3d Printed / Poured Concrete enclosure concept

[lunchmoney]

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

Unfortunately I just don't have access to the shop tools I once did.

[augerpro]

The only thing I don't like about sand is that it wouldn't actually tie the two walls together....

Exactly the benefit!

[zx82net]

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.

Imagine the mess if it was filled with water and it ever cracked! I once had a big resin print (~40cm) shipped to be by fedEX, it arrived in about 30 pieces. doh! On a practical note, I think you should definitely use spars between the walls to keep them stable. Also, when I tried filling the walls of a large print with plaster of Paris, I tried making one big pocket where everything was interconnected. After problems with working time and viscosity, I decided that next time I would make a number of individual pockets, so I could fill them one at a time, doing each one with a single pour and not having to stress about getting it done quickly. After filling them with plaster of Paris, I was weighing the prints daily, they were still loosing moisture after a week, I gave up waiting. Although the moisture cannot now easily escape, it can't get inside the enclosure either, so I'm not too bothered.

[tomzarbo]

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

hmmmm, 3/8" is not a lot of space, actually I don't think it would be thin enough to flow in very well. That's just not a lot of room between panels now that I think about how small 3/8" is.
Not unless you really went thin with the mix, then it would be weak and take forever to dry. I'm stumped.
TomZ

[tvrgeek]

Tom, Mortar CURES. It then will dry. It will cure under water. Correct, the wetter the mix, the weaker it is. One could easily vibrate the mix in dry and add water. That will get around the thickness question.

[oldloder]

I vote for the sand with a little extra bracing and vibrated by some means to settle it in well. Measure, tell us what you find and then do the concrete if you're not happy with it and measure again! My only thoughts about the concrete would be ringing due to discussion with John Kreskovsky about his experiment with a concrete baffle. But the way you are planning to use it I suspect that would be mitigated by contact to the enclosure ... that said, he effectively dealt with the ringing with vinyl matting and the cracking he experienced I imagine would not be an issue due to the printed enclosure wrap. As long as you are patient and it's placed in a warm area I think the concrete would dry in a reasonable amount of time.

[3rutu5]

Have you seen this guys concrete boombox? Might give some ideas for concrete choice etc
https://m.youtube.com/watch?v=a43LXqRwQC8&t=462s

[tvrgeek]

Just because you can, does not always mean you should. Just saying.

[tomzarbo]

Tom, Mortar CURES. It then will dry. It will cure under water. Correct, the wetter the mix, the weaker it is. One could easily vibrate the mix in dry and add water. That will get around the thickness question.

Ahh! Wasn't thinking along those lines. Pour In dry, add water after. I would do this In stages to be sure of an even mix, but that could work.

TomZ

[lunchmoney]

Exactly the benefit!

I meant more that the entire cabinet would be less structurally solid and rigid because the two walls wouldn't be held together like they would with concreted.... I didn't really consider it being a decoupled double wall.... interesting....

Well it's easy enough to add some connecting bosses between the walls to make it solid, in which case the sand seems ok.

[lunchmoney]

Now I can't see the time and expense of printing a cabinet I could make from MDF a few bucks and do quicker.

Where is all the supposed expense and time you speak ok? $20 worth of resin per cabinet, hit print and walk away. Then minimal supports to clean up, leave it in sunlight to post-cure, and it's done.

Yes it would be less than $20 of mdf, sure, but I don't care about that. If I were concerned about a few bucks I wouldn't be making speakers.

No port to mount, no screw holes to drill, no driver recesses to cut.

And if it's not right, adjust the cad and hit print again.

[zx82net]

Well said!

[lunchmoney]

Sand it is then. Thanks for all the input folks.

[lunchmoney]

I started a build thread here in the Project Gallery...

http://techtalk.parts-express.com/fo...led-enclosures

[3rutu5]

Where is all the supposed expense and time you speak ok? $20 worth of resin per cabinet, hit print and walk away. Then minimal supports to clean up, leave it in sunlight to post-cure, and it's done.

Yes it would be less than $20 of mdf, sure, but I don't care about that. If I were concerned about a few bucks I wouldn't be making speakers.

No port to mount, no screw holes to drill, no driver recesses to cut.

And if it's not right, adjust the cad and hit print again.

and not to mention you could halve that easy using PLA, but.....you are using resin which was the point

since i bought my printers my woodworking has really reduced, havent had the need with being in CAD all the time

Cant wait to see your concrete pour on your other thread, they are looking good.

[lunchmoney]

and not to mention you could halve that easy using PLA, but.....you are using resin which was the point

since i bought my printers my woodworking has really reduced, havent had the need with being in CAD all the time

Cant wait to see your concrete pour on your other thread, they are looking good.

Thanks.... sand pour actually, the discussion here made me change course.

I'm actually not that crazy about the idea of using PLA for speakers.... it tends to have a slightly pourous nature, while resin is dead solid.

One such example of the "porous problem" for PLA (and FDM prints generally) is that they're not allowed for reusable medical devices that would require sterilizing or autoclaving. Blood or other liquids can soak into the pourous FDM material, and therefore can't be cleaned well.

How much of this is an issue for speakers? Not sure, but fundamentally it seems like a more solid material is the better move.... big prints are much tougher with resin though, requiring big, expensive resin printers, and higher cost of materials. Easier said than done, in other words.