Hi All!

I mail-ordered a Dubro 2.5" spinner to put on my ASP .91 2 stroke. The openings in the spinner cone are not wide enough for either an APC or MA 14" prop. Also the indented area on the back of the spinner plate is too small for the thrust washer to sit in.

I don't want to modify the spinner as I am likely to create balance problems so I want to return it and purchase another spinner. I know a DB Vortech spinner will have a flat backplate, but are the openings in the cone big enough for a 14-15" prop without modification?

Thanks!

David...

I can't answer your question, but I sure hope manufacturers are listening. THE &*^%$# spinners don't fit the props people like to use!!!!!

Seems like the engineering staff are suffering from "Rectal-Cranial Inversion"

My solution? Call Tru-Turn. 281-479-9600 or email them via www.tru-turn.com.

No cheap-***** spinner even comes close, and they will custom machine a stock item for you with perfect balance. Just tell them the engine and the prop...they'll do the rest.

They cost extra...But you get extra.

'Race

David,

If you can live with the lower flight performance (less thrust, a little less speed), Master Airscrew props nearly never need the spinner blade holes modified.

But this will not solve the backplate problem.

Curt,

If you cut that spar twice more, it will become long enough for sure...

The problem here is that manufacturers can not possibly know how you will use the spinner. All the clairvoyant engineers were spirited away by Microsoft back in the late 70's Therefore, they make the holes small so you, the end user, can enlarge them to suit your specific application. As DarZeelon hinted, it's always easier to remove material than it is to put it back. If the companies made the holes big enough to suit the largest propeller, then the holes would be much too large for many more common applications, and then those people would complain. It's a no-win situation for the manufacturers, so they go with the least-common denominator.

FWIW, it's really hard to get an aluminum spinner much out of balance, unless you're really ham-fisted about enlarging the holes. I generally cover the spinner with masking tape and map out my cuts, then carefully whittle away with a Dremel, and the spinners come out balanced just as well as they did from the factory.

Tru-Turn is the only spinner manufacturer out there that will custom-cut the holes in your spinner for the specific prop you want to use.

Matt...can't get an aluminum spinner out of balance?

Have you ever run a CB Associates spinner?

They take vibration to a new level. Junk.

It's either a Tru-Turn, or use the nut supplied with the motor. Those are the options the way I see it, and NO you won't have much luck accurately balancing a plastic spinner no matter how hard you try. They're garbage too.


'Race

Most spinners come with very small cutouts for the prop so you can cut your own holes. In fact, many Russian engines have no prop holes cut in. This is because of the wide variety of prop shapes. Take a Dremel and cut the hole large enough so that no part of the prop touches the spinner, otherwise you may cause prop failure. It's a pain, but not that hard to do.

Max

I have the DB 2 1/2in. spinner on mine, and I am using a 14 in. prop and it fits fine. It also comes with spacers that will allow you to use the spinner on dif size shafts. You must use the short prop nut adapter that is seperate from the spinner. For the money you think they would supply you with one. Had no balance problems with mine, and it looks real nice if you take the time to polish it up.

It would appear that I'm in the minority here, but....that's OK.

In 25 years of cutting my fingers with model airplane props, I have had or seen more vibration problems that could be directly attributed to good looking and poorly balanced/distorted spinners than I care to recall.

I guess it's all in what satisfies you.

Most of the cheap-o's are a little off to start with. As soon as you start chiseling material out to open it up to fit "X" prop...all bets are off. Sure...we're talking fractions of a gram. Consider a 1/2oz imbalance on a 40lb car tire will shake your teeth out at 55mph. What does a 1/4 gram do to a 1oz spinner at 12,000rpm?

You're radio will tell you. Sooner or later.

Shake on!

'Race

Curt, everybody.

An imbalance 1"-1.5" from center (as in a spinner) causes much less vibration than the same imbalance 5" out, like on a prop blade.

If a spinner has a bad imbalanced, it can cause the fillings to fall from your teeth... But if you modify the blade holes with a Dremel type tool, in a plastic spinner and you are no too far off, you will hardly feel it.