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.

[detox]

All of that fancy balancing means nothing if you have lots of harmful harmonics going on inside stuffing tube. Other than balancing, what is the trick for quiet resonate free spinning.

[HOTWATER]

Once you have cut a flat spot on the motor shaft, you have lost balance....where do we go from there....??

[properchopper]

All of that fancy balancing means nothing if you have lots of harmful harmonics going on inside stuffing tube. Other than balancing, what is the trick for quiet resonate free spinning.

Keith, I'm not claiming to be too knowlegdeable on this topic/situation but I'm going to make a somewhat educated assumption that the resonance/harmonics are in large part created by driveline imbalance coupled with loose tolerances. Tackling/curing these conditions may be the answer. My first Drifter had a major resonance that had me trying everything you could imagine, like lining the hull with Dynamat and greasing the heck out of the shaft. The current owner still has this situation which can be temporarily handled by using gobs of thick marine grease on the flex cable, but as it heats up and thins out it returns. My current Drifter is lined with CF and uses a wire drive, with no real vibration/resonance. I'm guessing that the wire drive/collet is better balanced, although my prop balancing skills leave a lot to be desired.

[properchopper]

I recently was provided with several samples of a stainless drive dog to test. Gave one to Jay,Brian & Darin to try out. Just put it on the balancer & it balanced as perfect as it could be right out of the "box" . Octura's lately have been drilled out too much causing a tiny wobble BTW.

[LarrysDrifter]

Are the stainless dogs from Octura?

[properchopper]

Are the stainless dogs from Octura?

Larry, Not Octura. Uncool for me to promote competitors to OSE, so I "kint" say where they're from [they're now available]

[m4a1usr]

All of that fancy balancing means nothing if you have lots of harmful harmonics going on inside stuffing tube. Other than balancing, what is the trick for quiet resonate free spinning.

None of us can change harmonics related to rotational imbalances unless we specificaly target each part of the rotating items. You tackle the prop, so next you move onto the other components. But we cant spin each particular compontent to make the necessary imbalance adjustments to improve that particular or specific issue. The reason is due to one of the very common issues we deal with. We allow for "slack" in our drive lines. The gap we allow on the azz end is our weakness. Harmonics have a range of influence over the operating rpm range. You might have a 1st order at 5k, a second at 12k and a 3rd or 5th higher. Your never going to correct those issues unless you reduce imbalance at every possible avenue. Hopefully you minimize it to a level that is at best described as adequate. But with slack in the driveline we do the one thing verbooten in propulsion systems. So we suffer imperfection. I dont have the answer to making it perfect. We tackle it were known weakness is expected. Not picking on you but choices have to be made and rotational mass should be the one getting the attention first.

John

[dasboata]

Apples and Oranges,,, That is a balancer designed with a motor to pick up Vibration much like a Hi Speed tire balancer, that looks very interesting. But the guys here spinning props on a Magnetic balancer are just wasting there time !! And PS not to pick on you Properchopper I know your a old NY guy but you have a heavy blade there in your video !! Send me that prop I will do it for free for you !!! And then you can put it back on a Vid

[Mike Caruso]

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

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

That's plenty of rpm AND YOU STAY COOL AT THE SAME TIME.
Finger speed is plenty don't over think it. Use clay on the light side so you can see where you need to remove weight 180 from the light spot.

[Mike Caruso]

None of us can change harmonics related to rotational imbalances unless we specificaly target each part of the rotating items. You tackle the prop, so next you move onto the other components. But we cant spin each particular compontent to make the necessary imbalance adjustments to improve that particular or specific issue. The reason is due to one of the very common issues we deal with. We allow for "slack" in our drive lines. The gap we allow on the azz end is our weakness. Harmonics have a range of influence over the operating rpm range. You might have a 1st order at 5k, a second at 12k and a 3rd or 5th higher. Your never going to correct those issues unless you reduce imbalance at every possible avenue. Hopefully you minimize it to a level that is at best described as adequate. But with slack in the driveline we do the one thing verbooten in propulsion systems. So we suffer imperfection. I dont have the answer to making it perfect. We tackle it were known weakness is expected. Not picking on you but choices have to be made and rotational mass should be the one getting the attention first.

John

Hi John,
Sorry I did not see your reply's above.
You know my friend very cool setup. People have no idea how much good you can do with a balancer. I can still see the strobe light and the part moving through the critical rpm. No computer read out for the heavy position back in the 70's ha wish I did have it.
Mike

[properchopper]

All of that fancy balancing means nothing if you have lots of harmful harmonics going on inside stuffing tube. Other than balancing, what is the trick for quiet resonate free spinning.

Mark and I, not twenty minutes ago, were discussing some SAW setup details, and both agreed that wire drives eliminate a bunch of resonance. The resonance is noise, and noise is energy better used for propulsion. My SAW Drifter S record holder with a wire drive is quite resonance free, so much so that the sound of the prop beating on the water's surface is highly audible. Jeff Wholt wire & coupler, btw.

[HOTWATER]

Tony, what size boat ,power and what size wire are you using...I have an .078 from jeff that I have yet to use...just curious...I have an ML hydro that I am still thinking about as far as what I will be using for a drive line....was wondering the same thing about the wire being truer than a flex.....giddyup!!!

[properchopper]

I use a .078 in the Drifter S (26") with UL-1 power on 4S. Mark does the same on his FE30 for spec and P-Sport. USE AS LITTLE BEND AS POSSIBLE.

Here's what an out of balance flex driveline setup sounds like [ yellow boat at 2:05 ; 2:26 ; 2:56 seconds ]

http://www.youtube.com/watch?v=N0ixeztr-wE


Here's my Drifter {UL-1 motor/4S} with the wire drive

http://www.youtube.com/watch?v=dOPTQrj-0RM

[TheShaughnessy]

tony are you using ball bearings, lead teflon or brass bushing?

[properchopper]

tony are you using ball bearings, lead teflon or brass bushing?

I've found that ball bearings have a short lifespan in marine applications. I prefer L/T but I use both L/T & brass depending on the boat.