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New Cornwall Midrange Horns


greg928gts

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Guest David H

How thick masonite? I don't think I've seen masonite thicker than 1/4", which of course does not mean it's not available. It looks like you're using 3/8" thick masonite.

I am using 1/8" masonite double laminated, I have not had any issues with gaps using the screws. The brad nails however don't agree well with the masonite and mdf. I had much better luck with the stapler.

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The brad nails however don't agree well with the masonite and mdf. I had much better luck with the stapler.

Masonite it very difficult to drive fasteners through.

I've been using the bendable lauan, and it's easy to work with, but the last sheet I got has tiny cracks in it, so the inside face wasn't as smooth as I'd have liked. By the time I got four coats of paint on it, the cracks had pretty much filled in, but still.

Are you pre-drilling for the screws? What type of glue are you using?

This last batch of horns that I built (Fc 260Hz, wooden horns) took 35 hours to complete. That's cutting the pieces, assembling, sanding to even out the edges, installing the rear motorboard braces, filling and sanding, filling and sanding, making the motorboards, and painting. Five pairs, so 7 hours per pair. Then there's time to pack them up. Material costs were around $400, including the packing materials, so $80 per pair. Of course there's no time in there for going to get the materials, cleaning up the shop, setting up and putting away the jigs, replacing the band saw blad that broke, etc... I've raised my price to $375 per pair packed up ready to ship.

Thanks for the info.

Greg

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Guest David H

I was predrilling, the discovered the 1/2" metal framing screws, that work very nicely. If you run them in reverse it will punch a hole through the masonite, the forward drives them in.

Glue, I have been using Titebond 2, but saw you using the Gorilla Glue, I gave that a shot on the last few paris of horns I built, and it works well. I may switch to that for good. I have used Gorilla many times in the past, and I like the way it fills and or eliminates voids. I also like that it crates a dampening material between the layers. Are you still sold on the gorilla, or are you on to something new?

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"""That's cutting the pieces, assembling, sanding to even out the edges, installing the rear motorboard braces, filling and sanding, filling and sanding, making the motorboards, and painting......... Then there's time to pack them up. ......... Of course there's no time in there for going to get the materials, cleaning up the shop, setting up and putting away the jigs, replacing the band saw blad that broke, etc......."""

Try doing all that while a pager keeps going off.......and have to walk away during critical steps....now that's a real pain.....

jc

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I was predrilling, the discovered the 1/2" metal framing screws, that work very nicely. If you run them in reverse it will punch a hole through the masonite, the forward drives them in.

Glue, I have been using Titebond 2, but saw you using the Gorilla Glue, I gave that a shot on the last few paris of horns I built, and it works well. I may switch to that for good. I have used Gorilla many times in the past, and I like the way it fills and or eliminates voids. I also like that it crates a dampening material between the layers. Are you still sold on the gorilla, or are you on to something new?

I wonder if smaller shank metal framing screws are available? There would be less chance of splitting the 3/4" plywood that way. The screws are only doing their job for a few hours.

I started using Gorilla Glue, but it was too messy, and the scrape out inside the horn was a PIA, so I switched to Titebond III, which I think is the same as II, but made for outdoor use (waterproof), which is probably not important, but it costs the same, so what the heck.

You are correct that the Gorilla Glue fill voids, but it does not offer bonding strength when there are voids. It's always necessary to have the pieces of wood tight together. This is why I was asking about screwing with so few screws.

Damping is good, especially between the two laminated layers.

Greg

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Guest David H

How thick masonite?

Greg, I made an error in an earlier post, I am using 1/8" masonite, very plyable, I have it double laminated.

As for the Gorilla glue, I especially like to use this between the laminations. At one point and time I used liquid nail, becuse it stays plyable, but again messy to work with. I have never used titebond 3, just #2. I also picked up a bottle of gorilla wood glue, and dont care for it becaue it dries white.

I would really like a thick wood glue to reduce running.

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I would really like a thick wood glue to reduce running.

Exactly! I've thought the same thing, especially when I'm putting 3/4" panels together to make bass bins. I want something with a little more body. When I built the Jamborees I used PL Polyurethane contruction adhesive, but man what a mess cleaning it up. A lot of work, but I really think it's part of the solidity of the cabinet. My Jamborees are rugged as heck, and that's partly due to the all 3/4" construction, lots of braces, and the glue I used. I think it's a small part of why those particular cabinets sound so good.

There's got to be a glue out there that is like Titebond II, but with more body. Probably commercially available. I wonder if we could mix liquid nails and wood glue together? Maybe I'll try that, and see if it has the same easy cleanup as the wood glue. Maybe there's a water-based liquid nails to mix with the wood glue, I bet that would clean up easily.

Greg

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How far out from the motorboard can the horns sit without interfering with the grills?

I don't have any grills for my Cornwalls. These are the ones I bought from an ad in the paper that said "mint condition" $400. So I went to see them and they had lots of woodwork issues, no grills, and Grateful Dead stickers on the motorboards. I talked the guy down to $250!

Anyway, I can't remember if the cloth is glued to the frames of the Cornwalls. I think it IS glued to the frame, but I wonder if one could turn the grills face down and gently pull the cloth away from the frame around where the horn holes are and keep it away from the frame with some wood blocks to make the cuts to the frame?

Greg

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cornwall 1 has zero space between grill and motorboard since the grill is wrapped around the motor board.

cornwall 2 ?

Cornwall 2.5?

Cornwall 3?

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Guest David H

How far out from the motorboard can the horns sit without interfering with the grills?

Not very far, I built these horns to go behind the motor board like the original.

Greg, yo umay be able to slip a piece of 1/8 hardboard through the woofer cutout and slide it upwards to protect the grill cloth and use a router on the back to cut the grill to accomodate the larger mid horn.

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I've still got my mind working on a way for the average person to be able to install a kit in their Cornwalls.

If the cloth can be pulled away, and wood slipped in between the cloth and the grill frame, could the grill frame be cut with a utility knife?

Whoever installs the kit in the motorboard is going to have to jigsaw out the hole, so I guess power tools are part of the equation no matter what. A circular saw or router to cut out the grill frame seems excessive, and probably beyond the abilities of most.

Greg

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