Gun drilling without a gun drill...
 

Not easy...

..3125" through 7" of 304SS on the lathe with a 12" extension drill with
about 3" of flutes. This gave me .2" of nudging it along before
unlocking the tailstock and pulling the whole thing back to clear chips
before shoving it back in, locking the tailstock and nudging another
..2". Took forever and a day in my 99F shop, but somehow I got it done.

Gun drilling without a gun drill...
 

"Pete C." fired this volley in news:53d59c7f$0$12266
:

Not easy...

.3125" through 7" of 304SS on the lathe with a 12" extension drill with
about 3" of flutes. This gave me .2" of nudging it along before
unlocking the tailstock and pulling the whole thing back to clear chips
before shoving it back in, locking the tailstock and nudging another
.2". Took forever and a day in my 99F shop, but somehow I got it done.

Yeah, it's a chore... and I'll bet it's _perfectly_axial_ to the chuck the
whole way through, too! not G

Lloyd

Gun drilling without a gun drill...
 

"Pete C." wrote in message
. com...

Not easy...

.3125" through 7" of 304SS on the lathe with a 12" extension drill
with
about 3" of flutes. This gave me .2" of nudging it along before
unlocking the tailstock and pulling the whole thing back to clear
chips
before shoving it back in, locking the tailstock and nudging another
.2". Took forever and a day in my 99F shop, but somehow I got it
done.

That's about the only job I still use my little AA/Sears lathe for
instead of the South Bend, because the little guy spins so much
faster.
-jsw

Gun drilling without a gun drill...
 

"Lloyd E. Sponenburgh" wrote:

"Pete C." fired this volley in news:53d59c7f$0$12266
:

Not easy...

.3125" through 7" of 304SS on the lathe with a 12" extension drill with
about 3" of flutes. This gave me .2" of nudging it along before
unlocking the tailstock and pulling the whole thing back to clear chips
before shoving it back in, locking the tailstock and nudging another
.2". Took forever and a day in my 99F shop, but somehow I got it done.

Yeah, it's a chore... and I'll bet it's _perfectly_axial_ to the chuck the
whole way through, too! not G

Lloyd

It looks pretty good actually. It was a high quality drill, Guherig
(sp?), so it behaved pretty well. At any rate, it is coaxial with the OD
at the start point, so if I flip it around and center that end in the 4
jaw, with the tailstock in the exit hole and then re-turn the OD it
should center it up. The 1.75" OD ends up at 1.25" so there is plenty
left to remove.

Gun drilling without a gun drill...
 

"Pete C." fired this volley in news:53d5a550$0
:

so if I flip it around and center that end in the 4
jaw, with the tailstock in the exit hole and then re-turn the OD it
should center it up. The 1.75" OD ends up at 1.25" so there is plenty
left to remove.


Over only 7", it won't curve much, but you can be pretty certain the hole
isn't merely angled, but actually arc'd.

Chucking it isn't the way to get the two ends true to center. Catch the
piece between centers, and dog it.

Lloyd

Gun drilling without a gun drill...
 

"Lloyd E. Sponenburgh" wrote:

"Pete C." fired this volley in news:53d5a550$0
:

so if I flip it around and center that end in the 4
jaw, with the tailstock in the exit hole and then re-turn the OD it
should center it up. The 1.75" OD ends up at 1.25" so there is plenty
left to remove.


Over only 7", it won't curve much, but you can be pretty certain the hole
isn't merely angled, but actually arc'd.

Chucking it isn't the way to get the two ends true to center. Catch the
piece between centers, and dog it.

Yes, but it will be close enough since I turned the OD at the starting
end. If I center that to a tenth the hole will be centered. I might do
it between centers, depends on my ambition level and the shop
temperature. I needs to be pretty accurate given the projectile passing
through, but it's got a fair amount of clearance so It can tolerate a
little misalignment.

Gun drilling without a gun drill...
 

"Pete C." fired this volley in news:53d5b563$0
:


Yes, but it will be close enough since I turned the OD at the starting
end

If you didn't need accurate drilling, why'd you call it "gun drilling"?

A 7" deep hole 5/16" in diameter ain't really much of a challenge,
anyway. A conventional "aircraft drill" would have turned the trick.

If you really needed it true, you'd have drilled it undersized and reamed
it to diameter, then turned it between centers to true up the o.d..

Lloyd

Gun drilling without a gun drill...
 

"Lloyd E. Sponenburgh" wrote in message
. 3.70...

"Pete C." fired this volley in news:53d5b563$0
:


Yes, but it will be close enough since I turned the OD at the starting
end

If you didn't need accurate drilling, why'd you call it "gun drilling"?

A 7" deep hole 5/16" in diameter ain't really much of a challenge,
anyway. A conventional "aircraft drill" would have turned the trick.

If you really needed it true, you'd have drilled it undersized and reamed
it to diameter, then turned it between centers to true up the o.d..

Lloyd

=================================================

A 5/16 hole 7-in. long, drilled undersize, isn't going to provide enough
side force to make a reamer run true. The reamer would just follow the
drilled hole.

There is a way to drill a hole like this straight, without a real gun drill.
Start the hole with a regular drill bit, drill it maybe 1" deep, and follow
up with a home-made single-lip drill (a D-bit). Unlike a real gun drill,
you'll have to peck it to get the chips out, and it's God-awful slow. But it
works.

--
Ed Huntress

Gun drilling without a gun drill...
 

"Lloyd E. Sponenburgh" wrote:

"Pete C." fired this volley in news:53d5b563$0
:


Yes, but it will be close enough since I turned the OD at the starting
end

If you didn't need accurate drilling, why'd you call it "gun drilling"?

A 7" deep hole 5/16" in diameter ain't really much of a challenge,
anyway. A conventional "aircraft drill" would have turned the trick.

If you really needed it true, you'd have drilled it undersized and reamed
it to diameter, then turned it between centers to true up the o.d..

Lloyd

You work with what you've got.

Gun drilling without a gun drill...
 

"Ed Huntress" fired this volley in
:

A 5/16 hole 7-in. long, drilled undersize, isn't going to provide
enough side force to make a reamer run true. The reamer would just
follow the drilled hole.

There is a way to drill a hole like this straight, without a real gun
drill. Start the hole with a regular drill bit, drill it maybe 1"
deep, and follow up with a home-made single-lip drill (a D-bit).
Unlike a real gun drill, you'll have to peck it to get the chips out,
and it's God-awful slow. But it works.


Ed, they make reamers that small with flutes 6" long. That would provide
plently of 'guide' surface. The reamer could bend some, but wouldn't if
you took it slowly.

But anyway... unless you have a coolant-ported drill and a high-pressure
coolant pump, you're going to have to peck anyway, past about six drill
diamters deep.

I didn't even consider a d-bit to be in his options; especially
considering he's talking about just re-chucking to true the piece up.

Pecking IS a pain. Some day, I'm going to make that lever drilling
attachment I've always envied, or put together a right proper carriage
drill holder.

LLoyd

Gun drilling without a gun drill...
 

"Ed Huntress" wrote in message
...
... There is a way to drill a hole like this straight, without a
real gun drill. Start the hole with a regular drill bit, drill it
maybe 1" deep, and follow up with a home-made single-lip drill (a
D-bit). Unlike a real gun drill, you'll have to peck it to get the
chips out, and it's God-awful slow. But it works.

--
Ed Huntress

In my limited experience D bits are tricky to sharpen without a
surface grinder and fixturing, to keep them cutting at the center and
not binding at the full-sized OD behind the cutting edge as it wears
smaller. They don't cut at all if the center point is high and can't
tolerate it being too low because the thin wire left in the middle
becomes an obstruction.

I use D bits to ream tapered holes in fluid nozzles for my
experiments, not for deep hole drilling since grease passages in axles
don't need to be straight. They can cut brass and aluminum if simply
ground half-round from unhardened drill rod without normal edge relief
clearances and forced into the pilot hole with the tailstock
handwheel.

-jsw

Gun drilling without a gun drill...
 

"Jim Wilkins" wrote in message ...

"Ed Huntress" wrote in message
...
... There is a way to drill a hole like this straight, without a real gun
drill. Start the hole with a regular drill bit, drill it maybe 1" deep,
and follow up with a home-made single-lip drill (a D-bit). Unlike a real
gun drill, you'll have to peck it to get the chips out, and it's God-awful
slow. But it works.

--
Ed Huntress

In my limited experience D bits are tricky to sharpen without a
surface grinder and fixturing, to keep them cutting at the center and
not binding at the full-sized OD behind the cutting edge as it wears
smaller. They don't cut at all if the center point is high and can't
tolerate it being too low because the thin wire left in the middle
becomes an obstruction.

I use D bits to ream tapered holes in fluid nozzles for my
experiments, not for deep hole drilling since grease passages in axles
don't need to be straight. They can cut brass and aluminum if simply
ground half-round from unhardened drill rod without normal edge relief
clearances and forced into the pilot hole with the tailstock
handwheel.

-jsw

================================================== =======

[Ed]

There are several configurations of drill bits and reamers that are called
"D-bits." It sounds like you're making the kind with a center point. They're
a b**ch to make, as you suggest. I've had much better luck with the simpler
kind that's flat on the end.

I learned to make these from the old English MAP hobbyist books, which
describe several types. This article from a 1967 issue of Popular Science
describes D-bits pretty well:

http://tinyurl.com/qdcnuoa

--
Ed Huntress

Gun drilling without a gun drill...
 

"Ed Huntress" wrote in message
...
"Jim Wilkins" wrote in message ...

In my limited experience D bits are tricky to sharpen ...

-jsw

================================================== =======

[Ed]

There are several configurations of drill bits and reamers that are
called "D-bits." It sounds like you're making the kind with a center
point. They're a b**ch to make, as you suggest. I've had much better
luck with the simpler kind that's flat on the end.

I learned to make these from the old English MAP hobbyist books,
which describe several types. This article from a 1967 issue of
Popular Science describes D-bits pretty well:

http://tinyurl.com/qdcnuoa

--
Ed Huntress

That version is easier to make than the ones in Lindsay's "Deep Hole
Drilling". I stop at the step where the lathe tailstock needs to be
aligned, since trade school apes misused the original spindle on my
lathe as an anvil horn. The dealer swapped it but the replacement is
loose, drill bits visibly jump up to the center of rotation when they
bite into the work.

Centering with one of these center drill collets instead of a drill
chuck helps a lot:
http://www.collistoolholder.com/cgi-..._9_TYP_Q_GRP_1

-jsw

Gun drilling without a gun drill...
 

On Monday, July 28, 2014 8:53:50 AM UTC-4, Ed Huntress wrote:
"Jim Wilkins" wrote in message ...



"Ed Huntress" wrote in message

...

... There is a way to drill a hole like this straight, without a real gun

drill. Start the hole with a regular drill bit, drill it maybe 1" deep,

and follow up with a home-made single-lip drill (a D-bit). Unlike a real

gun drill, you'll have to peck it to get the chips out, and it's God-awful

slow. But it works.



--

Ed Huntress



In my limited experience D bits are tricky to sharpen without a

surface grinder and fixturing, to keep them cutting at the center and

not binding at the full-sized OD behind the cutting edge as it wears

smaller. They don't cut at all if the center point is high and can't

tolerate it being too low because the thin wire left in the middle

becomes an obstruction.



I use D bits to ream tapered holes in fluid nozzles for my

experiments, not for deep hole drilling since grease passages in axles

don't need to be straight. They can cut brass and aluminum if simply

ground half-round from unhardened drill rod without normal edge relief

clearances and forced into the pilot hole with the tailstock

handwheel.



-jsw



================================================== =======



[Ed]



There are several configurations of drill bits and reamers that are called

"D-bits." It sounds like you're making the kind with a center point. They're

a b**ch to make, as you suggest. I've had much better luck with the simpler

kind that's flat on the end.



I learned to make these from the old English MAP hobbyist books, which

describe several types. This article from a 1967 issue of Popular Science

describes D-bits pretty well:



http://tinyurl.com/qdcnuoa



--

Ed Huntress

Gotta love that Popular Science archive.

Gun drilling without a gun drill...
 

"Jim Wilkins" wrote in message ...

"Ed Huntress" wrote in message
...
"Jim Wilkins" wrote in message ...

In my limited experience D bits are tricky to sharpen ...

-jsw

================================================== =======

[Ed]

There are several configurations of drill bits and reamers that are called
"D-bits." It sounds like you're making the kind with a center point.
They're a b**ch to make, as you suggest. I've had much better luck with
the simpler kind that's flat on the end.

I learned to make these from the old English MAP hobbyist books, which
describe several types. This article from a 1967 issue of Popular Science
describes D-bits pretty well:

http://tinyurl.com/qdcnuoa

--
Ed Huntress

That version is easier to make than the ones in Lindsay's "Deep Hole
Drilling". I stop at the step where the lathe tailstock needs to be
aligned, since trade school apes misused the original spindle on my
lathe as an anvil horn. The dealer swapped it but the replacement is
loose, drill bits visibly jump up to the center of rotation when they
bite into the work.

Centering with one of these center drill collets instead of a drill
chuck helps a lot:
http://www.collistoolholder.com/cgi-..._9_TYP_Q_GRP_1

-jsw

================================================== ====
[Ed]

Yeah, that looks good. I have some similar tailstock collets that I
inherited in the pile of tooling junk that my uncle passed along. I've never
used them, though.

--
Ed Huntress

Gun drilling without a gun drill...
 

"Lloyd E. Sponenburgh" wrote:

"Ed Huntress" fired this volley in
:

A 5/16 hole 7-in. long, drilled undersize, isn't going to provide
enough side force to make a reamer run true. The reamer would just
follow the drilled hole.

There is a way to drill a hole like this straight, without a real gun
drill. Start the hole with a regular drill bit, drill it maybe 1"
deep, and follow up with a home-made single-lip drill (a D-bit).
Unlike a real gun drill, you'll have to peck it to get the chips out,
and it's God-awful slow. But it works.


Ed, they make reamers that small with flutes 6" long. That would provide
plently of 'guide' surface. The reamer could bend some, but wouldn't if
you took it slowly.

But anyway... unless you have a coolant-ported drill and a high-pressure
coolant pump, you're going to have to peck anyway, past about six drill
diamters deep.

I didn't even consider a d-bit to be in his options; especially
considering he's talking about just re-chucking to true the piece up.

Pecking IS a pain. Some day, I'm going to make that lever drilling
attachment I've always envied, or put together a right proper carriage
drill holder.

LLoyd

I've thought about improvising a gun drilling setup on the lathe, an
adapter to hold the drill in the boring bar toolpost holder, a cheap HF
electric pressure washer adapted for a coolant pump, and I guess I might
have to make some more gears to get the power feed on the lathe slow
enough. Something to consider if I do more of these.

Gun drilling without a gun drill...
 

"Ed Huntress" wrote in message
...
"Jim Wilkins" wrote in message ...

...
Centering with one of these center drill collets instead of a drill
chuck helps a lot:
http://www.collistoolholder.com/cgi-..._9_TYP_Q_GRP_1

-jsw

================================================== ====
[Ed]

Yeah, that looks good. I have some similar tailstock collets that I
inherited in the pile of tooling junk that my uncle passed along.
I've never used them, though.

--
Ed Huntress

Using it requires moving the tailstock since its overhang is much less
than a chuck's. It's fine for single parts but not so good if I need
to drill several to the same depth.
-jsw

Gun drilling without a gun drill...
 

On Mon, 28 Jul 2014 09:14:58 -0500, "Pete C."
wrote:


"Lloyd E. Sponenburgh" wrote:

"Ed Huntress" fired this volley in
:

A 5/16 hole 7-in. long, drilled undersize, isn't going to provide
enough side force to make a reamer run true. The reamer would just
follow the drilled hole.

There is a way to drill a hole like this straight, without a real gun
drill. Start the hole with a regular drill bit, drill it maybe 1"
deep, and follow up with a home-made single-lip drill (a D-bit).
Unlike a real gun drill, you'll have to peck it to get the chips out,
and it's God-awful slow. But it works.


Ed, they make reamers that small with flutes 6" long. That would provide
plently of 'guide' surface. The reamer could bend some, but wouldn't if
you took it slowly.

But anyway... unless you have a coolant-ported drill and a high-pressure
coolant pump, you're going to have to peck anyway, past about six drill
diamters deep.

I didn't even consider a d-bit to be in his options; especially
considering he's talking about just re-chucking to true the piece up.

Pecking IS a pain. Some day, I'm going to make that lever drilling
attachment I've always envied, or put together a right proper carriage
drill holder.

LLoyd

I've thought about improvising a gun drilling setup on the lathe, an
adapter to hold the drill in the boring bar toolpost holder, a cheap HF
electric pressure washer adapted for a coolant pump, and I guess I might
have to make some more gears to get the power feed on the lathe slow
enough. Something to consider if I do more of these.

I did a bunch of OmniTurn CNC lathes with 350lb high pressure coolant
pumps a few years ago at Gertler Industries. We were drilling up to
6" deep with 3/8" and bigger coolant ported drill bits at a dead run
in all manner of alloy steels. .003-..008 per rev feed rates

They liked the first one so well they had me do another 17 machines

Gunner

--
"Living in the United States now is like being a Tampon.
We're in a great place, just at a bad time."