I now understand what Dave was saying. When I looked at the dimensions of the top and bottom, I admit to misreading. [read: egg on face]. In my mind this was a trapezoidal prism, aka a pyramid with the top cut off.
Man, you have to be careful, this coulda turned ugly with me ending up at the bottom of the pile.
Hey natural sound, give us a sketch or something next time would ya? Ol' Cal was wondering what others were thinking when they were doin' the same at me. I couldn't understand X's math even though I know he's good. When Dave stepped in I had to take a step back as his first comment was WTF? [to me that is]
So, I go pick up my wife from the train, come back, read the first post again and let out a big sigh.
Am I still allowed in this thread?
Man, you have to be careful, this coulda turned ugly with me ending up at the bottom of the pile.
Hey natural sound, give us a sketch or something next time would ya? Ol' Cal was wondering what others were thinking when they were doin' the same at me. I couldn't understand X's math even though I know he's good. When Dave stepped in I had to take a step back as his first comment was WTF? [to me that is]
So, I go pick up my wife from the train, come back, read the first post again and let out a big sigh.
Am I still allowed in this thread?
The volume in cubic inches (to keep unit homogeneity) is:
(9+6)/2 in x (7+4)/2 in x (height) in =
7.5" x 5.5" x H"= V cu in
being:
in = " = inch
H = height in inches
V= volume in cubic inches.
Divide V by 1728 to get cubic feet.
By the way: that looks like a pretty small box, definitely narrow and thin, what speaker will live in it?
EDIT: Carl, I also see it as a truncated pyramid, only base is not square or rectangular but a trapezoid.
So we have to compensate on 2 out of 3 dimensions.
Hope now the OP does not add: "oh, I forgot, top and bottom are not parallel"
(9+6)/2 in x (7+4)/2 in x (height) in =
7.5" x 5.5" x H"= V cu in
being:
in = " = inch
H = height in inches
V= volume in cubic inches.
Divide V by 1728 to get cubic feet.
By the way: that looks like a pretty small box, definitely narrow and thin, what speaker will live in it?
EDIT: Carl, I also see it as a truncated pyramid, only base is not square or rectangular but a trapezoid.
So we have to compensate on 2 out of 3 dimensions.
Hope now the OP does not add: "oh, I forgot, top and bottom are not parallel"
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I am re-reading the OP post 1 and see a completely different geometry now: 9x7 rectangle bottom and 4x6 rectangle on top wall. Still don't have height. But if height is 12 for sake of assumption, volume is now average of top area 4x6 and bottom area 9x7 times height which is assumed to be 12 or (24/2+63/2)x12=522 cubic inches. A picture IS worth a thousand words in this case!
I now understand what Dave was saying. When I looked at the dimensions of the top and bottom, I admit to misreading. [read: egg on face]. In my mind this was a trapezoidal prism, aka a pyramid with the top cut off.
Man, you have to be careful, this coulda turned ugly with me ending up at the bottom of the pile.
Hey natural sound, give us a sketch or something next time would ya? Ol' Cal was wondering what others were thinking when they were doin' the same at me. I couldn't understand X's math even though I know he's good. When Dave stepped in I had to take a step back as his first comment was WTF? [to me that is]
So, I go pick up my wife from the train, come back, read the first post again and let out a big sigh.
Am I still allowed in this thread?
Yes all is welcome on my post no matter what cal
. This is the height of the box all the way around. The box is 40 inchs tall. The front and back's are the same which is the bottom is 11 inchs wide and the top is 6 inchs wide. The sides are 10 inchs on the bottom wide by 2 inchs on the top wide. Now I used 3/4's birch ply-wood. The box was cut wrong and the guy who was helping me was in a hurry and was not listening to me. Cost me a lot of money and time so he got fired. I had to finsh Cutting angle cuts on a broken table and with a circle saw is not fun for a first time user. Jeff
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Okay here are some pictures of the boxes I have been working on and testing a drivers the Fostex Fe 126en drivers sounded very natural and modd by me in the blue boxes. Then I re-did the boxes in black stain with the Fostex FF 125WK drivers and they turned out very, very nice sounding . I cut a hole for a driver I thought I was going to use but, I messed up. I will start from the ground up and redesign my boxes. This is why I wanted to figure out how to get the right cubic feet in a trapeziod. Jeff
. I cut a hole for a driver I thought I was going to use but, I messed up. I will start from the ground up and redesign my boxes. This is why I wanted to figure out how to get the right cubic feet in a trapeziod. JeffAttachments
Fill it with water and then pour the water into a measuring cup.
line with a plastic bag first. This works.
Yes all is welcome on my post no matter what cal
I see dimensions of 10 in and 11 inches and 2 inches now, how are original 4, 6, 7, and 9 inches related to these numbers???? At least we know it is 40 inches tall. A drawing w dims would be helpful ad I am more confused than ever.
Sorry the first set of numbers were an example and trying and get the ball rolling and helping me out? Duhhhh? I feel like a big dummy. I should have told you the right box dimensions a mistake on my part. As for the drawings they are long gone. Now I have to cut the boxe sides off to see how I built them. I have forgotten and I have been thru the mill this last year been ruff. Jeff
It's not that difficult, but in order to simplify things:
Online Conversion - Volume of a Trapezoid tank
Volume of a Rectangular Trapezoidal Trough
Online Conversion - Volume of a Trapezoid tank
Volume of a Rectangular Trapezoidal Trough
Technically, the divide by two should be into the sum of the top and bottom areas (parenthesis div by 2) to get the average area x height, which is the same as what I said in post 3 and all along. And it works for any prismatic shape with parallel top and bottoms and prism can be skewed to side and doesn't have to be straight up and it still works. Very simple formula. Planet10 and I agree.
A big Thank you to everyone in helping me out. It helps me out a lot and it keeps me going on my speaker projects. So please see if I got this right below? It's my first time doing this kinda math.
So here go's let see if I get this right? ( 5 + 8 * into 2 = 6.5 x 40 = 260. So is this right? (or is it 5+5+8+8 = 26 * 2 = 13 x 40 = 520?)
So here go's let see if I get this right? ( 5 + 8 * into 2 = 6.5 x 40 = 260. So is this right? (or is it 5+5+8+8 = 26 * 2 = 13 x 40 = 520?)
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Again, not sure where you are getting your numbers from (5, and 8?)?
Based on your earlier post it would seem that the top lid is a rectangle 2 x 6 inches and the bottom panel is a rectangle 10 x 11 inches right? And the height is 40 inches?
Using the formula that Dave and I stated above:
Average of area of top and bottom x height = (area_top + area_bottom)/2 x height,
area_top = 2x6 square inches, area_bottom = 10x11 square inches, or
(2x6 + 10x11)/2 x 40 = (12+110)/2 x 40 = 122/2 x 40 = 61 x 40 =
2440 cubic inches.
2440cu in / 1728 cu in per cu ft = 1.412 cubic feet
The numbers 5 and 8 have to do with a box I just cut out a few days ago. Nothing to do with this project. I just had my head in another area. Yes your correct about 2x 6 and 11 and 12 and 40. Thanks again I understand now. Jeff
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