Freestyle Impeller tuning/pitch

[Yami-Rider]

Sent my impeller off to impros, skat 7/14, measured out in my torrent gauge to 10/14. I asked for it to be repitched to a 6/12, got it back and now it measured out to be 9/12, impros told me it is a 6/12, so maybe I'm missing something? ..

Leading edge lined up with 9


Trying to line up leading edge with 6



What do most use to bend the prop? I've straighten many couch props in the passed, alway use my prop holder and a crescent wrench.

 

[SmittySX]

Looks like 9* to me. I had a similar issue with impros before. Paid a lot of money for a plcustom prop and it was way off. They told me to get effed.

if i were you I’d bend it myself. If not send it off to someone like tricky

 

[Yami-Rider]

Ya. This is what he told me:
Yea the calculated variable pitch angle is an infinity end result, and those gauges cannot show that.

I dont understand what he means..

Threw my digital gauge on there and it says 9.2 degrees

 

[Big Kahuna]

Install it and test. They may measure differently than the gauge your using.

 

[Chase Musetti]

Leading edge seems very subjective on the actual degree depending on who is reading it. I don’t know the technical term for the curved shape that our leading edge uses, but I think that’s where the confusion plays in. That’s why the trailing is so black and white and easy to read.

I think the actual curved portion of the leading edge, the first couple inches, is what matters most for how it will “bite”.

I’d say run it as is now, and if it needs more, start slightly tweaking the leading edge yourself with a crescent wrench little by little until it grabs how you want.


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[Big Kahuna]

Leading edge seems very subjective on the actual degree depending on who is reading it. I don’t know the technical term for the curved shape that our leading edge uses, but I think that’s where the confusion plays in. That’s why the trailing is so black and white and easy to read.

I think the actual curved portion of the leading edge, the first couple inches, is what matters most for how it will “bite”.

I’d say run it as is now, and if it needs more, start slightly tweaking the leading edge yourself with a crescent wrench little by little until it grabs how you want.


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If you are at a race and need a prop pitched and you take it to Tim Judge, He does not break out a guage, He ask what you are needing and then bends accordingly. He measures how much he moves the blades, but not with one of those guages.

 

[Yami-Rider]

I was running a 9/15 148, so I know a 9 leading edge 155 is going to be too much.
Also, a buddy of mine has the exact same hull,engine,TL,pipe, pump as me and a 6/12 on my gauge works perfectly.
Impros wont tell me how they measure, so I have no way of telling them what I need, so I guess I'm going to bend it myself. Waste of $130...

 

[Storbeck]

I dunno, I look at that and I see very clearly not 6 degrees. I'm with Yami-Rider on this one.

 

[Chase Musetti]

I was running a 9/15 148, so I know a 9 leading edge 155 is going to be too much.
Also, a buddy of mine has the exact same hull,engine,TL,pipe, pump as me and a 6/12 on my gauge works perfectly.
Impros wont tell me how they measure, so I have no way of telling them what I need, so I guess I'm going to bend it myself. Waste of $130...

That does suck- plus with it starting out as a 10, and trying to bend down to a 6 is a big jump and will mess with your wear ring clearance and cause more gap, so be sure to measure it, you might be within range.

And when you bend it yourself, focus more on the curved portion and not so much on where you are measuring. Basically form an imaginary 90 degree line off the curved portion to paint a better picture of what the true leading edge is. It’s hard to see from the pics but where you measure seems to be where you’d almost expect the blade to start slowly forming into a higher degree as it tapers to the trailing edge.

But like stated, don’t focus too hard on the number, just start tweaking little by little.

What motor is this, just curious?


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[Chase Musetti]

I was running a 9/15 148, so I know a 9 leading edge 155 is going to be too much.
Also, a buddy of mine has the exact same hull,engine,TL,pipe, pump as me and a 6/12 on my gauge works perfectly.
Impros wont tell me how they measure, so I have no way of telling them what I need, so I guess I'm going to bend it myself. Waste of $130...

Someone stated that they only have 2 molds for this props, one for high pitch and one for low pitch and then they tweak them by whatever standard they use. I think your friend got their “low pitch mold” and you got the “higher pitch mold”


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[Storbeck]

I've always taken that to mean the root angle will always be the same, and the outer edge is adjusted to the various pitch angles. Since 7/14 and 6/12 are both pretty much at the vary bottom of the pitch range it would seem very strange to me if they didn't use the same mold. I think these go up to something like 15/22 for couch applications.

 

[Yami-Rider]

Thanks for the tips.

Someone stated that they only have 2 molds for this propsTapatalk

Ya, I've heard that before, possibly.

Ski:
Fv-pro full carbon, xscream ss900, pfp, msd TL, titanium setback 155 mag

 

[Yami-Rider]

Had to make a couple special tools, but got it down to 6 degrees

 

[Big Kahuna]

Did you run it first?

 

[Yami-Rider]

No. I was running a 148 9/15 prior, so I know a 9 155 would be too much, also my friend has the identical ski/engine, at 6/12.

 

[SmittySX]

What tools did you use to bend it?

 

[Big Kahuna]

No. I was running a 148 9/15 prior, so I know a 9 155 would be too much, also my friend has the identical ski/engine, at 6/12.

Not trying to be argumentative, but, you sent it to an expert and did not even run it, He may measure it different than you do, His way even though it appears to be different than what that gauge may say, may have been the optimal setup for you based on what your requested him to do. I have also heard that some of these type guages are not totally accurate. Something with printing to a flat surface and then applying to a cylindrical surface. I just think you should have at least installed it the way it was and tried it.

 

[Yami-Rider]

What tools did you use to bend it?

A 3/4" plate with a 5/8" stud welded in the middle, then bolted that to my 1000lbs steel bench to hold the prop in place.
Then I took a 3 foot long piece of 1-1/4 bar stock, cut a notch in the front of it, hard faced, then hardened it.
Made easy work of it.



All my prop bending experiences has been straightening seadoo props, I had a special tool to hold the props in the vice and my 12" snapon crescent always did the job, but it wouldnt touch this thin blade skat, much harder material and likes to flex a lot and not bend, so that's why I had to make thses new overkill tools.

Not trying to be argumentative, but, you sent it to an expert and did not even run it. ..

I hear ya.
Used the same tool to measure both props, so they will be the same pitch.
I can always go back steeper if need be.

 

[Christian_83]

my 02 cents:
I think its bulls chit if Impros wont tell you how the messaure the pitch. I mean you ordered 6/12 and got 9/12 (and it impeller was 10/14)
So obviously they hit the trailling edge on the exact same pitch, however they messaure it - how will the leading edge be any diffrent?
Now im gonna get flames - but just becasue impros are "known in the industry" dosent mean they are experts or the best (at least in my books).
If they will not tell you HOW the messaure the pitch after you paid them to re-pitch your impeller, i would never ever put money in their pocket again.

With that said, have you ever messaured you friends impeller or is its 6/12 deg on the "box" ?

about the 2 molds, it could have been me. I talked wot Glen from Skat-Trak a few years back.
Ive been stupid enough to loose my notes from that conversation.
But he told me for their impellers they have 2 molds.
Low pitch i think was around 8/16
high pitch around 13/19

then they worked up and down from there and like @Chase Musetti states, these angles will be somehow static at the root of the impeller.

So in the real world you can have 2 impellers that both messaure 10/14 but "born" diffrent, and they will perform diffrent.

Be carefull when you bend it, a freind of mine was unlucky with his long blade impeller

 

[mikidymac]

my 02 cents:
I think its bulls chit if Impros wont tell you how the messaure the pitch. I mean you ordered 6/12 and got 9/12 (and it impeller was 10/14)
So obviously they hit the trailling edge on the exact same pitch, however they messaure it - how will the leading edge be any diffrent?
Now im gonna get flames - but just becasue impros are "known in the industry" dosent mean they are experts or the best (at least in my books).
If they will not tell you HOW the messaure the pitch after you paid them to re-pitch your impeller, i would never ever put money in their pocket again.

With that said, have you ever messaured you friends impeller or is its 6/12 deg on the "box" ?

about the 2 molds, it could have been me. I talked wot Glen from Skat-Trak a few years back.
Ive been stupid enough to loose my notes from that conversation.
But he told me for their impellers they have 2 molds.
Low pitch i think was around 8/16
high pitch around 13/19

then they worked up and down from there and like @Chase Musetti states, these angles will be somehow static at the root of the impeller.

So in the real world you can have 2 impellers that both messaure 10/14 but "born" diffrent, and they will perform diffrent.

Be carefull when you bend it, a freind of mine was unlucky with his long blade impeller

View attachment 392294

Just and FYI, Glen from Skat now owns Impros.