KR> Mold and part fabrication to make a spinner

[Mark Langford]

Wayne Delisle wrote:

> Have you looked at Mark L.'s spinner page?

That spinner page is at http://www.n56ml.com/spinner/.  It happens that 
I made a spinner last weekend, and another one yesterday.  I had to make 
the second one because the first one was floppy (2 layers of 5.85 oz "KR 
cloth"), and I neglected to put deck cloth on the outside.  Both took 
about 2.5 hours to make, although they are only fiberglass and not 
nearly as gorgeous as Jeff's carbon fiber one.  I  thought about making 
them out of carbon fiber, but carbon fiber is more stubborn about 
following compound contours (like the nose) in a wet layup, and the CF 
would be more difficult to match drill to the existing backing plate's 
nut plates (can't see through it!).  And I was a bit more concerned 
about the tearout at the fasteners, as CF doesn't wear well when thin 
(although I'd have done like Jeff did...cover it with a fiberglass tape 
to help with that).

The one I made for N56ML lasted just fine the last thousand hours I flew 
N56ML, with no signs of wear.  It weighs just 235 grams, and is two 
layers of RA5277 9 ounce fiberglass with no other reinforcement.  The 
one I built yesterday is just like it, with a layer of deck cloth on the 
outside to smooth it all over and reduce the finish work on it.  It'll 
probably take me an hour to smooth it out with micro and sanding, and 
another hour to fit the blade cutouts (I have a head start with the old 
spinner) and another hour to match drill the backing plate.  As it turns 
out, Steve Glover sent me a fiberglass fiberglass backing plate that 
fits the contour of this new spinner, so I'll be using that and saving 
more weight. See the enclosed photo for the weights and the spinner 
examples (mine are in the foreground, and the "molds" are in the back). 
  And again, the rest of the story is at http://www.n56ml.com/spinner/. 
  I did get a little more professional about it this time and waxed and 
PVA'd the spinner rather than duct tape.  Note from the enclosed photo 
that my new spinner (far right) is a less than a third of the weight of 
the white mold that it was made from.

Mark Langford
ML at N56ML.com
http://www.n56ml.com

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KR> Mold and part fabrication to make a spinner

[Wayne]

Jeff,

You have created the Rolls-Royce of spinners. It's beautiful and matches 
your prop. Have you looked at Mark L.'s spinner page?

> KR> Mold and part fabrication to make a spinner Jeff Scott
> jscott.planes at gmx.com Mon Apr 13 11:11:20 EDT 2015
>
> Previous message: KR> Fwd: I had a few visitors this weekend Next
> message: KR> Mold and part fabrication to make a spinner Messages
> sorted by: [ date ] [ thread ] [ subject ] [ author ] I thought the
> work I've done over the last couple of weeks might be of interest to
> some of you.  5 weeks ago I had yet another aluminum spinner crack.
> This one had lasted several hundred hours, but it seems that the
> stresses left from spin forming and from me making such large cuts
> around the blades on my prop, they are all destined to eventually
> fail.  I really liked this particular spinner in that it turned true,
> so decided rather than spend $150 for another aluminum dome, I
> thought I would pull a mold and make an exact replica of my spinner.
> By the time I was done buying supplies and tooling to making the
> mold, I had spent many times over the cost of a new spinner dome, but
> the new one shouldn't fail, and if it does, I have the mold to
> fabricate another.  Now that the mold is completed, I can produce
> additional spinners for myself for a relatively low cost.
>
> I published this page to demonstrate the process, not to sell
> spinners as I don't have the time to go into production (and you
> wouldn't want to pay my labor rate!).
>
> 
>
> -Jeff Scott

KR> collapsing gear

[dfeiger]

tommy w
I recall a visit by two young lawyers from the Eugene, OR area flew in a C172 
to look at my project spring of 1982???  If the pictures you have show my KR 
basically done minus any paint then that was him.  Both were determined to 
build one, even tried to buy mine.  Recalled that as we drove down from the 
airport we saw quite a few mule deer, they were surprised when I said that they 
were a nuisance around town.  We are rural, John Day with 1700 plus souls,  is 
the largest city in Grant County (larger than a couple eastern state in size) 
with a population just over 7,000.
Dave

KR> Spinner cracks

[laser147 at juno.com]

The blade cut-outs in the aluminum spinner that came with my plane didn't
work with the Prince prop I bought soon after I got the plane home back
in 2006.  I got the bright idea to use the aluminum spinner as a mold and
thought to make myself a new spinner out of fiberglass, like Mark
outlined on his website.  I filled the spinner with foam and used the
resulting plug as a mold to lay up the glass.  I think I ended up doing
it twice before I was happy with the result.  I did some finish work on
it and did the cut-outs to fit the new Prince and then put it on the
plane.  I didn't paint it but it looked pretty well done but when I got
out to look at it with the engine running I could see the spinner tip
wasn't centered.  There was a little wobble.  A little wobble is too much
wobble so I gave up on making a fiberglass spinner and ordered a new
aluminum one from Great Plains.  I can't remember just how I screwed up
the new spinner - I either dropped it and dented it so badly I couldn't
get the dent out, or I mis-cut the cut-outs so badly it made the spinner
unusable - my memory is hazy on this - but I ended up ordering yet
another one from Steve & Linda.  This one I was more careful with and
managed to get the cut-outs just right.  I took the spinner to a metal
anodizing shop and had it anodized in a gold color.  With the black
Prince prop it looked great.  Even though I took the Prince off once I
ruined the leading edges in rain (and after I'd learned just how
inefficient the "P-tips" actually are), the cut-outs I'd cut for the
Prince fit nicely on the new Sterba 52-56 I bought as a replacement.  The
gold spinner and new Sterba are still on the plane.  The point of this
story is that there had been cracks around the cut-outs on the original
aluminum spinner.  I'd repaired them with JB Weld and pop rivets.  After
some grinding and polishing that works okay as a spinner repair.  It
helps to have your own prop balancing equipment - the Dynavibe in my
case.  But back to the point of this story . . . with the new anodized
spinner I cut sheet metal inserts that follow the curves of the cutouts
and used JB Weld to glue these doublers around the inside of the spinner
cut-outs.  This has prevented any cracks from occurring in the anodized
spinner.  This has turned out to be a good idea.  Cut and attach some
doublers to the inside of the aluminum spinner cut-outs and it will
prevent cracks.  Do a prop balance after any changes to spinners or
props.  Somebody in your local EAA chapter surely has a Dynavibe by now. 
I consider mine to be an essential hangar tool.  It is vibration that
causes the spinner cracks in the first place, so keeping the prop/spinner
balanced is really important.   

Mike
KSEE


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KR> Fwd: I had a few visitors this weekend

[John Martindale]

Hey Paul

The photo attached your email is the inside of an eyeball or is some kind of 
mysterious virus at work here :-)

John

John Martindale
29 Jane Circuit
Toormina NSW 2452
Australia

ph:61 2 6658 4767
m:0403 432179
email:john_martindale at bigpond.com




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