How to calculate this torque? (steel ball in a spiral tube)

AI Thread Summary
To calculate the torque needed for a steel ball to move upwards at a uniform speed in a spiral tube, several parameters must be considered, including the masses of the ball and tube, the angle of inclination, and friction coefficients. The torque can be expressed as a function of the gravitational force acting on the ball and the geometry of the spiral, specifically using the sine of the helix angle and the tilt of the shaft. The discussion highlights the importance of understanding the static and dynamic forces at play, particularly how the ball's position affects the torque calculation. Additionally, the conversation touches on the complexities of energy conservation and the need for precise measurements of the spiral's dimensions. Ultimately, the goal is to derive a formula that accurately reflects the torque required to lift the ball consistently.
  • #101
@Baluncore , After all of our work I hardly believe I am posting this.

Last night, I began to consider that I had made an error in my above calculation by using D2*π as the distance the ball traveled for each wrap of the helix in my in my F = E/n/(D2*π) calculation; when, I should have used:
F =E/n/(sqrt((D2*p)^2+H2^2) for that formula.

After making that revision this morning, I appear to have verified its accuracy because with that revision my calculation result for F at 90° is exactly the same as the simple F = Ma*sin(33°) = 16.60N result, (unfortunately I failed to check that for my original calculation after seeing my correlation with your result at 45°).
Obviously, the main issue that creates is that at α = 45°, that revision reduces my original T = .835N-m value to
T = .693N-m and reduces the values in my curve but not its profile and still calculates T = 0 at α= 0°; but, no longer correlates with your results.

Please review this revision and let me know your thoughts.
 
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  • #102
I have not yet looked at your revision, but the agreement between our numbers was close to numerically perfect.
Code:
Pitch angle 33.995 °
Torque at a = 45°, 0.835437 Nm
alpha Baluncore JBA difference
90.0 1.#NAN00000 1.181486720 % 1.$E+00
85.0 1.#NAN00000 1.176990806 % 1.$E+00
80.0 1.#NAN00000 1.163537282 % 1.$E+00
75.0 1.#NAN00000 1.141228536 % 1.$E+00
70.0 1.#NAN00000 1.110234352 % 1.$E+00
65.0 1.#NAN00000 1.070790615 % 1.$E+00
60.0 1.#NAN00000 1.023197514 % 1.$E+00
55.0 0.967817262 0.967817262 0.0E+00
50.0 0.905071337 0.905071337 0.0E+00
45.0 0.835437272 0.835437272 3.3E-16
40.0 0.759445025 0.759445025 2.2E-16
35.0 0.677672942 0.677672942 0.0E+00
30.0 0.590743360 0.590743360 1.1E-16
25.0 0.499317864 0.499317864 5.6E-17
20.0 0.404092257 0.404092257 -5.6E-17
15.0 0.305791265 0.305791265 3.3E-16
10.0 0.205163016 0.205163016 4.4E-16
5.0 0.102973353 0.102973353 -1.2E-16
 0.0 0.000000000 0.000000000 2.1E-16
[code]
 
  • #103
Note: I have done multiple edits of this post so see the below post for my latest input.
 
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  • #104
@Baluncore

Thankfully, my issue is now fully resolved and we still have full correlation.

My late night investigation just revealed that: Atan(L1/(D2*PI) = 33.995°, so using D2*PI() is the correct interpretation for my analysis.
Sometimes the hardest part of getting an answer to an issue is figuring out what question to ask.
 
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  • #105
JBA said:
Sometimes the hardest part of getting an answer to an issue is figuring out what question to ask.
When we know the right question, we also know the answer, and so do not need to ask it.

“The only interesting answers are those which destroy the question”. —Susan Sontag.
 
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