Refinishing a Wood Prop

[Kyle Boatright]

I've noticed that my prop is beginning to show signs of wear -chips in the
leading edge, and cracks in the clear finish. Given that I'm having shoulder
surgery in a couple of weeks (and probably won't be up to flying until the
arm is substantially healed), I should have some time on my hands to
refinish the prop.

My plan is to remove the existing finish by sanding with ~220 grit
sandpaper, then to use epoxy (with cabosil?) to fill any dents, etc, and
sand/scrape the repaired areas back to the appropriate profile. Also, I
plan on doing some repair work to the leading edge which is an epoxy based
product. On the leading edge, I'll probably grind into any damaged areas,
then fill with one of the putty type epoxies and sand/scrape to the correct
profile, finishing with a very fine sandpaper.

Finally, I'll check the balance of the prop before finishing, and adjust
balance by either a little more sanding on the heavy blade or an extra coat
or two of urethane on the light blade.

What steps have I missed, and are there any fine points I'm missing?

Thanks in advance,

Kyle

[Gerry Caron]

"Kyle Boatright" > wrote in message
. ..
> I've noticed that my prop is beginning to show signs of wear -chips in the
> leading edge, and cracks in the clear finish. Given that I'm having
> shoulder surgery in a couple of weeks (and probably won't be up to flying
> until the arm is substantially healed), I should have some time on my
> hands to refinish the prop.

Don't know what brand of prop you have, but the manufacturer should have
some guidance available. Sensenich provides the following:
http://www.sensenichprop.com/sen_html/aircraft_cet/install/cf-a.pdf

> My plan is to remove the existing finish by sanding with ~220 grit
> sandpaper, then to use epoxy (with cabosil?) to fill any dents, etc, and
> sand/scrape the repaired areas back to the appropriate profile. Also, I
> plan on doing some repair work to the leading edge which is an epoxy based
> product. On the leading edge, I'll probably grind into any damaged areas,
> then fill with one of the putty type epoxies and sand/scrape to the
> correct profile, finishing with a very fine sandpaper.
>
> Finally, I'll check the balance of the prop before finishing, and adjust
> balance by either a little more sanding on the heavy blade or an extra
> coat or two of urethane on the light blade.

On the Sensenich web site "repair info" page, it states that they repair
props IAW AC43.13-1B, so you might check it out (under wood repair and
finishing.) Also they Care and Feeding doc (above link) says that they use
spar varnish for the finish.

Gerry

[[email protected]]

On Jul 30, 6:47 pm, "Kyle Boatright" > wrote:

Hey, Kyle...

Don't laugh, but give JB Weld a try :-)

Yeah, I know... hell of a ding. Big enough so that we're talking real
divots here. The patch had to have some serious structural strength.
Used a dental pick to create a key, added the JB Weld in three
applications, about twenty minutes apart, coarsely finished with a
rasp between layers 1-2 & 2-3. Let it cure about a week.

Use the water trick to make sure you've got the contour right. (ie,
arrange the thing so a flow of water across the divot catches the
light, tells you when there's no difference in contour between the
original surface and the divot. Use a sponge. W&D paper on a
stick.) All cleaned up (your FINGERS are more accurate than your
eyes), you can return the balance to near-zero by tapping lead foil
into a drilling on the tip, to zero-zero with PAINT when you blacken
the back-side.

I'm sorry to hear about the arm but damn happy to know it isn't
catching :-)

-Bob

[Copperhead144]

On Jul 31, 9:19*am, " > wrote:
> On Jul 30, 6:47 pm, "Kyle Boatright" > wrote:
>
> Hey, Kyle...
>
> Don't laugh, but give JB Weld a try :-)
>
> Yeah, I know... hell of a ding. *Big enough so that we're talking real
> divots here. *The patch had to have some serious structural strength.
> Used a dental pick to create a key, added the JB Weld in three
> applications, about twenty minutes apart, coarsely finished with a
> rasp between layers 1-2 & 2-3. *Let it cure about a week.
>
> Use the water trick to make sure you've got the contour right. *(ie,
> arrange the thing so a flow of water across the divot catches the
> light, tells you when there's no *difference in contour between the
> original surface and the divot. *Use a sponge. *W&D paper on a
> stick.) *All cleaned up (your FINGERS are more accurate than your
> eyes), you can return the balance to near-zero by tapping lead foil
> into a drilling on the tip, to zero-zero with PAINT when you blacken
> the back-side.
>
> I'm sorry to hear about the arm but damn happy to know it isn't
> catching :-)
>
> -Bob

I don't know what part of the countryyou live in Kyle but if you were
close to TN I'd make a trip to your homebase and help out just to pull
a mold off half of your prop. :-).FWIW don't rule out having a local
E.A.A. chapter member that's into prop building hellping you out in
exchange for the opputunity to make a duplicate of your prop.

Joe

[Kyle Boatright]

>"Copperhead144" > wrote in message
...
>On Jul 31, 9:19 am, " > wrote:
> On Jul 30, 6:47 pm, "Kyle Boatright" > wrote:
>
>> Hey, Kyle...
>>
>> Don't laugh, but give JB Weld a try :-)
>>
>> Yeah, I know... hell of a ding. Big enough so that we're talking real
>> divots here. The patch had to have some serious structural strength.
>> Used a dental pick to create a key, added the JB Weld in three
>> applications, about twenty minutes apart, coarsely finished with a
>> rasp between layers 1-2 & 2-3. Let it cure about a week.
>>
>> Use the water trick to make sure you've got the contour right. (ie,
>> arrange the thing so a flow of water across the divot catches the
>> light, tells you when there's no difference in contour between the
>> original surface and the divot. Use a sponge. W&D paper on a
>> stick.) All cleaned up (your FINGERS are more accurate than your
>> eyes), you can return the balance to near-zero by tapping lead foil
>> into a drilling on the tip, to zero-zero with PAINT when you blacken
>> the back-side.
>>
>> I'm sorry to hear about the arm but damn happy to know it isn't
>> catching :-)
>>
>> -Bob
>
>I don't know what part of the countryyou live in Kyle but if you were
>close to TN I'd make a trip to your homebase and help out just to pull
>a mold off half of your prop. :-).FWIW don't rule out having a local
>E.A.A. chapter member that's into prop building hellping you out in
>exchange for the opputunity to make a duplicate of your prop.
>
>Joe

I'm based at VPC - Cartersville, GA, which is about 30 miles NW of
Hartsfield Jackson. I live right off I-75 in Marietta, just outside the
perimeter highway for Atlanta...

If you're still interested in making a mold, drop me a line. By the way,
what does one do with a prop mold?

KB

[[email protected]]

On Jul 30, 6:47*pm, "Kyle Boatright" > wrote:
(snip)
> What steps have I missed, and are there any fine points I'm missing?

Kyle ..........

Shoulder surgery, hmmm. . . I remember three months after mine I was
finally able to lift my arm enough to wash underneath without using a
stick. Good luck on the sanding!

I used an electric random orbiltal on my Sterba prop and was surprised
at the irregularities in the surface. I just kept at it until all the
original varnish was gone and the last dip was sanded smooth, then
finished up to a 320 grit. I figured that all that sanding might
either improve the efficiency or thin the airfoil enough to increase
the rpm a bit. Neither one happened - I couldn't tell a bit of
difference.

The leading edge on a Sterba prop is made from a softer urethane
material that resists dings and it didn't need repair. Some tips on
wood prop maintenance are available here: http://www.greatplainsas.com/edmtce.html

When I was satisfied with the quality of the spray can urethane
finish, I made a steel "spud" that fit the center hole. I constructed
a wood jig in the shape of a "U", cut two grooves in the top edges and
inserted two extra blades from my jointer. Then I could lay the prop
in the jig with the spud resting on the sharp edge of the jointer
blades. One extra coat on one blade of the prop and it balanced.

Rich S.

[Copperhead144]

On Jul 31, 5:40*pm, "Kyle Boatright" > wrote:
> >"Copperhead144" > wrote in message
> ....
> >On Jul 31, 9:19 am, " > wrote:
> > On Jul 30, 6:47 pm, "Kyle Boatright" > wrote:
>
> >> Hey, Kyle...
>
> >> Don't laugh, but give JB Weld a try :-)
>
> >> Yeah, I know... hell of a ding. Big enough so that we're talking real
> >> divots here. The patch had to have some serious structural strength.
> >> Used a dental pick to create a key, added the JB Weld in three
> >> applications, about twenty minutes apart, coarsely finished with a
> >> rasp between layers 1-2 & 2-3. Let it cure about a week.
>
> >> Use the water trick to make sure you've got the contour right. (ie,
> >> arrange the thing so a flow of water across the divot catches the
> >> light, tells you when there's no difference in contour between the
> >> original surface and the divot. Use a sponge. W&D paper on a
> >> stick.) All cleaned up (your FINGERS are more accurate than your
> >> eyes), you can return the balance to near-zero by tapping lead foil
> >> into a drilling on the tip, to zero-zero with PAINT when you blacken
> >> the back-side.
>
> >> I'm sorry to hear about the arm but damn happy to know it isn't
> >> catching :-)
>
> >> -Bob
>
> >I don't know what part of the countryyou live in Kyle but if you were
> >close to TN I'd make a trip to your homebase and help out just to pull
> >a mold off half of your prop. :-).FWIW don't rule out having a local
> >E.A.A. chapter member that's into prop building hellping you out in
> >exchange for the opputunity to make a duplicate of your prop.
>
> >Joe
>
> I'm based at VPC - Cartersville, GA, which is about 30 miles NW of
> Hartsfield Jackson. *I live right off I-75 in Marietta, just outside the
> perimeter highway for Atlanta...
>
> If you're still interested in making a mold, drop me a line. *By the way,
> what does one do with a prop mold?
>
> KB- Hide quoted text -
>
> - Show quoted text -

Hmmm! Your about a three hour drive from my location, let me check my
schedule and I'll get an e-mail to you. Now, with regard's to a mold
of the prop, you use the split mold to cast a copy of the mold, smooth
it up if necessary and then use it as a master in a propeller
duplicator. Or at least I hope so any way, I'm researching the heck
out of prop building and mapping out plans for a propeller duplicator.
Blame it all on Bob Hoover, he's got me believing I can do the
impossible. :-). It's nice when people encourage you to try new things
and reachout a bit further isn't it?

Joe

[dpilot]

On Jul 31, 10:19 am, " > wrote:
> On Jul 30, 6:47 pm, "Kyle Boatright" > wrote:
>
> Hey, Kyle...
>
> Don't laugh, but give JB Weld a try :-)
>
> Yeah, I know... hell of a ding. Big enough so that we're talking real
> divots here. The patch had to have some serious structural strength.
> Used a dental pick to create a key, added the JB Weld in three
> applications, about twenty minutes apart, coarsely finished with a
> rasp between layers 1-2 & 2-3. Let it cure about a week.
>
> Use the water trick to make sure you've got the contour right. (ie,
> arrange the thing so a flow of water across the divot catches the
> light, tells you when there's no difference in contour between the
> original surface and the divot. Use a sponge. W&D paper on a
> stick.) All cleaned up (your FINGERS are more accurate than your
> eyes), you can return the balance to near-zero by tapping lead foil
> into a drilling on the tip, to zero-zero with PAINT when you blacken
> the back-side.
>
> I'm sorry to hear about the arm but damn happy to know it isn't
> catching :-)
>
> -Bob

Just a nit to pick on here.
The "back" side of a prop is the side the pilot cannot see
The "front" side of a prop is the side that you should "blacken"

JimV.

[Stealth Pilot[_2_]]

On Sat, 9 Aug 2008 21:08:23 -0700 (PDT), dpilot >
wrote:

>On Jul 31, 10:19 am, " > wrote:
>> On Jul 30, 6:47 pm, "Kyle Boatright" > wrote:
>>
>> Hey, Kyle...
>>
>> Don't laugh, but give JB Weld a try :-)
>>
>> Yeah, I know... hell of a ding. Big enough so that we're talking real
>> divots here. The patch had to have some serious structural strength.
>> Used a dental pick to create a key, added the JB Weld in three
>> applications, about twenty minutes apart, coarsely finished with a
>> rasp between layers 1-2 & 2-3. Let it cure about a week.
>>
>> Use the water trick to make sure you've got the contour right. (ie,
>> arrange the thing so a flow of water across the divot catches the
>> light, tells you when there's no difference in contour between the
>> original surface and the divot. Use a sponge. W&D paper on a
>> stick.) All cleaned up (your FINGERS are more accurate than your
>> eyes), you can return the balance to near-zero by tapping lead foil
>> into a drilling on the tip, to zero-zero with PAINT when you blacken
>> the back-side.
>>
>> I'm sorry to hear about the arm but damn happy to know it isn't
>> catching :-)
>>
>> -Bob
>
>Just a nit to pick on here.
>The "back" side of a prop is the side the pilot cannot see
>The "front" side of a prop is the side that you should "blacken"
>
>JimV.
>
only on a pusher....

[Ron Wanttaja]

On Sun, 10 Aug 2008 20:27:24 +0800, Stealth Pilot
> wrote:

> >Just a nit to pick on here.
> >The "back" side of a prop is the side the pilot cannot see
> >The "front" side of a prop is the side that you should "blacken"
> >
> only on a pusher....

Jim should have used "Face" instead of "Front," but the "Back" side of the blade
is indeed the side the pilot cannot see. Think relative wind. When the engine
is turning the prop on a tractor engine, the side the pilot CAN see is the side
that is impacted by the oncoming air. Only when the engine is windmilling does
the relative wind hit the side of the blade seen from in front.

This is a boat site, but it illustrates the issue:

http://www.propline.com/Propeller-General-Information/Propeller_Terminology.htm

Ron Wanttaja