H
hugh hargett
Guest
Read an article sometime back By Andy Kunz on this. Sounds like a great idea. Seems like something that could be put together with a small brushless motor/esc, a propeller shaft a strobe and microcontroller and like the audruino you fellas are so fond of.Built and executed correctly this has alot of potential. Ideas????
"Spin Balancing
After you have finished static balancing, you need to make sure your prop will stay balanced when running at top speed. This is a lot more difficult to do, and it's where I sometimes cheat myself. If you've taken the time to balance your prop as described above, you're already doing better than 95% of the rest of the guys out there. Here's how to get that extra 5%.
Spin balancing is what they are doing to your car tires when you have them balanced at a garage. The tire is spun, and a computer inside the tire balancer tells the operator where to place a weight and how big it should be. He will spin the tire multiple times, until the computer tells him it's done. Since there aren't any such tools available for us, we need to make do with what we can. This is another one of the other reasons I like my Top Flight balancer.
Basically, we will be spinning the propeller while using the stroboscope to make it appear as if it isn't moving. If it isn't running true, we remove weight from the heavy blade until it is balanced. Here's how to do it:
First, make a small mark with a permanent marker on the tip of one blade. Next, you spin the prop on the balancer shaft. While it spins, shine the strobe on the prop, watching carefully to see if the shaft is rotating perfectly. By watching carefully, you will be able to see if the shaft is running true or moving in a circle. The ink mark will allow you to identify which blade is heavier (the heavy blade will appear to be on the outside of the wobble). Lightly oil sand the heavy blade to adjust it. Repeat this until the prop is moving in a perfect circle, with no movement of the shaft. If you have done a perfect job of this, your prop will still be perfectly static balanced. If it isn't, you will have some vibration at certain speeds but not at others. The goal is to make it perfect at all speeds, but if you can't do that, just make sure it's perfect at operational speed. The ideal spin balancer would spin the prop at the speed you would be turning it on the water. I don't have a tool, which would allow me to do that, so I just spin the shaft with my fingertips. If I ever figure out how to get 30K RPM on the balancer, it will be a good day at the races!
Mount the prop on the drive shaft in your boat, and run the motor up to the expected operational speed, using the optical tach to find that speed. It will probably be between 50% and 75% of the maximum speed your motor turns, so you can work it from that angle as well. (This is where stick radios with the spring return taken out can be very handy.) Check to make sure the prop runs true at operational speed. If it doesn't, you can find the heavy blade as you did on the balancer, but it might not be the prop that's out of balance! Try making sure your drive shaft is balanced as well - it should run true at even full RPM. This is a very fine detail, but it will help keep you from wasting power. One little hint - always mount the prop the same way on the drive shaft. I like to make a very tiny notch, which identifies how the prop mounts to the drive dog. This will help you keep your drive system balanced, not just the prop.
Author, Andy Kunz."
excerpt taken from http://www.modelpowe...eller-balancing
COOL B)
"Spin Balancing
After you have finished static balancing, you need to make sure your prop will stay balanced when running at top speed. This is a lot more difficult to do, and it's where I sometimes cheat myself. If you've taken the time to balance your prop as described above, you're already doing better than 95% of the rest of the guys out there. Here's how to get that extra 5%.
Spin balancing is what they are doing to your car tires when you have them balanced at a garage. The tire is spun, and a computer inside the tire balancer tells the operator where to place a weight and how big it should be. He will spin the tire multiple times, until the computer tells him it's done. Since there aren't any such tools available for us, we need to make do with what we can. This is another one of the other reasons I like my Top Flight balancer.
Basically, we will be spinning the propeller while using the stroboscope to make it appear as if it isn't moving. If it isn't running true, we remove weight from the heavy blade until it is balanced. Here's how to do it:
First, make a small mark with a permanent marker on the tip of one blade. Next, you spin the prop on the balancer shaft. While it spins, shine the strobe on the prop, watching carefully to see if the shaft is rotating perfectly. By watching carefully, you will be able to see if the shaft is running true or moving in a circle. The ink mark will allow you to identify which blade is heavier (the heavy blade will appear to be on the outside of the wobble). Lightly oil sand the heavy blade to adjust it. Repeat this until the prop is moving in a perfect circle, with no movement of the shaft. If you have done a perfect job of this, your prop will still be perfectly static balanced. If it isn't, you will have some vibration at certain speeds but not at others. The goal is to make it perfect at all speeds, but if you can't do that, just make sure it's perfect at operational speed. The ideal spin balancer would spin the prop at the speed you would be turning it on the water. I don't have a tool, which would allow me to do that, so I just spin the shaft with my fingertips. If I ever figure out how to get 30K RPM on the balancer, it will be a good day at the races!
Mount the prop on the drive shaft in your boat, and run the motor up to the expected operational speed, using the optical tach to find that speed. It will probably be between 50% and 75% of the maximum speed your motor turns, so you can work it from that angle as well. (This is where stick radios with the spring return taken out can be very handy.) Check to make sure the prop runs true at operational speed. If it doesn't, you can find the heavy blade as you did on the balancer, but it might not be the prop that's out of balance! Try making sure your drive shaft is balanced as well - it should run true at even full RPM. This is a very fine detail, but it will help keep you from wasting power. One little hint - always mount the prop the same way on the drive shaft. I like to make a very tiny notch, which identifies how the prop mounts to the drive dog. This will help you keep your drive system balanced, not just the prop.
Author, Andy Kunz."
excerpt taken from http://www.modelpowe...eller-balancing
COOL B)
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