Hi,
anti-skate force is a ~99% function of the OVERHANG!... have I been missing something?!
Without overhang, no vector force, no skating force.
If you had "underhang" you'd create a vector force once again, but it is not of practical interest other then in the consideration of the vector forces.
Axel |
Hi guys,
this developing argument reminds me somehow of what Søren Kierkegaard (19th century Danish philosopher) who once said: "If you get married you'll regret it, if you don't get married you'll also regret it, and if get married or do not get married you'll regret it.
Oh, he also said: "If you hang yourself you'll regret it, and if you don't hang yourself.... :-)
Now replace 'anti-skate' for the 'married' or 'hanged' bit, and see what it looks like...
I'd say: you regret it :-)
Greetings,
Axel |
Dear Mark,
use your test, whereby the tip of the stylus only touches the vinyl.
The contact area thereby sees no off-set, and simply assumes the shortest point between contact area and pivot = one of the vectors. Overhang to the spindle is creating another sector, with the spindle to pivot a third.
Thereby off-set is not involved, yes?
Axel |
another *sector* should of course read: another *vector*... |
Hm,
I still don't get it, call me stupid alright :-)
Put any (hypothetical) 20, 60, 90 deg. off-set angle on a POINT contact only stylus (I'm not talking distortion right now) just spinning on a blank vinyl -- what effect will you notice as long as the point contact to pivot would be the same?
No difference at all is what I stated earlier.
(no 'spade' is getting dragged through some sludge or a groove at this test!)
The stylus' point, sliding over smooth (no groove!) vinyl, will want to align the arm wand in a straight line *pivot to centre of rotation*.
Now increase the over-hang and then what happens?
The more overhang, the longer the frictional force's lever. It will pull the arm wand harder in line (pivot to centre pin) = more skating force? I think so.
Or no change at all? I do not think so.
In deed, what means off-set angle with regard to a 'round' point (contact stylus tip) any way?! - as long as the over-hang length is not affected?
Axel |
Hi,
funny, talking with my 'learned friends' I find *experiment most ALWAYS precedes scientific explanation...* :-)
I just now proved to myself by simply sliding my SME V arm forward from its ~ 18mm overhang to some more without changing VTF = 1.25g and anti-skate 1 on the arm scale which keeps the arm in balance on the blank area of my test record.
Slide the arm enough forward (increase overhang) and ---- the skate force increase enough to now pull the arm to the centre.
Now let's consider a cart like my Windfeld with more then twice! the VTF (2.6g) and the result should be even more telling.
Greetings,
Axel |
Ok, move the SME arm forward you change the off-set angle yes.
Again, if you are running on the pin-point of the stylus, it has NO influence at all, at what angle that pin point rubs on smooth vinyl as a pin has no unequal sides --- unless that is only the case in my universe...
The change in friction force caused by a change in VTF of that pin-point is of course of MUCH greater influence and goes hand in hand higher VTF asking (all things being equal, which in the groove they are not...) for higher anti-skate compensation.
Also, the over-hang for a given arm is a ~ fixed parameter and as such it can actually be disregarded, fair enough.
There the variable is the VTF / friction force => stylus geometry.
As to the "off-set" it is the same as with the over-hang i.e. fixed also for any particular arm geometry and therefore also can be disregarded.
Axel |
Al,
I'm fine by that, it does not contradict any of my own findings.
Axel |
Thank you Mark,
but you are missing the friction force in your test suggestion, present in variable degrees due to variable VTF / stylus shape / friction, as mentioned.
Therefore there will *always* be a skate force present even at 0 mm over-hang :-)
There will be MORE skate force with more overhang, my initial argument and proven by test.
The influence of the VTF => friction is (as I said also) of much more influence i.e. over-hang may therefore be ignored as be off-set, since they are a non-variable parameter (in theory at least) according to a specific arm geometry.
The test: lift the stylus of the vinyl and you'll have 0 skate force where ever the arm is :-)
Greetings,
Axel |
Mark,
am I having a different understanding of what is off-set?
It may explain perhaps some crossed wire...
"Off-set" in my vocab is the angle that a head-shell / cart /cantilever is mounted out of the true / straight line with the tone-arm-wand i.e. 0 deg = no off-set.
As to the various measured forces caused by friction between various materials I have no issue with at all.
In fact, and often, the faster the speed the LESS the friction force e.g. when an object starting to plain on water, rather then being dragged through it is some extreme case in point.
If a tiny tip of a stylus is 'dragged' over smooth vinyl, I can see that no measurable difference in friction force would be the case.
However, no friction force *NO* skate force!
It is this friction that wants to pull the stylus tip with it. Since it can't, due to the arm pivot holding it back, it will do the next best thing and pull the arm in line with the center of rotation. This would also be the shortes distance from pivot to center of rotation, right?
Like a pendulum being pulled (eventually) to the shortest distance from pivot to the center of gravity.
No gravity force, the pendulum will remain where ever is happens to be.
Axel |
Mark,
ja now fine, and so we have even more discrepancies since I, for the sake of TRUE simplification, been talking over and again about BLANK vinyl, and the stylus point riding on this smooth surface --- AND THEREBY taking any of this groove tangent stuff OUT OF THE EQUATION.
There IS a skate force WITHOUT any groove! Therefore NO tangent, what so ever comes into play as I tried real hard to get across.
Taking things into the groove, with all this stuff Perrew is on about is no good, if the basics are not cleared up, yes?
So, again, NO friction force, NO skate force, period.
Tangent has NOTHING to do with it at this point, *if we are NOT in any groove*!
As such all this talk about tangent, or off-set, etc. only serves to cloud the basics of the skate force issue --- unless you are much more deeply into the details then at this point was my understanding.
As such, and going back to the SIMPLE, *no groove*, model Dertonarm is NOT right in assuming a zero skate force at a 0 groove tangent angle.
I can prove that, as soon as there is friction, there is a skate force.
His (Dertonarm's) point is such only of any relevance, if at 0 tangent groove angle -- and as he assumes --- there be less friction force than at any other angle.
If this be so in the first place (and I have no explanation why it should be so!), it be so minute a difference, as to have no measurable effect.
Therefore off-set is as little part of the PRACTICAL equation as is Over-Hang. If one groove side is traced a micro-millimetre later (or earlier) then the other --- what be the increased friction due to that?
None! for a spherical stylus, and none for most any other stylus as well, even it the sides be a sharp as it gets.
It will make a mess of the signal, oh yes, but that is another discussion all together i.e. correct cart alignment.
Axel |
Mark,
+++ The frictional force vector is in the direction of relative motion between the stylus and the vinyl. +++
>>>Yes!
When the stylus is following a groove, this direction is tangent to the groove curvature.
>>>Yes!
When the stylus is not following a groove, this direction is tangent to the scribed arc of the stylus on the vinyl.
>>>Yes!
+++
I completely agree with all the above.
I have no idea where you see a: "false dichotomy"
in my statements of: No friction = no skate force, no groove = no "off-set" in the groove (well there is NONE).
The only other angle is that angle between pin-point stylus to pivot and the pivot to centre of rotation. This angle seeks itself to be closed as soon as a friction force is applied.
If indeed it is what you keep referring to, we have no argument only an issue with terminology.
"Off-set angle" is by definition (in my universe and also at least SME's) the angle the head-shell and thereby the stylus is "off-set" in relation to the tone-arm-wand. This "off-set", (specific to each tone-arm) should produces two null-punkt (0 deg tangent angle) spots on the vinyl after correct alignment.
This tangent (tracing) angle is a constantly changing angle whilst the tone arm moves toward the centre of rotation, or end of record.
I am starting to think you are using "off-set" in place of this variable "tangent trace angle"?!
Sen wat we hav here is se problem mit de "Begriffsbestimmungen", oh mein Gott!?
Failure to communicate?
Axel |
Dertonarm,
I'm a bit lost with the concept "that the bearing of the tonearm is not able to *completely support* the resulting force towards the inner groove"
All that means to me the friction of the tonearm-bearing subtracts itself from the skate force as it is an opposed force?
If you tighten up the bearing that much so is equals the skate force, the arm will not be moved by the skate force anymore.
Where it fits into the understanding of it all I'm not sure right now.
The friction force will create a vector forces due to the arm held at the pivot and produce a resultant force - the skate force. Actually pretty simple, until you want to actually calculate what this resultant force would be.
All we know, it's pretty much proportional to the actual friction force --- that force which we usually don't know and keep guessing about.
Axel |
Ok,
more "off-set" friction.
I'm lost, but learned to be stuck, just being with the question :-)
More to learn as it seems. So thank you all for your patience and kind participation, massaging my lack of awareness in this matter.
Axel |
