Calling all math whizzes.

[paulthenurse]

OK I want to make up a copper manifold to sit at the bottom of a mash tun with an internal diameter of 24.5". I want an octagonal manifold and will put a few cross pieces in to draw wort from the middle of the grain bed.

(I won't drill holes towards the corners of the octagon, so no-one need hammer me that I'll be pulling all the wort down the sides and having an inefficient system. Please spare me.)

So, who is a math whiz? What are the lengths of the sides of an octagon within a circle with a 24.5 inch diameter? 3/4 inch copper is expensive and I don't want to experiment to find the answer.

Give an old man a break. The last time I took algebra was Mr Mugaro's 7th grade algebra in 1971 and I spent the whole year gazing in awe at Nancy Givens as she grew a spectacular pair of breasts . I don't remember a freaking thing about algebra but that class firmly cemented my unending love of sweater meat. Alas, Nancy grew up and discovered that she had only one marketable skill and started to push kids out of her uterus like she was getting paid to do it, which given that we're talking about Massachusetts in the late 1970's, she was. Last time I saw her those perky puppies were down south of her belt.

The horror. The horror.

PTN

 

[motobrewer]

10 1/8"

 

[AnOldUR]

This?
9-3/8"

 

[motobrewer]

9 3/8" is accurate. my bad. i did 24.5" flat-to-flat

 

[AnOldUR]

My math skills have gone dormant with old age,
but having CAD on a computer helps. :cross:

 

[GilaMinumBeer]

Might want to dble check OldUR. I'd never trust a guy with a Canadian on his computer.

 

[paulthenurse]

I'm starting to feel that same warm feeling I used to get whenever Nancy had to go up and solve a problem on the chalkboard. You guys are the best.

So, not for nuttin' but how did you calculate that? What is the formula?

Algebra... the new Viagra.

PTN

 

[bob1852]

Algebra... the new Viagra.

PTN

Geometry?

 

[paulthenurse]

So if I cut the sides at 8 inches I'll be well inside the circumference of the circle and won't have any problems with pulling wort down the sides, right?

PTN

 

[paulthenurse]

Geometry?

Whatever. I wasn't that hot in Geometry either. But Laura Bretton was in my Geometry class and man, did she have a great rack.


PTN

 

[Cape Brewing]

Hey... *******!!!! Seven inches.... Like I said.

 

[paulthenurse]

Does anyone alse hear that annoying whine?

PTN

 

[Cape Brewing]

Hey Paul... I am not sure you saw my question on the other thread.

How long should each length of an octogonal manifold be for a 24.5 inch tun?? I am just waiting for an answer since I cant seem to get it right.

 

[RonRock]

Why not do it like this? No math needed.

 

[ultravista]

Post the formula and calculation for us brain smart brewers.

 

[Cape Brewing]

How I came up with it is in paul's signature now. And before anyone jumps all over it, i know the whole "seven plus seven (two seven times a half given the 45s)" isnt mathatically accurate.

Its close enough for what Paul is trying to do.

 

[AnOldUR]

Post the formula and calculation for us brain smart brewers.

(SIN(22.5dgrs) X 12.25) X 2 = 9.3757

Its (7 inches) close enough for what Paul is trying to do.

Algebra... the new Viagra.

Geometry?

Whatever. I wasn't that hot in Geometry either. But Laura Bretton was in my Geometry class and man, did she have a great rack.

Actually, I think it's trig, but I aslo suffer from rack blindness.

 

[Cape Brewing]

Right.... And like I said in the "calculation", 9 inches would place it right up against the edge of the tun... Which is a mistake.

 

[AnOldUR]

The question was . . .

What are the lengths of the sides of an octagon within a circle with a 24.5 inch diameter?

It's up to Paul to figure out clearance and allowances for the 22.5 degree elbows he'll be using.

 

[Cape Brewing]

LOL! Ok. I stand corrected then. My bad.

I speak fluent Paul so I was answering his question of, "uhhh. How long does I haffta cut them there coppah pipes?" on another thead... and I told him about 7 inches. I wanted to keep it to a reasonably round number as I didnt want to confuse him further. He didnt want to accept that so he started this thread... Only he asked the wrong question (shockingly) since he doesn't want a 24.5 inch diameter. He wants something that sit more appropriately in a 24.5 inch diameter tun.

 

[AnOldUR]

Right.... And like I said in the "calculation", 9 inches would place it right up against the edge of the tun... Which is a mistake.

4.5 / SIN(22.5) X 2 = 23.518

so that's about 1/2" clearance on all sides.

 

[Cape Brewing]

And still in the wrong spot.

 

[AnOldUR]

Never said it would make good beer.
Just answering a call to "math whizzes."



. . . or is that math wusses.

 

[Cape Brewing]

I think we are both getting caught up in the fine print and losing sight if the big picture fact.... and that is that Paul's a schmuck.

 

[paulthenurse]

Ya. What he said.

PTN