01-06-2018, 06:17 PM
More accurate RPM/SFM data:
I spent some time this afternoon getting accurate RPM readings with my tachometer. The trick to getting accurate readings is to angle the tachometer so that the light does not reflect back into the sensor.
The unaltered control box gave a speed range of 1338 to 2900 RPM. Using the formula circumference x RPM = SFM, a four inch drive pulley = .334 feet. Therefore, .334 x 3.14 = 1.05
1.05 x 1338 = 1405 SFM That is not much slower than the Kally with the 1725 RPM motor, although is is just over half the speed of the Viel with the 1725 RPM motor and the six inch drive pulley.
Using the control box where I adjusted the pots, the low speed was 740 RPM, which would be
1.05 x 740 = 777 SFM.
I adjusted the control pots conservatively. The speed could have been lower.
Adjusting the speed can be done independently of the conversion. The motor and control box are connected by a plug. I have been using my modified control box with both motors. I just switch plugs back and forth. My original control box has a reversing switch added to it. I plan to eventually adjust the low speed and add a reversing switch to the second motor control. As a practical consideration, plan to purchase a digital tach (not expensive) if you plan to adjust the motor speed.
Stay tuned........
Ken
I spent some time this afternoon getting accurate RPM readings with my tachometer. The trick to getting accurate readings is to angle the tachometer so that the light does not reflect back into the sensor.
The unaltered control box gave a speed range of 1338 to 2900 RPM. Using the formula circumference x RPM = SFM, a four inch drive pulley = .334 feet. Therefore, .334 x 3.14 = 1.05
1.05 x 1338 = 1405 SFM That is not much slower than the Kally with the 1725 RPM motor, although is is just over half the speed of the Viel with the 1725 RPM motor and the six inch drive pulley.
Using the control box where I adjusted the pots, the low speed was 740 RPM, which would be
1.05 x 740 = 777 SFM.
I adjusted the control pots conservatively. The speed could have been lower.
Adjusting the speed can be done independently of the conversion. The motor and control box are connected by a plug. I have been using my modified control box with both motors. I just switch plugs back and forth. My original control box has a reversing switch added to it. I plan to eventually adjust the low speed and add a reversing switch to the second motor control. As a practical consideration, plan to purchase a digital tach (not expensive) if you plan to adjust the motor speed.
Stay tuned........
Ken