is simple, using what's called the "Three Tube" - Brass Tubing Method.
One Brass Tube fits into the other, like a telescoping Antenna. The size
of the tubing required, depends on what your model needs. I use 1/8" rod
for shaft, 3/32" tubing for sleeve bearing, and 5/32" tubing for
stuffing box and grease tube. For large models with props bigger than 2"
you should increase the size of the brass. If you already have props
then you will want to start with a shaft that fits the hole in the prop.
LEFT: parts to make a stuffing box.
RIGHT: stuffing box mounted in hull.
Since I build displacement hulls, I didn't need to buy
expensive props that would be hidden most of the time in a kort nozzle.
I decided to make my own and can make five props from a sheet of brass
that costs around $2.00.
If you have a graphics program you can use this pattern to
make your own props.
First I drew a pattern for a
left and right handed
prop, then I scale it
to the size I needed and print it out.
After I printed the
pattern, I used spray adhesive to stick it to a sheet of brass stock.
I trimmed the stock with tin snips as
close as possible. Then I used a Dremel Moto-tool with a fiberglass cut
off wheel to trim to the outline of the prop.
After I got the
patterns cut out, I took the moto-tool and "polished" the brass. Click
on the images and notice how it looks like real turned props on the
prototypes. I did this by holding the cutoff disk at an angle and going
from the center outward turning the prop a little with every horizontal
Since I build
displacement hulls instead of fast planning hulls, balance and pitch is
not all that important. I use 1/8" brass rod for my shaft and use a
punch to center the hole in the prop and drill it out. I then place the
rod in helping hands and get the alligator clamp level to where the prop
will sit level on it. Then I put paste on the area to be soldered, used
a soldering gun to get it hot and use rosin core solder to solder the
prop to the shaft. If you wipe the flux off while it's still warm it
comes off easier.
After the solder
cools, I use the moto-tool to "polish" the solder area and this is how
I finish that, I bend a pitch in the prop. The more pitch you have the
more thrust you have and more load on the motor. If you use a motor less
than 4000rpm or have it geared down, then a sharp pitch is alright. I
you run direct with motors above 5000rpm, then you shouldn't bend as
much pitch to it. As you see in the photo I use a square to get my angle
of each blade the same. Use a piece of 3/32" tubing in the clamps so the
shaft can be turned. Angle the helping hands slightly so the top blade
won't hit the square. Check the blades at the bottom and bend until all
four brush the square the same. I never balance my props because of the
low rpm, but if you want to try it, below is a home made setup River
BALANCING - The PROP & SHAFT
about a 4" length of scrap - block wood, and glue a pair of Single or
Double - Edge Razor Blades to each end of the block, as shown in this
drawing. Then lay your Drive Shafts & Props, across the balancer to
check them ( as shown in the bottom drawing ). The heavy shaft - side,
will roll to the bottom. That Indicates a need for weight to be removed,
so "Polish Off a small portion of "Solder" around the Prop - in the
heavy area, where the fluke is soldered to the bushing & shaft - itself,
to gain a better balance. Then rotate and recheck - balance again, to
insure its right and repeat until correctly balanced.
NOTE ... Be sure the
table your using to balance things, is also "LEVEL", before you use this
system, it can effect Shaft balancing.
And this balance system, is
not made to adjust "High Speed" props for Race Boats, but works on the
same principle - as theirs do!