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Woodturning (rec.crafts.woodturning) To discuss tools, techniques, styles, materials, shows and competitions, education and educational materials related to woodturning. All skill levels are welcome, from art turners to production turners, beginners to masters. |
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#1
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Turning large out of balance posts
Background info:
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 |
#2
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Turning large out of balance posts
"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. |
#3
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Turning large out of balance posts
On Tue, 20 Oct 2009 21:07:41 -0500, Ted wrote
(in message ): Background info: 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 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. |
#4
Posted to rec.crafts.woodturning
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Turning large out of balance posts
"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? |
#5
Posted to rec.crafts.woodturning
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Turning large out of balance posts
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... -- Kevin Miller Juneau, Alaska http://www.alaska.net/~atftb In a recent poll, seven out of ten hard drives preferred Linux. |
#6
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Turning large out of balance posts
On Fri, 23 Oct 2009 16:13:31 -0500, Kevin Miller wrote
(in message ions): 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. -- I will find a way or make one. |
#7
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Turning large out of balance posts
The slime idea is intriguing. But I already have all the post turned
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 |
#8
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Turning large out of balance posts
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 http://community.webtv.net/almcc/MacsMusings |
#9
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Turning large out of balance posts
"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 headstock (clip) ^^^^^^^^^^^^^^^^^^^^^ 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. |
#10
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Turning large out of balance posts
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. Turn to Safety, Arch Fortiter http://community.webtv.net/almcc/MacsMusings |
#11
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Turning large out of balance posts
On Mon, 26 Oct 2009 17:04:35 -0500, Arch wrote
(in message ): 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. Turn to Safety, Arch Fortiter http://community.webtv.net/almcc/MacsMusings try this: http://patimg2.uspto.gov/.piw?Docid=...Fpatft1.us pt o.gov%2Fnetacgi%2Fnph- Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DP ALL%2526p%3D1%2526u%3D%25252 Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%25 26f%3DG%2526l%3D50%2526s1%3D 5095786.PN.%2526OS%3DPN%2F5095786%2526RS%3DPN%2F50 95786&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 -- I will find a way or make one. |
#12
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Turning large out of balance posts
On Mon, 26 Oct 2009 22:24:26 -0500, tom koehler wrote
(in message . net): On Mon, 26 Oct 2009 17:04:35 -0500, Arch wrote (in message ): 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. Turn to Safety, Arch Fortiter http://community.webtv.net/almcc/MacsMusings try this: http://patimg2.uspto.gov/.piw?Docid=...2Fpatft1.us p t o.gov%2Fnetacgi%2Fnph- Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DP ALL%2526p%3D1%2526u%3D%2525 2 Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%25 26f%3DG%2526l%3D50%2526s1%3 D 5095786.PN.%2526OS%3DPN%2F5095786%2526RS%3DPN%2F50 95786&PageNum=&Rtype=&Secti o 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 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 -- I will find a way or make one. |
#13
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Turning large out of balance posts
On Mon, 26 Oct 2009 22:54:04 -0500, tom koehler wrote
(in message . 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! tom koehler -- I will find a way or make one. |
#14
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Turning large out of balance posts
"Leo Lichtman" wrote in message
... "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 headstock (clip) ^^^^^^^^^^^^^^^^^^^^^ 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. Hanta Virus? Does he live in the SW? |
#15
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Turning large out of balance posts
On Tue, 27 Oct 2009 7:26:40 -0500, Ralph E Lindberg wrote
(in message ): In article , (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/Glase...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, tom koehler -- I will find a way or make one. |
#16
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Turning large out of balance posts
"LDosser" wrote: Hanta Virus? Does he live in the SW? ^^^^^^^^^^^^^^^^^^^^^ Yes, I believe that is it. SF Bay Area. |
#17
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Turning large out of balance posts
"Leo Lichtman" wrote in message
... "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. |
#18
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Turning large out of balance posts
Get the router bracket for the Vega duplicator and a router with a spiral bit.
You can turn at very low rpm, down to 0 .... |
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