Question for the CNC folks

[KromeDome]

Greetings to all,

First things first...thanks to all of you for a fantastic forum! I have been lurking and studying for a year or so now, and maybe I'll post a little blurb soon to introduce myself.

I have been tossing around a lot of ideas for my winter home theater project, which will include a 5.1 arrangement utilizing JBL compression drivers and ring radiators. I have been pouring over many threads that have discussed wooden horns, and zeroed in on John W's wonderfully crafted walnut expression of the H9800 and 076. What I would like to know is if anyone here has digitized and/or CNC'd the bells/phase plugs of a 076 or 077? Originally, I wanted either to veneer the faces of a couple of 076s or 077s (and turn out walnut phase plugs of the 077 to match), however the prices on these have been crazy as you all are aware.

I have several 2402 motors here that I plan to use as donors, but I need to find someone who can supply the rest. I am fairly certain that I can find a local shop to do the machining, but they will need a 3D Autocad file, correct? It is a long way down the road, but I would like to have as many ducks in a row as I can early on.

Your comments and suggestions are most appreciated.

[SMKSoundPro]

First of all, welcome to the forum!

I, too, have been considering making some 2405 phasing plugs out of something other than acrylic or aluminum.

My friend, the admiral, and I have been vexing on this adventure to make some different colored phasing plugs and are yet to come up with a jig to start the process.

Is anyone else interested in different color slot phasing plugs? or even in different wooden species?


Please add your thoughts. This could be fun!

Scott.

[Allanvh5150]

Hi Guys,
I have been doing CNC programing and maching for years and if you want some 2402 horns and phase plugs made, all you need do is supply the originals to a firm with a copy lathe. it will be very cheap as well.

[KromeDome]

Hi Guys,
I have been doing CNC programing and maching for years and if you want some 2402 horns and phase plugs made, all you need do is supply the originals to a firm with a copy lathe. it will be very cheap as well.

Thank you for the response, Allan. Actually, I am interested in duplicating the externals of the 076 and/or the 077 in wood with a minimum of hand carving or shaping needed. You can sure help by telling me what type of digital files are needed for the CNC machine. I confess, I have not done a great deal of research on this yet. What little I have come up so far tells me that the 3D digitizing will cost around $1000. I think it will be a fun winter project, so I plan to be diligent yet relaxed about it. I am finding that I have become more interested in the technology than I am in the result, as cool as these horns will be....

[John W]

I've been really happy with small horns on the 2407h drivers. I made these the same diameter as the 07*s so they mount on existing baffles.

http://audioheritage.org/vbulletin/s...63&postcount=2

Machining something like this with a screw on mount would be another worthy project. Fewer parts too.

[Mr. Widget]

Actually, I am interested in duplicating the externals of the 076 and/or the 077 in wood with a minimum of hand carving or shaping needed.

While a copy lathe will work well for an 075, both the 077 and 076 have undercuts or negative draft. This is why both of these horns are assembled from part rather than simple castings... you will have the same issues in machining them from wood. You could of course machine them in pieces as JBL made them and then assemble the wood pieces.

You can sure help by telling me what type of digital files are needed for the CNC machine.

Most CNC machines are programmed by secondary software such as Mastercam, Surfcam, or one of dozens of others... these programs typically accept any 3-D model that is exported in IGES, DXF, or one of several other translation formats. As long as your digital model is well built in Solidworks, Pro/E, AutoCad, or any other professional level modeling package you should be fine.


Widget

[KromeDome]

Thanks Mr. Widget, that makes sense now. I had assumed all this time that JBL had sandcast both of these bell designs in one piece to achieve the negative curves. And thanks for the CNC info. One last question for you if you don't mind: Have you had any experience with 3D scanning and digitizing any horns?

And John, I followed that thread when it first appeared. Lovely horns, and a great idea. The 2407H appears to be a nice unit, especially for the money. I may have a source for the some threaded inserts for future 1-3/8" couplings. I'll see what I can come up with.

Thanks again!

Brian