Hood Construction Advice

[SkiFletch]

Hey all, been wanting to work on making my own hood for a while now and I'm ready to start the undertaking . I'm not a stranger to woodworking and since part of my job includes working in a machine shop I have access to all the appropriate power tools you could imagine . However I have three concerns here stemming from the fact that this hood will be over the top of a large portion of heated saltwater

The first is, what should I use as far as timber goes to survive these harsh conditions. Plain wood or treated? Soft or hard? I was thinking about just using some plain untreated 1x6 pine and sealing it up with varnish? Would this work?

The second question, is the hinge. What sort of material should I be using as a hinge? I'm a little worried about selecting something thats going to corrode and rust away under the salty conditions. I was thinking either brass or stainless steel would be my only real choices for hinges, and I'm worried about brass for its high copper content. What do you guys think I should use?

And last but certainly not least, sealing and swelling in the hood. Should I calculate dimensions with some amount of swell in mind or will this be negligable despite the increased humidity? I'm planning on cutting all edges (except the bottom) with a 45 angle and wood gluing them together. Then a slight rabbit around the inner rim of the hood to fit the outer rim of the tank along with posts at the corners for extra support. The whole thing will be varnished multiple times for a seal and a bead of silicone run along the inner seams. Will that be enough waterproofing and strengthening? Or will I need screws or brackets to support the glued seams?

Thanks in advance for the advice, Rather do this right the first time

 

[jelwyoming]

Good questions! I am about to start the same project and was wondering some of the same things.
One thing that I have seen as I have been searching this out, is that alot of people use slide out panels in the front instead of a hinged access. I would think that the swelling issue would make that somewhat of a problem.
I am also wondering if any offset should be put in behind the reflectors and the panel above it? 400w MH's get pretty hot and Image that the panel would also.

 

[jstraka1]

I would use a frame and panel construction and use regular lumber, the chemicals they treat the wood with might be bad for the tank. Finish it with any stain you like outside, paint the inside white, and top coat with helmsman spar urethane.

Definateley use real/solid stainless steel hinges.

The glued seams wont be very strong because you are gluing end grain to endgrain, so I would use some kind of fastener or joint, for example... pocket holes, biscits, mortise and tennon, dovetails, wood screws, to name a few.

And definately account for swelling, in fact I would suggest letting the wood sit near your tank for a while before construction, that might acclimate it a little to reduce swelling. I would think 1/16" oversized around the rim would be fine.

Hope this helps.

 

[SkiFletch]

It does a lot jstraka1, thanks . Glue wont be enough on its own huh? Even though its not supporting much weight? I'm pretty skilled with both biscuits and mortise and tennon, but not dovetails (just never tried it). Wood screws, meh I'd like to keep the edges clean looking. Maybe smaller staples like my stand but definitely not wood screws or nails. Anyway, thanks for the advice, anybody else have some input?

 

[ReeferMac]

I would definintely go for a joint of some kind (ok, that does sound a little weird out of context, but you know what I mean ). Whatever fastener type you use _should_ be fine (ultimately, you're going to cover it somehow), however I wouldn't rely on just glue. Some kind of joinery should be used, especially if you've got a fancy router + table + jig. Hell, I kill for an excuse to break mine out.
I refinished one hood using epoxy paint, and have been in love with it. I'd really recommend something along those lines, as the Eurathane projects I've finished that have come into contact w/ my tanks have all started deteriorating at some point/in some way. Even my drill couldn't touch that epoxy once it was cured.... Dulled 2 bit's trying to add a hole I forgot to put in prior to sealing.

- Mac

 

[jstraka1]

Glue alone makes a very strong joint on long grain, but end grain it does not. Since you have access to a biscit joiner, then I would use them along with the mitre joints and glue.

 

[zanclus]

I Built a frame then sheeted it with a nice furniture grade Birch ply. Painted the inside with a few coats of white latex and stained the outside to the color of my choice and finshed it with a few coats of poly. For my hinges i used stainless steel cabinet hinges and if they show signs of corrosion I can easily replace them.