I do a lot of spiral milling instead of drilling on my little high speed
(RPM) mills. There are a couple reasons. One is it allows for fewer tool
changes. I can point vent, dump vent, rough cavities and make the holes for
pins and clamping screws all with the same little 1/8 SE end mill. The
other is those little high speed spindles just aren't suitable for drilling.
I've worked out a few operations I can drill with them, but they just aren't
suited for it. It takes a lot of figuring and testing to find something
that gets the speed, feed, and HP curve to all line up so it drills without
smearing the drilling in the collet, wearing out the drill prematurely,
breaking the mill, or causing lost steps. I am sure somebody has it all
worked out, but that is not what I am asking.

Here is what I am asking. When I am spiral milling to drill holes I noticed
at more than about 0.40 inches it starts making some noise that annoys my
primordial hind brain. Since I work with a lot of 1/2" bar stock that
leaves me finishing on the drill press among my other secondary operations.
What causes that eerie noise, and what can I do about it? I am already
blasting the area with water soluble flood coolant. If I could spiral mill
all the way through it would save a fair amount of time in secondary
operations. Often I have several molds to do the hand finish stuff on at
once. Each half will have atleast two alignment pin holes, and anywhere
from 2 to 20 clamping screw holes to be finished.

0.40" depth? How long are your flutes? are chips getting backed up in the hole? Or... have you tried changing spindle and/or step speeds? maybe something is getting resonant.

Bob La Londe wrote:


Here is what I am asking. When I am spiral milling to drill holes I
noticed at more than about 0.40 inches it starts making some noise that
annoys my
primordial hind brain. Since I work with a lot of 1/2" bar stock that
leaves me finishing on the drill press among my other secondary
operations.
What causes that eerie noise, and what can I do about it? I am already
blasting the area with water soluble flood coolant. If I could spiral
mill all the way through it would save a fair amount of time in secondary
operations. Often I have several molds to do the hand finish stuff on at
once. Each half will have atleast two alignment pin holes, and anywhere
from 2 to 20 clamping screw holes to be finished.
I do some of this on instrument panels. They are typically 1/8" thick
aluminum, and the holes usually go all the way through. For small holes, I
spot and drill. But, for holes over 1/4" diameter, I mill out all the holes
and other panel cutouts with a 1/8" carbide end mill. Since this is on a 1J
Bridgeport, my top speed without overspeeding the motor is ~2720 RPM.
(pretty slow for carbide.) Anyway, I usually make the holes with 3 depth
steps, so that is something like .050" step down in Z. I cut all the way
through first, leaving .010" on the walls, and then finish to final
diameter. Oh, and always climb cut! I do now have a routine for spiraling
down, it is maybe a little faster, saving maybe a whole orbit or so per
hole. I don't notice it having much difference in hole quality.

Jon

"rangerssuck" wrote in message
...

0.40" depth? How long are your flutes? are chips getting backed up in the
hole? Or... have you tried changing spindle
and/or step speeds? maybe something is getting resonant.

I suppose I could try breaking it up into two or three operation so the head
raises and lowers giving the coolant stream a chance to hit the hole at
different angles. I do hit the cutter fairly high so the spray shoots
downward off of it.

I have not tried different speeds. I guess maybe a lower RPM with higher
torque requirements could change something. Its worth a try.

On 19/04/2017 6:10 AM, Bob La Londe wrote:

Here is what I am asking. When I am spiral milling to drill holes I
noticed at more than about 0.40 inches it starts making some noise that
annoys my primordial hind brain. Since I work with a lot of 1/2" bar
stock that leaves me finishing on the drill press among my other
secondary operations. What causes that eerie noise, and what can I do
about it?

I suspect end mill deflection, which though slight, becomes ever more
pronounced as depth increases, causing a sort of chatter due to the
rubbing contact of the flutes. Might try stub end mills, and relieve the
shank a bit behind the flutes.

Jon

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

In article ,
"Bob La Londe" wrote:

I do a lot of spiral milling instead of drilling on my little high speed
(RPM) mills. There are a couple reasons. One is it allows for fewer tool
changes. I can point vent, dump vent, rough cavities and make the holes for
pins and clamping screws all with the same little 1/8 SE end mill. The
other is those little high speed spindles just aren't suitable for drilling.
I've worked out a few operations I can drill with them, but they just aren't
suited for it. It takes a lot of figuring and testing to find something
that gets the speed, feed, and HP curve to all line up so it drills without
smearing the drilling in the collet, wearing out the drill prematurely,
breaking the mill, or causing lost steps. I am sure somebody has it all
worked out, but that is not what I am asking.

Here is what I am asking. When I am spiral milling to drill holes I noticed
at more than about 0.40 inches it starts making some noise that annoys my
primordial hind brain. Since I work with a lot of 1/2" bar stock that
leaves me finishing on the drill press among my other secondary operations.
What causes that eerie noise, and what can I do about it? I am already
blasting the area with water soluble flood coolant. If I could spiral mill
all the way through it would save a fair amount of time in secondary
operations. Often I have several molds to do the hand finish stuff on at
once. Each half will have atleast two alignment pin holes, and anywhere
from 2 to 20 clamping screw holes to be finished.

If chips are collecting in the bottom of the hole and being recycled
into the cutter, you might try pilot drilling the hole through the part
first so that the chips can be flushed away.

"Mark Storkamp" wrote in message
...

In article ,
"Bob La Londe" wrote:

I do a lot of spiral milling instead of drilling on my little high speed
(RPM) mills. There are a couple reasons. One is it allows for fewer tool
changes. I can point vent, dump vent, rough cavities and make the holes
for
pins and clamping screws all with the same little 1/8 SE end mill. The
other is those little high speed spindles just aren't suitable for
drilling.
I've worked out a few operations I can drill with them, but they just
aren't
suited for it. It takes a lot of figuring and testing to find something
that gets the speed, feed, and HP curve to all line up so it drills
without
smearing the drilling in the collet, wearing out the drill prematurely,
breaking the mill, or causing lost steps. I am sure somebody has it all
worked out, but that is not what I am asking.

Here is what I am asking. When I am spiral milling to drill holes I
noticed
at more than about 0.40 inches it starts making some noise that annoys my
primordial hind brain. Since I work with a lot of 1/2" bar stock that
leaves me finishing on the drill press among my other secondary
operations.
What causes that eerie noise, and what can I do about it? I am already
blasting the area with water soluble flood coolant. If I could spiral
mill
all the way through it would save a fair amount of time in secondary
operations. Often I have several molds to do the hand finish stuff on at
once. Each half will have atleast two alignment pin holes, and anywhere
from 2 to 20 clamping screw holes to be finished.

If chips are collecting in the bottom of the hole and being recycled
into the cutter, you might try pilot drilling the hole through the part
first so that the chips can be flushed away.

****
I do a lot of spiral milling instead of drilling on my little high speed
(RPM) mills. There are a couple reasons. One is it allows for fewer tool
changes. I can point vent, dump vent, rough cavities and make the holes
for
pins and clamping screws all with the same little 1/8 SE end mill. The
other is those little high speed spindles just aren't suitable for
drilling.
****

On my big mill I spot drill and drill all the holes with its 5HP Leland
motor driven 3600 rpm spindle. Its an awesome drilling machine. I have a
hard time not getting good holes by drilling this way on that machine.
Unfortunately the little 24000 RPM spindles (referenced in this thread) with
just about zero useable torque below 12000 RPM just don't work out very well
for me for drilling. They are awesome for higher feedrate tiny cutter
milling, but drilling is a different animal.

I am sure somebody has it all
worked out, but that is not what I am asking.

No, moving parts from one machine to the other really isn't the answer
either. Each machine has its own work to do. Often all 4 of my CNC mills
are running at the same time. Sometimes even while I have the bandsaw
cutting parts and I am turning something on one of the lathes.

"Jon Anderson" wrote in message ...

On 19/04/2017 6:10 AM, Bob La Londe wrote:

Here is what I am asking. When I am spiral milling to drill holes I
noticed at more than about 0.40 inches it starts making some noise that
annoys my primordial hind brain. Since I work with a lot of 1/2" bar
stock that leaves me finishing on the drill press among my other
secondary operations. What causes that eerie noise, and what can I do
about it?

I suspect end mill deflection, which though slight, becomes ever more
pronounced as depth increases, causing a sort of chatter due to the
rubbing contact of the flutes. Might try stub end mills,

*** Unless you are using long reach end mills 1/8 inch shank anything pretty
much is a stub end mill.

and relieve the
shank a bit behind the flutes.

*** That is not at all a bad idea. I may have to look into that. Even a
couple thousandths would probably do if deflection from rubbing is the
issue.

Jon

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On 20/04/2017 2:06 AM, Bob La Londe wrote:

*** Unless you are using long reach end mills 1/8 inch shank anything
pretty much is a stub end mill.

I've forgotten the name of the company, but there is an outfit that
specializes in small end mills. They have stub end mills that have
-very- short flute lengths. Like maybe 1/8 for a 1/8" end mill.

Only other thing I could suggest would be to interp the hole small
enough to leave enough material for a light finish pass, eliminating any
chance of deflection. At the cost of increasing run time however.
Giving this a try on a few holes though, might confirm or deny the
deflection theory.

Jon

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On Tue, 18 Apr 2017 13:10:04 -0700, "Bob La Londe"
wrote:

I do a lot of spiral milling instead of drilling on my little high speed
(RPM) mills. There are a couple reasons. One is it allows for fewer tool
changes. I can point vent, dump vent, rough cavities and make the holes for
pins and clamping screws all with the same little 1/8 SE end mill. The
other is those little high speed spindles just aren't suitable for drilling.
I've worked out a few operations I can drill with them, but they just aren't
suited for it. It takes a lot of figuring and testing to find something
that gets the speed, feed, and HP curve to all line up so it drills without
smearing the drilling in the collet, wearing out the drill prematurely,
breaking the mill, or causing lost steps. I am sure somebody has it all
worked out, but that is not what I am asking.

Here is what I am asking. When I am spiral milling to drill holes I noticed
at more than about 0.40 inches it starts making some noise that annoys my
primordial hind brain. Since I work with a lot of 1/2" bar stock that
leaves me finishing on the drill press among my other secondary operations.
What causes that eerie noise, and what can I do about it? I am already
blasting the area with water soluble flood coolant. If I could spiral mill
all the way through it would save a fair amount of time in secondary
operations. Often I have several molds to do the hand finish stuff on at
once. Each half will have atleast two alignment pin holes, and anywhere
from 2 to 20 clamping screw holes to be finished.

Greetings Bob,
Are you using carbide endmills? It sounds like you have a rigidity
problem. .400 depth of cut for a 1/8 endmill is pretty long.
Especially for HSS. I think what is happening is chatter. You can
make things stiffer, slow the cutter, and increase the feed to help.
Sometimes these options are not viable. But there are also cutter
options. Carbide cutters are made in 1/8 diameter with 3 flutes that
are not evenly spaced. This helps with resonant vibrations which I
think is what you are experiencing. What size are the holes you are
making? When spiral milling are you cutting a .125 slot? Is the hole
diameter smaller than .25 so that the chips have somewhere to go? You
may be having problems with chip evacuation which leads to chip
recutting.
Eric