Rotational speed for magnetic prop balancing

[Cooper]

Hey guys I don't know if any of you have done this or tried this but I found a way to get my prop up to ungodly speed on simple magnetic balancers, I always have a can of compressed air around and im all thumbs when trying to spin the darn things and always spin them with my own wobble or even just bounce the thing off, so I just give it a squirt of air and if you think your balanced for speed you can keep spraying and I don't know what the rpm's get up to but it's a hell-of-a-lot more than my clumsy thumbs can generate! Just my two penny's worth. If anyone hasn't already thought of it it helps.

[HOTWATER]

[siberianhusky]

LOl I use my compressor to do the same thing, Now take it one step farther and use a strobe light to "freeze" the prop. I put a small sharpie mark on one blade, this way you can see which blade is the heavier at speed by the wobble of the shaft frozen in the strobe flash!
I wish I could find the link to the page on balancing I borrowed this idea from.
Need to figure out some type of magnetic coupling so I can use a motor to spin up the prop balancer to actual running rpm.
Interesting difference between a statically balanced prop and a dynamic balance isn't there?

[HOTWATER]

LOl I use my compressor to do the same thing, Now take it one step farther and use a strobe light to "freeze" the prop. I put a small sharpie mark on one blade, this way you can see which blade is the heavier at speed by the wobble of the shaft frozen in the strobe flash!
I wish I could find the link to the page on balancing I borrowed this idea from.
Need to figure out some type of magnetic coupling so I can use a motor to spin up the prop balancer to actual running rpm.
Interesting difference between a statically balanced prop and a dynamic balance isn't there?

That is actually a pretty cool idea...kind of like the timing on an engine! You go bro!

[properchopper]

Or a window fan across the room can create an interesting phenomenon :

http://www.youtube.com/watch?v=Qa_psjdj7XU

[HOTWATER]

Now THAT is ingeniuty at it's finest!!! Love the barn brawling music...LOL!

[properchopper]

On a serious note, I never could understand why so much care is taken to balance a prop when the flippin' drive dogs are so unbalanced. Am I missing something ?

[tharmer]

Yeah...you need to balance the entire Assy, from motor coupler to prop nut--as a complete unit.
T

[properchopper]

Yeah...you need to balance the entire Assy, from motor coupler to prop nut--as a complete unit.
T

I kinda' figured that, but it seems this doesn't get mentioned much. Glad you confirmed this as it makes major sense.

[siberianhusky]

Once you get everything balanced it's amazing how quiet the boat gets.

[AndyKunz]

When you use air, you need to give a little time for it to stabilize. The air puts a slight wobble onto the prop, just as with finger spinning.

That's why I said in my how-to, "If I ever figure out how to get 30K RPM on the balancer, it will be a good day at the races!" - well, air will get you there but you have to remember it's not perfect.

I'm still thinking I might be able to find a fine flexible drive that would work on one end, with the other supported by a magnet. But now things are getting complex on the balancer equipment.

Air's a good idea - just remember that it's not perfect.

Andy

[dasboata]

Not sure what you guys are spining the props for,, it is all about where there land and the heavy blade area ,, not about see how fast you can spin them ??

[HOTWATER]

Not sure what you guys are spining the props for,, it is all about where there land and the heavy blade area ,, not about see how fast you can spin them ??

I hear ya bro...lol! ......???

[m4a1usr]

On a serious note, I never could understand why so much care is taken to balance a prop when the flippin' drive dogs are so unbalanced. Am I missing something ?

Your pretty darn close Tony. Its not just a drive dog that can add to imbalance (set screw size) but the whole rest of the driveline on many levels. I recently got into a banty with Jay about free floating bushings in struts and stingers. What it boils down to is tolerances. The greater the tolerance, the more movement, therefore if only one component of the driveline is not balanced the system as a whole will suffer increased friction and imbalance. It only takes one part of imbalance to ruin the whole shabang. I do have to refrain from pounding my logic into others. I cannot always explain it well enough in words to not appear arguementive. Having said that and not trying to defend myself from past statements. The cards lay where they fall. But to expound upon the OP about prop spinning here is a pretty awesome prop balancer that can do what none of us can do by eye alone. Its a Schenck dynamic balancing system designed to spin turbo impellers up to 17k. Works good for props too!

John

[properchopper]

Your pretty darn close Tony. Its not just a drive dog that can add to imbalance (set screw size) but the whole rest of the driveline on many levels. I recently got into a banty with Jay about free floating bushings in struts and stingers. What it boils down to is tolerances. The greater the tolerance, the more movement, therefore if only one component of the driveline is not balanced the system as a whole will suffer increased friction and imbalance. It only takes one part of imbalance to ruin the whole shabang. I do have to refrain from pounding my logic into others. I cannot always explain it well enough in words to not appear arguementive. Having said that and not trying to defend myself from past statements. The cards lay where they fall. But to expound upon the OP about prop spinning here is a pretty awesome prop balancer that can do what none of us can do by eye alone. Its a Schenck dynamic balancing system designed to spin turbo impellers up to 17k. Works good for props too!

John

OK Bro, now I know where to send my props to get balanced ! lol

Another thought I've had ( I try not to think too much) is that the in/out/in/out of a surface piercing prop likely causes much deflective vectoring of the rotating mass of the prop/dog/shaft. John, I agree totally that close tolerances are important to avoid premature wear or potential harmful harmonics.