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Prop Saver Installation

Old 07-10-2008, 12:15 AM
  #1  
jakc
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Default Prop Saver Installation



Ive got a TowerPro motor and bought a prop saver from some hong kong mail order firm.

Bit confused on how to install the prop saver.

1. Do I need to hack saw the motor axle down so that its flush with prop?

2. Only one washer was supplied with prop saver - should this tie around one prop arm or go over both (latter dont think will happen).

3. I noticed the screws on the prop saver, when fully tightened, do not actually protrude onto the inner axle. They stop just short -Is this right?

Some simple steps on how to set this up would be great.
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Old 07-10-2008, 02:03 AM
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Laggard
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1. I usually don't cut down the shafts for that type of motor. The advantage of doing it is that there's less chance of bending the shaft in the event you nose over. The disadvantage is that you can no longer use that motor without a prop saver.

2. The O-Ring is used like this:

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Old 07-10-2008, 02:58 AM
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pd1
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Originally Posted by jakc View Post


Ive got a TowerPro motor and bought a prop saver from some hong kong mail order firm.

Bit confused on how to install the prop saver.

1. Do I need to hack saw the motor axle down so that its flush with prop?

2. Only one washer was supplied with prop saver - should this tie around one prop arm or go over both (latter dont think will happen).

3. I noticed the screws on the prop saver, when fully tightened, do not actually protrude onto the inner axle. They stop just short -Is this right?

Some simple steps on how to set this up would be great.
1. I think it is preferable to cut the excess shaft off the motor, after the prop saver is on.
2. The washer you have shown in the picture is for the nut arrangement. Not for the prop saver.
3.The screws should protrude into the center of the prop saver.
Those screws are what holds the prop saver onto the shaft.

I slide the prop saver onto the shaft and tighten the screws.

Then I use a Dremel with a cut off wheel to remove excess shaft.

I remove the excess shaft because If the plane does a face plant the shaft has more chance of bending if it is long.

Some prop savers come with small adaptor rings.
Find the ring that best fits into the recess on your prop.
Put that ring on the saver, then the prop.

Some prop saver/ prop combination do not require the adaptor rings.
Some prop savers have two different diameter collars that protrude.
If one of those collars match up with your prop then just use that side of the prop saver outward.

I use two O-rings. O-rings can crack over time and if you only have one, you can lose your prop.
Some people have had good luck with cutting surgical tubing and using that instead of O-rings.

Hope some of this helps.
Paul
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Old 07-10-2008, 10:32 AM
  #4  
jakc
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Ok Im a bit clearer now.

1. I think it is preferable to cut the excess shaft off the motor, after the prop saver is on.

Ok, so I just pop the prop saver on, put it right up against the end of the axle (nearest motor) and then cut off the axle flush with the prop saver. (bit weary on doing this as it will mean I will lost all the threaded part of the axle)

2. The washer you have shown in the picture is for the nut arrangement. Not for the prop saver.

This has kind of confused me - not sure if we are thinking of the same thing. Do you consider the O-Ring to also be called as washer cos i do. (Im from UK, we call O-Rings washers). Does not matter as I understand that I will need to either buy a bigger O-Ring or a second one of the same size (The one supplied with p-saver does not stretch over the whole prop.

3.The screws should protrude into the center of the prop saver.

Bit of a problem then - With the prop saver off the axle, the screws tighten just before protruding into the centre of the p-saver.
Not sure if this is a dodgy prop saver, the threads look fine on the screws and on the p-saver. Might just have to buy another one if no-one can think of a remedy?
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Old 07-10-2008, 10:51 AM
  #5  
M.T.
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Originally Posted by jakc View Post
Bit of a problem then - With the prop saver off the axle, the screws tighten just before protruding into the centre of the p-saver.
Not sure if this is a dodgy prop saver, the threads look fine on the screws and on the p-saver. Might just have to buy another one if no-one can think of a remedy?
Sounds like the threads have not been cut cleanly.
I'd run a tap through the threads..... or try a bit off 'brute force' on the screws (with the prop saver NOT fitted) before buying a new one!
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Old 07-10-2008, 01:05 PM
  #6  
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Yep, watt Paul explained is how I do it. You can always use a prop adapter on the cut off shaft to bolt on your prop if you don't like the prop saver. And looking at the pic I think MT has the right idea, something must be stopping the screws because they look long enough.
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Old 07-10-2008, 01:16 PM
  #7  
pd1
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I think MT and Smoke are right, there is probably a poor thread stopping the screws.

But,
On the off chance you have a one of a kind prop saver that doesn't mount this way, take a pin or something and make sure the screw holes go completely through.

Ive never seen this, but the possibility exist the prop saver is held on with the two nuts in the picture.

The round circular rubber thing is what we call O-rings.
It won't easily go over the prop and the screws.
Matter of fact it is pretty hard to get it over the prop.

I made a tool to make the installation easier.
I used a piece of brass tubing and cut a little piece away.
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The O-ring is going on crooked because I'm doing it one handed, so I can do the camera with my other hand.

Paul
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Old 07-10-2008, 11:13 PM
  #8  
jakc
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Thanks - great step by step pics.

Managed to use brute force (vice + wrench!) to get the screws to touch the break though to other side.

Couple more Qs before I start hacksawing.

The + and - of prop savers. Jasmine pointed out that they can cause virbations and wobble. However id imagine (being a beginner) the amoutn of props ill save should be in my favour to put the p-saver on?

Also - Can I still put the plastic nose cap on the prop after ive put the prop saver on?

And just to absolutley double check - I cut the motor axle flush with the prop saver, and should the prop saver sit flush (or near enough) to the motor?
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Old 07-10-2008, 11:31 PM
  #9  
smokejohnson
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It's important to make sure your prop is sitting flat on the saver. If it is teeter tottering (hole too small) on the saver it will wobble when you try to run the motor. It also can't slide side to side (hole too big) on the saver if it is sitting flat. If the prop is sitting flat with no side to side play you are in good shape.

Leaving the shaft sticking through the prop will defeat the purpose. If the shaft is going through the prop when the prop hits the ground it will bend the shaft.

Along the same principals the longer the shaft the easier it will be to bend. I slide my prop savers as close to the bell as possible and then cut the shaft with no more than an 1/8" sticking out.

Here's a few more pics including my source for surgical tubing.
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Old 07-11-2008, 03:56 AM
  #10  
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The prop MUST sit snugly on the saver.

Look at my third picture, the prop is on with out the O-Ring.

If the prop doesn't sit flat and snug it will WOBBLE.
The motor won't run right and you could shed the prop.

The motor in the picture is 250 watts, I have a number of planes with that size motor and the prop savers.
They work well, but you must be careful.

Paul
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Old 07-11-2008, 04:29 AM
  #11  
TheDustyPagan
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Yeah, anything over 100-125W of power.. you have to be careful if using a propsaver.
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Old 03-15-2011, 06:58 AM
  #12  
rogerleslie
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Default reverse prop saver?

I have one of the little park jets with a prop saver. I have not had the o-ring break or release the prop, but it could be quite dangerous if the prop let loose as I launch the plane.

Has anyone tried reversing the prop saver so that the prop is between the motor and the prop saver with the prop saver being nearest the end of the shaft? The idea is that the prop would be trapped on the shaft between the motor and the prop saver. If the o-ring breaks the prop would not fly off and injure someone.

Roger

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Old 03-15-2011, 05:28 PM
  #13  
hankg
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jakc,

Pay particular attention to Smoke's and Roger's note on surgical tubing...O rings work until they begin to dry out and crack, and they will during warm weather flying. Those types of O rings are made for compression, not expansion. They are made to fit into a round groove and then another flat piece of steel is bolted over the ring and compresses it into the groove.

If they fail when your plane is in the air, you will loose control of the plane. If they fail when you are checking for prop rotation etc while on the ground, you or someone standing near can loose an eye. Surgical tubing with a 3/8" outside diameter and 1/16" walls seems to work best for me.

Regards,

Hankg
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Old 03-15-2011, 06:09 PM
  #14  
kevinm
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if the prop flys off , the plane is instantly in "deadstick- land it soon" mode, hopefully the weight of the (now resting calmly on the ground prop) doesnt tail heavy the plane out of obedience- on my planes i try to be several hairs noseheavy
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Old 03-15-2011, 11:59 PM
  #15  
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As far as cutting threaded shafts, the way to do it to make sure that you don't have problems is to thread a nut onto the shaft before cutting it, then to back the nut off through the cut threads and the threads in the nut will straighten out whatever you messed up with whatever you cut it with.

If you're good, sometimes you can clean up the cut threads using an abrasive cutting wheel, sanding disk/drum... but why risk it if you have a fool proof way by threading a nut on it first.
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