Model Forum / Radio Controlled / Air Models / September 2006

I have never used obeche or basswood...simpler to use spruce and pre
drill the servo screw holes with a 1/16 drill bit...no splitting in
many decades of r/c installations.... I use 3/8 square spruce...and
sometimes I cut strips of 1/4 inch five ply plywood and make servo
bearers out of that....all predrilled with 1/16 bit...never any
problems...no splitting..no pulling out of the wood...why do it the
hard way searching for obechi and basswood and other somewhat exotic
woods??
Frank

Boo Wrote:

Bass is not a 'flavor' of balsa, it's a completely different species.
Spruce, and perferrably Sitka Spruce, is considerably stronger tha
bass, and is the wood of choice for structural components.

Obechi is somewhere between bass and spruce in hardness, which makes i
suitable for sheeting.  OTOH sheeting with balsa and covering wit
epoxy/glass results in a less expensive and more durable skin.

Bass isn't really all that good for our sort of modeling because it'
more brittle and less tolerant of bending loads than spruce, an
because it's heavier than balsa.

I use plain old Red Oak for servo bearers.  It's not all that muc
heavier than spruce or bass, and it's a good deal harder and stronger.
The weight penalty for Red Oak mounts is negligible, and you can make
-lot- of mounts from a 1x12x48 Red Oak plank from The BORG.

I also use 'these
(http://www.microfasteners.com/catalog/products/TWSSHWHMS.cfm) serv
mounting screws.  The socket head makes it a lot easier to drive tha
standard servo mount screws.

You should be using a hard wood for servo bearers, not bass or spruce
although you can 'get away with' the softer woods.

You won't split any more bearers if you pre-drill the screw holes a
Frank pointed out

--
the-plumbe

There's nothing wrong with spruce, except that it's a bit slow to stick with
cyano. You should drill pilot holes in servo bears whatever they're made of,
I just hold the servo in place and drill through the centre of the mounting
hole with a small dremel type drill.

Greg

Bass is about as good as it gets for hard balsa replacement - its a fine
grained stiff and even wood. Makes great struts and spars.

Obeche is lighter and not as strong. I have used it on very small models
to make e.g. wing and tail outlines..its very fine grained and sandable,
and in fact I reckon that 3/32" obeche sanded well down weighs the same
a 1/8" hard balsa, and is more reliable and sands better.

Bass is a great, straight-grained wood and is commonly used for servo rails,
spars, etc. Of course, you should always drill pilot holes for servo screws.

Obechi is a pretty wood if clear-coated, and is most often used as a veneer
sheeting. It's biggest problem is the wavy grain it has -- it's horrible to
plane or carve. It's also quite light.

Someone else mentioned Spruce as being slow to accept CA glues; to fix this
just sprinkle some baking soda in the palm of your hand and run the strip
through the powder, just get a thin coating then wipe most of it off.

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