Musing about movers and shakers: quieting them with harmony

No, not about a balancing act to curb influential turners. I'm wondering about harmonic balancing for my over stressed Nova 3000. The poor thing is all shook up trying to rotate some heavy rough NIP logs. I've lessened its agony as much as I can with low speed, a strong heavily weighted bench, secure tail support, a well trimmed log and all the usual therapies _including gentle cuts with a sharp spindle roughing gouge. It continues to move and shake. :(

I know, I know, "give up and treat yourself to a Stubby, Arch", but what about trying some harmonic balancing first? I mean a rod with an adjustable weight. You don't hear much about it these days, but I hope that if some of you have used or considered this way to quiet a vibrating lathe you will answer some questions and offer suggestions and/or opinions pro & con.

I thought of bolting a piece of 1" allthread to one of the holes for the optional outboard toolrest and adding an adjustable barbell weight between two bolts at the outboard end. Before I mess around with this, is this contraption likely to work? If you think it might, where do I attach this abortion? axial? Radial? Headstock? Bed? Bench? Length of allthread? size of the weight? How to tune it? Static? Dynamic? So many questions--so little ability. I need help.

Turn to Safety, Arch Fortiter

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Arch
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Arch, back in 1983 I build a copy of Ed Moulthrop's faceplate lathe. It weighed about 450 lbs., and some of the pieces I turned weighed more than the lathe. Needless to say, it moved!! I ended up bracing the lathe with

2" diameter aluminum pipe to the rafters of the shop, along with bolting it to the floor. This still didn't solve the problem, so I made a 15" diameter 3/8" thick steel disc that I mounted on the outboard end of the spindle. 9/16" holes were drilled every 1 1/4" around the perimeter of the disc. I also collected about 50 lbs of wheel weights and melted them down, then poured them into aluminum pie pans. They were poured to varying depths, and peeled right out of the aluminum when cool. Then I bored 9/16" holes in them with a spade bit in a drill press. To balance a piece, I would loosen the belt, let the wood settle down, then put a piece of 1/2" all thread rod into the top hole in the disc. A nut on each side of the disc held the all thread rod. Then I would simply slide on the lead weights until it was nearly statically balanced. It made a huge difference in the speed that I could turn. However, as you turn, the piece of wood becomes more balanced, and periodically you have to stop and take off some of the weights.

One piece I turned was rotted throughout one side, and I ended up with 40 lbs of weight on the balancing disc. Without the balancing disc, I could not have turned the piece at all.

This solution is not perfect, but it will enable you to turn really out-of-balance pieces.

Hope this helps, James Johnson

Reply to
JRJohnson

Arch, I start my bowls between centers. Before turning on the power I support the blank loosely between the point of the drive center and the point of the live center. With just these two points holding the wood, it is easy to determine the heavy side. I just keep trying different spots to balance to wood as closely as possible. When that is achieved, I tighten up the tailstock. This works really well and is something I learned from David Ellsworth.

If you try this, keep a sharp eye on how tight the wood is held. With a heavy chunk of wood and the 'thunk-thunk' of getting it round, the drive center digs into the wood. You need to keep tightening the tailstock. But on the bright side, the drive center gets you started on hollowing the blank! :o)

Harry

Reply to
Harry Pye

If this thread doesn't attract Lyn Mangiameli, then we know something is really wrong. I believe he was testing a harmonic balancer about the time he got sick. The attachment point should be at the headstock. All-thread sounds like a good idea, but be careful--to work effectively, the balancer has to be tuned to resonance, which means that it will be vibrating A LOT. The stresses in the metal near the attachment point could get high enough to crack the steel, and having threads in that area will make things worse (stress raiser.)

Arch, you should also recognize that this discussion has gone in two different directions: you asked about harmonic balancing. A number of the responses have been about static balancing, which is an entirely different thing. If you can get a piece in balance, that is good, but it is not always an option. You may want to turn around an axis that does not go through the center. You may be turning a piece that is non-uniform in density. That is where harmonic balancing would be called for.

Reply to
Leo Lichtman

Yes indeed, where are you Lyn? The responses are interesting to me and I hope for others, whether or not we ever try harmonic balancing.

James' point about about changing the static balancing weights as the piece changes into round has me scratching my head. Hadn't thought about that.

Leo's warning about the stresses on the lathe and the device as they resonate is scary when I realize that I know nothing about the forces involved. Also I have no idea of the frequency / wave length range and if there might be standing waves with nodes & nulls along the rod.

Truth be told, I might seem to know what I'm talking about, but I'm way over my head here and I'm thinking I better follow Harry's and James' advice and leave harmonic balancing to mind experiments performed in my arm chair. Even so, I hope to learn more from someone with knowledge and experience. Remember that not too long ago vacuum chucking for woodturning seemed foolish and too dangerous to be considered seriously?

Turn to Safety, Arch Fortiter

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Reply to
Arch

Hi Arch

I seem to recall a post and picture of someone trying to make a dynamic balancer.

If I recall right, he had a a pipe bolted to the headstock vertical and above, there was a weight that could be raised/lowered to find the best position to lower the "shakes".

I don't recall how successful it was, also I have no idea as to the forces involved, or if the device could increase the shake/shudder and make things worse under certain conditions.

I know counter rotating shafts are used to minimize engine vibrations, but I have more questions than answers on that.

My way of dealing with the unbalanced blanks has been adding weight to the lighter side, last time the large 24" willow burl that I did was screwed to a large MDF platter and weights bolted to the platter, it worked just fine.

Have fun and take care Leo Van Der Loo

Reply to
l.vanderloo

You let them lay on one side too long, eh? Wet on one, dry on the other. Rotating your stock has meaning beyond the market or the lathe.

Those must be some monsters. I dummied up and swung a waterlogged 16x6 piece of hard maple at 680 on mine the other day. Then, just for the heck of it, I tried to turn it. Call it nostalgia, call it stupid, It was like the first couple of minutes with Blue and his 600+ minimum speed. Nice to have 360, and difficult to comprehend anything that would shake the lathe at

180.

Static balance is my answer. Holes, sinkers and screws. Easy to determine and do, but if you'd rotate your logs a week or two before turning, the problem'd go away.

Reply to
George

No argument here about the superiority of static balancing for woodturning now and in any future that I can foresee. I just wanted to remind some of you and inform others that might not know it exists, that harmonic balancing is a possibility and I think worthy of being discussed by woodturner's 'pro tem' then archived for later reference.

Perhaps h.b. is a boring subject now, but you never know. Could you ever have imagined a headstock that swivels and slides? Or a gouge that won't get mad and lose its temper no matter how hard you grind on it? :)

WebTv makes posting a url tedious, so to get anyone interested up to speed (poor choice of phrase) I'll ask someone to post the archived thread in which Lyn and others, particularly Russ Fairfield, brought this technique to our attention with good explanations. Not sure if h.b. was ever published in "More Woodturning". Maybe we can get Russ and Fred to post an informed review & update. Still hoping others will jump in re harmonic balancing so we will have a state of the art in mid '06 for reference. Many TIAs.

Turn to Safety, Arch Fortiter

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Arch

Trivia: The phrase 'movers and shakers' originates in a poem by a Kentuckian circa 1850 about the industrious Hoosiers across the Ohio at New Albany building sternwheelers. Dan

Reply to
Dan Bollinger

Hello Arch,

I've never used the harmonic balancing technique, but I did see it demonstrated several years ago. At the moment, I can't even remember who was demonstrating it. I believe it may have been at the first Puget Sound Woodworking Symposium in

2000, but am not sure. The fellow had a bar attached to the lathe bed that stuck out on the opposite side of the lathe and then a vertical piece of all thread with two nuts and a weight on it attached at the end of the bar. As I recall, he balanced out vibration by moving the weight up and down. I'll look in my photo archives and see if I can find a photo of it. As I recall, it dampened out the vibration quite well.

Fred Holder

Reply to
Fred Holder

I have my lathe sitting on machine mounts. They are some sort of rubber and dampen the movement of the lathe when turning unbalanced pieces.

I have also used the spinning plate with counter balancing weights. I've done this in two ways. One is to use a plywood circle mounted on the spindle with weights attached. as the turning progresses, the weight distribution changes and I move the weights. Simply use screws into the plywood. For very large pieces you can use a large plywood disk.

The other method I've used and plan to use more often is to use my jumbo jaws as the plate. Michael Werner uses machine screws into the bumper holes on the back of the jaws while mounting the turned piece on the front of the plates with screws. This works great.

Joe Fleming - San Diego

Reply to
Joe Fleming

============================ Arch, Some years ago, I saw an "automatic" or "self balancing" wheel balancer in a JC Whitney auto parts catalog. I wondered about it at the time, but didn't try to check it out. It mounted between the tire and the hub, and dynamically balanced as the vehicle was driven. I did ask a mechanic about it later, and he said truckers had used somrthing like that for some time. I always guessed that they used some viscous material or metal bead material. Don't know if you could find anything lilke that on the web, or at least some theory on how it would work, but it might be worth a look.

Ken Moon Webberville, TX.

Reply to
Ken Moon

It was a circular tube, hula-hoop style, with a dozen or so ball bearings inside and filled with mineral oil. I'm not sure it would have sufficient moment arm to counteract the large forces in some work.

Dan

Reply to
Dan Bollinger

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If that works for the small weight differences in a wheel, then a larger one could be fabricated for large lathe work. Just don't know if the results would be worth the effort.

Ken

Reply to
Ken Moon

Many thanks to Ken for bringing this up and to Dan for following up, Could you two and others explain a little about how this works. Maybe suggest references.

Turn to Safety, Arch Fortiter

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Arch

I would suggest searching US patents. Patents disclose enough information that a reasonably adept person could duplicate the work. Dan

Reply to
Dan Bollinger

Hello Arch,

Lyn wrote an article for More Woodturning, which was published in the June 2002 issue, I've printed that page out to a PDF file and will e-mail it to any who wish to try making up a balancer for their lathe. Lyn had it mounted on his Nova

3000. This was a Glaser design that was never brought to the market as far as I know.

Fred Holder

Reply to
Fred Holder

Hello Arch,

Lyn wrote an article for More Woodturning, which was published in the June 2002 issue, I've printed that page out to a PDF file and will e-mail it to any who wish to try making up a balancer for their lathe. (sorry, forgot the e-mail address . Lyn had it mounted on his Nova 3000. This was a Glaser design that was never brought to the market as far as I know.

Fred Holder

Reply to
Fred Holder

Who do you think was the very last variety show entertainer who did the spinning plates on the dowels bit? D'ya think he knew he was the end of the line? I recall seeing this act as a kid in the '60s and always thought it fun - when those first plates began wobbling on the stick...

Did this act have an official name? What title does one call the guy who does it?

Reply to
Owen Lowe

I think they still do this. Seems like I saw one on the tube sometime in the past 4 or 5 years. Some things just never go out of style. Probably been plate spinners since plates were invented and probably will be as long as we've got breakable plates.

Reply to
Lobby Dosser

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