help me here

[Taylor]

ill be the first to post here for sure lol!!!

when people talk about cupping and back cutting and all that stuff what area of the prop are they working on could you guys point out what area of the prop is worked for these different methods? id like to start testing these procedures on props know the names and kinda what they do but surely don't know what to work on the prop?!?!

[lectriglide]

ill be the first to post here for sure lol!!!

when people talk about cupping and back cutting and all that stuff what area of the prop are they working on could you guys point out what area of the prop is worked for these different methods? id like to start testing these procedures on props know the names and kinda what they do but surely don't know what to work on the prop?!?!

http://rcboat.com/prop.htm

[westbeach]

heres a link to a previous thread. http://forums.offshoreelectrics.com/...t=cupping+prop .Don't be afraid to use the SEARCH button!

[m4a1usr]

Or use this for info http://www.castlemarine.co.uk/your.htm and dont forget this classic one http://www.rcprops.com/TechNotes/rcprop_tech_info.htm

John

[DISAR]

The most important is to have a balanced and very sharp "razor" prop. Then, there are various modifications such as detongue, backcut, burcut, cupping, reduce diameter etc...These mods could make a propeler more efficient and could increase rpm but depends on many other factors.
I have tried almost all of these mods, and my best ones are detongue (slightly) and backcut 2mm. My best prop is a 447/3 cut down to 445/3 detongued, backcut with slight cup.
Chosing the right prop depends also on the boat type.

EDIT. Here are some photos from some old props of mine (I have about 50 all prepared by me) showing the detongue and backcut

[longballlumber]

ill be the first to post here for sure lol!!!

when people talk about cupping and back cutting and all that stuff what area of the prop are they working on could you guys point out what area of the prop is worked for these different methods? id like to start testing these procedures on props know the names and kinda what they do but surely don't know what to work on the prop?!?!

FIRST AND FOR MOST... Master the art of balancing, sharpening, and thinning a prop. If you don't know how to S/B all of those other mods will have less meaning.

Later,
Mike

[Taylor]

dasar, the cupping back cutting and the other things you listed could you pointout what section or side, piece of the prop is worked to achieve those effects?

[Taylor]

if i have read right the backcuting help the motor rev faster also the detongue helps with that as well?? i have a 41 inch falcon cat i have a prather 275 and a 6717 3 blade havent run the 3 blade yet but i use to have a propshop 7016-2 from bonzi sports they re balanced it and sharpend it jeez had 80 bucks in that thing. w/e i went to run it after i had ben running a raw s275 put the 7016-2 on it and jesus the boat did nothing it would barely take off i havent a clue what was going on with it had the strut down a bit further adjusted anything that coulda be adjusted and nothing helped the 260 pum was still being broke in no idea if that what was doing it or what..but the motor is stock

[detox]

FIRST AND FOR MOST... Master the art of balancing, sharpening, and thinning a prop. If you don't know how to S/B all of those other mods will have less meaning.

Later,
Mike

Ever try balancing, sharpening, and THINNING the smaller ABC three blade props? Lots of work.

[DISAR]

dasar, the cupping back cutting and the other things you listed could you pointout what section or side, piece of the prop is worked to achieve those effects?

Here is what I do with an Octura raw prop, all with a dremel tool with different tips

1) remove imperfections from blades edges, hub and drive dog slot
2) sharpen and thin the blades
3) make the trailing edge flat with sharp edges
3) balancing with a magnetic balancer
4) detogue and backcut (if required) the baldes must be identical
5) balancing again
6) drysanding and then wet sanding to polish (180-400-600-1000-2000-polish cream)


remove material from;

for sharpening-thinning & balancing - from side facing the drive dog
for backcut - from trailing edge, more at the blade root-hub- about 2mm and none at the tip of the blade (1st photo)
for detongue - from the 'tongue' slightly

for cupping the tips of the blades are slightly bent towards the direction of rotation (2nd photo- prop of xzesparated http://forums.offshoreelectrics.com/...&highlight=mph)

for the sanding I use a small piece cut from pool noodle to reach the difficult areas

[egneg]

Here is another good link. RCU has had this thread going for 5 years.

http://www.rcuniverse.com/forum/m_3120686/mpage_1/key_/tm.htm

[longballlumber]

Ever try balancing, sharpening, and THINNING the smaller ABC three blade props? Lots of work.

Yes Sir... I sure have....

I never spend less than 3 on any prop before it's done. In most cases I spend more.

A properly thinned prop will turn more RPM than a non-thinned prop... It's more noticeable on a nitro boat than in an FE.

Later,
Mike

[igottalongone]

For you guys with no patience (like myself) who are using dremels to work your props. WEAR YOUR MASK!!! And make sure it fits right, no leaks!!! The copper barillium dust is DEADLY!!! The man who taught me how to work a prop is now 63 with severe emphazema (whatever, you know what I mean) Never smoked a day in his life or worked around anything hazzardous, except Props! He sold his worked props in our store for 25 years... Now hits sits around on oxygen and can't walk to the mailbox... But, keep in mind, you are more likely to get cancer from the dust than you are emphazema.. Wear a mask!
Ron