After a six month, ground up restoration of the lathe I purchased last summer I was finally able to turn a pulley to test the torque of the 42mm Hurst motor. I'm pleased to report that the little guy was able to spin up the cast iron platter from a Thorens TD124 TT in less than 1/2 turn from a cold stop.I loosened the belt to reduce motor bearing stress and it still got to speed within one turn. Now I feel confidant to proceed with my TT design employing this motor.
As soon as I figure a way to isolate the test chassis I'll do some vibration tests, but by feel I am encouraged. The motor plate is sitting in 60 year old Thorens gummimuffins. There is significant vibration on the motor plate, which is to be expected because the plate is small and aluminium, but the vibration is barely detectable on the chassis and undetectable on the platter.
As soon as I figure a way to isolate the test chassis I'll do some vibration tests, but by feel I am encouraged. The motor plate is sitting in 60 year old Thorens gummimuffins. There is significant vibration on the motor plate, which is to be expected because the plate is small and aluminium, but the vibration is barely detectable on the chassis and undetectable on the platter.
One way to add mass is lead. It can be cast/poured to fit a shape too. Mounted in something energy absorbing, like rubber of the proper hardness/softness and that in turn in/on a solid high mass mount...
That does nothing to change the inherent noise from bearings or alter the electromechanical production of LF energy due to the way the rotor is "pushed" in order to rotate. But it will minimize the direct transfer of that energy and the potential for resonances in the mounting system.
Another interesting approach that may have some merit is to add an idler pulley to isolate one belt from another - and a "flutter" wheel, like used in tape transports may help too...
...but then yer gettin' fancy!
That does nothing to change the inherent noise from bearings or alter the electromechanical production of LF energy due to the way the rotor is "pushed" in order to rotate. But it will minimize the direct transfer of that energy and the potential for resonances in the mounting system.
Another interesting approach that may have some merit is to add an idler pulley to isolate one belt from another - and a "flutter" wheel, like used in tape transports may help too...
...but then yer gettin' fancy!
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