Stylus force digital scales


Digital scales from Clearaudio and others range from $200-500. Amazon has 'em for $20. Why cant I use one of these instead and save big bucks?
tbromgard
@lewm it may not be an issue of interaction with the pan but an effect upon the mechanism itself, I guess you might know by seeing if bringing the cartridge close to a previously loaded pan reduced the measured weight?
The very expensive Rega scale does its job nicely and quickly. It always tares itself before weighting. The weight pan is a little dish so the actual measurement level is very close to record´s surface. Highly recommended for all vinyl lovers. Many thanks Folkfreak :)
VTF only changes when you hit a warp because of inertia - the same reason you feel more force (and then less force) when driving over a bump in the road. It has nothing to do with the angle of the tonearm. The only change in the vertical force vector is as the stylus is raised vertically is due to the change in gravitational force as you move [mm to cm] further away from the center of gravity, and therefore the force of gravity changes. This is why it's called "Vertical" tracking force - vertical states the direction of the force vector.
@nrenter wrote The only change in the vertical force vector is as the stylus is raised vertically is due to the change in gravitational force as you move [mm to cm] further away from the center of gravity, and therefore the force of gravity changes. This is why it's called "Vertical" tracking force - vertical states the direction of the force vector.
This statement is incorrect and you gave the reason in the body of your response. The force of gravity is at its greatest when perpendicular to the earth's surface (you call it vertical).  With a pivoted tonearm, the cartridge travels in an arc and within that arc, there can only be one position in which the stylus tip is perpendicular to the playing surface and it is in this position in which the force of gravity is at it's maximum.  Any deviation from perpendicular will result in a less gravitational force. 

This is the same rationale as why weigh scales must be place on a flat surface to read accurately, otherwise the weight will not be transferred perpendicular to the earth's surface.
Folkfreak,  I took a powerful magnet to the weigh pan of my digital VTF scale, and there was zero attraction of the magnet to the weigh pan or even to the body of the scale itself.  Seems that even though your plastic-bodied scale and my metal-bodied scale look alike (maybe exactly alike), there actually was a good reason why mine cost more money, other than the metal outer shell. For once in my life, my extravagance paid off.

nrenter and brf, You both got it right for the wrong reasons.  My physics professor in college would have given you both an "F", but he was mean.  The force of gravity never changes.  What changes is the magnitude of the force vector in the vertical direction, when you rotate the tonearm in a vertical arc away from or down towards the LP surface.  The magnitude of the vertical force vector due to gravity changes because you are shifting the center of mass toward the pivot (if you raise the tonearm) or away from the pivot (if the arm wand moves toward the LP surface).  It's like a seesaw. When you raise the tonearm, some of its mass is shifted toward the pivot and thus the pull of gravity on the cartridge is partly borne by the pivot, not the cantilever, during that moment.