On Sat, Mar 23, 2024 at 09:14 PM, Peter Eacmen wrote:
How are you getting a torque wrench on the RA?
I'm not suggesting a torque wrench and adapter.? Just the moment arm and force applied.? With the RA balanced and horizontal we slide the counterweights outward (same if inward).? ?We configure weights such that at some position the clutch slips.? For the weight chosen the difference in the center of mass positions calculates as (|"torque at slip" - "torque at balance"|).
Example, my 150mm refractor weighs 32# balanced/horizontal with a stack of 7# (inner) and two 11# (outer).? The outer two 11# balance at 12" (mass center).? On moving the two weights the clutch slips when moving 5" (I tensioned the clutch very tight).? The torque at 12" is 24 ft-lbs (12lbs * 2 * 12in / 12 in/ft) and there exist an equal opposing force (balanced).? The force at 17" becomes 34 ft-lbs.? Added torque to slip the clutch becomes then | 34 - 24 | or 10 ft-lbs.
{It's equivalent to saying, remove the weights at the balanced position and place them at the point of slippage or 17".? At 17" this requires 17# to balance but we place 7# more than that.? That extra 7lbs applies 7lbs * 1.4 ft or 10 ft-lbs.}
Balanced
Slipping
