I do not do
production work.

Dan

Dan
Greetings Dan,
If I was drilling the same hole in one of the CNC machines with a
twist drill I would still drill a pilot hole just because it would put
the hole in faster. With a coolant through spade drill and the 15 HP
CNC lathe I would probably drill a 1 inch hole in one shot. But I did
a job where I had to put a large hole in several 17-4 PH SS parts and
even though I used a coolant through spade drill the hole was so large
that I drilled a pilot hole. I was able to then nearly triple the
spade drill feed compared to using the spade drill to remove all the
material.
Eric

On Wed, 08 Jul 2015 17:36:35 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

" fired this volley in
:

I recently bought an annular cutter off ebay. Due to circumstances
beyond my control, I have not used it for real work. But I think it
will be the bees knees for drilling largish holes.

When did 0.468" become a "largish" hole? What we want to know is the make
and model of the drill bit. That's an extraordinarily good life for a
'common' twist drill... split point or not.

Lloyd

2 weeks ago I drilled (16) 4.5" holes, then tapped them in a
reasonable sized chunk of 4140

Shrug...size is simply relative to what you have to work with.

Gunner

On Wed, 08 Jul 2015 19:34:24 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

" fired this volley in
:

Not all that large, but big enough that I would drill a pilot hole if
using a regular drill.

I might 'pip' the hole to make sure it started without any vibrations, but
pilot? (I assume you mean full-depth) With THAT small of a bit?

If my machines can't hold center better than that, I'd better quit or
rebuild their spindles! G

Lloyd

Even the best machines will still let a bit wander and walk for a
varity of reasons not related to the machine itself.

Gunner

On Wed, 8 Jul 2015 18:40:46 -0700 (PDT), "
wrote:

On Wednesday, July 8, 2015 at 8:34:26 PM UTC-4, Lloyd E. Sponenburgh wrote:
" fired this volley in
:

Not all that large, but big enough that I would drill a pilot hole if
using a regular drill.

I might 'pip' the hole to make sure it started without any vibrations, but
pilot? (I assume you mean full-depth) With THAT small of a bit?

If my machines can't hold center better than that, I'd better quit or
rebuild their spindles! G

Lloyd

The pilot hole is not to make sure that the machines hold the center . It is to eliminate the pressure needed to have a decent feed rate. On stainess as Eric describes it in his message, it makes a huge difference with normal hobby grade drill presses. If you do not do that , you end up work hardening the stainless and or stalling the drill press.

Sure if I buy an industrial grade drill press, it is not necessary. But this lets me use a cheap ( less than $600 ) drill press. I just can not justify spending more for a drill press since I do not do production work.

Dan

Dan

Very well stated!!!

Gunner