I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. I'm feeding at about .025"/min.
with mist cooling/lube. I cut .510" then flip the disk and cut another
..510" then knock out the slug with a BFH. I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

This job is REALLY boring and anything to go faster would be
appreciated. BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

Also, I'm looking for an output hose and nozzle for a "Kool Mist" mister
that somehow got lost. I can get a new one for about $20 but if someone
has it for sale please let me know.

On Fri, 01 Jun 2012 02:43:02 -0400, Tom Gardner Mars@Tacks wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any

Man I stand in awe. I would have said no way can you trepan 1"+ deep
in a hard material.

I would have used the mill. A CNC makes a job like this trivial. Maybe
its time for you to learn, WAY easier than ladder logic. A rotary
table is another approach. If you don't care if your knockout is a bit
ruff, chain drill all the way around, then put in the same size
endmill and milldrill between each hole. This goes way fast, drilling
is the fastest way to remove material.

Karl

On Fri, 01 Jun 2012 02:43:02 -0400, Tom Gardner Mars@Tacks wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. I'm feeding at about .025"/min.
with mist cooling/lube. I cut .510" then flip the disk and cut another
.510" then knock out the slug with a BFH. I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

You should get higher surface speeds, but not necessarily higher feed
rates. Yes, they're more likely to break, but there should be no
difference with a continuous cut. They're more brittle but they're at
least as strong.

You probably could get better performance with a stiffer toolholder.

It's interesting that you found 5% cobalt square bits (M35 or T4?). I
was looking fo rthem for years, because I inherited some and they
worked great in my South Bend. I no longer have the need so I quit
looking. M42 was too brittle for interrupted cuts on my SB. They
chipped. I was cutting grooves in splined shafts.


This job is REALLY boring and anything to go faster would be
appreciated. BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

If you get really bored, have them blanked with wirecut EDM. You're
looking at about 1/2 hour per cut. Is your time worth $30 per blank?

--
Ed Huntress


Also, I'm looking for an output hose and nozzle for a "Kool Mist" mister
that somehow got lost. I can get a new one for about $20 but if someone
has it for sale please let me know.

Tom Gardner wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. I'm feeding at about .025"/min.
with mist cooling/lube. I cut .510" then flip the disk and cut another
.510" then knock out the slug with a BFH. I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

This job is REALLY boring and anything to go faster would be
appreciated. BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

Also, I'm looking for an output hose and nozzle for a "Kool Mist" mister
that somehow got lost. I can get a new one for about $20 but if someone
has it for sale please let me know.

Plasma cut (CNC?) and then finish up? Plasma doesn't care about the
hardness of the material, only the conductivity. Should take about 10
seconds per hole.

"Ed Huntress" wrote in message
...
...M42 was too brittle for interrupted cuts on my SB. They
chipped. I was cutting grooves in splined shafts.


I surface-ground the worn lower surface of the compound on my 10L so I
could tighten the gibs to cut tapers, and solved several other
looseness problems as well. The toolpost slot area and the two "OIL"
pads gave enough distributed support on the mag chuck.

jsw

On Fri, 01 Jun 2012 06:26:52 -0500, Karl Townsend
wrote:

On Fri, 01 Jun 2012 02:43:02 -0400, Tom Gardner Mars@Tacks wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any

Man I stand in awe. I would have said no way can you trepan 1"+ deep
in a hard material.

I would have used the mill. A CNC makes a job like this trivial. Maybe
its time for you to learn, WAY easier than ladder logic. A rotary
table is another approach. If you don't care if your knockout is a bit
ruff, chain drill all the way around, then put in the same size
endmill and milldrill between each hole. This goes way fast, drilling
is the fastest way to remove material.

Karl
I trepanned a bunch of 2 inch discs in 1 inch 6AL4V titanium plate to
save time. To avoid tool breakage when breaking through I trepanned
from both sides. The face of the tool was ground at an angle so that
when the disc broke free there was still a web to support the disc in
the hole.
Eric

On 6/1/2012 7:26 AM, Karl Townsend wrote:
On Fri, 01 Jun 2012 02:43:02 -0400, Tom GardnerMars@Tacks wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any

Man I stand in awe. I would have said no way can you trepan 1"+ deep
in a hard material.

I would have used the mill. A CNC makes a job like this trivial. Maybe
its time for you to learn, WAY easier than ladder logic. A rotary
table is another approach. If you don't care if your knockout is a bit
ruff, chain drill all the way around, then put in the same size
endmill and milldrill between each hole. This goes way fast, drilling
is the fastest way to remove material.

Karl

Oh boy, I SURE remember doing this job on the drill press! Then, on a
very old lathe driven by leather belts, then drilling with up to 3"
drills. I still have those big bits, thank God I haven't used them for
many, many years. Thanks for the memories!

I would love a CNC mill, maybe someday...

On 6/1/2012 9:02 AM, Ed Huntress wrote:
On Fri, 01 Jun 2012 02:43:02 -0400, Tom GardnerMars@Tacks wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. I'm feeding at about .025"/min.
with mist cooling/lube. I cut .510" then flip the disk and cut another
.510" then knock out the slug with a BFH. I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

You should get higher surface speeds, but not necessarily higher feed
rates. Yes, they're more likely to break, but there should be no
difference with a continuous cut. They're more brittle but they're at
least as strong.

You probably could get better performance with a stiffer toolholder.

It's interesting that you found 5% cobalt square bits (M35 or T4?). I
was looking fo rthem for years, because I inherited some and they
worked great in my South Bend. I no longer have the need so I quit
looking. M42 was too brittle for interrupted cuts on my SB. They
chipped. I was cutting grooves in splined shafts.


This job is REALLY boring and anything to go faster would be
appreciated. BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

If you get really bored, have them blanked with wirecut EDM. You're
looking at about 1/2 hour per cut. Is your time worth $30 per blank?


I figure my time isn't worth anything, I only spend about an hour or so
a day on it so far. I have the tool holder fit perfectly to a
quick-change so it's as rigid as can be, I learned THAT lesson long
ago. Rigidity is KING! We remachined and ground the cheapie
quick-change post and tool holders and replaced the metric fasteners
with SAE but it is clearly at the limits for that toolpost, It's not the
biggest one

On 6/1/2012 9:07 AM, Pete C. wrote:

Tom Gardner wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. I'm feeding at about .025"/min.
with mist cooling/lube. I cut .510" then flip the disk and cut another
.510" then knock out the slug with a BFH. I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

This job is REALLY boring and anything to go faster would be
appreciated. BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

Also, I'm looking for an output hose and nozzle for a "Kool Mist" mister
that somehow got lost. I can get a new one for about $20 but if someone
has it for sale please let me know.

Plasma cut (CNC?) and then finish up? Plasma doesn't care about the
hardness of the material, only the conductivity. Should take about 10
seconds per hole.

Would there be a heat-affected zone that would be hard? I still have to
finish the bore with a boring bar and machine two slots for drive pins.
The disks will be rotary knives for wire cutting.

Tom Gardner wrote:

On 6/1/2012 9:07 AM, Pete C. wrote:

Tom Gardner wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. I'm feeding at about .025"/min.
with mist cooling/lube. I cut .510" then flip the disk and cut another
.510" then knock out the slug with a BFH. I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

This job is REALLY boring and anything to go faster would be
appreciated. BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

Also, I'm looking for an output hose and nozzle for a "Kool Mist" mister
that somehow got lost. I can get a new one for about $20 but if someone
has it for sale please let me know.

Plasma cut (CNC?) and then finish up? Plasma doesn't care about the
hardness of the material, only the conductivity. Should take about 10
seconds per hole.

Would there be a heat-affected zone that would be hard? I still have to
finish the bore with a boring bar and machine two slots for drive pins.
The disks will be rotary knives for wire cutting.

Probably, but not likely that thick. Waterjet would probably do nicely
without any heat, but it's certainly less DIY.

On Jun 1, 12:43*am, Tom Gardner Mars@Tacks wrote:
I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. *I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. *So, I'm trepanning the hole. *I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. *I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. *I'm feeding at about .025"/min.
with mist cooling/lube. *I cut .510" then flip the disk and cut another
.510" then knock out the slug with a BFH. *I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. *I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. *One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. *Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

This job is REALLY boring and anything to go faster would be
appreciated. *BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

Also, I'm looking for an output hose and nozzle for a "Kool Mist" mister
that somehow got lost. *I can get a new one for about $20 but if someone
has it for sale please let me know.

I did something like this only with cast iron rounds, the outer 1" had
been chilled by the continuous casting process, so was a real bear
with normal HSS bits. I got some Tantung-branded bits, no more
problems. The higher percentage cobalt HSS bits will hold an edge
longer and/or will run faster, but only if you get the right geometry,
they get more brittle the higher percentage Co you go. You could see
the transition between the inner grey iron and the chilled area, the
swarf went from grey powder to small shiny white curls. With HSS,
that was where the bits went dull after a couple of revs. I like
Tantung stuff for large internal threading, it means I don't have to
stop mid-job, sharpen the bit and pick up the thread again. Don't
even know if it's available now, has a lot of now-expensive elements
in it that used to be a whole lot cheaper. A non-steel tool
material. Touch it up with a diamond hone after grinding and your cut
surface will be almost polished.

Stan

On Fri, 1 Jun 2012 09:15:11 -0400, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
...M42 was too brittle for interrupted cuts on my SB. They
chipped. I was cutting grooves in splined shafts.


I surface-ground the worn lower surface of the compound on my 10L so I
could tighten the gibs to cut tapers, and solved several other
looseness problems as well. The toolpost slot area and the two "OIL"
pads gave enough distributed support on the mag chuck.

jsw

I probably could tighten up my machine to that it would do better. But
mine was never in commercial, military, or school service, so it's not
worn. The frosting is still visible over the entire bed. It's been a
lightly-used hobby machine since my uncle bought it as unused surplus,
still in its navy Cosmoline in 1948.

--
Ed Huntress

On Fri, 01 Jun 2012 10:51:12 -0400, Tom Gardner Mars@Tacks wrote:

On 6/1/2012 9:02 AM, Ed Huntress wrote:
On Fri, 01 Jun 2012 02:43:02 -0400, Tom GardnerMars@Tacks wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. I'm feeding at about .025"/min.
with mist cooling/lube. I cut .510" then flip the disk and cut another
.510" then knock out the slug with a BFH. I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

You should get higher surface speeds, but not necessarily higher feed
rates. Yes, they're more likely to break, but there should be no
difference with a continuous cut. They're more brittle but they're at
least as strong.

You probably could get better performance with a stiffer toolholder.

It's interesting that you found 5% cobalt square bits (M35 or T4?). I
was looking fo rthem for years, because I inherited some and they
worked great in my South Bend. I no longer have the need so I quit
looking. M42 was too brittle for interrupted cuts on my SB. They
chipped. I was cutting grooves in splined shafts.


This job is REALLY boring and anything to go faster would be
appreciated. BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

If you get really bored, have them blanked with wirecut EDM. You're
looking at about 1/2 hour per cut. Is your time worth $30 per blank?


I figure my time isn't worth anything, I only spend about an hour or so
a day on it so far. I have the tool holder fit perfectly to a
quick-change so it's as rigid as can be, I learned THAT lesson long
ago. Rigidity is KING! We remachined and ground the cheapie
quick-change post and tool holders and replaced the metric fasteners
with SAE but it is clearly at the limits for that toolpost, It's not the
biggest one

Aha. Well, I'm sure you've figured out where any potential flexing may
be in the toolholder, but a shop-made holder probably could be deeper
and wider. And there's no reason to harden it; it wouldn't be any
stiffer if you did. You could make it from 12L14 or 1018 and it would
be as stiff as tool steel.

Good luck.

--
Ed Huntress

"Karl Townsend" wrote in message ...
On Fri, 01 Jun 2012 02:43:02 -0400, Tom Gardner Mars@Tacks wrote:

I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any

Man I stand in awe. I would have said no way can you trepan 1"+ deep
in a hard material.

I would have used the mill. A CNC makes a job like this trivial. Maybe
its time for you to learn, WAY easier than ladder logic. A rotary
table is another approach. If you don't care if your knockout is a bit
ruff, chain drill all the way around, then put in the same size
endmill and milldrill between each hole. This goes way fast, drilling
is the fastest way to remove material.



The piece of D2 he's dicking around trying to salvage is worth about $15.00 each--apparently, his time isn't very valuable....

On 6/1/2012 2:02 PM, Stanley Schaefer wrote:
On Jun 1, 12:43 am, Tom GardnerMars@Tacks wrote:
I have 12 each D-2 disks that are 1.050" thick that need a 4" bore. I
want the inside pieces of D-2, they are great for small dies, jigs and
other tooling. So, I'm trepanning the hole. I haven't seen any
commercial trepanning tooling or core saws that fit my budget so I hand
ground a number of bits using 1/2" square HSS tool bits and modified a
big lantern-style tool bit holder to fit the quick-change post. I've
only broke one bit but I learned to grind the bit with a very slight
negative rake and very little relief. I'm feeding at about .025"/min.
with mist cooling/lube. I cut .510" then flip the disk and cut another
.510" then knock out the slug with a BFH. I've only got 3 disks done so
far.

I ground the bits from some 60+ year-old bits. I have no complaints, I
only have to touch the tip to a grinding wheel once per side of each
disk. One of my engineers bought some new tool bits that are 5% and 10%
Cobalt. Should I get better performance and higher feed rate or will
the Cobalt be more likely to break?

This job is REALLY boring and anything to go faster would be
appreciated. BUT, I haven't done it for years and it's kinda' nice to
make chips again once in a while even though I get pulled away fairly often.

Also, I'm looking for an output hose and nozzle for a "Kool Mist" mister
that somehow got lost. I can get a new one for about $20 but if someone
has it for sale please let me know.

I did something like this only with cast iron rounds, the outer 1" had
been chilled by the continuous casting process, so was a real bear
with normal HSS bits. I got some Tantung-branded bits, no more
problems. The higher percentage cobalt HSS bits will hold an edge
longer and/or will run faster, but only if you get the right geometry,
they get more brittle the higher percentage Co you go. You could see
the transition between the inner grey iron and the chilled area, the
swarf went from grey powder to small shiny white curls. With HSS,
that was where the bits went dull after a couple of revs. I like
Tantung stuff for large internal threading, it means I don't have to
stop mid-job, sharpen the bit and pick up the thread again. Don't
even know if it's available now, has a lot of now-expensive elements
in it that used to be a whole lot cheaper. A non-steel tool
material. Touch it up with a diamond hone after grinding and your cut
surface will be almost polished.

Stan

If (when) I break another bit I'll try the 5%. I did get one more done
today in just over 45 minutes. (between disasters)

Nowadays, I do this sort of stuff with a CNC milling machine, milling
out a helical spiral. I just give it a command and go away until it is
finished, I do not care how long it takes.

i

On 6/1/2012 11:23 PM, Ignoramus20751 wrote:
Nowadays, I do this sort of stuff with a CNC milling machine, milling
out a helical spiral. I just give it a command and go away until it is
finished, I do not care how long it takes.

i

Show off!