Spinner problem

Stuka Stunt Main Forum · 15 of 15 known posts recovered

rootbeard · Feb 23, 2004 02:17 PM

Hello Flying Friends,
I have purchased a spinner for our first real trainer. The spinner is going on a McCoy .19 (Black Head). I pulled the prop, and put the back plate of the spinner on the shaft with the correct shaft spacer in front of the drive washer. I then put on my new Brodak wooden 9-4 prop. Installed the washer and nut. Here is the problem:
The nut when tight just fits with no threads to spare. And the 1 3/4 inch spinner will not fit over the prop. The instructions say that the spinner should not touch the prop. Well the notches on the spinner are not big enough to allow the spinner to go all the way to the spinner back plate. So do I trim out the notches or go to a bigger spinner? And what about the space that the back plate is taking up not letting the nut expose some threads on the prop shaft? I like to see a few threads after I tighten a nut.

Thanks
Paul

I am a retread, - I did C/L in my youth and did not know what I was doing then other then having fun. And not much has changed.

Randy · Feb 23, 2004 02:22 PM

#1 source

Hmm, as long at the nut is all the way on the shaft, even if no shaft is exposed, it should be fine. Just want to make sure that all threads of the nut are engaged. As to the spinner fit, just trim the prop slots in the spinner until it fits over the prop. Make sure you're even with your trimming so the spinner stays in balance.

Randy Powell

Randy Ryan · Feb 23, 2004 02:38 PM

#2 source

Randy is correct about the threads, any protruding from the nut are doing nothing because the strength of the thread is in the length of the nut, the exposed threads are doing nothing, somes pretty ideal to me.

If you have a Dremel tool, you can make quick work or the spinner, just take light cuts, a few on one side, the same on the opposite side. Otherwise a sharp Exacto will work but its harder to control. A sharp rat tail file will work, but an old one will probably just wear out your hand.

Randy Ryan
AMA 8500
SAM 36
I fly 'em all and love it!

rootbeard · Feb 23, 2004 04:08 PM

#3 source

OK, I will cut out the prop slots.
and...

Would you guys recommend using a dab of loc-tight on the prop nut?
I just have a fear of things flying that are not attached to the plane. =)

Thanks
Paul

I am a retread, - I did C/L in my youth and did not know what I was doing then other then having fun. And not much has changed.

Harleyman · Feb 23, 2004 04:23 PM

#4 source

LAST EDITED ON Feb-23-04 AT 04:24 PM (CDT)

Paul,
As long as the nut is fully engaged, no loc-tite is needed, tighten as usual. If the shaft ends inside the nut with a ½ or more threads of the nut exposed, do not use the spinner.

If flush or more you’re good. Stay away form the loc-tite.

Chris

SRiese5283 · Feb 23, 2004 06:51 PM

#5 source

RULE of thumb for all mechanical applications is at least three threads showing above the nut. However, your problem is SO common for spinners just be careful.

Scott

Scott Riese

rootbeard · Feb 26, 2004 02:08 PM

#6 source

Well I tried a 7x4 prop on my spinner and it fits a lot nicer then the 9x4. Problem is the 7x4 prop will not work with the plane. I have a 9x4 brodak wooden prop that is on the plane. In order to make this prop work I will need to do two things.

1. The back plate of the spinner has two pins that the prop needs to fit between in order to line up with the slots. The prop is too wide for the pins. So I would have to cut the pins off.
2. I would have to cut a lot from the slots in order get the prop in far enough and have space between the prop and the slots. The instructions say that the prop should not touch the spinner.

So should I cut the pins off and cut out the slots. I am more concerned about cutting the pins off.
Please advise.

Thanks
Paul

I am a retread, - I did C/L in my youth and did not know what I was doing then other then having fun. And not much has changed.

Bob Reeves · Feb 26, 2004 02:46 PM

#7 source

I am thinking your best bet would be get a different spinner. You probably have a Dubro Plastic which leaves little room for a prop in the size you have. Look at other manufactures, Great Planes makes a plastic spinner with better prop clearance.

Tim McTigue · Feb 26, 2004 04:26 PM

#8 source

"Look at other manufactures, Great Planes makes a plastic spinner with better prop clearance. "

Or you could go with a 2" spinner - that's what I plan to do with a McCoy .19 this spring...

Tim

MAAC 65703

duck · Feb 26, 2004 04:32 PM

#9 source

You can cut the pins off. Open the slots. I've used a 1 3/4" dubro spinner with an 11-5 prop. Had to cut alot out of the slots and pins off. No big deal. Plastic spinners do not really have any balance issues but if your unsure, just put it on a prop balancer. I had an aluminum one that was new and never touched that vibrated badly. I balanced it by removing material from the inside.

Rob Duckering....MAAC #14457

CR · Feb 26, 2004 05:27 PM

#10 source

Paul,
You might want to check the fit between the backplate of the spinner and the prop thrust washer on the McCoy 19, I had to grind 8 little dimples for my 19 thrust washer into the backplate of the spinner to snug up the fit. I also gained one thread more coming through the propnut. Hope this helps.

Alan Hahn · Feb 26, 2004 05:41 PM

#11 source

LAST EDITED ON Feb-26-04 AT 05:42 PM (CDT)

Paul,

A comment on your Brodak 9x4 prop.

I bought 3 from Brodak last summer. Two of the props had very thin roots, while the third was a bit beefier. I put one of the thin ones on my LA25 (at the time I wasn't really paying much attention), and when it flew, the vibration was intense. I think this was due to blade flutter. When I went to remove the prop nut, I grasped one of the blades to fix the crankshaft. However when I tried to remove the prop nut, the blade I was holding broke off!

I think Brodak has changed the design (the beefier prop is the new design I believe), but I would look closely at your prop and make sure that the root, down near the hub looks sturdy. It shouldn't be easy to twist the blade.

Alan

rootbeard · Feb 26, 2004 06:10 PM

#12 source

Thanks Allen Noted. Will test it.
Thanks
Paul

I am a retread, - I did C/L in my youth and did not know what I was doing then other then having fun. And not much has changed.

Randy Ryan · Feb 26, 2004 07:34 PM

#13 source

Scott,

This has been taught and passed on for years but the fact is any thread protruding from the nut does zilch, in fact it could be cut off to save weight if someone was so inclined. Total strength of a bolt and nut joint is in the strength of the nut alone unless the bolt is softer then the nut. This is never the case with a crankshaft.

Randy Ryan
AMA 8500
SAM 36
I fly 'em all and love it!

wcrane · Feb 26, 2004 07:43 PM

#14 source

LAST EDITED ON Feb-26-04 AT 07:50 PM (CDT)

All the excess threads didn't help a dang bit at the Hyatt here in KC. Course, not following the dang blueprints didn't help either.

Meanwhile, I'm am suffering from a similar problem. I have a Spinner on my Mustang and although everything is running well, I cannot use a thicker prop than the APC 10x5. A 10x6 will not leave me enough threads thanks to that thick hub. Does anyone make a a counter sunk nut like I've seen on the Saito I used to have where I had to bore the prop and slip the stud into. I think the Fox Prop extenders are like that, but I don't need to extend the prop, just open up the hub a bit and slip this kind of nut on.

From somewhere near Parkville, Mo.
William Crane
AMA 6733