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Quick math question (not what you think)

MichaelD

MichaelD

Lifer
Yes; I know an 8th grader can do this. I was never good at math.

I'm trying to figure the diameter cutout I need for a speaker; I.E. how big to cut the hole.

If I take a tape measure and measure the diameter of the speaker (the part that actually goes into the cutout) and divide by 3.14, will I get the size hole I need (in inches)?

It needs to be exact...within 1/16 of an inch.

The manufacturer says it needs a 11.1 inch cutout. I have been burned by manuf specs before; they may say "cutout diameter 11.25 inches" and you cut that and it's way too big! :|

Help, please.
 
Holy crap, people!

If I would've posted "I need the Rand Radical Tran Angle of the Hypotenuse of the Space Shuttle...under water...but it's oil...on Mars...on a Sunday" you would've had the answer already!!!!
 
NO 😛 You don't DIVIDE by 3.14, you MULTIPLY!!! (i'm assuming you want the circumference of the circle)

C = pi * d

I'm in ninth grade BTW
 
Originally posted by: MichaelD
If I take a tape measure and measure the diameter of the speaker (the part that actually goes into the cutout) and divide by 3.14, will I get the size hole I need (in inches)?
Click to expand...

I don't get what you are asking -- you are measuring the diameter and asking how big of a hole (diameter) to cut?
 
Originally posted by: stinkynathan
you don't need anything to do this. just cut it out at 11 1/8

nate
Click to expand...

So...does 11.1 inches = 11 1/8? Doesn't the .1 inches mean 1/10th of an inch? 😕
 
Easiest way is to cut a piece of string at 89/4 and attach it to a pencil. hold down the string and you have a ghetto protractor. proceed with drawification. use scissors and cut.

edit: as for the measurements, inches is measured in 8ths and 16ths, confirm and remeasure.
 
Originally posted by: MichaelD
Yes; I know an 8th grader can do this. I was never good at math.

I'm trying to figure the diameter cutout I need for a speaker; I.E. how big to cut the hole.

If I take a tape measure and measure the diameter of the speaker (the part that actually goes into the cutout) and divide by 3.14, will I get the size hole I need (in inches)?

It needs to be exact...within 1/16 of an inch.

The manufacturer says it needs a 11.1 inch cutout. I have been burned by manuf specs before; they may say "cutout diameter 11.25 inches" and you cut that and it's way too big! :|

Help, please.
Click to expand...

Yes, you will

Remember, Circumference = 2 * Pi * R = Pi * Diameter

So given the diameter, you can find the circumference using the above formula.

Also, when measuring the diameter, make sure you take multiple readings and then average them out to reduce the probability of an error.

and AFAIL, 11 1/8 is not equal to 11.1 (11 1/8 = 11.125)

 
Originally posted by: MichaelD
Holy crap, people!

If I would've posted "I need the Rand Radical Tran Angle of the Hypotenuse of the Space Shuttle...under water...but it's oil...on Mars...on a Sunday" you would've had the answer already!!!!
Click to expand...


I have seen you rant. I have seen you rave. I have seen you give everybody a piece of your mind, but I have never seen you whimper, whine and cry.

Where oh where is the MichaelD we all used to love and look forward to? 😕

 
Originally posted by: HappyPuppy
Originally posted by: MichaelD
Holy crap, people!

If I would've posted "I need the Rand Radical Tran Angle of the Hypotenuse of the Space Shuttle...under water...but it's oil...on Mars...on a Sunday" you would've had the answer already!!!!
Click to expand...


I have seen you rant. I have seen you rave. I have seen you give everybody a piece of your mind, but I have never seen you whimper, whine and cry.

Where oh where is the MichaelD we all used to love and look forward to? 😕
Click to expand...


Oh, he's still here. :evil: However, he needs to build a complex subwoofer enclosure tomorrow. MDF and shop time is expensive.

Check this out. 😀

That's what I like to do in my spare time. It makes me happy. Plus, if I can blow my windshield out 500 yards or so, that also makes me happy. Puppy.

Get it? Happy. Puppy? 😕 I liked it. 😎

For those that are still reading, I have two D612D4's and will be feeding them 1.5Kw. 😀
 
Originally posted by: MichaelD
Yes; I know an 8th grader can do this. I was never good at math.

I'm trying to figure the diameter cutout I need for a speaker; I.E. how big to cut the hole.

If I take a tape measure and measure the diameter of the speaker (the part that actually goes into the cutout) and divide by 3.14, will I get the size hole I need (in inches)?

It needs to be exact...within 1/16 of an inch.

The manufacturer says it needs a 11.1 inch cutout. I have been burned by manuf specs before; they may say "cutout diameter 11.25 inches" and you cut that and it's way too big! :|

Help, please.
Click to expand...

where have you been, michaelD.. I haven't seen you in forever.

anyway.. if you measure the diameter of the thing you want to fit in the hole.. then.. that's how big the diameter of the hole should be.. no multiplying required?

for example.. if I wanted to make a hole a cd would fit in, I'd measure the cd.. and this handy dandy tape measure the welcome wagon lady in danville gave me in 1979 says that a cd is 4 and 11/16th inches, I think.. lets just pretend that's what it is, as long as I measure my hole with the same tape measure to the same point, it really doesn' t matter what the number is. so.. if I want the cd to fit in the hole.. I'd make the hole 4 and 11/16 inches. or, perhaps.. I'm better with math than I am with power tools.. if you want a really precise hole, then you'd need to take in to consideration the amount of wood that your.. tool you're using to cut out the hole is going to chew up.. if it's an appreciable amount, make your hole that amount smaller.. and it'll end up being the right size?

edit: heh.. I know nobody would want to make a hole a cd would fit in, it was just the only round thing I could find at hand to measure. 🙂

anno
 
Originally posted by: anno
Originally posted by: MichaelD
Yes; I know an 8th grader can do this. I was never good at math.

I'm trying to figure the diameter cutout I need for a speaker; I.E. how big to cut the hole.

If I take a tape measure and measure the diameter of the speaker (the part that actually goes into the cutout) and divide by 3.14, will I get the size hole I need (in inches)?

It needs to be exact...within 1/16 of an inch.

The manufacturer says it needs a 11.1 inch cutout. I have been burned by manuf specs before; they may say "cutout diameter 11.25 inches" and you cut that and it's way too big! :|

Help, please.
Click to expand...

where have you been, michaelD.. I haven't seen you in forever.

anyway.. if you measure the diameter of the thing you want to fit in the hole.. then.. that's how big the diameter of the hole should be.. no multiplying required?

for example.. if I wanted to make a hole a cd would fit in, I'd measure the cd.. and this handy dandy tape measure the welcome wagon lady in danville gave me in 1979 says that a cd is 4 and 11/16th inches, I think.. lets just pretend that's what it is, as long as I measure my hole with the same tape measure to the same point, it really doesn' t matter what the number is. so.. if I want the cd to fit in the hole.. I'd make the hole 4 and 11/16 inches. or, perhaps.. I'm better with math than I am with power tools.. if you want a really precise hole, then you'd need to take in to consideration the amount of wood that your.. tool you're using to cut out the hole is going to chew up.. if it's an appreciable amount, make your hole that amount smaller.. and it'll end up being the right size?
Click to expand...

/waves at Anno

Howdy! 🙂

I've been back for awhile now. I just don't post as much as I used to. Not that I have a shortage of ass-kickery to mete out; I just don't have the time anymore. 🙁

Anyway, Thanks for your suggestions!

The issue is that the mounting diameter of a subwoofer can't be measured "on the outside" like measuring the overall diameter of a CD.

The mounting diameter of a speaker is actually the diameter of the frame under the rim...the width of the "body" of the frame, not the overall diameter.

 
Originally posted by: MichaelD
Originally posted by: HappyPuppy
Originally posted by: MichaelD
Holy crap, people!

If I would've posted "I need the Rand Radical Tran Angle of the Hypotenuse of the Space Shuttle...under water...but it's oil...on Mars...on a Sunday" you would've had the answer already!!!!
Click to expand...


I have seen you rant. I have seen you rave. I have seen you give everybody a piece of your mind, but I have never seen you whimper, whine and cry.

Where oh where is the MichaelD we all used to love and look forward to? 😕
Click to expand...


Oh, he's still here. :evil: However, he needs to build a complex subwoofer enclosure tomorrow. MDF and shop time is expensive.

Check this out. 😀

That's what I like to do in my spare time. It makes me happy. Plus, if I can blow my windshield out 500 yards or so, that also makes me happy. Puppy.

Get it? Happy. Puppy? 😕 I liked it. 😎

For those that are still reading, I have two D612D4's and will be feeding them 1.5Kw. 😀
Click to expand...


Interesting. When I worked for one of your employer's subsidiaries we were granted free shop time. :evil: We did, of course, have to provide our own materials. 🙁

Good luck with your boombox, I'm sure your ears and those of many others will appreaciate it. 😛



 
Originally posted by: MichaelD
Originally posted by: anno
Originally posted by: MichaelD
Yes; I know an 8th grader can do this. I was never good at math.

I'm trying to figure the diameter cutout I need for a speaker; I.E. how big to cut the hole.

If I take a tape measure and measure the diameter of the speaker (the part that actually goes into the cutout) and divide by 3.14, will I get the size hole I need (in inches)?

It needs to be exact...within 1/16 of an inch.

The manufacturer says it needs a 11.1 inch cutout. I have been burned by manuf specs before; they may say "cutout diameter 11.25 inches" and you cut that and it's way too big! :|

Help, please.
Click to expand...

where have you been, michaelD.. I haven't seen you in forever.

anyway.. if you measure the diameter of the thing you want to fit in the hole.. then.. that's how big the diameter of the hole should be.. no multiplying required?

for example.. if I wanted to make a hole a cd would fit in, I'd measure the cd.. and this handy dandy tape measure the welcome wagon lady in danville gave me in 1979 says that a cd is 4 and 11/16th inches, I think.. lets just pretend that's what it is, as long as I measure my hole with the same tape measure to the same point, it really doesn' t matter what the number is. so.. if I want the cd to fit in the hole.. I'd make the hole 4 and 11/16 inches. or, perhaps.. I'm better with math than I am with power tools.. if you want a really precise hole, then you'd need to take in to consideration the amount of wood that your.. tool you're using to cut out the hole is going to chew up.. if it's an appreciable amount, make your hole that amount smaller.. and it'll end up being the right size?
Click to expand...

/waves at Anno

Howdy! 🙂

I've been back for awhile now. I just don't post as much as I used to. Not that I have a shortage of ass-kickery to mete out; I just don't have the time anymore. 🙁

Anyway, Thanks for your suggestions!

The issue is that the mounting diameter of a subwoofer can't be measured "on the outside" like measuring the overall diameter of a CD.

The mounting diameter of a speaker is actually the diameter of the frame under the rim...the width of the "body" of the frame, not the overall diameter.
Click to expand...

oh. well then.. we have a semantics issue. 🙂 you wanna measure the circumference of that frame under the rim... and then divide by 3.14ish to get the right diameter for your hole? I think. 🙂

anno (obviously too stupid.. er.. ignorant 🙂 to understand the problem, and too chicken to understand the tools, but still posessing a few old-school math skills..)
 
Ruler. Measure diameter of speaker from its front. Turn it over. Measure the width of the 'lip'. Multiply by 2. Subtract from the first measurement. Done.

Mark
 
Originally posted by: Minjin
Ruler. Measure diameter of speaker from its front. Turn it over. Measure the width of the 'lip'. Multiply by 2. Subtract from the first measurement. Done.

Mark
Click to expand...

Oooh...didn't think of that. I actually understand what you're saying! :Q Amazing (that I understand)

Thanks!
 
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