No wait all hot melt approach
I segmented the back and hot melt glued in sections before glue hardens. Having two hot melt guns and four hands would make this easier as I had to lay down the bead of hot melt furiously fast. It is fast and no wait but there is no room for error. Here is one panel glued on the back. I made the portion that covers the speaker chamber circular to ensure a good seal. One of the Son of Cornucopya is now done. This may not work so well for larger ones as you would really need to segment a lot. An alternative is to use 5 minute epoxy as that would be more forgiving than the 30 seconds one has with hot melt.
I segmented the back and hot melt glued in sections before glue hardens. Having two hot melt guns and four hands would make this easier as I had to lay down the bead of hot melt furiously fast. It is fast and no wait but there is no room for error. Here is one panel glued on the back. I made the portion that covers the speaker chamber circular to ensure a good seal. One of the Son of Cornucopya is now done. This may not work so well for larger ones as you would really need to segment a lot. An alternative is to use 5 minute epoxy as that would be more forgiving than the 30 seconds one has with hot melt.
Attachments
Leave the back plain - there is little reason to dress something up that will only be on the wall.
Whatever SWMBO wants for the trim. Easy answer?
Where will binding posts go? I think trim only goes on front like picture frame. If you slightly angled trim outwards you will get additional horn expansion to direct sound forward and louder. Mucho mas basso senor...
So I got a bunch of stuff today!
Front and back panels, 1/4" baltic birch. Chosen mainly for aesthetic purposes. A quick coat of polyurethane and they should look like a millon bucks.
A bunch of sheets of foamcore from the Dollar Store. Some black, some white. Golly, this stuff is cheap. The backing paper is basically a child's construction paper. The foam fine. Yes, it will be easy to shape, and strong enough at the horn's origin because there will be so much of it.
A sheet of 'nice' foamcore. From the graphics store, it has backing paper that is essentially poster-board, with the foam center. Much sturdier, much smoother, I am planning on using it for the parts of the throat that shows.
The rolled up paper is the scaleable .pdf that Dave made. It's scaled to have the outside of the horn at 30", as that is the dimension of the birch ply.
A new knife.
The large piece of lumber is a very straight bit of oak that was in the cut-off bin at the lumberyard. It will be by gauge and cutting edge for the foamcore.
That's one of the ones I was talking about. The ferrite version is very heavy. I would feel a plywood face necessary for that version.
QC. The foreman is coming home from work right now. She is actually interested in the project!
Yes, the wood is going to be a bit more attractive than the underlayment, but I wasn't turned off by that, I figured a quick bit of paint would have fixed it. However, I like the birch better.
The question in my mind is if the glued edges of the spiral will be able to support the weight of the birch front and the driver. It might be no problem at all, but at this point it's unknown. (There is quite a bit of glue area...) Somebody thought some dowels towards the terminus of the throat would be a good idea for resonance control or reinforcement. I will look into it if there is an issue of strength.
The driver is the Planet-10 FF125wKeN --
Cool looking, eh?
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Ooh! That's a great idea! I never thought about that part, other than using through bolts and fender washers on the back. The tube is a great idea.
The dowels I'm envisioning near the end of the horns... to brace where the outer panels are furthest from the foamcore.
I have been collecting the corrugated plastic spindles from cash receipt printers (Dalis the girl at the post office does the actual collecting). Some of them are long enuff to be perfect for this.
dave
You can order them and have it in a few days. I have ordered boxes from this company before. They seem to have a wide variety of sizes at a reasonable price.
Foam Board, Foam Core in Stock - ULINE
Foam Board, Foam Core in Stock - ULINE
Ferrules, I never though of that. Pretty dumb for a guy in the roofing business, no?
