I think it’s weird that Flipsky and maytech even promote their motors with these cheap 3,5hp props. Why would they do so, if it is not matching at all?
Hello,
Becuse production of props its not easy
We ar made in 2 year more then 2500 props and we have need loot of time to deweloped and finde rigt production proces… we thinking that we need more time for props like for the motor 
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I did this before but the balance is not better than cutted by hand. These chinese props are not very well balanced to begin with. But because I remove alot of weight far from the center it will always be better than before.
Very nice piece of work. What is the final diameter of your prop ?
That’s correct. Even branded propellers are not always that well balanced. To a certain degree, its probably not even a huge problem. In most cases the waterflow where the propeller works is not even for all blades so there is usually always some degree of “imbalance” even if the propeller it selves is perfectly balanced. So with careful job like You did, probably batter than from the factory.
Thank you! My last one is 145mm. For the flipsky motor I also have 125mm, but 145mm gives a better accelaration and top speed is almost the same.
This is a factory “cut” propeller. This is possible one way to modify, but to achieve the notch in the tip is probably not easy.
Metr Log /vesc Log would be really interesting
Does this notch improve the efficiency ? Which brand is the original prop from ? Reminds me of a Solas Amita 3.
A home-made 4 axis CNC could do that… Or someone who’s skilled with a good file… 
I have the swordfish x300a so I can make some logs with it. What logs do you like to see? With the 125mm prop and 145mm prop? I can not see the speed that I get but rpm and Amps are possible. Best would be speed and watts at the same speed but that is difficult for me.
This is a Michigan wheel Ballistic propeller. Its “as is” from the shop, its designed like this. Its a pretty well know type in speed boats, more user friendly than a cleaver but faster than most standard props.
Not sure about the idea behind the notch and is it really superior to a straight design.
My idea was that maybe this style of cut would be relative easily to do for a DIY project trying to reduce the surface area of a outboard prop, as they are typically a bit heavy to spin for direct drives.
An unbalanced prop is a HUGE problem. It’s the reason that seals and bearing fail early! Then once the seal fails you’ll end up with water inside the motor.
You are right, if things get damaged it is a huge problem. The sensitivity is still kind of a mystery in e foil application. On small outboards pepole drives with dented propellers, propellers loosing a part of the tip for years without issue. Not saying its good, but that how it is. Off course with big damages also here will be issues. Still the seals / bearing systems are usually extremely simple. Is it so that small outboards are built much more sturdier, bigger bearings or is it the use of gear oils that makes them much less sensitive?
It shouldn’t be too difficult to automate a process with an IMU lying on the motor to locate the blade or the N-1 blades that unbalance the propeller, much like tires are balanced in repair garages. For us it could be by addition of material on the lightest blade or removal on the N-1 heaviest blades.
Hi.
It’s not hard to balance a prop. You just need a rod to put the prop on. The heavy part will rotate to the bottom. File, sand, grind, or polish a bit and test again until balanced.
See rc prop balancers. Watch YouTube videos on boat prop balancing.
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This process is really time consuming. I don’t think it’s optimal when like FR you manufacture several hundred units. Impellers and also parts of vaccum cleaners need to be balanced as well. We will be using a dynamic balancing machine making this way more easily and precisely done.
If you are interested, take a look at one of these machine here :
Happy to share with the community 
Hi.
Yes. Good point. I’m not talking about the method David is using. I’m talking about for the DIY guys. Jezza points out the damage caused by out of balance props on these motors. I posted this just to say, don’t be discouraged from cutting down your prop yourself. You can balance it yourself easily.
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Nice video but what about 3 blades prop 
I did that with my modified Solas prop , not that easy on 3 blades , easier on 2 or 4 …
Hi.
You still can balance 3 blade props using this method. The heavy spot will want to be at the bottom. It’s trial and error to get it balanced. If the heavy spot it between two blades you take a little off both lower blades. And test again. You get a feel for it after awhile. In the beginning it takes many times.
I balance props using a cheap balancer for rc propellers, to balance 3D printed propellers I drill hole in the hub fast and Working nicely
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