I don;t know what others do but drilling always seems faster and can
remove more meat for me, so I usually keep stepping up drill sizes
until I either egt up to the largest drill I have or get close to the
size I need and then finish with a boring bar. I would thik a lathe
would be the best for this job as compared to a DP. Once I usually get
a hole thorugh a piece I usually feel better, and things go a lot
faster. I do assume you are step drilling. If not it will make things
a lot easier and quicker.


The bigger the diameter of the boring bar the less deflection you have
so it would stand to reason to use the biggest hole you can bore to
start off with followed by using the biggest boring bar you have.



On Fri, 11 Jul 2003 01:07:05 GMT, "ATP"
wrote:

x-I am boring out two 3" lengths of 1 1/2" round steel bar to 1 1/8 ID. I am
x-working with a South Bend 10" Heavy lathe. I also have a 21" geared head
x-drill press but only a 6" vise to work with.
x-
x-Doing the whole job on the lathe, how large of a hole should I drill to
x-start out with? Is the idea to drill a hole just big enough to start the
x-boring bar?
x-
x-Using the drill press to do the job, what type of bit would be recommended?
x-I drilled holes up to 7/8" in one of the bars today and it was a lengthy
x-process. Even at 150 rpm and a downfeed of 4 thousandths with plenty of oil,
x-the bits would have a tendency to start jamming as soon as they got deep.
x-Then it took plenty of stopping and pulling out to finish the job. Thanks
x-for any advice.
x-

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jim rozen wrote:
In article , "ATP"
says...

Doing the whole job on the lathe, how large of a hole should I drill
to start out with? Is the idea to drill a hole just big enough to
start the boring bar?

I think the drill does a faster job of stock removal.

My attempt at doing this would start with a 1/8 or 1/4 inch
pilot hole, and then I would step up to the largest drill
size that my 10L could handle, in back gears, before the
belt slipped. Which would be something like maybe 9/16
inch or so. Then I would step up from there in 1/8 or
so inch increments, or in increments that again did not
tax the drive on the machine. Probably start out in
the highest back gear speed.

At some point (probably around 3/4 inch or so) I would
run out of drills with shanks that fit the MT2 tailstock
at the machine and then switch over to a large boring
bar.

At that point I can pick exactly how much to open
up the bore at a whack.

I was concerned about how big a drill bit the lathe could safely handle
without damage to the machine. The belt does provide a safety factor, as
opposed to the DP which will just snap anything in its way if you don't stop
it quickly enough.

I have a problem with the old chuck on the tailstock, do you recommend using
all MT2 shanked drills and dispensing with the use of a chuck altogether? I
was considering installing a used 14N or larger ball bearing Jacobs chuck.

On Fri, 11 Jul 2003 05:13:06 GMT, "ATP"
wrote:

I have a problem with the old chuck on the tailstock, do you recommend using
all MT2 shanked drills and dispensing with the use of a chuck altogether? I
was considering installing a used 14N or larger ball bearing Jacobs chuck.

I will insert my 2 cents worth at this point. A major concern using
either a tailstock chuck or morse taper drills is the taper slipping.
Drilling larger diameters in steel requires a lot of torque. Most
tailstocks are not keyed and so the taper can slip. You need to
axially lock the drill or the drill chuck when doing this (some sort
of clamp/bar locked to the drill/chuck and supported by the tool
post/topslide.) That having been said I support those who recommend
step drilling as far as you can then going to the biggest/most rigid
boring bar you can fit. Set the boring bar no further extended than
necessary.
Regards
Bob

Drill a 3/8 pilot then hit with a 1" 4 flute endmill at .020 ipr.
"ATP" wrote in message
et...
I am boring out two 3" lengths of 1 1/2" round steel bar to 1 1/8 ID. I am
working with a South Bend 10" Heavy lathe. I also have a 21" geared head
drill press but only a 6" vise to work with.

Doing the whole job on the lathe, how large of a hole should I drill to
start out with? Is the idea to drill a hole just big enough to start the
boring bar?

Using the drill press to do the job, what type of bit would be
recommended?
I drilled holes up to 7/8" in one of the bars today and it was a lengthy
process. Even at 150 rpm and a downfeed of 4 thousandths with plenty of
oil,
the bits would have a tendency to start jamming as soon as they got deep.
Then it took plenty of stopping and pulling out to finish the job. Thanks
for any advice.

Morse taper bits are the only proper way to go with large holes drilled from
the tailstock. You can make up a torque arm to stop the bit from rotating
by clamping a lathe dog on the shank of the bit. A vise grip also works.
Make sure it hits a piece of wood set on your ways to protect the machined
surface.
A proper fitting and clean Morse taper will take a lot of torque and
usually the bit will not rotate in the tailstock socket.
Randy

"ATP" wrote in message
et...
jim rozen wrote:
In article , "ATP"
says...

Doing the whole job on the lathe, how large of a hole should I drill
to start out with? Is the idea to drill a hole just big enough to
start the boring bar?

I think the drill does a faster job of stock removal.

My attempt at doing this would start with a 1/8 or 1/4 inch
pilot hole, and then I would step up to the largest drill
size that my 10L could handle, in back gears, before the
belt slipped. Which would be something like maybe 9/16
inch or so. Then I would step up from there in 1/8 or
so inch increments, or in increments that again did not
tax the drive on the machine. Probably start out in
the highest back gear speed.

At some point (probably around 3/4 inch or so) I would
run out of drills with shanks that fit the MT2 tailstock
at the machine and then switch over to a large boring
bar.

At that point I can pick exactly how much to open
up the bore at a whack.

I was concerned about how big a drill bit the lathe could safely handle
without damage to the machine. The belt does provide a safety factor, as
opposed to the DP which will just snap anything in its way if you don't stop
it quickly enough.

I have a problem with the old chuck on the tailstock, do you recommend using
all MT2 shanked drills and dispensing with the use of a chuck altogether? I
was considering installing a used 14N or larger ball bearing Jacobs chuck.

I will insert my 2 cents worth at this point. A major concern using
either a tailstock chuck or morse taper drills is the taper slipping.
Drilling larger diameters in steel requires a lot of torque. Most
tailstocks are not keyed and so the taper can slip. You need to
axially lock the drill or the drill chuck when doing this (some sort
of clamp/bar locked to the drill/chuck and supported by the tool
post/topslide.) That having been said I support those who recommend
step drilling as far as you can then going to the biggest/most rigid
boring bar you can fit. Set the boring bar no further extended than
necessary.
Regards
Bob


Unfortunately, step drilling and Morse tapers do not go hand in hand. The feed
pressure helps keep the taper from slipping, and when step drilling you don't
have much feed pressure - unless you are taking large steps.

Seating the taper quickly will help, and the extra mass of a chuck will help
the taper seat even tighter. Sometimes, however, the only solution is a dog
clamped on the drill shank.

John Martin

rjs wrote in message . ..
On Fri, 11 Jul 2003 05:13:06 GMT, "ATP"
wrote:

I have a problem with the old chuck on the tailstock, do you recommend using
all MT2 shanked drills and dispensing with the use of a chuck altogether? I
was considering installing a used 14N or larger ball bearing Jacobs chuck.

I will insert my 2 cents worth at this point. A major concern using
either a tailstock chuck or morse taper drills is the taper slipping.
Drilling larger diameters in steel requires a lot of torque. Most
tailstocks are not keyed and so the taper can slip. You need to
axially lock the drill or the drill chuck when doing this (some sort
of clamp/bar locked to the drill/chuck and supported by the tool
post/topslide.) That having been said I support those who recommend
step drilling as far as you can then going to the biggest/most rigid
boring bar you can fit. Set the boring bar no further extended than
necessary.
Regards
Bob

If the shank is clean and the mating hole has no marks or ridges in
it, Morse tapers will hold even drilling in low backgear in a lathe.
I've gone to 3/4" in a SB model A 9". Biggest Morse taper drill I own,
boring bar is used over that size. Wasn't fast but it worked. Now on
that tailstock, I think there's a couple of pins for the end of the
shank to work against. I wouldn't try drilling a pilot hole in the
drill press, it'll wander and you'll have a hell of a time when you
finally get the piece into the lathe. One of the old-timey dodges is
to chalk three or four marks lengthwise on the taper shank, it won't
twist in the socket after that assuming everything is is good
condition.

Stan

In article ,
ATP wrote:
I am boring out two 3" lengths of 1 1/2" round steel bar to 1 1/8 ID. I am
working with a South Bend 10" Heavy lathe. I also have a 21" geared head
drill press but only a 6" vise to work with.

Doing the whole job on the lathe, how large of a hole should I drill to
start out with?

Well ... how big a hole will your lathe's tailstock turn, and
how big a bit do you have? It lightens the load on the machine somewhat
to start out with a smaller bit -- about the diameter of the width of
the chisel point on the larger bit -- and follow with the larger one.
But your 3" length may limit that. I've got some long (about 6" flute)
0.370" bits with a MT-1 shank, and that would make a good starting hole
for the follow-up of a larger bit -- say a 3/4" or 1" if your tailstock
will take the MT-3 shanks (mine will -- 12x14" Clausing).

Is the idea to drill a hole just big enough to start the
boring bar?

The drill removes metal faster than any other technique, so
drill as big as you can (under the size of the final diameter), and use
as large a boring bar as you have. If it involves a lot of "stickout",
I like using a 1" bar if I can -- but sometimes I wind up using a 1/2"
solid carbide bar with insert tooling to get rid of the chatter. For
that, I can start it in a 1/2" hole, as long as the target diameter is
large enough to cover the diameter resulting from the extension of the
insert off one side. My first pass, I will position it so the back side
of the bar travels in the clearance made by the insert. (In other
words, without the insert cutting the back of the bar would hit the
workpiece, but with it, it won't. I like to minimize the depth of cut
until I get a few passes in there so there is more clearance for the
chips generated.

Using the drill press to do the job, what type of bit would be recommended?

I wouldn't. Use the lathe with Morse taper shank drills to fit
the taper. The heavy 10 should have at least a MT-2 (which can get you
up to 3/4"). It may even take a MT-3 (which can comfortably get you up
to 1" diameter.

I drilled holes up to 7/8" in one of the bars today and it was a lengthy
process. Even at 150 rpm and a downfeed of 4 thousandths with plenty of oil,
the bits would have a tendency to start jamming as soon as they got deep.
Then it took plenty of stopping and pulling out to finish the job. Thanks
for any advice.

I think that you can get better clearance of the chips with the
lathe -- and a horizontal hole -- and you don't have to worry about it
being on center.

Good Luck,
DoN.
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