What considerations apply to material selection for cartridge mounting bolts?

For wood bodied carts such as ClearAudio, that have no mechanical receptor, plastic cartridge bolts may be considered.

RB, Your quoted responses from ChatGPT suggest that it does not know what it does not know. Which is to say that it ought to understand the concept of effective mass, but it does not seem to.  I would say that the same reasoning applies to the calculation of the effective mass in the horizontal plane as it does to the effective mass in the vertical plane, which is related to the distribution of the mass, from the stylus tip to the joint between the arm wand and the track upon which it moves. Plus for horizontal EM, perhaps there should be a fudge factor for any friction in the air bearing, which of course is likely to be very low in magnitude. I welcome any objections to my non-answer. (There is on the internet a formula for vertical EM.  Distribution of the mass seems like a problem in integral calculus, to me.)

@lewm 

Your quoted responses from ChatGPT suggest that it does not know what it does not know. Which is to say that it ought to understand the concept of effective mass, but it does not seem to.

Good to have you back after the Christmas break!

Unfortunately, I did not bother to post my original question to ChatGPT, and its answer.  I just commented that it was what a text book would have contained.  It only addressed the effective mass of pivoting arms.

I tried to show how ChatGTP then in fact did learn from my tightened-up question sequence. The second answer to the same question was better than the first answer.  In effect, I trained it to think more deeply.

To put it as simply as I can, in calculating or measuring effective mass for a Holbo arm system, we are talking about a purely mechanical system which pivots in the vertical plane, but slides in the horizontal plane.

Effective mass means the equivalent amount of mass, positioned at the stylus tip, that would produce the same inertia as the real mass of the moving part.  Inertia is resistance to an applied force and is described by Newton's First Law of Motion.  It is a fundamental property of mass.

In mechanics, a pivot implies a lever.  The effective mass of each contributing element must be multiplied in proportion to its distance from the pivot point. Mass at the pivot point has a zero contribution factor.  Mass at the tip has a contribution factor of 1.

You are right, for an arbitrarily complex tone arm shape, you have to add up the contribution from every atom.  This can be vastly simplified if the tone arm comprises simple shapes, whose contributions can be added. Somewhere in between, if equations representing the shape of the tone arm are known, you can use the dreaded calculus, or fluxions in Newton-speak.

With a sliding object, the distribution of mass does not matter at all.  You have to push against the inertia of the whole thing.  Effective mass and actual mass are the same thing.

I'll just add that Newton's First Law of Motion is completely counter-intuitive compared with our lived experience on earth!  Nothing on earth continues to move indefinitely in a straight line - friction always wins.

It is just as hard to comprehend as quantum mechanics, where little behaves the way we intuitively think it should.  That does not mean quantum mechanics is wrong - its equations are an excellent predictor of behaviour.- even if that behaviour seems incomprehensible to us.

Newton was careful to postulate his laws against a rectilineal view of space. Einstein showed this is incorrect, but practically Newton;s Laws can still be used for space flight calculations.  Einstein matters for GPS satellites, however, where their time slows down relativistically.