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mikem
03-09-2004, 12:06 AM
When I install home speaker systems in new houses, I put in some rough-in brackets (like picture frames made from 3/4" plywood)onto the rafters for the drywallers to find the right place to cut the drywall out. This works, usually, but sometimes the frames aren't up directly against the backside of the drywall and then the speaker mounting ears are too shallow to grip the combined thickness.

So as a fix to this problem, I have been thinking about using sheet metal rather than plywood. This would give me a lot more leeway on the thickness. But my question to you guys is how to make the frames from sheet metal. They would have about a 2" frame around a 7.5" by 10.75" opening. When they are cut out, I would bend a 90* lip around the outside edges with my brake to stiffen them up. I am thinking about stacking the sheets (maybe 16 sheets thick)of metal on my BP milling table and drilling the starting point and milling out the rest of the rectangular opening with an endmill.

What size of endmill would work? Anyone have a better idea?

J Thornton
03-09-2004, 03:13 AM
Mike
Why not make a jig and weld them using strips or angle?

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Jesse

Excitable Boy
03-09-2004, 04:16 AM
I am a manufacturer's rep in the home theater business and in my experience each inwall manufacturer uses a somewhat proprietary bracket. Save yourself a lot of grief and pick out the speakers you're going to buy and get the appropriate brackets.

Just my humble opinion.

John

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Pursue Excellence and the rest will follow.

Bill Cook
03-09-2004, 09:38 AM
That's a lot of milling under poor conditions.

*A* proper way would be to spotweld 4 pieces together.
With the use of stops, the parts can be pumped out at amazing speed.

A jig or locating features on the parts would speed up the spotwelding.

A notcher would round out the nessessary equipment.

For rust resistance use galvanealed(sp) or equivalent. It has zinc on it AND spotwelds well.

bc

Paul Alciatore
03-09-2004, 01:26 PM
If I am seeing this right, you are putting the frames between studs before the drywall in installed and they are behind it. The drywall guys then make a cutout to match your frame and you mount the speaker in the combined hole. The problem is there is sometimes extra space between the frame and the drywall.

Why couldn't you continue using the plywood brackets and just mount them with strips (1-2 inches wide) of sheet metal so they can be pulled against the drywall when mounting the speakers.

If you really want to use sheet metal, I would make four sides and pop rivet them into a rectanglar frame. Easier cutting and less waste. You need to drill or better yet, punch two holes in each corner for the rivets. The rest is just bending.

Paul A.

mikem
03-09-2004, 03:19 PM
Thanks to all for the replies. My favorite generic speaker doesn't have a rough-in frame available anymore and when they did, they were flimsy plastic and about $15 per pair.

The plywood frames take a lot of time to build, as well as being too thick sometimes. The strip idea with pop rivets is good--I will try to make one or two and see how it goes. thanks--mike.

debequem
03-09-2004, 07:34 PM
Okay, from my old speaker building days for rock and roll bands and studios...

You want the densest material you can get. Particle board is great. Concrete is better! Plywood sucks because the loose knots will rattle with the bass.

Sheet metal is worse yet since it will buzz. I have heard of cabinets built out of plate aluminum, but that is expensive.

If you do use sheet metal, try and put a soft gasket material on the metal so it won't buzz on the wall board. Glue is a great idea. Anything than makes things rigid will really improve the sound quality.

Marv