Say you've laid out the end of a shaft for a center hole
to take a dead center and the hole comes out a bit off
center. How would you go about 'moving' the hole
back to center?
Phil Kangas



--
Posted via a free Usenet account from http://www.teranews.com

Phil Kangas wrote:

Say you've laid out the end of a shaft for a center hole
to take a dead center and the hole comes out a bit off
center. How would you go about 'moving' the hole
back to center?
Phil Kangas




PITA but possible. You have to set up the shaft with a steady rest
and use a tiny boring tool to bore the center hole true. Swivel
around the compound and use that to feed it in, of course.

GWE

-cut off the drilled length
-hold the shaft in a chuck and turn a centered hole
-weld fill the hole
-drill a hole where you're started it & plug it

Bob

"Phil Kangas" wrote in message
Say you've laid out the end of a shaft for a center hole
to take a dead center and the hole comes out a bit off
center. How would you go about 'moving' the hole
back to center?
Phil Kangas


Guess I'd better add some more info on this. The bar is
1.75" 4140 B7 , rough finish surface, too big to pass
through
the spindle, 30" long, no extra length. I managed to do it
but
got curious what others would do.
Phil



--
Posted via a free Usenet account from http://www.teranews.com

Phil Kangas wrote:
"Phil Kangas" wrote in message
Say you've laid out the end of a shaft for a center hole
to take a dead center and the hole comes out a bit off
center. How would you go about 'moving' the hole
back to center?
Phil Kangas


Guess I'd better add some more info on this. The bar is
1.75" 4140 B7 , rough finish surface, too big to pass
through
the spindle, 30" long, no extra length. I managed to do it
but
got curious what others would do.
Phil

Brass bush , steadyrest , and a very pointy lathe bit . And as Grant said ,
a PITA . I've been turning some 4140 lately , what fun !
Almost as much fun as the Ampco 18 ...
--

Snag aka OSG #1
'90 Ultra , "Strider"
The road goes on forever ...
none to one to reply

Phil Kangas wrote:

How would you go about 'moving' the hole
back to center?

Make a kerf with a cold chisel (in the cone) and drill a bit deeper. It will
move in the direction of the kerf.

Nick
--
The lowcost-DRO:
http://www.yadro.de

On Sep 10, 3:43 am, Nick Mueller wrote:
Phil Kangas wrote:
How would you go about 'moving' the hole
back to center?

Make a kerf with a cold chisel (in the cone) and drill a bit deeper. It will
move in the direction of the kerf.

Nick
--
The lowcost-DRO:
http://www.yadro.de

The type of cold chisel to use is called a Half Round Nose and it cuts
a semicircular groove. You can grind a pin punch or nail set on an
angle to make a quick one. Sorry, couldn't find a good picture.

jw

Using an electric hand drill and a suitable sized drill bit, start the
drill operation in the hole, holding the drill axis at an angle towards
the desired coordinates. As the point of the drill crosses the
coordinates, slowly adjust the axis of the drill path back towards
perpendicular. Drill a short distance and your done. This technique
requires good H/I coordination and experience drilling accurately by hand.
JR
Dweller in te cellar

Phil Kangas wrote:
Say you've laid out the end of a shaft for a center hole
to take a dead center and the hole comes out a bit off
center. How would you go about 'moving' the hole
back to center?
Phil Kangas





--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."

"Snag" wrote in message
Phil Kangas wrote:
"Phil Kangas" wrote in message
Say you've laid out the end of a shaft for a center hole
to take a dead center and the hole comes out a bit off
center. How would you go about 'moving' the hole
back to center?
Phil Kangas


Guess I'd better add some more info on this. The bar is
1.75" 4140 B7 , rough finish surface, too big to pass
through
the spindle, 30" long, no extra length. I managed to do
it
but
got curious what others would do.
Phil

Brass bush , steadyrest , and a very pointy lathe bit .
And as Grant said ,
a PITA . I've been turning some 4140 lately , what fun !
Almost as much fun as the Ampco 18 ...
--

Snag aka OSG #1
'90 Ultra , "Strider"
The road goes on forever ...
none to one to reply



Voi ye, this dumb 'ol Finn went and did it the hard way,
again, but then I
have a lot of free time sometimes! So what's my story? Ok.
The original
holes were actually quite close to the center of the bar
ends but when the
bar was first placed between centers it rotated on its own
to a certain
spot, time after time. ? Shouldn't do that, eih? The bar is
rough all right,
lots of fat spots, a belly along its length and a very
slight bow. The bow
would not come out even in the press at 24 tons and 0.130
displacement!
Some tough iron this is but at $24/foot it better be! And I
don't plan to
shovel off pricey metal to get a good usable bar. So the
center holes even
though they were good for the ends they were not in the
natural centerline
of the bar! So they have to be moved to that line but how?
heh heh .......
now the fun begins:
First thing, replace the spindle dead center with a combined
drill / csk
( mine is a #6 mounted directly into a salvaged 3MT drill
shank) then
move the faceplate dog to the tailstock end but left loose
for now.
Then a steady rest was mounted close to the faceplate with a
DI on it
reading at 12 o'clock position. A wood v-block was placed
near the
tailstock for convenience. Another DTI w/mag base was set on
the rear
apron for test measurements along the bar. The bar was then
set in place,
run up on the center drill with the rear on the tailstock
center. The bar was
turned watching the DI's and figuring where are the errors.
The high spot
was set at 12 o'clock and the dog set at the tailstock end
to stop rotation .
At the steady rest the rollers at 4 and 8 were brought in
contact then
backed off ever so slightly. The roller at 12 was then
brought in contact
and the DI zeroed. With the gearbox in lowest gear the
spindle was
started and the top roller turned down hard while watching
the drill cut
and the DI reading changing. It didn't take a lot of
pressure to do this
and as soon as the required distance was reached the
tailstock was
nudged ahead to clean up the hole back to round. Worked
pretty
good actually and set me to gloating about it. The bar can
stay in
place and readings can be taken to assess the situation. The
bar
can be swapped end for end to take care of anomalies at that
end
if needed. I gotta admit I spent a lot of time playing with
this but was
worth it! Here I am, 60 years old and still learning a fun
hobby!
Hope you youngsters out there learned something today too,
eih?
Phil Kangas



--
Posted via a free Usenet account from http://www.teranews.com

Phil Kangas wrote:
"Snag" wrote in message
Phil Kangas wrote:
"Phil Kangas" wrote in message
Say you've laid out the end of a shaft for a center hole
to take a dead center and the hole comes out a bit off
center. How would you go about 'moving' the hole
back to center?
Phil Kangas


Guess I'd better add some more info on this. The bar is
1.75" 4140 B7 , rough finish surface, too big to pass
through
the spindle, 30" long, no extra length. I managed to do it
but
got curious what others would do.
Phil

Brass bush , steadyrest , and a very pointy lathe bit . And as Grant
said , a PITA . I've been turning some 4140 lately , what fun !
Almost as much fun as the Ampco 18 ...
--

Snag aka OSG #1
'90 Ultra , "Strider"
The road goes on forever ...
none to one to reply



Voi ye, this dumb 'ol Finn went and did it the hard way,
again, but then I
have a lot of free time sometimes! So what's my story? Ok.
The original
holes were actually quite close to the center of the bar
ends but when the
bar was first placed between centers it rotated on its own
to a certain
spot, time after time. ? Shouldn't do that, eih? The bar is
rough all right,
lots of fat spots, a belly along its length and a very
slight bow. The bow
would not come out even in the press at 24 tons and 0.130
displacement!
Some tough iron this is but at $24/foot it better be! And I
don't plan to
shovel off pricey metal to get a good usable bar. So the
center holes even
though they were good for the ends they were not in the
natural centerline
of the bar! So they have to be moved to that line but how?
heh heh .......
now the fun begins:
First thing, replace the spindle dead center with a combined
drill / csk
( mine is a #6 mounted directly into a salvaged 3MT drill
shank) then
move the faceplate dog to the tailstock end but left loose
for now.
Then a steady rest was mounted close to the faceplate with a
DI on it
reading at 12 o'clock position. A wood v-block was placed
near the
tailstock for convenience. Another DTI w/mag base was set on
the rear
apron for test measurements along the bar. The bar was then
set in place,
run up on the center drill with the rear on the tailstock
center. The bar was
turned watching the DI's and figuring where are the errors.
The high spot
was set at 12 o'clock and the dog set at the tailstock end
to stop rotation .
At the steady rest the rollers at 4 and 8 were brought in
contact then
backed off ever so slightly. The roller at 12 was then
brought in contact
and the DI zeroed. With the gearbox in lowest gear the
spindle was
started and the top roller turned down hard while watching
the drill cut
and the DI reading changing. It didn't take a lot of
pressure to do this
and as soon as the required distance was reached the
tailstock was
nudged ahead to clean up the hole back to round. Worked
pretty
good actually and set me to gloating about it. The bar can
stay in
place and readings can be taken to assess the situation. The
bar
can be swapped end for end to take care of anomalies at that
end
if needed. I gotta admit I spent a lot of time playing with
this but was
worth it! Here I am, 60 years old and still learning a fun
hobby!
Hope you youngsters out there learned something today too,
eih?
Phil Kangas

You take the high road ... your setup was more of a milling function , if
you think about it . Worked , and that's what matters . And now I have
gained the benefit of a different perspective . That's what I like about
this NG , you get a lot of different points of view .
--

Snag aka OSG #1
'90 Ultra , "Strider"
The road goes on forever ...
none to one to reply

"Phil Kangas" wrote in message
.. .
Say you've laid out the end of a shaft for a center hole
to take a dead center and the hole comes out a bit off
center. How would you go about 'moving' the hole
back to center?
Phil Kangas

My favorite hole moving tool is a block of metal (steel preferred,
depends on what you have and the material you're moving the hole in) and a
gun barrel drill bit. Drill the hole in the guide block and attach that to
your material. It's essentially a drill bushing. A gun barrel drill (IIRC,
it's been awhile) only cuts on the face, so will cut without wanting to pull
off center too much.

On Sep 10, 7:47 pm, "Phil Kangas" wrote:
...
First thing, replace the spindle dead center with a combined
drill / csk
( mine is a #6 mounted directly into a salvaged 3MT drill
shank) ...
Phil Kangas

I guess size does matter...

I've tried that in a mill with a #2 (Keo, I think) and broke the tip
off in the hole.

jw