Torque Meter Question

[WatosBats]

My J&H torque meter broke. I want to replace the broken wire with a thicker one (0.025 inch in diameter). Is there a way to figure out how much torque 1 rotation is or do I have to just get a new meter?

[coachchuckaahs]

The wire torque meter readings will go with the 4th power of wire diameter. I do not have details on what the J&H uses, nor that the full scale was.

However, for an example, lets say it was 0.020" wire and 2 oz-in for one turn. Replacing that with 0.025" wire, the resulting full scale torque will be (0.025/0.020)^4*2=4.88 oz-in. Therefore, the full scale torque reading is very sensitive to wire diameter! Be sure to accurately verify the wire diameter.

This all assumes you keep the wire length the same. The full scale reading will vary inversely linearly with wire length.

If you want complete details:

Alpha = ( 584(T)(L) ) /( (D^4) (G) ) , where alpha is the angle of rotation in degrees, T is the torque in oz-in, L is the length of the element between supports in inches, D is the diameter of the element in inches, G is the modulus in psi, which someone found experimentally at 11,434,801, +/- about 5% (so really don't need all those sig figs!), and 584 is a constant. Reference the formula here: https://www.rcgroups.com/forums/showthr ... rsion-data, and the testing of modulus here: https://www.endlesslift.com/steel-torqu ... libration/. I used that modulus for K&S 0.020 wire and got 9" for 2 oz-in full scale (360 degrees).

Coach Chuck