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Posted by Jeff on October 4, 2006, 11:51 am
 
schooner wrote:

Someone mentioned that the use it for street signs, after it has been
bonded. It'll be well sealed.

   I'm more concerned about making strong joints...

   Jeff

  If I were going with wood frame I


Posted by Morris Dovey on October 4, 2006, 12:24 pm
 
Jeff (in XeNUg.6758$o71.2570@newsread3.news.pas.earthlink.net) said:

| schooner wrote:
|| Does MDF stand up well for exterior use?
|
| Someone mentioned that the use it for street signs, after it has
| been bonded. It'll be well sealed.
|
|    I'm more concerned about making strong joints...

Strongly suggest you take time to ask about this in
news:rec.woodworking

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto



Posted by Solar Flare on October 5, 2006, 12:30 am
 Strong joints in MDF take biscuits  or long metal screws to effect.



Posted by Mike on October 4, 2006, 8:52 pm
 Hi Jeff


If MDF gets wet it swells up and looses all its strength ie. it will fall to
bits. Its not really designed for outdoor use.
But you can use it if thoughly sealed inside and out, condensation inside
the case will be a problem unless sealed.
I have used the 2 pack sealer on MDF that is exposed to water and it worked
ok, takes 3 coats allowing 4-8 hrs between each (depends on temperature).
But any fastenings attached to the case must also be sealed to prevent water
getting in around screw threads etc and softening the material.

I would tend to use an exterior or marine grade ply for the cases (costs
more though), it would still have to be protected against the elements, but
if some water gets in it wont be an issue.



Yes squashing around a metal rod in short lengths to create a groove works.
Aluminium comes in various grades of hardness, you will have to experiment
with some of the flashing material to see how difficuilt it is to bend. Thin
smear of heatsink paste and riveted every 4 inches should clamp it nicely.
You could use a small hydraulic bottle jack pushing down on the center of a
heavy piece of wood with the rod clamped to it, the flashing sits on a wood
base with a square channel made with 2 strips of hard wood. Crank the two
together and it will form a smooth even grove down the length of aluminium.



Generally lay 3 horizontal wooden rails across the roof (use exterior
treated timber) 4x2, one at each end and center of your case. The rails must
be securely bolted with long bolts to the underlying rafters. Depends on
what your roof is constructed of. Just make sure any roof penetrations are
well sealed with an exterior silicon.

The cases are screwed to the rails using small L brackets made from bent
galv strapping. Use 6 brackets for each case. galv or stainless 1/4" x 1.5 "
screws.
If you elect to mount the cases directly on the roof then possibly the roof
material will cut into your case breaking the paint seal, especially if you
have a tiled roof with rough sharp edges. The brackets and screws in this
case would have to be compatible with the roof (if metal) to prevent
corrosion caused by electrolysis.


Hard work is good for you !

Mike



(corflute)


Posted by schooner on October 4, 2006, 9:30 pm
 There may also be off gassing of the glues used in it as well when it gets
damp.



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