How to change effective mass of a SME V.

It's actually very easy.

You know the effective mass of the SME V.

You know its effective length. Call this Xel.

You know the mass of the extra headhsell weight.

You can take the counterweight off and weigh it (in grams). Call this M.

You can measure the counterweight's distance from the pivot before the additional weight and after it. Call these Xb and Xa.

The counterweight's additional contribution is then given by

M . (Xa^2 - Xb^2 / Xel^2)

The new effective mass of the arm is the sum of this number, the original effective mass and the additional headshell weight.

Mark Kelly

BTW for a first approximation you can simply assume that the counterweight's contribution will be approximately 10% of the added headshell weight's.

If you wish to add say 5 g overall, you would add a headshell weight of about 4.5 g and expect the counterweight movement to get you (most of) the rest.

Mark Kelly

God I hate that I can't edit

The bracket is in the wrong place, the equation is

M . (Xa^2 - Xb^2) / Xel^2

Mark Kelly