Brushless Motor Construction Discuss design and construction of custom Brushless motors

Help!! How do I put a prop on this?

Old 01-12-2011, 06:15 PM
  #1  
chinaclipper
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Default Help!! How do I put a prop on this?

I FINALLY got my 750kpm motor.
It uses a M4 nut for the prop shaft.
I admit I am a bit perplexed.....
How do I put a prop on this shaft?

Wouldn't I need the prop to stay put along the shaft length somewhere?
How does one do that?

Pardon my stupid questions....
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Old 01-12-2011, 06:24 PM
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gdhampton
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Originally Posted by chinaclipper View Post
I FINALLY got my 750kpm motor.
It uses a M4 nut for the prop shaft.
I admit I am a bit perplexed.....
How do I put a prop on this shaft?

Wouldn't I need the prop to stay put along the shaft length somewhere?
How does one do that?

Pardon my stupid questions....
A threaded motor shaft is rather unusual. Most are smooth and some have a flat spot for a grub screw.

So, you could use 2 nuts and 2 washers with the prop in between. Put the first nut on and then a washer. Put the prop on followed by another washer and tighten down the second nut to hold it in place.

Or, use a standard prop collet - which will tighten down on the shaft as you tighten the prop nut.
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Old 01-12-2011, 06:27 PM
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Grasshopper
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Hey CC,

There are several ways to do it. The easiest is to put one nut on, then a 4mm flat washer, then your prop, then a second 4mm flat washer then another nut to lock it down. One problem with this method is that the prop is rigid and the shaft can bend if struck on the ground.

A second method is to use a prop saver like this one: http://www.headsuprc.com/servlet/the...-3.17mm/Detail
Most people cut most of the shaft off so that it just protrudes through the prop saver. This method holds the prop in place but allows it to move if struck on the ground, saving your motor shaft.

The third method is to use a collet type adaptor that slides over the shaft and clamps down on it as the prop nut is tightened.

The method most people prefer is the prop saver but it's really a personal preference and depends on the application you're using it on.
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Old 01-12-2011, 06:28 PM
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Grasshopper
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Apparently I type slower than gdhampton.
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Old 01-12-2011, 06:31 PM
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gdhampton
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Originally Posted by Grasshopper View Post
Apparently I type slower than gdhampton.
Great minds think alike!?! Good call on the prop saver - I didn't even think about that. It is a small motor so it makes total sense.
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Old 01-13-2011, 04:49 AM
  #6  
CHELLIE
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Originally Posted by chinaclipper View Post
I FINALLY got my 750kpm motor.
It uses a M4 nut for the prop shaft.
I admit I am a bit perplexed.....
How do I put a prop on this shaft?

Wouldn't I need the prop to stay put along the shaft length somewhere?
How does one do that?

Pardon my stupid questions....
Hi Chinaclipper There are no stupid questions here, its stupid not to ask Questions LOL

On the prop saver, if your going that way, push the prop saver all the way back to the bell and cut the motor shaft with 1/8" of the motor shaft sticking out of the prop saver, reason being, is that makes the motor shaft shorter and less likely to bend, also, grind 2 flat spots on the motor shaft where the prop saver screws touch the motor shaft at, that will keep the prop saver from turning on the motor shaft, also use blue lock tight on the prop saver screws.

(1)The Bell motors have a couple of weak spots, this will cure that, Remove the Rear radial motor mount, 2 screws, and use some 5 min epoxy on the motor where the radial mount slips on the motor, and reassemble, That keeps the motor from wanting to turn in the radial mount and keeps the motor wires from pulling and breaking, make sure no epoxy gets on the rear bearing.
(2) the wires that come out of the motor are not very well supported and will vibrate and break, ask me How I know epoxy the wires to the windings to give them a little more support, cover the magnets with some masking tape, so no epoxy gets on the magnets, Now you have a bell motor that will last a long time trouble free, Hope that helps, Chellie
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Old 01-13-2011, 05:15 AM
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chinaclipper
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Default Thanks everyone!

Thanks to all who answered my questions.
I think I can "get 'er done" now.
CC
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Old 01-13-2011, 12:27 PM
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philipa_240sx
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Originally Posted by gdhampton View Post
Or, use a standard prop collet - which will tighten down on the shaft as you tighten the prop nut.
I wouldn't recommend using a collet adapter on a threaded shaft. It should be smooth.

I have had a few motors of similar types. I usually swap the shaft with a smooth one and use collet adapters.

The motor is rated for ~135W continuous. This is a bit high for my comfort level when using a prop saver. You'll want to use decent O-rings and double them up. Great Planes sells some heavy duty ones, but your local hardware store may have something similar.
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