Spinner retrofit

Share your thoughts, photos and general help to all builders

Postby flyalaz » Tue Feb 07, 2006 4:48 pm

Hello once again,

Now that the engine rebuild is finished, the next item on the list is to fit new spinners. With a new installation, it's relatively easy to just position the spinner and drill through into the backplate.
When installing a new spinner, unless you want to make the backplate look like Swiss cheese, it's going to take a little finess to line up and mate the holes.
I think I have a way to do everything in one shot, but I haven't started yet. In my case, the old spinners were cut for the bi-props, and are too large for the P-tip profile. What I did so far was to use masking tape to block out the cutout and make it smaller to match the P-tip. So far so good.
The next step I have in mind, is to use a spinner I made from ABS as a template. I slip the old one inside, mark the cutout locations, and at the same time backdrill the holes. This should position the new spinner properly, as well as maintain a proper gap.

Anybody else have another idea?

Blue skies,
Karl
User avatar
flyalaz
LazairNUT
 
Posts: 352
Joined: Tue Sep 30, 2003 3:18 pm
Location: Montreal, Canada

Postby art » Thu Feb 09, 2006 12:42 am

Karl, where did you get new spinners? Thanks Art
art
LazairNUT
 
Posts: 170
Joined: Tue Apr 26, 2005 8:38 pm
Location: Brewster, New York

Postby flyalaz » Thu Feb 09, 2006 12:39 pm

Hi Art,

I bought them from John Nagy either last year or two years ago, along with four wheel halves. I don't know if he has any more.
I also made a spinner mould and then thermo-moulded some ABS plastic over it. The process still needs fine tuning, and I still need to spin test them to make sure they don't fly apart, but so far, the ABS seems to be bulletproof. Right now, I need to get some more material and mould a few more.

Karl
You do not have the required permissions to view the files attached to this post.
User avatar
flyalaz
LazairNUT
 
Posts: 352
Joined: Tue Sep 30, 2003 3:18 pm
Location: Montreal, Canada

Postby flyalaz » Fri Feb 10, 2006 7:54 pm

First spinner almost done.

Took a little finageling, but the cutout is the right size. I used the dummy spinner to give me the approximate height, then after locating some 1/8" plate on the front of the motor, used a small washer like a little wheel with a pencil through the hole to follow the contour of the prop and transfer the shape to the spinner to give me an exact match.

Hole drilling next.

K.
You do not have the required permissions to view the files attached to this post.
User avatar
flyalaz
LazairNUT
 
Posts: 352
Joined: Tue Sep 30, 2003 3:18 pm
Location: Montreal, Canada

Postby Shannon » Sat Feb 11, 2006 7:31 pm

Karl what type of screws will you be using on the spinners ? Years back I quit using the original type self-tapping sheet metal screws in favor of threaded stainless machine screws. I also use a flat washer under each screw as well as loc-tite.

Shannon
Shannon
SHANNON
 
Posts: 1082
Joined: Thu Jan 15, 2004 10:05 pm

Postby flyalaz » Sat Feb 11, 2006 9:44 pm

Hi Shannon,

I use some MS flush head screws that are gold plated! I redrilled and tapped the backplate to fit and carefully countersunk the spinner to fit the screws. There are no knife edge conditions in the spinner holes, which would lead to cracking, and I plan on doing the same with these new ones.
The screws have been installed with locktite of course. I have been flying with this installation for the last three years absolutly fault free.

Knifedge conditions were a BIG no-no when I was working on biz jets, and my rough drawing will show what I mean for anyone who isn't familiar with the term.

Cheers,

Karl
You do not have the required permissions to view the files attached to this post.
User avatar
flyalaz
LazairNUT
 
Posts: 352
Joined: Tue Sep 30, 2003 3:18 pm
Location: Montreal, Canada

Postby Shannon » Sat Feb 11, 2006 10:46 pm

Sounds like what you have works fine. Reason I asked was several spinnner plates I've seen had cracks that were apparently caused by self-tapping screws. Evidently the self-tapping screws had expanded the metal causing cracks to form on the plate flange.

It's good practice to keep a check on the spinners, screws, and plates. You will quickly become a believer after one blows apart on you.

Shannon
Shannon
SHANNON
 
Posts: 1082
Joined: Thu Jan 15, 2004 10:05 pm

Postby flyalaz » Sun Feb 12, 2006 6:02 pm

I've heard a lot of stories about the old stock plates, and I gave mine a thorough cleaning and inspection before mounting them. There were a lot of score marks left on them from the fabrication process, so I blended them all out then polished them.
I don't know what alloy they are, and I know some types will crack more readily along a score mark so I didn't take a chance. You are most likely right about how others have failed, those self-tapping screws basically forcing their way into the metal, and I hope I never have to witness flying shrapnel on mine!
Drilling and tapping is definitely the way to go, and a proper pre-flight inspection is just good practice.

Karl ;)
User avatar
flyalaz
LazairNUT
 
Posts: 352
Joined: Tue Sep 30, 2003 3:18 pm
Location: Montreal, Canada

Postby Shannon » Sun Feb 12, 2006 9:47 pm

The first indication of spinner plate problems was posted in Tech Update 8 (Aug, '83). I'm not aware if new plates were ever developed and sent out ?

Shannon
Shannon
SHANNON
 
Posts: 1082
Joined: Thu Jan 15, 2004 10:05 pm

Postby flyalaz » Mon Feb 13, 2006 1:07 am

Perhaps Mr. Kramer would have an answer to that?
User avatar
flyalaz
LazairNUT
 
Posts: 352
Joined: Tue Sep 30, 2003 3:18 pm
Location: Montreal, Canada

Next

Return to Re-Building tips and info

Who is online

Users browsing this forum: No registered users and 9 guests

cron