Curved Cabinet Volume calculation?

[Hdale85]

Thanks David no rush I won't be starting these for at least another week probably lol. Just trying to get a plan down on how I want to build them.

[Hdale85]

That top is just being a real pain in my butt lol. The curve is different because the piece is longer. Working on it though.

[Hdale85]

I think I've about given up on trying to draw out the top for this thing. Unfortunately it's part of the skeleton so I need to have it on first there for I can't just do the sides and then put the top on and use a flush trim bit around it. If I can ever get it drawn out properly I may have a CNC buddy cut it out along with the braces for me.

David I'm not sure how you'd feel about this but do you think if I email you my parts and what not you could try and help me with the top? lol I'm not sure why I can't do it there is probably some trick to doing something like this that I don't know about.

[David_D]

Hi Doug,
OK here's the latest & greatest. I think you will find every thing jives.

Full Empty Volume:
Volume = 5064.11 cubic inches
82.986 Liters

Brace Volume:
Volume = 41.46 cubic inches
0.679 Liters

Slanted Top Volume
Volume = 574.89 cubic inches
9.421 Liters

Cross sectional Area of straight portion:
Area = 111.61 in2
720.063 cm2

[Dennis H]

Doug, if you're working with something soft like MDF, you could always do it the low-tech old-school carpenter way. Glue up part of it oversize but kinda sorta close -- sides first or top first, not sure which is easiest -- and use a huge sanding block (full sheet of 80 grit glued to a piece of MDF with a handle on the back) to trim it to the final shape. You can tell it's right when the block lays flat. Glue on the other part and repeat. 5 minutes sanding can remove a heckuva lot of MDF.

Edit: thinking about it a bit more, I'd do the sides first. Then set it on a level floor and tip it forward to whatever angle you want on the top. Use a tape to mark equal distance from the floor around the perimeter. Cut it a bit strong with a jigsaw and then go to work with your big sanding block.

[Hdale85]

I'm thinking more then likely I'm going to get the top braces and bottom and possibly depending on how I make the skeleton the front and rear baffle all CNC'd so they fit together perfectly. Then I'll just cut the grooves in the MDF and attach the sides and use some epexy or resin to fill in the gaps and what not and sand it down.

[Hdale85]

Figured I'd post up these pics for you guys. David and I talked a bit and he quickly came up with this and it's excellent. I thank him very much for all the help This is going to change a bit as I decided I wanted to just have the braces and stuff CNC'd so now the baffle will go the length of the speaker in the front and back. The top bottom and braces will all lock into the baffles to create a skeleton.

[Hdale85]

Some pictures of the final cabinet minus some adjustments on the front baffle.



David really did an amazing job

Hey David with all the braces and what not in there now is it possible for Solidworks to tell me how much volume is in each part? I may have to change the divider for the mid enclosure a bit and do it like halfway through the cabinet and then a wall behind the mids.

[impala454]

looks awesome... SSWWMTM or WWWWMTM?

[Hdale85]

Wwwwmtm

[Hdale85]

Ok well we were having issues with clearance of the angled top and the top mid so we had to get rid of the angle. Also added dado's for everything pretty much so it should all fit together completely perfectly and now its all getting CNC'd even the sides.



There is a little over 76 liters for the woofers now as well Which is just perfect!

[Ezcl]

This is looking really, really cool. I can't wait to see these things when they're done! How exactly are you going to make the sides curved? I'm not sure how you mean to do that.

[Hdale85]

This is a picture of the sides of the cabinet. As you can see there are lots of slits through it they will give the wood enough relief to bend to the curve of the cabinet.

[Ezcl]

Oh, interesting. I didn't realize you could do that and not have the wood break.
I'm guessing then that this 'slitting' doesn't affect the performance of the speaker at all?

[Hdale85]

Nope shouldn't effect it at all. Lots of people have built curved cabinets this way. The only other way I would have done it is to use like 1/4" MDF and multiple layers. I like the idea I'm going with better though. If your anal about the rigidness of the sides you can try and fill them with something if you like. I think I may put a bunch of glue down the grooves right before I put them on and then when they dry they should hold their own shape quite well. Some people have put the ridges on the outside and then filled it with bondo/wood filler or something and sanded it down. I'm not sure I want to do all that because these are pretty large.

[Ezcl]

You mean people cut the slits on the outside and fill them all in? Sheesh... I'd have to agree with you... That'd be far too much work for a speaker this size.

[Hdale85]

Yes thats what I mean

In case anyone is wondering these will be finished in African Ribboned Mahogany. On the curved sided part the grain will run horizontal and then on the front top and rear it will run vertical. After successful testing if it works out to my taste I'd like to use a blue aniline dye on them with a nice gloss clear coat. If I don't like the way the blue turns out on these I will probably go for a red dye.

[Hdale85]

In case anyone is still interested I received my bamboo veneer today..I'm not sure if I'm going to use this or not I've been thinking about quilted maple after I ordered the bamboo but now looking at the bamboo its very nice....although I still like quilted maple better. We'll see. I also received some of the cabinet parts and here are some pictures.

Braces and what not



Veneer

[Johnloudb]

That looks awesome Dougie! If you don't mind saying, what CNC shop did you use to get the wood cut? Where they local or was it shipped to you? I need to get wood cut as well and not sure where to get it done. Those cut pieces look real nice.

[Hdale85]

It's a guy I found on my CNC forums. They are a shop they were not local. Parts were shipped to me they had EXTREMELY reasonable prices. For all the parts for both cabinets they charged me 196 bucks.

[Hdale85]

Sorry forgot the website here is their website. It's not pretty but I got the quote from Kurt and seems Mike handles the money? You can give them a call as well. They do some nice work thats for sure. And its pretty fast and they have fast communication.

[Johnloudb]

Sorry forgot the website here is their website. It's not pretty but I got the quote from Kurt and seems Mike handles the money? You can give them a call as well. They do some nice work thats for sure. And its pretty fast and they have fast communication.

Thanks, that shop sounds great. I'll probably be building some boxes for a speaker in the near future. Oh, what's that website again? I can't see it, maybe a larger font will help.

[Hdale85]

Crap...I thought I pasted it.... http://www.mkincising.com/

Sorry about that :B

Are you going to do curved cabinets? Or just don't feel like cutting the wood your self?

[Johnloudb]

That helps, Thanks. :T

[Hdale85]

Sorry I edited this in lol but what are you planning on building? Curved cabinets?

[james5]

Dougie...was this a one sheet nest or did you have to go two? Also, how detailed were your CAD drawings? Did you draw all of the Dados (not too hard, but it takes time) or just tell him you wanted all the pieces as such?

I was thinking about doing some curved side statement monitors for my next project so you're input is appreciated.

[Hdale85]

Everything was drawn exactly how it was going to be when it was together. Including dado's and everything. I'm not sure how many sheets of MDF they used I just sent them the drawings and they gave me a quote. I'd imagine it needs at least 2 though as the sides are pretty big.

[David_D]

Everything was drawn exactly how it was going to be when it was together. Including dado's and everything. I'm not sure how many sheets of MDF they used I just sent them the drawings and they gave me a quote. I'd imagine it needs at least 2 though as the sides are pretty big.

Doug,
Did you actually detail all those parts into drawings or did you send them the solid models?

[Hdale85]

No the way Solidworks works is that you make up all the parts separately and then you assemble them. So the pictures I showed you guys before were just the assembled parts.

[David_D]

No the way Solidworks works is that you make up all the parts separately and then you assemble them. So the pictures I showed you guys before were just the assembled parts.

I'm sorry, I must not have made myself clear. Did you give your shop the SolidWorks SLDPRT files or did you detail them into 3 view drawings like this one?

[Hdale85]

Ohhh I sent them the SLDPRT files along with the assembly file. This way they could just load it into the machine and hit go.


Edit: Haha I didn't even realise who I was talking to

[Johnloudb]

Sorry I edited this in lol but what are you planning on building? Curved cabinets?

Cutting wood can be a challenge for me for a number of reasons. It's just less hassle if I order it. Nothing too fancy. A box with 2 8 inch Usher woofers per channel, with a B-G RD50 planer dipole Mid-Tweeter. So the top part is kind of difficult, due to the shape of the 50" long RD50 driver. I keep altering my plans, so my design isn't set in stone yet. However, I do have all the drivers.

[james5]

Doug,

How wide are the slits in your curved sides?

[Hdale85]

Hmm I'm not completely sure. I'm having some issues with my solidworks install but as soon as I get it working I can figure it out. David probably knows though if he happens to be around.

[David_D]

Hmm I'm not completely sure. I'm having some issues with my solidworks install but as soon as I get it working I can figure it out. David probably knows though if he happens to be around.

The slots are 1/8" (a typical kerf of a heavy duty saw blade).
The trick is in the number of slits. One measures the length of the arc on the outside determines the overall width. Measuring the arc on the inside and dividing by 1/8" determines the number of cuts. Better more cuts then less. The lesser the cuts and more the curve becomes a polygon.

[james5]

Thanks for the info David!

Has anyone here thought of using concrete for the construction of their cabinets? Maybe concrete sides and back with a wood baffle, top, and bottom? I work for a concrete company so I can get it pretty easy...any thoughts?

[Hdale85]

Umm..... I guess if you plan on never moving them.

[james5]

Concrete has a unit weight of 145#'s/cu ft. A sheet of plywood/mdf has a volume of roughly 2 cu ft...so that'd be 290#'s for a cabinet that is made from one complete sheet of ply/mdf (roughly of course). I bet you wouldn't really have to do any internal bracing depending on the thickness of the walls.

Would the walls have to be more heaviily treated for sound waves bouncing off and such? Just curious.

[Hdale85]

I don't know I think MDF or Birch ply is plenty good enough. Concrete is just a bit to drastic. I believe someone has asked this question before.

[Hdale85]

Well I got most of the parts in.

Image not available

The rest of the cabinet parts are coming tomorrow. Then I just have to work out when my friend can come pick me up to move them all to his house. Been working on how I'm going to layout my living room as well.



Should work out good until we get a house :B

[peter_m]

Good looking speakers. How did you decide on the final curved shape of the side walls? Why this curve as opposed to another one?

[Hdale85]

I don't know we just kind of did what looked good...

[impala454]

Concrete has a unit weight of 145#'s/cu ft. A sheet of plywood/mdf has a volume of roughly 2 cu ft...so that'd be 290#'s for a cabinet that is made from one complete sheet of ply/mdf (roughly of course). I bet you wouldn't really have to do any internal bracing depending on the thickness of the walls.

Would the walls have to be more heaviily treated for sound waves bouncing off and such? Just curious.

Don't take this too concrete (pun intended) but I'd imagine sound waves would reflect like crazy inside a concrete box, even if it were practical.

[Hdale85]

Should be taking it over to my friends tomorrow and then Diana is off sat and sun this week amazingly so I'll probably go over and get a lot of stuff done.

[Jed]

Hopefully it'll all fit together like a puzzle.

On another note it took me all day to cut out the holes for the towers and CC. Did they do that for you too?