HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Apr 06, 2011, 11:08 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Mini-HowTo
Prop Savers - Fitting, Using, Testing, & Making Thera-Band Bands

Prop savers are often criticized for how well they work, and they are often stated to be inadequate for use at certain power levels. The criticisms are most often undeserved and the problems are due to an improperly fitted or used prop saver or a prop saver band that is inadequate for the intended use.

Prop Saver Fitting - This video shows how to cut a shaft to length and fit a prop saver. The prop saver used there is the Maxx Products ACC366 tapered cone style prop saver. Tools needed are a Dremel tool, a #102 arbor, and a #409 metal cutting disc. I did not do it here but I would normally put the motor in a plastic bag with a hole for the shaft to prevent metallic particles from getting into the magnets or bearings:

Prop Saver Fitting.mp4 (4 min 11 sec)


The Loctite mentioned in the video is the key to the screws not loosening themselves in use. It is a thread locking compound that comes in different strengths and each strength is a different color. The one I recommend is the Loctite blue or #242 locking compound. The #271 red compound is stronger and it can create some problems in getting the screws loose later. But with any of them, applying some heat will soften and relax the bond, five seconds or so with a small flame (micro torch, cigarette lighter, etc.) will soften it and relax the bond.

OK, we have a prop saver on. Let's put a prop on it! We're going to use a home made tool made from a scrap of piano wire that is too short to be useful for anything on an airplane. And we are going to use The World's Greatest Prop Saver Bands because we work hard and deserve that kind of quality! And besides, these sooo cheap!:

Prop Mounting.mp4 (1 min 3 sec)


Once you get your prop saver fitted and have a prop on it, a little testing is in order. That is seen here using a GWS RS EP-1170 slow fly prop. I even spun up to a little bit more than it's recommended maximum RPM limits (45,000 / prop dia. in inches or 4,091 RPM) to demonstrate the look and sound of prop flutter but that turned out to be barely audible on the video:

Slow Fly Prop High RPM Testing.mp4 (2 min 9 sec)


When I fitted the prop to the prop saver I used the World's Greatest Prop Saver Band, the ones I make myself from Thera-Band blue surgical/physical therapy tubing. Here is the demo of how quickly you can make those for costs that range from the alluring "free" to a typical 2 Cents per band:

Making Thera-Bands.mp4 (2 min 2 sec)


I'll be glad to answer questions on the thread of course, harsh criticisms of my sanity and/or workmanship just clot up the thread so they can be addressed to me at "jacker at midmaine dot com".

Go forth and fly safe!

8 April 2011 - Adding this image that shows which of the various sizes or prop savers fits which brands of props if you have the saver with a stepped cylinder or the one that has a cone on one side and a cylinder on the other. Usually using the tapered cone side against the prop will let it fit all or nearly all props.

When using APC, Great Planes, and other props that come with an assortment of small bushings for reducing the hole, fit one of those that takes up all the side to side play and/or that places the prop on the tapered cone surface if there is one. I use small drop of CA when I put the adapters in so they are not lost later.

16 April 2011 - A couple have asked where they can get Thera-Band blue easily. There are a number of people selling it on eBay and at prices are cheap as $1.50 a foot including mail shipment. Search for "theraband" or "thera-band".

Will it work at 250 Watts with a 13-14" prop? You bet it will!

APC 13x8 on prop saver.mp4 (1 min 33 sec)


And here it is at over 700W with an APC 14x10 Thin Electric on a D4023-850 motor. Three Thera-Band bands for that one, thrust was about 2000g:

D4023-850 Brushless Motor 4S Test (1 min 45 sec)



13 May 2012 - Added link to the "big prop and high power test" Video.
16 Nov 2013 - Added link to the D4023-850 motor test with an APC 14 x 10 TE prop.
24 Jun 2014 - Added image of the Alltrade 6" Cable cutter I use for cutting bands


Jack
jackerbes is offline Find More Posts by jackerbes
Last edited by jackerbes; Jun 24, 2014 at 12:53 AM. Reason: Add a note...
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 06, 2011, 01:37 PM
Reduce the drama...
rick.benjamin's Avatar
USA, OR, Damascus
Joined Apr 2004
4,044 Posts
Jack;
I viewed your videos.
Then, I viewed some other propsaver videos on youtube.
Yours are the best.
Thanks for the effort you took.
Regards
Rick
PS your workbench is way too clean....
rick.benjamin is offline Find More Posts by rick.benjamin
Reply With Quote
Old Apr 06, 2011, 01:47 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Thanks, Rick.

That is the sawhorses with a piece of wood on them, the workbench is behind me and knee deep in tools and stuff.

But thanks for the kind words and thoughts!

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Apr 06, 2011, 02:14 PM
Registered User
United States, NV, North Las Vegas
Joined Sep 2009
1,075 Posts
Thanks for the videos!

About the only thing I do differnt is once I mark where the shaft needs to be cut I use a plastic/ziploc bag and poke the shaft through so that the motor is inside the bag with only the portion of the shaft to be removed poking through...of course I don't run the motor as I'm cutting... by doing it this way I make sure the magnets don't pull any metal dust inside the motor

The tiny particles may not be a problem... still I'd rather NOT let them get inside the motor.

I'm going to try the thera-band next time I get over to the medical supply...I've been using just plain surgical tubing(kinda tan in color) and so far it works very well... ugly in color but hey it's MUCH better than any O-ring I've tried!

John
shultz is offline Find More Posts by shultz
Reply With Quote
Old Apr 06, 2011, 02:54 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Thanks for mentioning that, John.

I left the bags off to get a little better video, I'll edit that and mention it though. I've also taped a shop vacuum nozzle down near the cutting and used that too but that adds another noise...

I think you'll find the blue Thera-Band to be a little better, heavier walls or maybe better rubber or something. I've used surgical tubing too and it was just a little thinner but, like you say, it worked very well.

They have Thera-Band in a number of color coded sizes:

Specs and info - http://www.thera-band.com/store/prod...p?ProductID=27

Color - size specs - Product Code (25-Ft) - Product Code (100-Ft)

Tan .062 ID x .031 wall (.125 O.D.) #21010 #21110
Yellow .200 ID x .045 wall (.290 O.D.) #21020 #21120
Red .200 ID x .057 wall (.314 O.D.) #21030 #21130
Green .200 ID x .069 wall (.338 O.D.) #21040 #21140
Blue .200 ID x .085 wall (.370 O.D.) #21050 #21150
Black .200 ID x .098 wall (.396 O.D.) #21060 #21160
Silver .200 ID x .125 wall (.450 O.D.) #21070 #21170

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Apr 06, 2011, 04:03 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,016 Posts
First mentioned on RCG in 2001
http://www.rcgroups.com/forums/showt...t=latex+rubber
Good ideas stay around to be discovered over and over again.
hoppy is offline Find More Posts by hoppy
Reply With Quote
Old Apr 06, 2011, 04:54 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
These are better, and I've used both. PM me a mailing address and I'll send you a few samples.

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Apr 18, 2011, 01:14 PM
just Some Useless Geek
Chicagoland
Joined Oct 2008
2,543 Posts
Jack was kind enough to send me some samples. After testing, I made the following observations:

The heavy wall eliminates one of the main problems I had encountered with using silicon tubing for prop saver bands in the past: they split at stress risers caused by notches made during cutting. The heavier wall makes those notches spread out, so the stress riser sorta integrates out and doesn't cause splitting.

These silicon bands have all kindsa stretchiness and shape retention. One of the problems with the el cheapo hair bands you get at Sally Beauty Supply is that they have to be removed after every flying session or you risk having them break the next time because they're all stretched out. Okay, so they cost $1.66 per 500 or whatever, but you still need them to work. The silicon stays soft and doesn't stretch over time, so you can leave them in place.

The silicon tubing is really tough stuff. Even though the bands are easier to install than O-rings (they have more stretch) they can take all kinds of twisting and abuse when you land or crash into something. I've already had a few "incidents" that would have either thrown off all the hair bands or broken an O-ring, and the silicon stuff just springs right back into shape.

I have a new favorite prop saver band.
A Useless Geek is offline Find More Posts by A Useless Geek
Reply With Quote
Old Apr 18, 2011, 02:04 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Thanks for the interesting and detailed report geek! You are finding them to better for the same reasons I did.

Hoppy,

I'm still waiting for your mailing address, if you would like to find out why these are better than the 2001 ones were, shoot a mailing address to me at "jacker at midmaine dot com".

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Apr 26, 2011, 07:29 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Feedback report from "Pink Foams Nicely"

Oops!
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Apr 30, 2011, 09:47 PM
gram obsessive
United States, AZ, Tucson
Joined Mar 2005
743 Posts
Jack,

Thanks for the beautifully done videos. Very informative.

T.B.
T.B. is offline Find More Posts by T.B.
Reply With Quote
Old May 01, 2011, 03:12 AM
Torn 'twixt buildin' and flyin
TheNightowl's Avatar
United States, TX, Austin
Joined Oct 2007
7,189 Posts
Very nice job, Jack. Thank you for making these instructional videos and making them available.

Nightowl
TheNightowl is offline Find More Posts by TheNightowl
Reply With Quote
Old May 01, 2011, 07:07 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Thanks guys, a couple of people have asked me where to get it so I'll post a link to one of the best deals goingn (and I do not get a cut!).

http://tinyurl.com/66tx7cg

If you're in the U.S. that will get you a foot of Thera-Band (I recommend the blue color) by mail for $1.50. And with that, a piece of 1/4" dowel, a razor knife, and a few minutes of time you're good to go for making almost 100 prop saver bands.

Jack
jackerbes is offline Find More Posts by jackerbes
Last edited by jackerbes; May 01, 2011 at 01:44 PM.
Reply With Quote
Old May 01, 2011, 01:27 PM
Registered User
Cumbria in the U.K
Joined Jan 2008
1,927 Posts
Thanks for the videos and information Jack.
Having complete faith in you I have splashed out $20 or so to get 6 feet of the blue band sent to the U.K.

Never going to have to buy a prop band ever again, 6ft is a heck of a lot of bands
sparklet is offline Find More Posts by sparklet
Reply With Quote
Old May 01, 2011, 01:40 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Quote:
Originally Posted by sparklet View Post
Thanks for the videos and information Jack.
Having complete faith in you I have splashed out $20 or so to get 6 feet of the blue band sent to the U.K.

Never going to have to buy a prop band ever again, 6ft is a heck of a lot of bands
Wow! You could become the king of the prop saver band industry for your club with all that.

I'm thinking you give them one sample and then sell them a packet of a dozen or so with they come back for another you'll get your money back. Or are you allowed to sell anything by the dozen in the UK any more? Maybe a packet of 10...

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Idea Need plans for making a foam plane using electronics of a crashed HZ Champ computerpc Foamies (Scratchbuilt) 4 Mar 23, 2011 08:43 AM
For Sale Prop Savers for 1.5mm and 2mm motor shafts scharlach Aircraft - Electric - Micro & Indoor Airplanes (FS/W) 10 Mar 21, 2011 09:29 PM
Sold 1mm prop savers, rubber bands & 11 mm horns Flying glass Aircraft - Electric - Micro & Indoor Airplanes (FS/W) 3 Mar 05, 2011 07:35 PM
Question Bands for prop savers ajreynolds 3D Flying 11 Nov 11, 2010 10:16 AM
Question Opinions on using prop savers on wings? jive Flying Wings 4 May 05, 2007 11:30 PM