Solved Cut down props- bad idea?

[Yusernaym]

I have a couple of fairly nice 10x5 APC props laying around from a plane that doesn't exist anymore, and I've been thinking about cutting one down to 6.5 to 7 inches to put on a different plane. My concerns are pretty obvious- balance and heat. A heavier prop with a higher pitch takes more juice to drive, but it'll move a lot more air for every rotation. I'm sure my motor could handle it, but I'd rather not kill my esc, so I'm checking in here. Does anyone here have experience cutting down props, and, if so, is it worth doing?

 

[Grifflyer]

People regularly cut down props with good success. If you were to shave down your 10 inch prop you'd have a 7x5 which isn't super aggressive. What props does the motor you have recommend? If it's anything near a 7x5 you should be fine.

 

[GrizWiz]

I wouldn't recommend it just buy new ones they are very cheap!

 

[Yusernaym]

the current motor is a 2207, which i've been running a 6x4 on without it getting even slightly warm. I don't know what's recommended for it but it wouldn't be a huge jump. I'll probably go out and buy properly sized ones eventually, I just want to try this as a project.

 

[LitterBug]

the current motor is a 2207, which i've been running a 6x4 on without it getting even slightly warm. I don't know what's recommended for it but it wouldn't be a huge jump. I'll probably go out and buy properly sized ones eventually, I just want to try this as a project.

2207, but what KV?

 

[Yusernaym]

2700kv

 

[Ranger_107]

2700kv

That should work, Maybe be a little slow on the throttle at first.
Whats the ESC size??

 

[Yusernaym]

That should work, Maybe be a little slow on the throttle at first.
Whats the ESC size??

it's a 20a esc, and I'm running 3s. I did take a closer look at the props and it seems like they wouldn't work on a pusher setup. There's a tapered part at the back that's supposed to sit against the motor but would just be against the nut, that amount of resistance might try to unscrew the nut, and I'd have to resolder the esc to get it going the right direction. so this project isn't happening anymore. I'll just order pushers in the right size and go with that.

 

[Piotrsko]

The only other issues with a cut down prop are the effective pitch increases ( except on flat plate props) because of the need to maintain disc loading, and a harmonics issue. Won't even go into worm hole of tip differences.

However these are all very hard core prop problems and not ones the hobbyist needs to worry about. Whack away, just make sure it'll balance

 

[Pieliker96]

The only other issues with a cut down prop are the effective pitch increases ( except on flat plate props) because of the need to maintain disc loading, and a harmonics issue. Won't even go into worm hole of tip differences.

However these are all very hard core prop problems and not ones the hobbyist needs to worry about. Whack away, just make sure it'll balance

Well put. I've personally cut down a 8x4.5 to a 7.25x4.5 with some side cutters and a few minutes of filing and balancing, no adverse effects to speak of.

 

[BATTLEAXE]

with a cut down prop are the effective pitch increases

I have heard this before, and I have asked to confirm this but there have been mixed answers. I know the tips of the prop have a flatter pitch then closer to the hub. Being most of the thrust comes at the tips effectively cutting the flatter tips off it appears that the tips pitch is increased. So that being said if you have a 9x5 and cut it down to 8" then you may have a 8x6 or something close. Does that make sense?

 

[Piotrsko]

Nailed it @BATTLEAXE

 

[Merv]

Turning a 10 prop into 9 inch prop will work without any issues.
But cutting one down to a 6.5 inch prop could be troublesome.

 

[BATTLEAXE]

I took an 8 down to a 6 and we are still good