How do you balance a prop ?????

[90profx]

Jay,
Here a question that I'd like to know the answer to.............................

How is a prop balanced, what is done to accomplish balancing and what tools do you use to do it ?????????

Not that I'm gonna get in the business, but I've always wanted to know how its done.

Thanks,

[downtime]

I tried to stand on one foot and put my Trophy plus in my right hand, but it didn't help :) so I sent it to J. He has went through it and am looking forward to getting my (downtime )out of weatherization and running it.

[Terry G.]

well if its like balancing a harley wheel, "REAL CARFULLY" i'd say-- heheh

[Jay Martin]

Jay,
Here a question that I'd like to know the answer to.............................

How is a prop balanced, what is done to accomplish balancing and what tools do you use to do it ?????????

Not that I'm gonna get in the business, but I've always wanted to know how its done.

Thanks,

Well! It's real simple, The balancer I use works off gravity, it has a shaft that fits through the prop then it has two cones that slide onto the shaft and are self locking once you slide them down tite, this also centers the prop on the shaft. the frame of the balancer has two precision bearings on each side, side by side this is were the shaft with the prop is placed, the heavy side will simply fall. Now to the dirty work! I remove material from the back side of the blade with a 2inch wide, 8 inch diameter 120 grit flapper wheel on a 2 hp 3450 rpm electric motor , this is a constant back and forth form balancer to flapper wheel until no matter how the prop is placed back onto the balancer, no blade will fall (it stay's perfect without moving), once this is done the prop is sanded with 320 grit to get all the sanding mark's out from the flapper. and for the final I double check the balance one more time before going to the polisher. You will never be able to tell that all this has been done when I finsh with it...This is my process, and will vary from one prop shop to another.. Here is a pic of a Trophy that has been Balanced and Blueprinted with a high polish.

[90profx]

Thanks Jay.

That's close to what I was thinking. We balance 36" diameter x 3" thick grinding wheels the same way at work. Grinding wheel goes onto a balanced arbor, then onto the knife edge bearing rollers, heavy side drops down.
Very neat to know that props are done the same way.:D:D:D

[Jay Martin]

That's they way it's done!! Tried to word it so that everyone that reads could understand ;);)...

[Jay Martin]

Like that new avatar Gary :D:D:D:D...

[downtime]

I think I've seen that prop before.I like how you stated (so that everyone that reads)so it leaves out some people!!!!

[Bullet20dc]

I gotta give ya credit Jay. I watched mine being hammered and checked by a bud. Man that takes some talent. Do you use pitch blocks or computerized dial system

[Jay Martin]

Neither one, I use the Rundguist 14inch race guage. I'll post a pic of it later.

[Jay Martin]

Here it is, Rundquist 14 inch race pitch guage, $1500.00 for this jewl... The prop you see is a bullet cut 28p chopper pitched to a 29, I was going to try it but it's not going to be enough for me. It is for sale, $200.00 plus shipping..

[Bullet20dc]

tricky lookin tool right there

[Jay Martin]

I love this thing, it's the same guage that spinelli used when he was open.

[lilmule]

The right tools for the job help.
Is that reworked 28 with an interchangeable hub? And would my wee 200 push it?
Or is that being overoptimistic.

[Jay Martin]

I did think about you when making this post but it's merc rubber hub, 15 spline but so is the OMC, With the right thrust washer it should work.

This prop might run good for ya! Want know till you try it. I'm returning this prop in the morning to the owner, if you like I can give you the info. PM me later on it..

[90profx]

That sure is some fancy stuff you got there Jay. It's very interesting to me, the whole prop reworking process that is...........cool stuff:):):)

[Jay Martin]

Just one of the tools of the trade :cool:...The pics are the pitch guage, there is another part that is used to measure the rake, guess I need to post those pics also :D:D:D...

[Jay Martin]

O.k.! Here is the Rake guage, simply used too measure the rake of a prop..
Rake is more less the tilt of the blade, more tilt (rake) more lift it will produce.

Adding cup to the tip of a blade is the same as giving it more rake.
A higher rake angle generally improves the ability of the prop to operate in a cavitating or ventilating situation. GARY! This means you :D:D:D...

[dennyd]

O.k.! Here is the Rake guage, simply used too measure the rake of a prop..
Rake is more less the tilt of the blade, more tilt (rake) more lift it will produce.

Adding cup to the tip of a blade is the same as giving it more rake.
A higher rake angle generally improves the ability of the prop to operate in a cavitating or ventilating situation. GARY! This means you :D:D:D...
Jay,
Would you recommend balancing all props? I have a Merc 90hp 4-Stroke with a 13x17 Trophy Plus.

[lilmule]

Gary is always ventalating,as for the prop most props benefit from balancing.
What you have to ask yourself is is it worth the extra dollars for such a small motor not running high up or fast.

[Jay Martin]

Let me just say that if it's a Trophy, YES!!!!...:D:D...A Balance and Blueprint would'nt hurt..

[dennyd]

Is the Trophy not a good prop?

[Jay Martin]

Yea, it's a great prop. But can be lots better. In your case it should last forever as long as you don't hit something..
On large horsepower, surface running, fast boats they have been known to throw blades. You want have to worry about this problem.
In your case you could gain 3-4 mph on a B&B, It all depends on how bad the prop is off out of the box. Most of the time it can be 1-2 pitch's off from one blade to another. A B&B will make all the blades equal to one another making a much more efficient prop, this will increase top speed and fuel mileage. This means you can turn the same rpm's but gain speed over a non-B&B prop.

[dennyd]

Jay,
Can you tell me the cost or should I go through your website? 13X17

[Jay Martin]

Trophy would be under the v-6 price list..