Help! Box measurements

KHPower · Post by **KHPower** » Sun Jun 22, 2008 1:03 pm

I am ready to build my box and now I wish I would of paid more attention in shop. I have never made a box with odd measurements , just basic easy to measure ones. Now that I have my box measurement I seem to have lost all knowledge of how I find these measurements on a ruler/tape measure

Can some one help me?

The measurements are/parts list

1 top and 1 bottom 18.31 x 31.5
1 front 1 back 16" x 30''
2 sides 16 x 18.31 "

Vent 1 top 1 bottom 7.15 x 11.25
2 sides 5.65 x 11.25

The measurements that are highlighted in BOLD is what I cant figure out. I used Google calculators and some others and it just converts them to a weird cm's that are even harder to find

these are the measurements I am having trouble with
7.15
5.65
18.31

I would appreciate the help if someone can point out where on a ruler these are

Post by **Jacampb2** » Sun Jun 22, 2008 1:33 pm

7 & 1/8" = 7.125"
5 & 5/8" = 5.625"
18 & 5/16" = 18.3125"

Those are the closest equivalents as fractional dimensions that you will be able to measure with a standard tape measure. Most tape's are only graduated to 1/16", very few will have 1/32nds which could get you closer, but it's not going to matter.

Later,
Jason

KHPower · Post by **KHPower** » Sun Jun 22, 2008 2:22 pm

Thanks a bunch. I was going to redesign everything to more even numbers but I would of messed up all my original calculations.

Post by **Jacampb2** » Sun Jun 22, 2008 2:31 pm

Try looking for a decimal to fractional calculator/converter. I have no idea if there is anything online, but my HP48GX does it. I know there are inexpensive hand held calculators marketed toward wood workers which include this function, or you can do it manually, look up how to convert decimal to fraction. It is fairly basic math.

Post by **stipud** » Mon Jun 23, 2008 7:32 am

Google works...

http://www.google.ca/search?q=7++1%2F8

Post by **Bfowler** » Mon Jun 23, 2008 8:30 am

Google does it all baby. i love google

KHPower · Post by **KHPower** » Mon Jun 23, 2008 11:56 am

Google is great! but when I was typing in my original numbers I was getting confused with the decimal/fraction I needed for easier measure. I have also found a website that has the most common.

I went out today to HD and Menards in search of a metal measure or ruler that measured down to 30ths and 100ths but no luck , where do I find stuff like that? at least a meter

Post by **stipud** » Mon Jun 23, 2008 11:59 am

Just eyeball it man... it's a sub box, not a space shuttle

Post by **Bfowler** » Mon Jun 23, 2008 12:22 pm

to be honest...unless you are doing all your cutting with a CNC...you will never be able to cut within that accuracy.

within a 1/16 of an inch is a perfect as you will likly get, or need.

Post by **Jacampb2** » Mon Jun 23, 2008 12:25 pm

KHPower wrote:Google is great! but when I was typing in my original numbers I was getting confused with the decimal/fraction I needed for easier measure. I have also found a website that has the most common.

I went out today to HD and Menards in search of a metal measure or ruler that measured down to 30ths and 100ths but no luck , where do I find stuff like that? at least a meter

It's called a machinist rule. You can get a import 6" rule graduated in 64ths from use-enco.com for probably about $10. To get US made, and something much longer than 6"s, you are starting to talk big money. Like hundreds of dollars. Add to that, that there is no way you are going to cut to those tolerances on a table saw, let alone with a circular saw, it makes it a serrious waste of your time and money. If you are not accounting for blade kerf alone you are chewing up 1/8 inch or so of your dimensions right there.

Later,
Jason

Post by **Jacampb2** » Mon Jun 23, 2008 12:29 pm

oh, and BTW, you will never be able to read anything graduated in 100ths. There is not enough room to print visable graduations. You need calipers or micrometers to get into 100ths and 1000ths.

Later,
Jason

KHPower · Post by **KHPower** » Mon Jun 23, 2008 1:25 pm

Thanks , I figured once I got to cutting on my saw table I wouldnt get as close to my measurements , and I realize now that I can just cut to a 8th of inch and be perfectly fine. I just need to build this thing and quit worrying about the small stuff and just measure to what Jason pinpointed and get this thing rollin

What I was mainly concered with was the 5.65" port. I think I found my frequency that will work well for this sub and I didnt want to mess up the tuning I designed , thus wanting a really accurate measure.

Now I just need to test out my router

All of the advice is appreciated.

Post by **stipud** » Mon Jun 23, 2008 1:29 pm

Where are you going to find a 5.65" tubular port?

Why aren't you building a slot port instead? They are much easier to build!

KHPower · Post by **KHPower** » Mon Jun 23, 2008 1:37 pm

stipud wrote:Where are you going to find a 5.65" tubular port?

Why aren't you building a slot port instead? They are much easier to build!

I wasnt making a cirlce port , in the other posts I was getting you and others to help me with the surface area so I could make a square port or slot port and I think I want a square port at the halfway point on the left side of the box because I think I may have found my sweet spot in my van and having the port there would hit that spot.