Freestyle How to bend a prop? Changing pitch..

Polish jet pilot

Polish jet pilot

4aces4aces4aces4aces4aces
Location
Warsaw, Poland
Hi all,

I currently use a cutback 08 prop on my small bore XFS (needed to prop up from 12/17 skat swirl due to the boat cavitating). I was thinking that maybe bending the prop for a bit more low end pop would be ok... so anybody bends their own.. any tips? Heat no heat? How to measure the change (assuming I do not have the Watcon pitch gauge)..?

Thank you all!
 
slinden

slinden

Location
SW FL
IDT that is something you want to tackle yourself. There is many vendors that will do it for you. Id def choose a pro that knows what they are going.
 
freestyle 650

freestyle 650

Location
prescott arizona
Do a search on the greenhulk and there are printable templates for the pitch gage. You can print this out on paper and then take it to a print shop and have it printed on a sheet of clear plastic.Then you can buy a tube of clear acrylic that is slightly larger than 144mm to tape the pitch template into and set the prop in in on a flat surface to check the pitch.to bend the prop you will want to bolt it down through the center hole and use a soft faced crecent wrench to tweek the pitch to you liking.
 
Polish jet pilot

Polish jet pilot

4aces4aces4aces4aces4aces
Location
Warsaw, Poland
great info! So the pitch gauge will have all info on it and I will be able to determine eg current pitch and the pitch I would like to have, right? Generally, the more steep the angles of the blades, the higher the pitch, or the other way around?
 
freestyle 650

freestyle 650

Location
prescott arizona
Yes, you just set the prop in the gage and see what line the blades line up with and that is the pitch if the prop. The variable pitch props have diffrent pitches for the leading and trailing edges of the prop blades, I.e. a 12/18 will have a 12 degree pitch on the leading edge and a 18 degree pitch on the trailing edge.when checking the variable pitch props you just check the first 1.5" or so of each side to get the pitch.The pitch gage will look very similar to the watcon.The higher the pitch the steeper the prop and will require more power to run it efficiently
 
beerdart

beerdart

4-Tec Jetmate
Location
CT
Printable PDF. You want to measure in the same spot ie: 1" up from the trailing edge. The number does not matter much as long as you increase or decrease for your needs. Make you bend gradual. A 24" adjustable wrench does the job or grind a slit into and old driveshaft.
 

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  • impeller pitch gauge Layout1 (1).pdf
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#ZERO

#ZERO

Beach Bum
Location
Florida - U.S.A.
I've found that those digital box type angle gauges work well but you need a flat surface to bolt the impeller for calibration like a perfectly flat table, trailer hitch jaw or in a lathe chuck works the best. I went to the trouble of making some pitch gauges out of clear acrylic with some printable clear adhesive labels for use with pitch templates but found the digital type gauges to be way more accurate There are a couple different versions of the pitch gauge templates that are downloadable in the tech section with the manuals and stuff. You can use a large adjustable wrench for tweaking the blades and changing the pitch or rake and use a digital gauge on the outer edges of the blades in various locations to check your angles.

Wixey-in-hand-2.jpg
 
Crab

Crab

thanks darin...noswad!
Location
Seattle
I have done my stuff plenty of times, never sent one out...usually clamp it up good in a big vise and use the giant adjustable and a hammer. Key is making all the blades exactly the same, especially the finished height off a flat surface if you lay it flat.
 
Last edited:
beerdart

beerdart

4-Tec Jetmate
Location
CT
There's an app for that.
#ZERO said:
I've found that those digital box type angle gauges work well but you need a flat surface to bolt the impeller for calibration like a perfectly flat table, trailer hitch jaw or in a lathe chuck works the best. I went to the trouble of making some pitch gauges out of clear acrylic with some printable clear adhesive labels for use with pitch templates but found the digital type gauges to be way more accurate There are a couple different versions of the pitch gauge templates that are downloadable in the tech section with the manuals and stuff. You can use a large adjustable wrench for tweaking the blades and changing the pitch or rake and use a digital gauge on the outer edges of the blades in various locations to check your angles.

Wixey-in-hand-2.jpg
Click to expand...
 
Crab

Crab

thanks darin...noswad!
Location
Seattle
Just to add, after watching a local prop repair guy work, he had different pitch guages made from thin sheet metal in the shape of a triangle. I made the same thing from folder paper, you curve them right at the edge of the blade with the prop set flat and can see how close to that pitch you are. The hardest part of bending the blade is getting close to the hub to grab the whole thing at once, usually your not bending it very much tho.
 
Last edited:
kevbo

kevbo

Location
dfw
Polish jet pilot said:
Hi all,

I currently use a cutback 08 prop on my small bore XFS (needed to prop up from 12/17 skat swirl due to the boat cavitating). I was thinking that maybe bending the prop for a bit more low end pop would be ok... so anybody bends their own.. any tips? Heat no heat? How to measure the change (assuming I do not have the Watcon pitch gauge)..?

Thank you all!
Click to expand...

I chuck the hub in an aluminum jaw vise and use a heavy brass hammer. A harder vise/hammer will leave marks in the prop. Just raise the aft outer edge .1". It will appear to match the angle of the overlapping blade above. Go slow and take lots of measurements.
 
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