In June 2005, I was having problems because my little 12" Delta
variable-speed drill press has a minimum speed of 500 rpm, which was a
real problem, especially when countersinking.

I had found an interim solution for larger holes: Put the countersink
in the hole and turn power on, releasing the downward pressure before
the press gets up to speed.

This did not work with small holes, and the 1/4-inch severance
countersink, working in 6061 aluminum, flooded with a water-based
coolant. I would have thought that a small countersink would be OK at
500 rpm, but the holes became ragged and misshapen.

Countersinking with a hand drill did work, making pretty holes, but
yielded inaccurate countersinks because it's so hard to drill straight
by hand.

I was busily tearing metal and hair when it occurred to me that tapping
is an extreme kind of machining, and yet one can get clean threads, with
the right lubricant. So I tried LPS Labs' "Tap-All". It worked, even
at 500 rpm.

Haven't tried it in steel and/or for large holes yet.

Joe Gwinn

"Joseph Gwinn" wrote in message
...

Haven't tried it in steel and/or for large holes yet.


If I had to bet money, I'd say you're not feeding fast enough (pushing hard
enough). You should be able to countersink a 1/2" hole in steel at 500 RPM
with some practice.

You have to feed *hard* into the material (you'll need a good chuck as most
countersinks have pretty hard shanks) and retract quickly when you're at the
desired depth - no dilly-dallying at the bottom or throughout the cut.

Your idea about the lube is good. Countersinks are easy to burn and hard to
sharpen.

HTH.

Regards,

Robin

In article ,
"Robin S." wrote:

"Joseph Gwinn" wrote in message
...

Haven't tried it in steel and/or for large holes yet.


If I had to bet money, I'd say you're not feeding fast enough (pushing hard
enough). You should be able to countersink a 1/2" hole in steel at 500 RPM
with some practice.

You have to feed *hard* into the material (you'll need a good chuck as most
countersinks have pretty hard shanks) and retract quickly when you're at the
desired depth - no dilly-dallying at the bottom or throughout the cut.

How do you keep from boring too deep? I guess one chews one hole up
finding the right depth to set the depth limit stop to.

Not that I trust the depth stop to really prevent motion when pushed
hard enough to avoid chatter.

This approach probably works better for large holes than for small ones.


Your idea about the lube is good. Countersinks are easy to burn and hard to
sharpen.

Haven't burned one yet - probably too chicken to push it that hard.

Was in a used tool place last week. Saw a 3/8 mill with irregular heat
colors, signs of heavy use in aluminum, and a bit of solidified aluminum
"soldered" to one flute. My guess is that it was on a CNC mill happily
hogging aluminum when the coolant flow failed.


Joe Gwinn

If I had to bet money, I'd say you're not feeding fast enough (pushing
hard enough). You should be able to countersink a 1/2" hole in steel at
500 RPM with some practice.

I'd bet that the drill press would probably stall with the necessary amount
of pressure being applied.
--


Regards,
Joe Agro, Jr.
(800) 871-5022
(908) 542-0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com

V8013-R

In article A93jf.226$xY2.167@trndny08,
"Joe AutoDrill" wrote:

If I had to bet money, I'd say you're not feeding fast enough (pushing
hard enough). You should be able to countersink a 1/2" hole in steel at
500 RPM with some practice.

I'd bet that the drill press would probably stall with the necessary amount
of pressure being applied.

I bet you are right, given my cute little drill press. Not that I've
managed to stall it yet. Usually, the drill bit slips in the chuck.

Joe Gwinn

If I had to bet money, I'd say you're not feeding fast enough (pushing
hard enough). You should be able to countersink a 1/2" hole in steel at
500 RPM with some practice.

I'd bet that the drill press would probably stall with the necessary
amount
of pressure being applied.

I bet you are right, given my cute little drill press. Not that I've
managed to stall it yet. Usually, the drill bit slips in the chuck.

Are there countersink tools available with three flats on the shank?
--


Regards,
Joe Agro, Jr.
(800) 871-5022
(908) 542-0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com

V8013-R

In article aQhjf.103$R02.75@trndny06,
"Joe AutoDrill" wrote:

If I had to bet money, I'd say you're not feeding fast enough (pushing
hard enough). You should be able to countersink a 1/2" hole in steel at
500 RPM with some practice.

I'd bet that the drill press would probably stall with the necessary
amount of pressure being applied.

I bet you are right, given my cute little drill press. Not that I've
managed to stall it yet. Usually, the drill bit slips in the chuck.

Are there countersink tools available with three flats on the shank?

I imagine that there are, but I haven't seen them. I imagine that the
better grade of countersinks do not have the flats, the expectation
being that one will use a better grade of chuck to match. My solution
was to upgrade the chuck. I'd love to get a ball-bearing Jacobs chuck,
but have not seen it offered with a J33 taper, only J3 and the like. My
next drill press will not have J33 taper - too limiting.

Joe Gwinn

In article , Joseph
Gwinn says...

I had found an interim solution for larger holes: Put the countersink
in the hole and turn power on, releasing the downward pressure before
the press gets up to speed.

I used to do this at work. Basically you are using the start windings
and the mechanical inertia of the spindle and motor to keep things
down to a slow enough speed that the c'sink doesn't chatter.

It also helps to use a single flute countersink.

Eventually I went with a VFD so now I can run those things slower
than I would want to - if I wanted to, if you catch my drift.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

--Plan B: go to the swapmeet and pick up a brace and bit; these
work OK for this sort of thing and they're *great* for tapping..

--
"Steamboat Ed" Haas : Bummed to be living in the
Hacking the Trailing Edge! : Golden Age of Bull****...
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

In article ,
steamer wrote:

--Plan B: go to the swapmeet and pick up a brace and bit; these
work OK for this sort of thing and they're *great* for tapping..

A brace and bit! Actually, I have one that I bought new in the late
1960s. Used it mostly for installing locks - it's the best way to cut a
clean 1-1/8 inch hole in a wood door without power tools. The trick was
to bore until the lead screw just poked through the back side, back out,
and complete the cut by boring from the back.

I hadn't thought of using it for tapping. It ought to work, at least
for larger sizes. If I can keep the tap properly aligned by hand. What
I've been using is a piloted tap wrench in the drill press.

Joe Gwinn

"Joseph Gwinn" wrote in message
...

I hadn't thought of using it for tapping. It ought to work, at least
for larger sizes.

The larger the tap, the greater the torque requirement (large at work is
M36). Could be difficult.

If I can keep the tap properly aligned by hand. What
I've been using is a piloted tap wrench in the drill press.

You should try a spiral-point tap, in the drill chuck. Ideally your drill
press reverses to pull the tap out. Probably still faster than hand tapping
if you can only run the tap under power forwards.

Regards,

Robin

In article ,
"Robin S." wrote:

"Joseph Gwinn" wrote in message
...

I hadn't thought of using it for tapping. It ought to work, at least
for larger sizes.

The larger the tap, the greater the torque requirement (large at work is
M36). Could be difficult.

So far, I have not needed to go beyond 3/8-16 and M8-1.25, but I have a
few 1/2-13 taps ready to go.


If I can keep the tap properly aligned by hand. What
I've been using is a piloted tap wrench in the drill press.

You should try a spiral-point tap, in the drill chuck. Ideally your drill
press reverses to pull the tap out. Probably still faster than hand tapping
if you can only run the tap under power forwards.

I do use spiral-point taps, and gun taps, but only by hand so far.
Isn't 500 rpm a bit fast for a tap? How do you stop in time?

I have also been using a thread-forming 10-32 tap for some very deep
blind holes in aluminum. I had been using various kinds of cutting
taps, but it was touch-and-go, and I did break a few taps until
switching to thread-forming taps for this job. None of the broken taps
were Asian. Some were Greenfield, and some were Sossner (sp?).

Joe Gwinn

Joseph Gwinn wrote:
: I do use spiral-point taps, and gun taps, but only by hand so far.
: Isn't 500 rpm a bit fast for a tap? How do you stop in time?
--Well if this is a money making proposition and you plan to
make bunches you might want to invest in a Tapmatic. Once you use one
of these beauties you'll wonder how you got along without one for so
long. OTOH they ain't cheap..

--
"Steamboat Ed" Haas : Bummed to be living in the
Hacking the Trailing Edge! : Golden Age of Bull****...
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

If you are able to vary the voltage to your DP, you will at least have more
controllable torque at the motor, and can likely keep the speed constant at
a given pressure.
Proly not the greatest thing for the motor over prolonged periods, but for a
duty cycle of, say, 20%, it should be OK.
A variac would do, or a big-assed dropping resistor.
Or, perhaps just two motors in series--a spare motor in series w/ your DP
motor!
----------------------------
Mr. P.V.'d
formerly Droll Troll
"Joseph Gwinn" wrote in message
...
In June 2005, I was having problems because my little 12" Delta
variable-speed drill press has a minimum speed of 500 rpm, which was a
real problem, especially when countersinking.

I had found an interim solution for larger holes: Put the countersink
in the hole and turn power on, releasing the downward pressure before
the press gets up to speed.

This did not work with small holes, and the 1/4-inch severance
countersink, working in 6061 aluminum, flooded with a water-based
coolant. I would have thought that a small countersink would be OK at
500 rpm, but the holes became ragged and misshapen.

Countersinking with a hand drill did work, making pretty holes, but
yielded inaccurate countersinks because it's so hard to drill straight
by hand.

I was busily tearing metal and hair when it occurred to me that tapping
is an extreme kind of machining, and yet one can get clean threads, with
the right lubricant. So I tried LPS Labs' "Tap-All". It worked, even
at 500 rpm.

Haven't tried it in steel and/or for large holes yet.

Joe Gwinn

Joseph Gwinn wrote:

I would have thought that a small countersink would be OK at
500 rpm, but the holes became ragged and misshapen.

Yes, it is. As others sayd: More feed. Most people fear to feed
countersinks and think the have to go sloooow. Noooo. :-)
The first few 1/10mm feed fast, and then you can go back with feed. This
helps.

If you have chatter, I guess your DP's table is not clamped (and so
swinging a tad left/right). Fix that.
Also, clamp your part to countersink in a (heavy) vice, and I bet your
problem is gone.

Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

In article ,
(Nick Müller) wrote:

Joseph Gwinn wrote:

I would have thought that a small countersink would be OK at
500 rpm, but the holes became ragged and misshapen.

Yes, it is. As others sayd: More feed. Most people fear to feed
countersinks and think the have to go sloooow. Noooo. :-)
The first few 1/10mm feed fast, and then you can go back with feed. This
helps.

OK. What seemed to be happening was that the countersink flutes became
clogged with chips, reducing one to drilling aluminum with an aluminum
tool. Not a good combination.


If you have chatter, I guess your DP's table is not clamped (and so
swinging a tad left/right). Fix that.
Also, clamp your part to countersink in a (heavy) vice, and I bet your
problem is gone.

Everything was clamped, but the misshapen hole was in a 3" disk made of
0.060" sheet, which is hard to really clamp.

I'll have to do some experiments on waste stock. Thanks,

Joe Gwinn

I have much better results in all materials, especially aluminum,
using this type of countersink:
look at Series 67
http://www.maford.com/taf/catalog.taf?category=a11

(top posted for your convenience)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Keep the whole world singing . . . .
DanG (remove the sevens)




"Joseph Gwinn" wrote in message
...
In article ,
(Nick Müller) wrote:

Joseph Gwinn wrote:

I would have thought that a small countersink would be OK at
500 rpm, but the holes became ragged and misshapen.

Yes, it is. As others sayd: More feed. Most people fear to feed
countersinks and think the have to go sloooow. Noooo. :-)
The first few 1/10mm feed fast, and then you can go back with
feed. This
helps.

OK. What seemed to be happening was that the countersink flutes
became
clogged with chips, reducing one to drilling aluminum with an
aluminum
tool. Not a good combination.


If you have chatter, I guess your DP's table is not clamped
(and so
swinging a tad left/right). Fix that.
Also, clamp your part to countersink in a (heavy) vice, and I
bet your
problem is gone.

Everything was clamped, but the misshapen hole was in a 3" disk
made of
0.060" sheet, which is hard to really clamp.

I'll have to do some experiments on waste stock. Thanks,

Joe Gwinn

Joseph Gwinn wrote:

Everything was clamped, but the misshapen hole was in a 3" disk made of
0.060" sheet, which is hard to really clamp.

OK, this is nearly impossible with the 3 flutes countersinks. You need
one with one flute of the type with one diagonal hole. They are good for
deburring, but in a material so thin, you are deburring.


Nick

--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige