markus76 said:
I'd tend to agree other than the fact that a negative is easy to produce from an existing waveguide prototype and duplicate the exact internal surface.... that's how the record industry does it...
There seem to be metal horns around, I've seen many in concert halls, etc. What metal do they use? We've already discussed a thin metal shell backed up with a simple cast material to eliminate the surface/dimensional problems, and any tendency to ring/resonate. If the polymer horns are hard plastic, what keeps them non resonant? Anyone measure their period?
As I said, it's just another option if someone wanted to pursue it.
Processes around signal processing, amplifier circuits, high voltage electrostatic speakers, etc. don't seem to be beyond the reach of your average DIY'er, judging from some of the topics I've seen... and some of them have steep learning curves...
cheers,
John L.
ok john, ill bite.
if you have an existing waveguide, why not buy two and save yourself the hassle? 😕
I should have been clearer and stated that I was approaching the problem from a "here is the equation for the waveguide profile, produce a pair of waveguides!"
So, how to produce the prototype or mandrel without an existing example?
see you know lots, I just ask silly questions in a bad way.
Nick.
PS: love the garage.
if you have an existing waveguide, why not buy two and save yourself the hassle? 😕
I should have been clearer and stated that I was approaching the problem from a "here is the equation for the waveguide profile, produce a pair of waveguides!"
So, how to produce the prototype or mandrel without an existing example?
see you know lots, I just ask silly questions in a bad way.
Nick.
PS: love the garage.
Somewhere I have seen a guy make horn with a templet mounted on a spindle forming plaster into horns
In case of only making the inner form fore casting makes it a lot easier
Plaster can be sanded and corrected with filler
The plug should be painted and waxed before casting
Ideal fore FOAM casting in a box like I showed earlier
In case of only making the inner form fore casting makes it a lot easier
Plaster can be sanded and corrected with filler
The plug should be painted and waxed before casting
Ideal fore FOAM casting in a box like I showed earlier
Attachments
tinitus said:
Yep.. I've got a potter's wheel, kiln, etc... and plenty of clay. I might just go that route since clay is cheap (I can dig it out of my yard) and easily metallized.
John L.
With plaster or clay you could even "build" an elliptical plug
Fore accurate throat use a center stick mounted on the bottom plate
If foam cast in a box, the center stick would steer in the middle throat-hole of box
Seems some compression driver may be mounted without mounting plate, some not
Fore accurate throat use a center stick mounted on the bottom plate
If foam cast in a box, the center stick would steer in the middle throat-hole of box
Seems some compression driver may be mounted without mounting plate, some not
Fore better toughness the plaster plug could be given a couple of layers of glassfiber and topcoat
It could then be used fore casting glassfiber waveguides as well😉
Thinking about the shape of an elliptical OS waveguide...wonder if anyone has the tools fore making a CAD drawing, just to get an idea about how the elliptical OS shape would look like, but I guess that when the transistion get into elliptical the sides gets more curved
It could then be used fore casting glassfiber waveguides as well😉
Thinking about the shape of an elliptical OS waveguide...wonder if anyone has the tools fore making a CAD drawing, just to get an idea about how the elliptical OS shape would look like, but I guess that when the transistion get into elliptical the sides gets more curved
Dumb question.
Could a manufacturer of plastic bowls, or those old 'Big Ear' dishes, possibly have the right gear to make these waveguides affordably?
Could a manufacturer of plastic bowls, or those old 'Big Ear' dishes, possibly have the right gear to make these waveguides affordably?
I'm came across this thread little while ago. Had tried a waveguide loaded dome tweeter, as per Zaph. Figured what the hell, tried to build my own for sh*ts and giggles.
I utilized the data/spreadsheets in this thread and this is what I came up with on a test piece. I've never casted anything before, and it shows quite readily, the piece is full of flaws, but I did have the bulk of the tools and materials on hand, so I gave it a shot. It was cast with care, but not precision. I wasn't particularly confident that it would even get this far, so "good enough" in making the mold was acceptable to me as I didn't feel like going all out if it were only to end in disaster. So, anyhow, I'm just posting to show my mistakes more than anything else. The process is straightforward enough, but accuracy is quite the b*tch.
I spent hours over the course of two weeks building the mold. Hour here, two there, not sure how many in total, but it adds up and is quite significant. In retrospect, knowing that I could pull it off, I would have put a lot more effort into it, because, as a proof of concept, it was way too much effort.
So, here are a few pics, flaws and all - mostly flaws. And it is mostly flaws. Numerous aspects are off by 1-2 millimeters. I used way too much mold release - one fear was it sticking to the mold - I used so much that it beaded (not obvious at the time, byproduct of the pour) and consequently that pitted the casting. Another fear was the polyurethane gelling before the pour was complete, and as a result, at one part near the mouth, the consequence of an incomplete mix is readily apparent.
I utilized the data/spreadsheets in this thread and this is what I came up with on a test piece. I've never casted anything before, and it shows quite readily, the piece is full of flaws, but I did have the bulk of the tools and materials on hand, so I gave it a shot. It was cast with care, but not precision. I wasn't particularly confident that it would even get this far, so "good enough" in making the mold was acceptable to me as I didn't feel like going all out if it were only to end in disaster. So, anyhow, I'm just posting to show my mistakes more than anything else. The process is straightforward enough, but accuracy is quite the b*tch.
I spent hours over the course of two weeks building the mold. Hour here, two there, not sure how many in total, but it adds up and is quite significant. In retrospect, knowing that I could pull it off, I would have put a lot more effort into it, because, as a proof of concept, it was way too much effort.
So, here are a few pics, flaws and all - mostly flaws. And it is mostly flaws. Numerous aspects are off by 1-2 millimeters. I used way too much mold release - one fear was it sticking to the mold - I used so much that it beaded (not obvious at the time, byproduct of the pour) and consequently that pitted the casting. Another fear was the polyurethane gelling before the pour was complete, and as a result, at one part near the mouth, the consequence of an incomplete mix is readily apparent.
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An externally hosted image should be here but it was not working when we last tested it.
Very good start - all the usual problems.
Is this a two part mold? How did you get the walls so thin (too thin IMO, I would make them thicker). And how did you make the mold? Could you post pictures of the mold?
Clearly you are proving what I have been saying from the begining, that casting in poly is the best way that I have found to do this, but even then its far from easy.
Great job!
Is this a two part mold? How did you get the walls so thin (too thin IMO, I would make them thicker). And how did you make the mold? Could you post pictures of the mold?
Clearly you are proving what I have been saying from the begining, that casting in poly is the best way that I have found to do this, but even then its far from easy.
Great job!
There is some interesting information on this thread:
http://www.aespeakers.com/phpbb2/viewtopic.php?f=3&t=1700
... using a 12" or 15" spun aluminum cone backed by two component polyurethane foam mounted into a woofer basket. Tricky!
http://www.aespeakers.com/phpbb2/viewtopic.php?f=3&t=1700
... using a 12" or 15" spun aluminum cone backed by two component polyurethane foam mounted into a woofer basket. Tricky!
I've been following this thread for some time,still can't understand why everyone wants to go to so much trouble to make a round horn(oops,sorry),waveguide without using a lathe...that's what they are for.
If you want metal patterns,seems to me it doesn't get any simpler than spinning them.
http://www.youtube.com/watch?v=Gwrk0SwDJhI&NR=1
If you want metal patterns,seems to me it doesn't get any simpler than spinning them.
http://www.youtube.com/watch?v=Gwrk0SwDJhI&NR=1
As a first step this is quite attractive - certainly more so that electro-plating, but there are still several steps left to go to get a functional device.
whas up with that?
So I guess metal is OKAY after all?
What is your beef with electroforming anyway? Yes, you need an initial mandrel, but that's true for any other technique as well. It's no more difficult or costly than buying a metal lathe for spinning and all its associated tooling, or pouring nasty resin mixes into expensive casting moulds. Certainly easier and less costly than building a tube amp from scratch, as many here in the DIY forum seem enamored with.
Unless, of course, it's the fact that it's capable of producing an EXACT copy of the INSIDE SURFACE of most any horn already in existance (oops, waveguide), including yours, which metal spinning can't do without a mandrel. That must be it. Stepping on IP I guess. Too bad... naivete and ego reign supreme
John L
gedlee said:
So I guess metal is OKAY after all?
What is your beef with electroforming anyway? Yes, you need an initial mandrel, but that's true for any other technique as well. It's no more difficult or costly than buying a metal lathe for spinning and all its associated tooling, or pouring nasty resin mixes into expensive casting moulds. Certainly easier and less costly than building a tube amp from scratch, as many here in the DIY forum seem enamored with.
Unless, of course, it's the fact that it's capable of producing an EXACT copy of the INSIDE SURFACE of most any horn already in existance (oops, waveguide), including yours, which metal spinning can't do without a mandrel. That must be it. Stepping on IP I guess. Too bad... naivete and ego reign supreme
John L
tinitus,
I was going to pm you...er, duh...I'll have to ask you to pm me. I would like to discuss an idea with you.
TIA
I was going to pm you...er, duh...I'll have to ask you to pm me. I would like to discuss an idea with you.
TIA
If made my WGs by cnc 3d milling.
Of course they are not so big as the WG I have seen here. (for ATC 3" combined with 1" Seas dome - Front ist 400 x 320 x 80.
The costs are not very much. But i think for the big WGs is better to do a form, perhaps out of aluminium and than per vacuum deep-drawing (hope this is the correct word in english).
To get the 3D model of the WG its the easiest way to to a 3D measurement. The costs are not sooo much.
But there are much other ways to get a good result. The first thing is, that anybody need/wants this WGs.
I would like to have some.
greetings
schauki
P.S. @gedlee if sent mail
Of course they are not so big as the WG I have seen here. (for ATC 3" combined with 1" Seas dome - Front ist 400 x 320 x 80.
The costs are not very much. But i think for the big WGs is better to do a form, perhaps out of aluminium and than per vacuum deep-drawing (hope this is the correct word in english).
To get the 3D model of the WG its the easiest way to to a 3D measurement. The costs are not sooo much.
But there are much other ways to get a good result. The first thing is, that anybody need/wants this WGs.
I would like to have some.
greetings
schauki
P.S. @gedlee if sent mail