I need to drill a hole in a grade 8 bolt. three actually, two cross and one
axially. I remember this was a stone bitch from last time I tried. I got one
shot this time. Should I drill it slow and hard like stainless, or fast and
light pecks? Other suggestions?

Karl

On 2009-07-28, Karl Townsend wrote:
I need to drill a hole in a grade 8 bolt. three actually, two cross and one
axially. I remember this was a stone bitch from last time I tried. I got one
shot this time. Should I drill it slow and hard like stainless, or fast and
light pecks? Other suggestions?

Grade 8 bolts drill nicely. In fact I will do the same today.

i

It depends on the material Karl not the rating as a bolt.
Carbon steel and Stainless are both avaliable in grade 8.

Its a steel bolt.

Grade 8 bolts drill nicely. In fact I will do the same today.

I hope you're right. This is a metric button head fine thread. Won't be easy
to find another. Murphy is my partner. I wouldn't even ask if i had a
practice bolt or two.

Karl

On Mon, 27 Jul 2009 20:16:21 -0500, "Karl Townsend"
wrote:


Grade 8 bolts drill nicely. In fact I will do the same today.

I hope you're right. This is a metric button head fine thread. Won't be easy
to find another. Murphy is my partner. I wouldn't even ask if i had a
practice bolt or two.

Unlike US alloy socket heads, metric socket heads come in different
grades. The most common (class 12.9) is similar to US alloy socket
heads, and perhaps 5 points harder than a grade 8 cap screw on the Rc
scale.

--
Ned Simmons

Karl Townsend wrote:
I need to drill a hole in a grade 8 bolt. three actually, two cross
and one axially. I remember this was a stone bitch from last time I
tried. I got one shot this time. Should I drill it slow and hard like
stainless, or fast and light pecks? Other suggestions?

It depends on the material Karl not the rating as a bolt.
Carbon steel and Stainless are both avaliable in grade 8.



--
John R. Carroll

John R. Carroll wrote:
Karl Townsend wrote:
It depends on the material Karl not the rating as a bolt.
Carbon steel and Stainless are both avaliable in grade 8.
Its a steel bolt.

Then you'll be good with a HSS Split point drill at 40 SFM and oil for a
lubricant.
Keep a good bite on your drill but it won't work harden and peck often as
you refresh the cutting oil.



The real difficulty is breaking through the far side.
Snug up the Z axis clamp a little and pay attention.
LOL



Got a trick to keep from breaking bits on the back side?

Karl Townsend wrote:
It depends on the material Karl not the rating as a bolt.
Carbon steel and Stainless are both avaliable in grade 8.

Its a steel bolt.

Then you'll be good with a HSS Split point drill at 40 SFM and oil for a
lubricant.
Keep a good bite on your drill but it won't work harden and peck often as
you refresh the cutting oil.
The real difficulty is breaking through the far side.
Snug up the Z axis clamp a little and pay attention.
LOL


--
John R. Carroll

So what's the size? Maybe one of us has a spare for you laying in the junk
drawer :-).

-----
Regards,
Carl Ijames

"Karl Townsend" wrote in message
anews.com...
I need to drill a hole in a grade 8 bolt. three actually, two cross and one
axially. I remember this was a stone bitch from last time I tried. I got
one shot this time. Should I drill it slow and hard like stainless, or fast
and light pecks? Other suggestions?

Karl

cavelamb wrote:
John R. Carroll wrote:
Karl Townsend wrote:
It depends on the material Karl not the rating as a bolt.
Carbon steel and Stainless are both avaliable in grade 8.
Its a steel bolt.

Then you'll be good with a HSS Split point drill at 40 SFM and oil
for a lubricant.
Keep a good bite on your drill but it won't work harden and peck
often as you refresh the cutting oil.



The real difficulty is breaking through the far side.
Snug up the Z axis clamp a little and pay attention.
LOL



Got a trick to keep from breaking bits on the back side?

Squeezing my butt cheeks together didn't seem to help, not the drill anyway.
Snugging the Z at the end will keep the drill from grabbing and that's the
problem.
On a manual machine, the spindle will release any slop or backlash as you
break through and drills turn into wood screws in a hurry.

I saw a guy rapid a drill an inch or more into an aluminum part once and
when the spindle came up, the drill stayed - unbroken - in the job.Ruined
the collet.
The part was a mold cavity so somebody had to figure out how to get the
thing out.
I'm glad that guy wasn't me.
The thing I've wondered about since is where the aluminum went?
The drill and the stock couldn't have occupied the same space but it sure
looked that way.
LMAO

--
John R. Carroll

On Mon, 27 Jul 2009 17:57:45 -0800, "John R. Carroll"
wrote:

Karl Townsend wrote:
I need to drill a hole in a grade 8 bolt. three actually, two cross
and one axially. I remember this was a stone bitch from last time I
tried. I got one shot this time. Should I drill it slow and hard like
stainless, or fast and light pecks? Other suggestions?

It depends on the material Karl not the rating as a bolt.
Carbon steel and Stainless are both avaliable in grade 8.
And technically, there is no such thing as a metric grade 8.
There is 4.8 steel , 5.8 steel, and 8.8 steel as well as 10.9 and
12.9 steel
There is A2 and A4 stainless (304 (or 305) and 316.

On Mon, 27 Jul 2009 20:58:02 -0500, cavelamb wrote:

John R. Carroll wrote:
Karl Townsend wrote:
It depends on the material Karl not the rating as a bolt.
Carbon steel and Stainless are both avaliable in grade 8.
Its a steel bolt.

Then you'll be good with a HSS Split point drill at 40 SFM and oil for a
lubricant.
Keep a good bite on your drill but it won't work harden and peck often as
you refresh the cutting oil.



The real difficulty is breaking through the far side.
Snug up the Z axis clamp a little and pay attention.
LOL



Got a trick to keep from breaking bits on the back side?

Drill and thread a block of sacraficical material (I'd use aluminium).
Thread the bolt in, drill through both.

I have to drill safety wire holes in a dozen bolts every month or so. I have
a jig to line it up and use an air drill.
http://www.aircraftspruce.com/catalo...rillingjig.php I bust an
HSS bit nearly every time, not bad for 36 holes. Since it always breaks
finishing the hole I can usually drive it back out with an automatic
centerpunch followed by a pin punch.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

Ned Simmons wrote:
On Mon, 27 Jul 2009 20:16:21 -0500, "Karl Townsend"
wrote:


Grade 8 bolts drill nicely. In fact I will do the same today.

I hope you're right. This is a metric button head fine thread. Won't be easy
to find another. Murphy is my partner. I wouldn't even ask if i had a
practice bolt or two.


Unlike US alloy socket heads, metric socket heads come in different
grades. The most common (class 12.9) is similar to US alloy socket
heads, and perhaps 5 points harder than a grade 8 cap screw on the Rc
scale.


Also I don't think the button head mentioned are made in 12.9, I think
they are only made upto 10.9, maybe due to the smaller socket limiting
the tightening torque possible. The supplier should know.

"Karl Townsend" writes:

I need to drill a hole in a grade 8 bolt. three actually, two cross and one
axially. I remember this was a stone bitch from last time I tried. I got one
shot this time. Should I drill it slow and hard like stainless, or fast and
light pecks? Other suggestions?

EDR


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

"Karl Townsend" writes:

I need to drill a hole in a grade 8 bolt. three actually, two cross and one
axially. I remember this was a stone bitch from last time I tried. I got one
shot this time. Should I drill it slow and hard like stainless, or fast and
light pecks? Other suggestions?

make that "EDM".....

Slow, messy, but does not care how hard it is...



--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

David Lesher fired this volley in news:h4n5jo$hnm$3
@reader1.panix.com:

make that "EDM".....

Slow, messy, but does not care how hard it is...

I guess most folks are lucky enough to have sinker style EDM shop
nearby. The only two in my area are wire machines.

But... I can buy a Rockwell drill bit via overnight web-order, and do
the job faster and cheaper than taking it out somewhere.

Or, I can anneal the bolt, drill it, then take it to any one of eight
or ten heat-treating shops around here.


LLoyd

On Mon, 27 Jul 2009 20:58:02 -0500, cavelamb
wrote:

John R. Carroll wrote:
Karl Townsend wrote:
It depends on the material Karl not the rating as a bolt.
Carbon steel and Stainless are both avaliable in grade 8.
Its a steel bolt.

Then you'll be good with a HSS Split point drill at 40 SFM and oil for a
lubricant.
Keep a good bite on your drill but it won't work harden and peck often as
you refresh the cutting oil.



The real difficulty is breaking through the far side.
Snug up the Z axis clamp a little and pay attention.
LOL



Got a trick to keep from breaking bits on the back side?

Back up the workpiece with a bit of scrap steel or even aluminum. The
workpiece (and the backing beneath it) should be in a vise.

Stupendous Man wrote:
I have to drill safety wire holes in a dozen bolts every month or so. I
have a jig to line it up and use an air drill.
http://www.aircraftspruce.com/catalo...rillingjig.php I bust
an HSS bit nearly every time, not bad for 36 holes. Since it always
breaks finishing the hole I can usually drive it back out with an
automatic centerpunch followed by a pin punch.

Yep, that's my experience as well.
(Butt cheeks squeezed tight or flappin' inthe breeze)

Lloyd E. Sponenburgh wrote:
David Lesher fired this volley in news:h4n5jo$hnm$3
@reader1.panix.com:

make that "EDM".....

Slow, messy, but does not care how hard it is...

I guess most folks are lucky enough to have sinker style EDM shop
nearby. The only two in my area are wire machines.

They should have a hole popper.
Those are very fast so you shouldn't have to spend much.

--
John R. Carroll

On Jul 27, 5:44*pm, "Karl Townsend"
wrote:
I need to drill a hole in a grade 8 bolt. three actually, two cross and one
axially. I remember this was a stone bitch from last time I tried. I got one
shot this time. Should I drill it slow and hard like stainless, or fast and
light pecks? Other suggestions?

Karl

They used to demonstrate that a Cole drill machine could drill through
a drill. Slow would seem to be sure.