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Manuka Jock
5th November 2008, 10:13 AM
Is this the answer we are all looking for ?
A bucket on a pole (http://www3.sympatico.ca/3jdw8/antivibration.htm)???

:D

Woodwould
5th November 2008, 11:30 AM
How do you moisten vibration and why? :roll:

Robomanic
5th November 2008, 12:31 PM
Some of his observations are great, but the maths behind his explanation is a bit patchy. The pole is acting like a spring and lever. The damped-spring-mass system (bucket of sand on a pole) IMHO would be the best. I would have to recommend against the pure spring-mass system (block of wood on a pole) because if he hits a resonant frequency I would not like to be standing close to it.

Woodwould
5th November 2008, 12:41 PM
It's unlikely a constant frequency would be met when turning an out-of-balance chunk of wood as the periphery and therefore the mass would be systematically reduced, but the danger could present itself once the chunk had been turned down and closer to being balanced.

It could also get ugly if the lathe is left running and the chunk isn't reduced in diameter.

A method of disengaging the weight would be essential.

Robomanic
5th November 2008, 01:02 PM
It is as you cross one of those points as it is being systematically reduced that bites you . Practical experience I'm afraid, when faced with the choice between stop switch or rough faster, I chose the latter and lived to tell the tail but not for the feint hearted.

Besides, the stop switch is only a temporary fix.

NCArcher
5th November 2008, 01:10 PM
How do you moisten vibration and why? :roll:
Hmmm..If you fill the bucket with water, as the vibration increases the likelyhood of moisturisation increases dramatically. :doh:

Manuka Jock
5th November 2008, 01:20 PM
An ingenious scheme for dealing with over dry wood eh :p

Woodwould
5th November 2008, 01:25 PM
Hmmm..If you fill the bucket with water, as the vibration increases the likelyhood of moisturisation increases dramatically. :doh:

I suspect that's when he switched to using sand.:U


All in all, I think I'd prefer a solid steel bench bolted to the concrete floor. You really don't need 50lbs. of bucket and sand distracting you while you're approaching the centre of a bowl-saving cut.

Texian
5th November 2008, 01:51 PM
A similar system came up on another forum. Seems like way more trouble than it could be worth. The purpose of the device, it was said on the other forum, was to enable one to spin out of balance pieces faster, and thus improve one's productivity. And if that fellow considers a 50 pound weight on a pole easily portable, he is younger and/or a lot stronger than I am now. Guess I'll do without this improvement.

Manuka Jock
5th November 2008, 02:08 PM
His turning work is good tho ,
its just his engineering that a tad odd :rolleyes:

joe greiner
5th November 2008, 08:55 PM
Sounds like the concept of a "tuned mass damper," sometimes used in very tall buildings to reduce swaying under earthquake or wind load. These are usually suspended heavy pendulums with hinges to provide counter-vibration in lieu of flexure in the pole. Resonance could be particularly hazardous, when/if a very significant number of oscillations exceed the pole's fatigue-cycle life at low flexural stress.

>>>> Please DON'T do this. <<<<

Yes, I'm a Structural Engineer.

Joe

Ed Reiss
6th November 2008, 01:03 AM
>>>> Please DON'T do this. <<<<

Yes, I'm a Structural Engineer.

Joe

Well, I'm not a structual engineer, brain surgeon, or even a rocket scientist...but even my dumb a** can see that this might not exactly be the best solution to vibration:no:

Kinda' scary:o

Manuka Jock
6th November 2008, 01:21 AM
If he wants to set up for turning outside in the summer , all he has to do is pour a block of concrete , with tie-down bolts cast in for the lathe .

Whats the point of all that up the pole crap .........:rolleyes:

NeilS
6th November 2008, 03:08 PM
This looks like a version of Glaser Tunable Vibration Absorber, details attached.

Seems to me that the same effect could be achieved by suspending the weights low down to the floor and then if something came adrift it wouldn't :brick:

Not that I'm suggesting the merit of such a system one way or the other.


Neil

Texian
6th November 2008, 04:05 PM
Yeah, that was it. Perhaps more useful on non variable speed lathe to help counterbalance the vibration when roughing. That make sense.

joe greiner
6th November 2008, 08:55 PM
Yes, I'm a Structural Engineer.

AND, I have stayed at Holiday Inn Express.:D

Joe

Cliff Rogers
6th November 2008, 09:02 PM
... >>>> Please DON'T do this. <<<<....

I wouldn't try Glasser's tunable one on the thin pole but I'm game to try the one with the bit of 2" water pipe.

My big lathes are bolted to concrete & not a problem but my Jet Mini has to be portable to go with me in the car & the bloody thing leaps all over the tent while I'm roughing something out.

I'll let you know how it goes. :D

Manuka Jock
6th November 2008, 09:19 PM
Take this one away camping Cliff .
On those wet mornings ,
ya won't even have to get of ya sleeping bag :roll:

Cliff Rogers
6th November 2008, 09:29 PM
Which one of the thunderbirds is that kid? :D

Manuka Jock
6th November 2008, 09:48 PM
Brains :cool:

Cliff Rogers
6th November 2008, 10:55 PM
Nailed it.... :2tsup: I couldn't remember his name but that sure looks like him. :p

oldiephred
7th November 2008, 10:06 AM
The main concern I see with trying to significantly reduce vibration in the name of greater production rates is that most do not look at the lathe closely to determine what will "give" next. The vibration is not being eliminated but , rather, transferred to some other point even though it may not be in the form of large movement.
Will the bearings, castings, etc, tolerate this transferred STRESS for extended time or will one end up with a non repairable, broken, machine?

Manuka Jock
7th November 2008, 11:07 AM
Good point .
Vibration , like pain , can be a signal that something is wrong , and getting worse .

Don't disguise it , Diagnose it ,

NeilS
7th November 2008, 11:42 AM
The vibration is not being eliminated but , rather, transferred to some other point even though it may not be in the form of large movement. Will the bearings, castings, etc, tolerate this transferred STRESS for extended time or will one end up with a non repairable, broken, machine?

Yes, Oldiephred, but that also applies if you bolt your lathe to the floor... which many of us have done.

Running an out of balance blank at or above vibration speed has never felt right to me. Like many other turners, I simply wind up the speed slowly on any unbalanced blanks until there is a slight vibration and then just back it off a tad. As the roughing progresses the speed can usually be nudged up a notch or two to complete the process. After all, the blank is only out of balance for a brief time if the completed piece is concentric.

If you specialise in large natural edge/inclusion/eccentric pieces there may be a case for extra measures, like upgrading to a more substantial lathe...:U Although I haven't found it necessary on eccentric pieces up to 50cm in diameter, like the piece on the left in the attached image which was heavily out of balance to start with.

Cliff's porta-lathe is another exception.

Neil

Cliff Rogers
7th November 2008, 07:17 PM
.... Cliff's porta-lathe is another exception.....
I wonder if an anti-vibration pole would work on a porta-potty. :think:

NeilS
7th November 2008, 07:26 PM
I wonder if an anti-vibration pole would work on a porta-potty. :think:

It may depend on whether you are producing any 'resonant frequencies' on it... :o

Neil

Ed Reiss
8th November 2008, 07:29 AM
It may depend on whether you are producing any 'resonant frequencies' on it... :o

Neil

....and the "duration" for same :doh:

hughie
8th November 2008, 08:08 AM
all in all it seems a lot of stuffing around, poles buckets of water etc. I think theres enough products out there to achieve something similar and at a reasonable cost factor.:?

If you shake your lathe to death, then I suspect your flogging it too hard beyond its recommend parameters, or perhaps you've got a chiwanese like me. :C :U


... and I must confess, I to, have stayed in the Holiday Inn........we're a sad lot :D