--Hi gang; new guy here. I've been turning wood for this and that
for a spell so I've got the basics down. I'm no artist; just makin' parts
for this project or that. But today I want to take a whack at turning down
the ends of a hunk of oak that measures 12" on the long axis and 1.5" x 5"
othat will be spinning, so to speak. Now the tricky part is that I want to
turn it eccentrically, so that the turned ends will be off the centerline by
an inch or so. In other words this hunk of oak is going to be flopping
around and will want to make my lathe gallop around the shop! I'm wondering
if there is some recognized method of adding counterweight to the thing, to
ocompensate for the unequal spinning mass. Any pointers appreciated.

--
"Steamboat Ed" Haas : Proud to be the
Hacking the Trailing Edge! : family crackpot!
www.nmpproducts.com
---Decks a-wash in a sea of words---

This can be done, but you will need to take the time to make a jig that will
allow you to keep the piece to be turned reasonably well balanced with
respect to the lathe centers. Don't skimp on the design. Your safety may
well depend on the quality of this jig. A piece of wood of similar mass
mounted on the opposite side is usually the easiest way to get the balance
that you need but the design of the jig will vary considerably depending on
the shape of the piece that you will be turning. Some disks fastened to each
end with the counter weight pieces mounted on them is a possible way of
doing this. After you build and mount whatever jig you make into your lathe,
start the lathe up on very slow speed and stand back out of the way. Then if
it spins and seems to be balanced OK, slowly increase the speed until you
reach about 150% of the max speed that you intend to work at to be sure that
it stays together and is safe. In my opinion I would never turn something
like this any faster than was necessary. I would also try to keep my body as
much out of the danger zone as possible while working and I would use
whatever kind of guarding that I could come up with to make the job as safe
as possible. Ready access to the off switch while working is also a must.

Good Luck,

Charley


"steamer" wrote in message
...
--Hi gang; new guy here. I've been turning wood for this and that
for a spell so I've got the basics down. I'm no artist; just makin' parts
for this project or that. But today I want to take a whack at turning down
the ends of a hunk of oak that measures 12" on the long axis and 1.5" x 5"
othat will be spinning, so to speak. Now the tricky part is that I want to
turn it eccentrically, so that the turned ends will be off the centerline
by
an inch or so. In other words this hunk of oak is going to be flopping
around and will want to make my lathe gallop around the shop! I'm
wondering
if there is some recognized method of adding counterweight to the thing,
to
ocompensate for the unequal spinning mass. Any pointers appreciated.

--
"Steamboat Ed" Haas : Proud to be the
Hacking the Trailing Edge! : family crackpot!
www.nmpproducts.com
---Decks a-wash in a sea of words---

Before giving you an answer, it's important to know something about
your lathe. What it is, how heavy it is, and the low-end speed.

On Oct 8, 9:15 am, steamer wrote:
--Hi gang; new guy here. I've been turning wood for this and that
for a spell so I've got the basics down. I'm no artist; just makin' parts
for this project or that. But today I want to take a whack at turning down
the ends of a hunk of oak that measures 12" on the long axis and 1.5" x 5"
othat will be spinning, so to speak. Now the tricky part is that I want to
turn it eccentrically, so that the turned ends will be off the centerline by
an inch or so. In other words this hunk of oak is going to be flopping
around and will want to make my lathe gallop around the shop! I'm wondering
if there is some recognized method of adding counterweight to the thing, to
ocompensate for the unequal spinning mass. Any pointers appreciated.

--
"Steamboat Ed" Haas : Proud to be the
Hacking the Trailing Edge! : family crackpot!
www.nmpproducts.com
---Decks a-wash in a sea of words---

"Wally" wrote in message
oups.com...
Before giving you an answer, it's important to know something about
your lathe. What it is, how heavy it is, and the low-end speed.


BINGO! The difference in mass will develop a force based on the square of
the velocity. So you can see that velocity is the prime consideration. Slow
is the way to go. Then you help yourself by removing as much unneeded mass
as possible on those portions most distant from the axis of rotation.

Then and only then consider counterweighting.

If you can get to the vicinity of 300 on your speed, you ought to be able to
handle a reasonable piece of wet oak on a rigid lathe.

steamer wrote:

--Hi gang; new guy here. I've been turning wood for this and that
for a spell so I've got the basics down. I'm no artist; just makin' parts
for this project or that. But today I want to take a whack at turning down
the ends of a hunk of oak that measures 12" on the long axis and 1.5" x 5"
othat will be spinning, so to speak. Now the tricky part is that I want to
turn it eccentrically, so that the turned ends will be off the centerline by
an inch or so. In other words this hunk of oak is going to be flopping
around and will want to make my lathe gallop around the shop! I'm wondering
if there is some recognized method of adding counterweight to the thing, to
ocompensate for the unequal spinning mass. Any pointers appreciated.


You've seen pieces of furniture with legs that look sort of like a
golf
club "driver" head feet? Not the true S curved carbiolet leg but
some-
thing similar. They do it on 30-36" legs so 12" isn't that big a
deal.

There are several "tricks" to this offset centers turning.

One is to only turn at and around the "null point" of rotation.
As you spin the work you'll notice that some areas outlines
are blurry and become more defined towards the centerline
of rotation. Other areas will have much less blurry outlines
and some will not be blurry at all but rather quite crisp and
defined. I've heard this blurry area referred to as the shadow
outline. The part of the piece with no shadow is where you
want to turn your shape, transitioning from it into the "just
a little shadowy" areas around it.

The second trick is to turn at a speed just below where the
piece begins to wobble your lathe. Fairly easy to do on a
variable speed lathe, less easy on a pulleys lathe. Start at
the lowest speed and SLOWLY increase the rpms 'til things
just start to wobble, then back off 'til the wobble stops.

The third trick is to use a Stebb Center on the head stock
end. When set right, the Stebb Center will let the piece
stop if you start to get a dig in - no nasty flying tool or
chunk of wood to deal with.

The fourth trick is - wear a full face face shield, perhaps
a chest protector and maybe even a cup. If something
does go wrong you want to protect your head, eyes, heart
and . . .

The fourth trick is to set the tool rest as close to where
you'll be turning. Set it, rotate the piece by hand to check
the clearance and move the rest closer or farther away
if need be. Then LOCK it down - nice and tight. You DO
NOT WANT IT TO MOVE DURING A CUT!

Fifth - get the tool on the tool rest with the cutting edge
way away from the spinning wood. Have the back of the
tool then contact the wood - again with any edge or corner
away from the wood and SLOWLY bring the bevel to the
wood and finally the edge, point or heel corner.

Initially make a lot of light cuts - but don't hurry things.
The Stebb Center will stop the wood if you try and take
too big a chunk at one time - though it's better to err
on the side of caution.

As the shape come into better focus stop and reset the
tool rest, check for clearance and resume removing wood.

If you have to force the cut it's time to resharpen your
tool. Sharp is important!

For a 1x5 that's 12" long it shouldn't be all that bad. I
have done some turned wooden spoons out of stuff
2x5 x 12" and it's not that scary - or difficult.

As for the oval - well there you'll have to ask somebody
else.

The illustration on this page may explain the "null point"
and shadow areas idea better and provide a graphical
method for deciding no the pairs of centers you need.

http://home.comcast.net/~charliebcz/...Turning14.html

Have fun - and be safe!

charlie b

"charlie b" wrote in message
...
The illustration on this page may explain the "null point"
and shadow areas idea better and provide a graphical
method for deciding no the pairs of centers you need.

http://home.comcast.net/~charliebcz/...Turning14.html

Have fun - and be safe!

Or, you could find a copy of Frank Pain's _The Practical Woodturner_, where
he shows the jigs and methods used by the old High Wycombe types to do this
type of turning.

Since I discovered they sell this type of leg cheaply in many species, I
have turned one set of four and no more.

Look at the Kelton eccentric face plate and ballancer.

steamer wrote:
--Hi gang; new guy here. I've been turning wood for this and that
for a spell so I've got the basics down. I'm no artist; just makin' parts
for this project or that. But today I want to take a whack at turning down
the ends of a hunk of oak that measures 12" on the long axis and 1.5" x 5"
othat will be spinning, so to speak. Now the tricky part is that I want to
turn it eccentrically, so that the turned ends will be off the centerline by
an inch or so. In other words this hunk of oak is going to be flopping
around and will want to make my lathe gallop around the shop! I'm wondering
if there is some recognized method of adding counterweight to the thing, to
ocompensate for the unequal spinning mass. Any pointers appreciated.