I just read this in micro RC world magazine <pdf> .

"Because this particular motor comes with a prop saver, the APC props would be as well suited in
this application as the GWS. I used both for the PARK-250 testing. One important thing I noted
with the first prop I installed on the 250. The “O” ring supplied with the motor has a 1/2 inch
I.D. When I ran up the motor for the first time at about half throttle the prop flew off the motor.
It turns out that size “O” ring is too big and therefore when it is wrapped around the prop and
the two screws it is too loose. I went to a smaller 3/8 inch I.D. “O” ring. This is a little harder to
install, but rest assured the prop is now on tight. I never threw another prop after making that
change."

I had the same problem . Is this a special kind of O-ring ? Do I need to go to a LHS ? Can I use one from a auto supply house ?

Should be able to get them at Home Depot., Hardware stores or industrial suppliers. I use two or three different sizes for different setups.

Gord.

"ACE" "TrueValue" is what I use.....needle nose pliers to put on is how I do it....take the old one and match it up

http://www.rcgroups.com/forums/showthread.php?t=924179

O-rings are meant to be in compression, not tension. They are not a good option for prop savers.

Go to ACE (or similar) and get yourself a foot or two of surgical tubing. Cut yourself 1/8" thick slices with a sharp scissors. Reliable & economical!

You can even use those skinny/tiny silicone hair bands you can get in most drug stores. They come in a bag of dozens.
You need several depending on the power/use but they are easy to put on.
It's like using thread instead of rope-a bunch of 'winds' is plenty strong.

I use O rings with no problems.

I'd like to use surgical tubing but can not find it anywhere.

You can get these o-rings at most hobby shops. But be careful, they come in different diameters and cross-sections. You need one that's somewhat matched to the prop.

Or... you can just use a stout rubber band, wrapped around and around the two screws and the prop hub. Not much worry about prop balance, because the rubber band's mass is low and it's so close to the rotation axis.

I got the slingshot rubber from Wallmart. I think it's the same type of rubber and doesn't deteriorate like the O ring rubber.

Gord.

Originally Posted by flydiver

You can even use those skinny/tiny silicone hair bands you can get in most drug stores. They come in a bag of dozens.
You need several depending on the power/use but they are easy to put on.
It's like using thread instead of rope-a bunch of 'winds' is plenty strong.

Those are my favorite. Cheap, and strong as anything!

Chuck

I'm going to agree with chuck and go back to the hair bands. The O rings are a bitch to put on.

Originally Posted by flypaper 2

I got the slingshot rubber from Wallmart. I think it's the same type of rubber and doesn't deteriorate like the O ring rubber.

Gord.

What he said..
Works great for me..

Yeah, O-rings don't work well. If they're stretched for long periods of time, they begin to split, and they will eventually let go.

Also, there's o-rings I found that were made specifically to be stretched for long periods of time, maimed at the RC market. Dunno where I found them, but they seemed to work pretty good. No splitting!

You can get the slingshot bands from many different sporting goods stores, too !

Originally Posted by Xpress..

Also, there's o-rings I found that were made specifically to be stretched for long periods of time, maimed at the RC market

Please don't use the word maim in a thread about prop savers.

I also can't find the slingshot bands anywhere. No Walmart here but I check Cabellas and Target with no luck.

Man ...........Now I'm confused....hair bands...sling shot, surgical? My local "tru Value" has no idea what I'm talking about