sushi2me

I also forgot to mention AquaCraft GrimRacer Performance Props which can be seen at AquaCraft at [link=http://aquacraftmodels.com/accessories/propellers.html]Grim Racer High Performance Props[/link]and ordered at Tower Hobbies, FunRCBoats, etc.

This "AquaCraft Grim Racer High Performance Metal Propellors" page not only shows & lists the props, it has an applications chart, sharpening balancing polishing instructions (see below). and MORE!!!!

Even though the literature/tech notes say that these can be used without SBP'ing (Sharpening, Balancing, Polishing), it's really talking about SPORT usage, and even for that use, it DOESN'T hurt to check because an out of balance prop can actually not only rob your boat of speed but can actually lead to damage of the other drive train components due to undue (like that one?) excessive vibration. So, obviously, if you're going to use your prop for Fast Electric = Speed/Racing, you really MUST BSP your props.

Also, always wear a paper mask (or better) and available at most dollar discount stores and/or paint/hardware stores and disposable latex gloves (at the same stores) because these are copper beryllium (and sometimes titanium also) props - when filing these props, beryllium can give off toxic dust.

Well, hopefully that's enough to help and encourage you to BSP your own props rather than paying almost double the cost of the prop to have a BSP service performed for you by the prop vendor.

Good luck and happy boating,

sushi

munro1656

Looks like they are basic enough to make to me i could just mill one up. i'll see how i go with the magnetic type thanks JAW some pics of that magnetic type would be super

jetpack

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If you're making up your own ceramic or neodendum(?) magnet type, be sure one side stays adjustable to bring the magnet close as possible without touching to the arbor on the one end to take as much drag as you can off the other so it stays sensitive as possible.

Justaddwata

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[link=http://www.berylliumdisease.net/]http://www.berylliumdisease.net/[/link]

Worth restating and spending 5 minutes to become a little informed about the dangers of that shiny prop on the transom. In no uncertain terms - the metal it is made from can kill you. Not today. Not tomorrow. But 30 years from now you could suffer a slow early death as a result of inadequate protection and handling of the props. While we are not throwing a lot of metal around (and props are not 100% berylium either) the amount of the exposure required to develop the reaction is also small. Play it safe

Ron Olson

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Here's the Top Flite: http://www3.towerhobbies.com/cgi-bin...&I=LXHY61&P=ML

jetpack

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Here is an additional reference to the different characteristics of Octura props:

fuelman8

I've been balancing my new prop. This is the first one I've done. I've followed this thread closely and tried to do things right. I made sure the prop was flat and square in the drive dog first.

I then sharpened and balanced it to the point where it stops at a straight horizontal plane on the balancer. Yet if I turn the prop in the balancer 180 degrees it wants to turn back to the original position. I'm not sure now how to or if I need to take any more off the prop?

Ron Olson

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How fussy do you want to be?
I've got a gas boat prop that I've been working on and I'm getting pretty much the same result. From what I learned, you should be able to spin the prop and it should stop at a different place every time if it's perfectly balanced.
From what I see, the lower blade is just a hair too heavy yet but it's very close. If I got it that close I'd leave it as is.

jetpack

My Feedback: (1)

So far so good, Fuelman. The prop should not want to stay on that one side, you'll have to work on getting it so that whole side is lighter. That means the balance from tip to tip is ok, it is just that that whole bottom side of the prop needs lightening.

Try taking a little off the tounge of the one side, and a little off the back side of the other. In other words, wherever you take weight off the prop just be sure it is below the centerline of your balance.

The prop should have a very hard time finding where it should stop when it slows down from a small spin.

jetpack

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True what Ron just said.

Another thought is have you checked just the balancer for balance? Is that what came with the Great Planes balancer? Mines longer and has plastic cones.

If the cones are out on your balancer, when you take your prop on and off of it several times and check it, the balance of the prop will show up a little different each time.

It's good that you checked the drive dog slot before you started. Sometimes also, the lip of the bore on each side of the hub has a strange shape to it because of a burr from it being drilled and reamed, or a sink mark in the casting.

This affects how the prop sits on the cones, and can throw the whole effort off on balancing. Where the cones seat the lip of the bore should have a good shape to it.

Those cones are convienent to design to fit several size bores, but as far as being the best idea to locate something for true balance isn't the best approach. A more accurate way is to use just the rod which is a slip fit inside the bore and use no cones - but all that would need to be special made to fit proper and have the tips put on.

fuelman8

Jetpack

Mine came with the rod and cones also, but when I checked the balance with just the rod and cones one of the cones was bottom heavy. So I tried the finger balancer and it was balanced perfectly, so I used it.

This is an ali prop so I may just leave it as Ron said and see how the boat runs.

Thanks Guys

FE_Chris

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Yeah great reading guys! Nice thread! I just got done working over a x572. I sharpened, balanced, de-tounged, barr-cut and polished it up. We'll see how it works.......

Vinnystoolbox

I suspect you'll say i need a real prop as i have just got my first boat and doing some upgrades

I have the standard plastic props do these need balancing?

Should i bin them straight away

jetpack

My Feedback: (1)

The plastic ones you're pretty safe that they are close to being balanced and lots of people change over to metal props. I think any nitro boat should use metal props, as I hear the plastic ones break and can cause a mess.

Vinnystoolbox

Thanks for your reply

I'm thinking of going brushless

I have received my hull setup and i think i'll need something stronger than the ones that came with that

toddlupton

I used to machine blow plugs in a machine shop made from copper beryllium. They would attach to a machine that blew moulds for plastic bottles. Anyway when machining these pieces, it would always be done under a spray of lubricating liquid to keep any particles under control. When I do any work on my (dangerous) props, I do it under running water in my shop sink. Which I believe would control and get rid of any particles made. I also polish with wet sanding paper under running water. I've been reading these threads alot recently, and learning alot ,and haven't heard anyone speak of this procedure. Was wondering if this actually was a good Idea, or am I going to be dead in 30 years due to beryilium exposure due to metal particles soaking thru my wet skin polishing my props. Hopefully I'll have a smile on my face.

jetpack

My Feedback: (1)

I'm no expert but I think you're safe. I believe it is the dust and the fumes from machine polishing that I would worry about.

I use emery polishing sticks and wet polish with mineral oil. I stop to worry when the final polishing comes with the cream and the rag.

The old rag will hold old polishing compound that already has done its work, and holds copper also.

Flinging this around and having the dry compound dust up out of the rag with the copper is not a good idea without precautions. You wont have this problem if starting with a clean rag so I just keep patches and throw them out when I'm done.

jetpack

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Here's a couple of instruction sheets.

The first one comes with the Octura Balancer, the other comes with Prather props.

munro1656

I posted this in the gas section but thought it could go in here as well. after picking up a new 2714 from danny at http://www.sonicracingaustralia.com/ thanks danny and haveing a little spare time today I made my way to my brothers house to do some balancing on his balancer thats used for turbine wheel balancing I have props that I have been using with out issue and thought they were balanced untill I put them on this we did a 'spool' test and at 18,000 rpm on one of my old props we found that after balancing true they would spool to 21,500 at same pressure! this level of balancing may be a over kill but goes to show that even with a top flight balanced prop you will still end up with drag/fiction because it's not quite true..... the first pic is of a turbine wheel beeing balanced

cheers craig

jetpack

My Feedback: (1)

That is a significant gain in RPM's. It definetly shows the benifits of balancing. RPM increase is sometimes overlooked in balancing, thinking all you're doing is helping it run smooth, and not tear up bearings.

One big step after balancing is checking the pitch of each blade, which matches its shape to the next.

Balancing is one big half-step in getting a prop correct, the other is matching the blades to one another for pitch. This pays off big by keeping the prop shake out of the picture. Something a balancer can't tell you.

Not many people take the step into checking pitch with a pitch gauge, it is very tedious work and time consuming. Another gauge has to be purchased too, to perform it and they can cost a bit of cash.

I don't own a pitch gauge and so far feel I don't really need one. If I balance a prop and do a careful job of polishing, I trust the manufacture on getting the blades right. If I feel I still have problems with bushing wear, or excessive shake after balancing, I'll put the prop aside and simply not use it. Sometimes it is something I have overlooked when prepping the prop, such as blade outline, or a bad drive dog area.

Nice machine Craig, I bet you're happy to use it. We should have one of those right here in the Lobby at RCU.

munro1656

do you think pitch on the following /back of the blade is as crutial as the leading face ? Thats the area that I took my material for balancing

jetpack

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The working side of the blade (face) should be the one to look out for. This cupped face is what gets most of the water. The back (front) of the blade is where the material should be removed. It is less critical on shape.

If you did a good job on balancing, the front of the prop that is hand worked should follow pretty close to what it should be unless you are trying to lighten up the whole prop by thinning each blade past the point of being simply balanced. That is where it is a good idea to use a pitch gauge where it measures the shape so the blades do not become too distorted to one another. The front of the blade is an airfoil, and actually helps feed the prop. If the airfoil profile is changed dramatically, the prop can loose its "lift" just like an airplane wing, and "stall" out, or what we call "cavitate".

When I balance a prop, I will first file and polish the hub (making that nice and round as I can, matching the drive dog diameter, removing the parting line) and each cupped blade face as carefully as I can (meaning just past the sandblast finish, careful to not change its shape) then check on the balancer to single out the heavy blade, and mark it.

The lighter blade front is then polished out and finished. You are now left with a fully polished prop, except for the front of the heavy blade. This is the only area of the whole prop that hasn't been touched or finished yet.

The heavy front is the last to go. This last surface is used for balance. This is the first time the metal file is used for balance. After it balances, the whole prop has now been polished except for the filed face, which also now gets polished. At this stage, the whole prop should now be polished and perfect looking, except for final sharpening and balancing.

Final sharpening and balancing is where you take your good looking prop, and with just slight touches with a fingerboard file to the heavy front brings it to perfect balance. The fingerboard should leave only slight marks that can then be easily polished out. It starts to be just slight swipes, polishing and checking after that point until it does not pay to touch it anymore.

I usually leave just the leading edges of the blades to use for final balancing, and don't stray from that area unless I have to. This will then let you work the sharpness into the blades. This balancing effort is now changed to being called just sharpening.

Sharpening areas of the prop should include the leading edges that I just explained, and also the kick-out lip or trailing edge of the blade. That ridge should be kept nice and sharp too. It is the last surface the water touches of the prop, and has the most effect on it being efficient.

Grimracer has a great picture with prop terms that he suppies with his props. Thanks Grim! [sm=thumbup.gif]

Let's hear if this helps, Munro I had to use my entire saturday morning brain power to write this (very weak to start with), and not sure if it is clear enough yet or any mistakes about, so everyone ask away, or throw in their own comments or proceedures they like best.

black talon

My Feedback: (5)

when i get to a point on my topflight balancer that i feel its almost done,i spin the prop a quarter turn on the balancer shaft and usually find the balance point changes with the relation of the shafts position.at that point i'm done.

Racer21

Thanks for all of the great detailed info on prop sharpening and balancing. I had no idea that rtr boats needed attention...I thought they were good right out of the box...

radiocontrolledboats

Hey thanks for all the tips here. I'm guessing that even since you buy a RTR boat its not really RTR.hahaha