Wally

That's what Datum's are for......and apparently China don't know what they are! LOL we went through a hair pulling exercise teaching a guy in China on how to read drawings!

Brad Christy

Wally,

Yup. And Datum -A- on a prop would definitely be the shaft bore.

Thanks. Brad.
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ICDEDPPL

in conclusion would you agree the second prop that I thought had 12* of rake has less than the first prop?

I know the first prop is a 15* rake and that what my measurement says so I`m going to pull a PQ90 and burry my head in the sand bacause what I measured and what the prop is matches so why would the second measurement be any different?

Diamond Dave

Measurements don't matter and we are not supposed to talk about them you should know better.

Wally

I concur

PQ290Enticer

Lol!!!! I will never be able to live that down. You forgot the "2". PQ290

Tartilla

Great point. Using a few different blades should have different angles if the rear hub face is not square to bore.

Twin O/B Sonic

I always assumed rake was based on the center line of a blade Vs center line of prop shaft.

if the first pixs are correct then if I trimmed the trailing edges of the blades then I would be changing rake?

If I am wrong and the pixs are correct……, I have been over thinking this for 30 yrs! 🤓

Brad Christy

Gary,

Since the prop is rotating on the shaft, everything should be measured relative to the shaft, if you can.

Thanks. Brad.

Tartilla

I assumed from the definition of rake, that the middle of the blade at the root, the angle to the prop tips.

With cleaver style props, it seems to be a little different, and uses the rear flat portion of the blades as the Rake Angle.

Using tHe shaft as the zero point, vs the rear hub surface that mau not be cut square.to the bore.

My '90s Rollas only have about 10° rake. You can see they have less of an angle. Hoping they have enough bow lift.