Turning large out of balance posts
Ted
I have started a job duplicating posts that are 8x8 by 31 inches. The
posts are made from 8/4 poplar that is glued up. These posts are
hollow on the inside and have about a 4 inch square hole running the
full length. I am using a Oneway 2436 and a Vega Pro duplicator to
turn them. They are held on the lathe with oak end caps. The
headstock end has a face plate screwed to oak end cap. Seems to work
well for most of the posts.
The problem:
Most of the posts are turning very well with minimal vibration and
look nice. I have to keep the lathe speed up to about 1500 rpm for the
duplicator to work right or it does a crappy job. I tried lower
speeds and the results were very bad. I called Vega and they
suggested at least 1500 rpm. I get a little vibration when I first
start but nothing I can’t live with.
The problem is that a few of the posts are having unacceptable
vibration. Even at lower rpms the 900 pound lathe is dancing around
the workshop. I am pretty sure that the individual pieces of poplar
used to glue up the posts are not all the same density and weight.
That makes them heavier on one side. Se even if I roughing those
particular pieces manually with a gouge first, it does help because
the wood is still heavier on one side than the other.
Any suggestions?
Has anyone run into this kind of problem before? I have thought of
using some kind of weight as a counter balance but I don’t know what
kind of weight could be used that would be able to be attached to a
post and I am not sure how to find out for sure which side of the post
is heavier or how much weight should be used.
Thanks for any ideas,
Ted J
thelatentlog.com
Leo Lichtman
"Ted" wrote: (clip)have thought of
using some kind of weight as a counter balance but I don�t know what
kind of weight could be used that would be able to be attached to a
post and I am not sure how to find out for sure which side of the post
is heavier or how much weight should be used.
Start by supporting the unbalanced post by its end caps between two live
centers. The heavy side will go to the bottom. Attach weights by trial and
error to the end caps, until it doesn't settle to one side. Let's hope that
the heavy side is heavy along its entire length--that way you can apply the
balancing weights equally at the two ends. If it appears that one end is
vibrating more than the other, you will have a more difficult trial and
error balancing problem. There are various ways you can hold the weights:
lag screws, threaded rods, C clamps, etc. You might go to a tire shop and
bum or buy some lead weights. These can be melted into a form that is easy
to deal with.
If your lathe bearings are not free enough to let the weight sink to the
bottom, try holding some kind of vibrator against it. An engraving tool
might do the job.
Keep us posted.
tom koehler
(in message
<647187b4-ea80-4bc3...@g31g2000vbr.googlegroups.com>):
Please bear with me, this will seem way off the chart. In motorcycle tire
balancing, sometimes a product called "slime" is used. It is a rubber or
latex compound of some sort, placed inside the tire. As the tire rotates,the
"slime" will move around inside the tire in such a way as to help balance the
tire. Don't know why or how. It just works.
Your posts are hollow. Make a plastic bladder that can fit inside the post.
Put about a cup of this "slime" inside the bladder. Inflate or pressurize the
bladder so it conforms to the interior of the post. Mount your end caps as
before.
tom koehler
--
I will find a way or make one.
Leo Lichtman
"tom koehler" wrote: (clip) Make a plastic bladder that can fit inside the
> Put about a cup of this "slime" inside the bladder. Inflate or pressurize
> the
^^^^^^^^^^^^^^^^^^^^^
I like the way your mind works, but I think you have overlooked a serious
obstacle. The inside of the posts is square. When it starts to spin,
centrifugal force will sling the slime randomly into the corners, probably
making the balance worse. Can you think of a way to put a cylindrical
bladder into the post?
Kevin Miller
--
Kevin Miller
Juneau, Alaska
http://www.alaska.net/~atftb
In a recent poll, seven out of ten hard drives preferred Linux.
tom koehler
(in message <nJ-dnXyFbdbGgX_X...@posted.gcicommunications>):
> Leo Lichtman wrote:
>> "tom koehler" wrote: (clip) Make a plastic bladder that can fit inside
>> the
>> post.
>>> Put about a cup of this "slime" inside the bladder. Inflate or pressurize
>>> the
>>> bladder so it conforms to the interior of the post. (clip)
>> ^^^^^^^^^^^^^^^^^^^^^
>> I like the way your mind works, but I think you have overlooked a serious
>> obstacle. The inside of the posts is square. When it starts to spin,
>> centrifugal force will sling the slime randomly into the corners, probably
>> making the balance worse. Can you think of a way to put a cylindrical
>> bladder into the post?
>>
>>
> Depending on the inside diameter, I'd look at using PVC pipe...
>
>
this could be a possible new tool - the dynamic balancing magafferator -
could be wrapped in layers of paper until it is a snug fit inside the item
being turned.
tom k.
Ted
and delivered. I got a tip from someone on the Oneway Forum. The
suggestion was to attach my large coles jaws on the outboard side of
the headstock and use them like a flywheel. I adjusted sets of
washers screwed into the jaws at various places using trial and error
until I found a point at which the post would balance. It worked on
all but one post. That particular post was so far out of square that
it wouldn't balance no matter how many washers I attached. Luckily,
as it turned out, I didn't need that post anyway.
Thanks for the suggestions,
Ted J
thelatentlog.com
Arch
Hi Ted,
Glad you got your problem solved. Another way to correct for an
imbalance of lathe & workpiece is harmonic balancing. We used to discuss
this technique here, but it seems not to have caught on. It is an
interesting concept.
IIRC, it's nothing more than a 12 to18 in. threaded rod bolted
perpendicular (not sure if horizontal or vertical matters) to the
headstock and a weight is adjusted along its length to find the best
vibration damping frequency. Some of you engineers correct me or
explain better. I have never actually made or even seen one, but it
makes for conversation. :)
Turn to Safety, Arch
Fortiter
Leo Lichtman
"Arch" wrote: (clip) Another way to correct for an
> imbalance of lathe & workpiece is harmonic balancing. We used to discuss
> this technique here,
Yes--it was one of the topics that Lyn Mangiamelli played with.
^^^^^^^^^^^^^^^^^^^^^
(clip)threaded rod bolted
> perpendicular (not sure if horizontal or vertical matters) to the
^^^^^^^^^^^^^^^^^^^^^
From a damping standpoint, it doesn't matter, but there is less chance of
overstressing the threaded rod if it is vertical.
Arch, do you know whether Lyn ever recovered from his lung problems? Last I
heard, he was not doing well at all.
For those too new to the group to remember, Lyn was an outstanding
contributor to this group years ago, until he contracted a very serious lung
disease from rat droppings in his wood pile.
Arch
Leo, I don't know about Lyn, but I sure miss him and so many others.
Fred might know.
If anyone here has info about or experience with harmonic lathe
balancing I'd sure like to read about it.
tom koehler
(in message <8834-4AE6...@storefull-3253.bay.webtv.net>):
try this:
http://patimg2.uspto.gov/.piw?Docid=05095786&homeurl=http%3A%2F%2Fpatft1.uspt
o.gov%2Fnetacgi%2Fnph-
Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%25252
Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D
5095786.PN.%2526OS%3DPN%2F5095786%2526RS%3DPN%2F5095786&PageNum=&Rtype=&Sectio
nNum=&idkey=NONE&Input=View+first+page
good gravy! that has to be a cut and paste!
It is the Patent office page link for the drawings of patent #5,095,786 which
is a method for dynamic balancing a brake drum lathe (or as we would
recognize it, a boowl turning setup.) It is a heavy mass - called an
ineretial mass, in the patent specification. The mass is linked to the lathe
arbor with elastic mounting material. This is a ring or concentric mass,
flexibly mounted to the lathe arbor. The whole spiel is lengthy, but the
effect is basically what has been discussed in this thread, except the mass
is a ring instead of a radially supported mass on a threaded rod.
If the link loses something in the move to this NG, then just go to the USPTO
site, and type in the patent number, in the patent number search. Somewhere
on the page that comes up will be a link for drawings. It will not only be
the drawings but the complete text of the patent specification as well.
Am going back to the data mines to see what else I can dig up. TTFN,
tom koehler
tom koehler
(in message <0001HW.C70BD21A...@news.frontiernet.net>):
Another patent is even more interesting. It is for a front loading washing
machiine, and uses an annular tub on the same shaft as the laundry tub. The
annular tub has water in it and sponge material. At high shaft speeds, the
water is spun out ot the periphery of the tub and balances it. Imagine a
fluid-filled ring associated with your chuck or faceplate. As the lathe is
running, this fluid-filled ring is balancing your lathe. See patent #
5709109
I could not pull up drawings on this one at the PTO site, don't know why.
Other reference sources should give up something.
g'nite again,
tom koehler
(in message <0001HW.C70BD90C...@news.frontiernet.net>):
> See patent #
> 5709109
> I could not pull up drawings on this one at the PTO site, don't know why.
> Other reference sources should give up something.
>
> g'nite again,
> tom koehler
>
>
forget the PTO website! Just type in the patent number in your google search
line, and you will come up with Google Patents! who knew? The full patent
spec is there and faster and easier than the gummint site. Also got all the
drawings there with no fuss. As i suspected, the ring is about half-full of
water, and when it spins up, it is clear of the sponge media, and balances
the drum at the fast spin-dry speeds. No moving parts, no seals or flexible
energy-absorbing material or other parts to fail, as in an engine crankshaft
balancer. Just an annular ring with fluid innit. I gotta try to make one of
these. G'nite, for sure, this time!
Ralph E Lindberg
al...@webtv.net (Arch) wrote:
> Leo, I don't know about Lyn, but I sure miss him and so many others.
> Fred might know.
>
I asked Fred awhile ago (a year) and he had heard nothing. Makes me
worried that no-one has heard a thing
--
--------------------------------------------------------
Personal e-mail is the n7bsn but at amsat.org
This posting address is a spam-trap and seldom read
RV and Camping FAQ can be found at
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tom koehler
(in message <n7bsn-DCEA95....@individual.net>):
> In article <8834-4AE6...@storefull-3253.bay.webtv.net>,
> al...@webtv.net (Arch) wrote:
>
>> Leo, I don't know about Lyn, but I sure miss him and so many others.
>> Fred might know.
>>
> I asked Fred awhile ago (a year) and he had heard nothing. Makes me
> worried that no-one has heard a thing
>
>
I do a bit of looking for things, on the web. I found this article and it
seems to be the balancing device you and others were talking about.
http://www.morewoodturning.net/Glaser%20Tunable%20Blanacer.pdf
There is also a very good picture of the balancer.
It is by Lyn Mangiameli, the man you are concerned about, now. I am a
latecomer to this group, and so am unfamiliar with this man's work. Having
read this article, I can say that I will bookmark the page where I found this
article, and read the rest.
Respectfully,
LDosser
news:lrKdnRrbmcRgi3vX...@giganews.com...
Hanta Virus? Does he live in the SW?
Leo Lichtman
"LDosser" wrote: Hanta Virus? Does he live in the SW?
^^^^^^^^^^^^^^^^^^^^^
Yes, I believe that is it. SF Bay Area.
>
LDosser
>
> "LDosser" wrote: Hanta Virus? Does he live in the SW?
> ^^^^^^^^^^^^^^^^^^^^^
> Yes, I believe that is it. SF Bay Area.
>>
>
>
Hantavirus is very bad, but I thought it was only found in the desert south
west. Doing a google proves me wrong about the geography and right about the
bad.
Ralph E Lindberg
"LDosser" <L...@invalid.invalid> wrote:
No, Hata can be found almost anywhere
name
You can turn at very low rpm, down to 0 ....