3d Printed / Poured Concrete enclosure concept

[Steve Lee]

Billet - Sand ^ would be excellent if it were tamped down on a vibrating surface and done in layers.

How about water?

If the speaker ever caught on fire it would be intrinsically safe, wouldn't it by putting its-self out?

[zx82net]

Lunchmoney,
I guess you probably know this, but just in case, there is no orientation that will print in well without supports on an FDM printer. You could avoid the use of supports by making the bottom plate a cap rather than an insert, and using a chamfer around the inside top surface to minimize bridging.

WRT filling. In case you are thinking about it as a material; I would advise against plaster of Paris, the working time is not great I found it a bit of a pain. I have heard that the heat from epoxy filler can soften prints as it cures, best avoided. Concrete setting is also an exothermic reaction, so it may be worth standing the print in a bucket of water while it is setting. Also, if you find filling doesn't work out, consider just dedicating a few kilos of plastic to it, and leave the walls solid. Longer to wait, but less work to do overall.

I know a few people here of the forum find this guy slightly abrasive, but I think this is a well researched and straight up video, which can be taken at face value:
https://youtu.be/n3wlmaENJio
(I realize concrete != wood but you get the idea.)

[lunchmoney]

Sand?

Holy cow wouldn't that be easy.... anyone else? Any thoughts on sand?!

[lunchmoney]

Lunchmoney,
I guess you probably know this, but just in case, there is no orientation that will print in well without supports on an FDM printer.

That's why I'm using a resin printer ;)

[zx82net]

Ah, cool.
Are you panning to leave it clear or paint it? Layering a couple of different colors of sand inside a clear resin could give you a very interesting effect.

[augerpro]

I always thought sand was worth looking into. I've used it in speaker stands and mic stands and it made them dead as a rock.

[tvrgeek]

Or plaster of Paris. Really, you might be overthinking this, but whatever. Cement being "high Q" so not sure it is really the best choice. But maybe combination with the very low Q plastic the result would be good.

Of course, you make doing a prototype harder. I suggest doing one out of MDF first as models are never quite right to verify your Vb and port size.

You have not taken as much advantage as you could with port radius.

If really trying for over the top, how about printing in an internal structure to hold the woofer magnet and then isolate it from the front panel? In the same token, several manufactures, SB among them, have been touting the advantage of isolating the tweeter. Seems to me installing it with a thick bead of RTV woudl work to that effect.

[lunchmoney]

Or plaster of Paris. Really, you might be overthinking this, but whatever. Cement being "high Q" so not sure it is really the best choice. But maybe combination with the very low Q plastic the result would be good.

Of course, you make doing a prototype harder. I suggest doing one out of MDF first as models are never quite right to verify your Vb and port size.

You have not taken as much advantage as you could with port radius.

If really trying for over the top, how about printing in an internal structure to hold the woofer magnet and then isolate it from the front panel? In the same token, several manufactures, SB among them, have been touting the advantage of isolating the tweeter. Seems to me installing it with a thick bead of RTV woudl work to that effect.

A 3d print is harder than an mdf enclosure? Not at all. Far less work. And if it needs tweaking I just print another one. I do 3D cad, printing, prototyping, etc professionally, so this is easy for me.

I can't imagine that flaring the ports further would make any meaningful difference. The small driver isn't moving that much air, and besides they'll be crossed to a sub at 80 hz.

Interesting idea for isolating the drivers, although I'm not looking to go over the top here. If I wanted to do a no-holds-barred design I wouldn't be going after a wall-mounted speaker, and it would be larger

[lunchmoney]

I always thought sand was worth looking into. I've used it in speaker stands and mic stands and it made them dead as a rock.

The only thing I don't like about sand is that it wouldn't actually tie the two walls together.... although it's easy enough to add features in the cad to to tie the walls together, so maybe it's just fine.

To cap off the top of the sand I could simply leave 1/8" or so un-filled, pour in more 3D print resin, and let it cure in the sunlight (the resin is UV-cure).

Can anyone else think of a reason not to use sand?

[lunchmoney]

zx82net:

I'm going to veneer them, if for no other reason than redemption from the last veneer job that didn't come out so great

[lunchmoney]

In the same token, several manufactures, SB among them, have been touting the advantage of isolating the tweeter. Seems to me installing it with a thick bead of RTV woudl work to that effect.

On a side note, SB is weird to me... they do all these innovative things, but then most of their drivers have plastic frames. No doubt I wouldn't hear the difference, blah blah blah.... but I just can't get myself to buy a plastic-framed driver.

[lunchmoney]

Also, if you find filling doesn't work out, consider just dedicating a few kilos of plastic to it, and leave the walls solid. Longer to wait, but less work to do overall.

Leaving the walls solid would require more resin than the printer vat can hold, and the increased cross-sectional area of any given layer increases the likelihood of printing issues.

[tomzarbo]

After thinking about this for awhile, I imagine the pouring of your choice of filler will be the hardest part of the whole thing. Not for you probably because you can print out a perfect funnel for this, but basically, I think that will be the "fun" part.

18 or so years ago my boss wanted some natural look paver stones in their back yard, I just couldn't get the normal bag mix with small aggregate to smooth out in the rock mold that they had picked out for their project. By that I mean that the stones wouldnt burry under the surface correctly because the mold was in the way of proper troweling of the surface.

I ended up getting a few bags of mortar mix with zero aggregate and that worked just beautiful for the pavers. I was worried because the stones add strength to the mix, but they looked perfect for years and never crumbled or showed signs of serious wear.
I suspect as long as you add some fiberglass strengthener into the mix (they sell this especially for concrete) you will be fine with regular cheapy mortar mix.

I'm looking forward to seeing how it goes!

TomZ

[lunchmoney]

After thinking about this for awhile, I imagine the pouring of your choice of filler will be the hardest part of the whole thing. Not for you probably because you can print out a perfect funnel for this, but basically, I think that will be the "fun" part.

18 or so years ago my boss wanted some natural look paver stones in their back yard, I just couldn't get the normal bag mix with small aggregate to smooth out in the rock mold that they had picked out for their project. By that I mean that the stones wouldnt burry under the surface correctly because the mold was in the way of proper troweling of the surface.

I ended up getting a few bags of mortar mix with zero aggregate and that worked just beautiful for the pavers. I was worried because the stones add strength to the mix, but they looked perfect for years and never crumbled or showed signs of serious wear.
I suspect as long as you add some fiberglass strengthener into the mix (they sell this especially for concrete) you will be fine with regular cheapy mortar mix.

I'm looking forward to seeing how it goes!

TomZ

Thanks Tom. Do you think the straight mortar would pour ok?

[lunchmoney]

Billet - Sand ^ would be excellent if it were tamped down on a vibrating surface and done in layers.

How about water?

If the speaker ever caught on fire it would be intrinsically safe, wouldn't it by putting its-self out?

Yes, tamped-down sand sounds good to me.... water would spook me, as I'm not sure if the cured resin would react with the water after years of just sitting there.

[tvrgeek]

On a side note, SB is weird to me... they do all these innovative things, but then most of their drivers have plastic frames. No doubt I wouldn't hear the difference, blah blah blah.... but I just can't get myself to buy a plastic-framed driver.

Your loss. "Plastic" is just another engineering material. My SEAS tweeters are all plastic "frames". Now I can't see the time and expense of printing a cabinet I could make from MDF a few bucks and do quicker.

Mortar is pretty thick so you would have to vibrate it into place. With a plastic shell, may take years for all the water to wick out. Not going to put thermoplastic in an oven to force it either. You could make a mix of epoxy with micro-balloon or talc fill. Might have to submerse it in water so it does not get too hot. Or, fill with sand and pour poly varnish in it. Layer by layer.

I for sure woudl just make a small prototype box to test first.