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Re: Wooden canopy.....
Sylvia asked:
"Are there any hard and fast rules on what wood to use or not use? A local
lumberyard suggested I use basswood, as they claim it's lighter even than
pine. I've never even heard of it."
"Also, are there any taboos on finishing type products (shellac,
polyurethanes, stains, etc.) that should not be used?"
"Any general tips, shortcuts, errors to be avoided, etc. would be
appreciated
as well."
I'm sure, given the nature of the list, that the following advice will
probably be contradicted, but here goes...... I've enjoyed woodworking as a
hobby since I was a kid and have built aquarium hoods and stands on several
occassions.
Make sure that the wood you use is kiln dried. In most lumber yards, this
will mean hardwood (i.e maple, oak, walnut, mahogany) as the common grades
and species of softwoods (ie. pine, spruce, cedar) are usually only air
dried. You _can_ buy kiln dried softwood, but you might have to go to
specialty lumber yard for it. Some dealers have started to stock specialty
woods for the do-it-yourself market that is kiln dried and surfaced on all 4
sides. Its more expensive, but its worth it. Avoid at all costs any lumber
which has been stored in an open shed or out of doors. The reasoning behind
all of this is that all wood contains moisture - kiln dried lumber that has
been stored properly will have minimal amounts of internal moisture. Air
dried and/or improperly stored lumber can have varying amounts of internal
moisture and as this moisture leaves the wood and it equilibriated with the
room conditions, the wood (and anything built from it) can warp and twist.
If you start with straight grained, knot free, kiln dried wood that has been
properly stored and then seal and finish it properly, your hood will stay in
one piece for years. (Home Depot should have the "specialty" woods I'm
talking about - that's where I buy mine).
Veneer core plywood is more stable dimensionally than solid wood. Again,
finding it can sometimes take a bit of looking. The absolute best plywood
that you can buy for a project like this is called "Baltic Birch". It is
imported into North America from Europe and is internally flawless (normal
plywood can have interior voids and faults which can affect performance
under some circumstances) and usually has a Birch or Maple face veneer which
is perfect for either a painted or clear surface finish. It should be
available from any good specialty lumber company which caters to
cabinetmakers (as opposed to carpenters or kitchen contractors). Each sheet
is 5' x 5' (regular plywood is sold in 4' x 8' sheets).
When you are selecting the pieces of wood for your project, make sure that
each is free from warp and twist. You want clear, straight lumber. Pay
attention to the way the grain runs and the way the wood was cut - wide
pieces of solid wood will have a tendancy to warp in the direction in which
it grew. This can sometimes be compensated for in the way you put the
project together.
Always pre-drill all holes and use stainless steel screws. Pay special
attention to the type of metal your screws are made from - especially if you
are building anything from Oak. The tannins in Oak can react with cheap
screws and cause them to deteriorate and stain the wood.
Use a yellow carpenter's glue (stay away from white glue, its not strong
enough, especially near moisture) and apply it properly. Use clamps (don't
overclamp) and/or hold things together with a combination of glue and
screws. Stay away from nails and staples.
The "traditional" clear finish for anything that is going to be exposed to
moisture is spar varnish but there are newer water based varnishes which
work perfectly for use in an aquarium hood. This sort of stuff should be
widely available anywhere (like Home Depot).
As to "tips" on what to avoid - try not to do this "on the cheap". It will
take the same amount of elbow grease to build something from cheap,
"construction grade" lumber as it will to build it from "cabinet grade"
lumber, but you will be happier longer if you start with good materials.
As for using Basswood in your project, that would depend upon how big its
going to be. Basswood is the lightest, softest and weakest of the native
American hardwoods. It is widely used for packing cases which will hold
food, and in beekeeping supplies and is often used for drafting tables. Kiln
dried Pine would be a stronger choice and is still very easy to work with.
Hardwoods such as Oak are a lot more trouble to work and I don't think I'd
recommend using Oak for a "first effort". Maple is strong and more difficult
to work than Pine as well. If you are close to a Home Depot you should be
able to see samples of all of them and pick what you like best.
It isn't nearly as difficult as you might think (to coin a phrase, "it
'ain't rocket science....") and can be very rewarding to build something
like a hood or a stand yourself.
Good luck.
James Purchase
Toronto