plexi0,
Check out Nanook's - he's the guy at the top of this page - unipivot. You'd have to look to hard to find a better place to jump into this madness.
http://www.diyaudio.com/forums/analogue-source/173861-my-latest-iteration-nanooks-219-tonearm.html
That magnet arrangement is interesting and might lead somewhere, but the description mentions "staying in the same plane," which could be a problem and I suspect that Earnshaw will show up somewhere.
Regardless, the kit isn't very expensive and experimenting with it might lead to something really worthwhile.
Check out Nanook's - he's the guy at the top of this page - unipivot. You'd have to look to hard to find a better place to jump into this madness.
http://www.diyaudio.com/forums/analogue-source/173861-my-latest-iteration-nanooks-219-tonearm.html
That magnet arrangement is interesting and might lead somewhere, but the description mentions "staying in the same plane," which could be a problem and I suspect that Earnshaw will show up somewhere.
Regardless, the kit isn't very expensive and experimenting with it might lead to something really worthwhile.
great, will do....
apparently 'eddy currents' have something to do with shroeders' use of magnets?
https://www.youtube.com/watch?v=zCUSXoL4SDE
apparently 'eddy currents' have something to do with shroeders' use of magnets?
https://www.youtube.com/watch?v=zCUSXoL4SDE
Hi plexi0,
In what sense do you feel this:
https://www.gyroscope.com/d.asp?product=INVERTERMAGNET
has anything to do with my thread/magnet bearing arms?
The point of the thread/magnet bearing is to simulate as high a mass as possible(=suspendable by a thin thread) to be displaced, WITHOUT having to deal with the problem of high friction/high eff. mass or undesirable energy storage. The eddy current damping and skating compensation that are "built into" the bearing are nice bonuses. In addition the bearing "isolates" the armwand assembly from the base mechanically to a large degree(inhibiting the transfer generated or picked up by the deck), - without sacrificing rigidity of the armwand-bearing gallows interface.
The suggested use of the principle utilized in the linked device would require extremely strong magnets to assure the same bearing rigidity. Its layout makes shielding the stray fluxlines impossible by design.
Magnetically stabilized unipivots are a different matter alltogether
All the best,
Frank Schröder
In what sense do you feel this:
https://www.gyroscope.com/d.asp?product=INVERTERMAGNET
has anything to do with my thread/magnet bearing arms?
The point of the thread/magnet bearing is to simulate as high a mass as possible(=suspendable by a thin thread) to be displaced, WITHOUT having to deal with the problem of high friction/high eff. mass or undesirable energy storage. The eddy current damping and skating compensation that are "built into" the bearing are nice bonuses. In addition the bearing "isolates" the armwand assembly from the base mechanically to a large degree(inhibiting the transfer generated or picked up by the deck), - without sacrificing rigidity of the armwand-bearing gallows interface.
The suggested use of the principle utilized in the linked device would require extremely strong magnets to assure the same bearing rigidity. Its layout makes shielding the stray fluxlines impossible by design.
Magnetically stabilized unipivots are a different matter alltogether
All the best,
Frank Schröder
I just ran across the tractor beam phenomena in a separate search. and was thinking out loud in that maybe it could be used for tonearm pivot point application.. Wasn't really imagining the magnets as the soul bearing for the pivot point but more of a stabalizing affect, instead of simply having a pivot point and letting the wand be thrown about by the dictates of the grooves.
I like the idea of suspending the pivot point so that it is not receiving the plinth vibrations which I can understand is being achived with the 'string tree'. I still have to look into exactly what your magnet arrangement is doing besides 'adding virtual mass' if I understand correctly, but I do understand that the tractor force idea is a separate issue. It just seems like such a neat phenomena, would be nice if it could be utilized ! that 1/8" 'still point' seems to me like some sort of center of a hurricane idea. But if the rest of the magnetic field disrupts other aspects of function, it would not be applicable. So what i was thinking was to use it to stabalize maybe the side to side aspect of a pure unipivot where the wand was free to move laterally as the groove dictates but still introduce some sort of control (backpressure) type of affect.
In any case, it's just thinking out loud at this point in the hopes something would strike someone else to see a way to utilize the idea (if at all possible)
to try and boil down my idea more:
from what little I understand, it does seem beneficial to allow a unipivot to 'rock back n forth' a bit like a rowboat for example. because this allows more info to be extracted from the groove, But the simple unipivot provides no control over this aspect..........that introduction of some measure of control is what i'm trying to understand and seems like your 'string tree' idea is in some way accomplishing this perhaps....
I like the idea of suspending the pivot point so that it is not receiving the plinth vibrations which I can understand is being achived with the 'string tree'. I still have to look into exactly what your magnet arrangement is doing besides 'adding virtual mass' if I understand correctly, but I do understand that the tractor force idea is a separate issue. It just seems like such a neat phenomena, would be nice if it could be utilized ! that 1/8" 'still point' seems to me like some sort of center of a hurricane idea. But if the rest of the magnetic field disrupts other aspects of function, it would not be applicable. So what i was thinking was to use it to stabalize maybe the side to side aspect of a pure unipivot where the wand was free to move laterally as the groove dictates but still introduce some sort of control (backpressure) type of affect.
In any case, it's just thinking out loud at this point in the hopes something would strike someone else to see a way to utilize the idea (if at all possible)
to try and boil down my idea more:
from what little I understand, it does seem beneficial to allow a unipivot to 'rock back n forth' a bit like a rowboat for example. because this allows more info to be extracted from the groove, But the simple unipivot provides no control over this aspect..........that introduction of some measure of control is what i'm trying to understand and seems like your 'string tree' idea is in some way accomplishing this perhaps....
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had some time to look through thread and see that it is primarily a strict clone diy and lots of great info, I will be gathering parts to make my version. The diversion into possibilities of using tractor force should have gone in another thread. I also was referring to an apparent early version that had two strings in a sort of pyramid instead of the single. these are apparently two different designs. I kind of liked the idea of the pyramid string and wonder why it was discarded in favor of the single centered string but it's also not appropriate for this thread,
regarding the single thread design. I assume its ok to use all or mostly hardwoods for the cylinder, top and bottom plates? I have lots of woodworking exp but no metal shop so unless I can find solid brass cylinders and metal top plates, I will likely use ebony or hard maple etc....for the arm i've got a hollow shaft of apparent carbon fiber golf club. If that does not sound decent, will try bamboo, since I don't know how you all are hollowing out a solid hardwood wand, uness you are leaving it solid and not hollowing it out....lots of questions but the basic design is coming into focus and looks like a good'un
regarding the single thread design. I assume its ok to use all or mostly hardwoods for the cylinder, top and bottom plates? I have lots of woodworking exp but no metal shop so unless I can find solid brass cylinders and metal top plates, I will likely use ebony or hard maple etc....for the arm i've got a hollow shaft of apparent carbon fiber golf club. If that does not sound decent, will try bamboo, since I don't know how you all are hollowing out a solid hardwood wand, uness you are leaving it solid and not hollowing it out....lots of questions but the basic design is coming into focus and looks like a good'un
Hi again,
No problem throwing another thought/option into the discussion. I was just trying to make sure that anyone not having gone through this loooong thread wasn't mislead.
I dropped the inverted Y because of the added complexity. It is a viable option, restricting the rotation around the longitudinal axis of the armwand, allowing for an easy pick of the pivot point height and location vs the overall mass distributon of the armwand/counterweight assembly, BUT it requires a longer thread. So, failing to pick the right thread material would bear the risk of stretching/changing length due to changes in humidity. Quite a few high tech fibres are prone to that...
Using hardwood for the plates is not a good idea.
My wands are not solid. The wiring is run through a 2mm hole. If you can drill a straight 2mm hole through a 12" long and 1/2" diameter hardwood stick, I take my hat off to you! Much easier to mill a slot and fill it after inserting the wiring or to glue two pieces of wood together after milling a slot into the surfaces facing each other, then turn it.
Good luck with your project!
Frank
No problem throwing another thought/option into the discussion. I was just trying to make sure that anyone not having gone through this loooong thread wasn't mislead.
I dropped the inverted Y because of the added complexity. It is a viable option, restricting the rotation around the longitudinal axis of the armwand, allowing for an easy pick of the pivot point height and location vs the overall mass distributon of the armwand/counterweight assembly, BUT it requires a longer thread. So, failing to pick the right thread material would bear the risk of stretching/changing length due to changes in humidity. Quite a few high tech fibres are prone to that...
Using hardwood for the plates is not a good idea.
My wands are not solid. The wiring is run through a 2mm hole. If you can drill a straight 2mm hole through a 12" long and 1/2" diameter hardwood stick, I take my hat off to you! Much easier to mill a slot and fill it after inserting the wiring or to glue two pieces of wood together after milling a slot into the surfaces facing each other, then turn it.
Good luck with your project!
Frank
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An externally hosted image should be here but it was not working when we last tested it.
Or use CF tube, very easy.
Hi zeonrider,
I didn't mean to brag... CF is perfectly fine for experiments(a conical golf club blank in particular!), - and many a DIYer will remain happy ever after. It is not my personal preference, but can be utilized to very good effect when combined with other materials. Which then means spending just as much time building a CF/composite wand vs. a wooden wand.
So pick your poison
Cheers,
Frank
I didn't mean to brag... CF is perfectly fine for experiments(a conical golf club blank in particular!), - and many a DIYer will remain happy ever after. It is not my personal preference, but can be utilized to very good effect when combined with other materials. Which then means spending just as much time building a CF/composite wand vs. a wooden wand.
So pick your poison
Cheers,
Frank
ok I see, thanks for the info! All makes sense........so apart from a small slot along the length, alot of guys are basically using a solid piece of hardwood for the wand......I'm sure I will find the answer to three other questions in the thread; aluminum, steel or brass for the plates (or is each viable), I wonder if a simple Ushaped one-piece of steel (laid sideways visually of course) would serve the purpose of the entire main structure............, and I've seen some talk of this mystical thread (fishing line is out), I wonder what is best!? my guess is something from the local nautical shop as far as buying something in town.
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so, after making it about half way through the thread I haven't seen the phenomenon of lateral movement being addressed. Could we discuss this for a bit?
The basic unipivot allows for side to side 'rocking' of the arm and provides no counter control other than natural forces that cause the arm to come back to a center point (even if it is from microsecond to microsecond). So the vinyl groove and/or warps in the record cause the cart and wand to rock side to side and it almost immediately comes back to its resting point. In this arm design, is the taught string providing the counter force to tame (while still allowing) this lateral movement? or is it the magnet field that does this? or both, or neither?
The basic unipivot allows for side to side 'rocking' of the arm and provides no counter control other than natural forces that cause the arm to come back to a center point (even if it is from microsecond to microsecond). So the vinyl groove and/or warps in the record cause the cart and wand to rock side to side and it almost immediately comes back to its resting point. In this arm design, is the taught string providing the counter force to tame (while still allowing) this lateral movement? or is it the magnet field that does this? or both, or neither?
An externally hosted image should be here but it was not working when we last tested it.
'roll' is the aspect I've been interested in discussing
I'm sure it was addressed at some point, but is the thread super taught? and is it loose inside the arm, i.e. does the arm wobble or twist if you where to rock it with your fingers? I'm trying to get a feel for how taught that 'roll' movement is/should be
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An externally hosted image should be here but it was not working when we last tested it.
btw, for anyone like me getting into this late, here's the best pic/explanation i've found that will get you up to speed as to how to build this arm. This pic and description will save hours of reading posts imo.....this is an awesomly elegant design it seems. can't wait to build...
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I need to to figure out dimensions and source parts still, and brush up on my drilling and tapping and cutting of brass/aluminum but the basic idea is starting to form at least. I wonder what the ideal force and resistance that magnet /string assembly should be but i guess this is where trial and error comes in
Just for fun.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
