Anyone good at Geometry?

[Doubleuj]

Need a bit of help with maths..
I want to build a barrel like shroud/ insulator for my boiler.
Ive got a heap of timber that I salvaged, they are 45x45x700mm.

B8661C4E-FF44-4013-8E23-860D32E807D5.jpeg

I’ll rip them down in half to be around 20x45mm like this

EB7155AE-09F3-41ED-B5B6-8EB91D7BDAE9.jpeg

Then I’ll shape the edges to suit the curve of the boiler, this is where I’m stuck.
I need to know the angle of the edge of the timber so it fits together like a barrel

Total inside diameter to be 640mm
What is angle a?

468E4398-6F46-45EE-A3B0-A82027D1F54A.jpeg

Cheers

[A&O]

Was great at maths when at school, but not so good now, lost too many brain cell during my twenties from over indulgence.

But this is how I worked out my keg cladding, which was awfully close, but not a carpenter exact.

640 / 45 = 14.222222 rounded up to 15 (approx number of planks needed)

360 / 15 = 24

24 / 2 = 12

90 - 24 = 78

Technically angles should be 78 ish degrees.

For me, I used wider planks and my calculations came to 71 degrees, but had no way of measuring this so Di my cuts somewhere between 75 & 80 degrees. Some got a bit more angle as when making the bits at the back it was trial & error to squeeze them in to make fit.

Edit: Sorry mate, I read 640mm as circumference, May need a fair bit of adjustment to my numbers :angry-banghead:

Sorry no photos at the moment as the table saw & keg is out the farm, and I’ve changed my mind about the wood I was using, which was Karri. When we milled it we cut the wrong way on the grain so the finish is all fuzzy, and won’t plane/sand smooth. So will try and find some red gum or marri or tingle or even pallet pine. Depends on how I’m feeling at the time.

Hope this helps. It’s certainly a hacks way but cut down on the trial and error. I’m sure there’s a chippy about that can correct me

[Doubleuj]

Cheers mate, I only a hack at the best of times.
I drew up a full scale drawing on the workbench and using a protractor got an angle of 86.75 degrees
Set the jointer to suit and the two test staves look close enough for me :handgestures-thumbupleft:
Using your circumference idea I’ll need 45 or so.

Cheers

[A&O]

:laughing-rolling: :laughing-rolling: :laughing-rolling:

that would make for some decent gaps :laughing-rolling:

[db1979]

45 mm is the length of the back edge of the plank. So we can't divide the circumference by 45 to find the number of panels needed.

If the radius is 320, with the panels on it'll be slightly longer than 340 (the angled edge of the panels will be slightly longer than 20).

Circumference is then approximately 340 x 2 x 3.14 = 2135.2

Since the circumference is a curve we can't just divide this number by 45 to get the number of planks needed because 45 is the measurement of the chord of the circle segment, not the length. Anyway I used it as a starting point and dividing 2135.2 by 45 gave just under 48 segments, 48 panels.

I then used an online calculator (cause the maths is too hard for me) https://planetcalc.com/1421/ to find the following:
Chord length: 44.47
Length: 44.51
Angle: 7.5

This angle is the angle of the segment of the circle. Each segment is an isosceles triangle and the other angles are then (180 - 7.5)/2 = 86.25.
90 - 86.25 = 3.75

So an angle of 3.75 off the sides of 44.47 wide panels should make it all the way around using 48 panels.

The only snag is that the inside face of the panels won't match the curve of the boiler, but a light sanding with some coarse sand paper on the side of the boiler should give it a good fit.

Sounds like a lot of stuffing around though :?

[Plumby]

45 mm is the length of the back edge of the plank. So we can't divide the circumference by 45 to find the number of panels needed.

If the radius is 320, with the panels on it'll be slightly longer than 340 (the angled edge of the panels will be slightly longer than 20).

Circumference is then approximately 340 x 2 x 3.14 = 2135.2

Since the circumference is a curve we can't just divide this number by 45 to get the number of planks needed because 45 is the measurement of the chord of the circle segment, not the length. Anyway I used it as a starting point and dividing 2135.2 by 45 gave just under 48 segments, 48 panels.

I then used an online calculator (cause the maths is too hard for me) https://planetcalc.com/1421/ to find the following:
Chord length: 44.47
Length: 44.51
Angle: 7.5

This angle is the angle of the segment of the circle. Each segment is an isosceles triangle and the other angles are then (180 - 7.5)/2 = 86.25.
90 - 86.25 = 3.75

So an angle of 3.75 off the sides of 44.47 wide panels should make it all the way around using 48 panels.

The only snag is that the inside face of the panels won't match the curve of the boiler, but a light sanding with some coarse sand paper on the side of the boiler should give it a good fit.

Sounds like a lot of stuffing around though :?

My brain hurts after reading that.

[Doubleuj]

45 mm is the length of the back edge of the plank. So we can't divide the circumference by 45 to find the number of panels needed.

If the radius is 320, with the panels on it'll be slightly longer than 340 (the angled edge of the panels will be slightly longer than 20).

Circumference is then approximately 340 x 2 x 3.14 = 2135.2

Since the circumference is a curve we can't just divide this number by 45 to get the number of planks needed because 45 is the measurement of the chord of the circle segment, not the length. Anyway I used it as a starting point and dividing 2135.2 by 45 gave just under 48 segments, 48 panels.

I then used an online calculator (cause the maths is too hard for me) https://planetcalc.com/1421/ to find the following:
Chord length: 44.47
Length: 44.51
Angle: 7.5

This angle is the angle of the segment of the circle. Each segment is an isosceles triangle and the other angles are then (180 - 7.5)/2 = 86.25.
90 - 86.25 = 3.75

So an angle of 3.75 off the sides of 44.47 wide panels should make it all the way around using 48 panels.

The only snag is that the inside face of the panels won't match the curve of the boiler, but a light sanding with some coarse sand paper on the side of the boiler should give it a good fit.

Sounds like a lot of stuffing around though :?

Cheers DB, thought you’d have the answer :handgestures-thumbupleft: so my guess at 86.75 wasn’t far off :happy-partydance:

[EziTasting]

:laughing-rolling:
Is it too late to suggest making a square box and filling it with high temp foam?
:laughing-rolling:

[Doubleuj]

Yeap! All ripped down and angles planed :handgestures-thumbupleft:
I’ll construct it next weekend, time for a beer

[A&O]

Awesome work guys, I'll be coming back to this page as a reference next time.

With my keg, the gap between the ribs is going to be filled with high temp/density foam/rubber that I'll scrounge from an ex workplace, to make my planks somewhat level with each other, then along the top, I'm going to use some curved angle to hide the gap at the top and to make all nice and neat.

[hillzabilly]

It would be nice ta tongue and groove them as well , will be tricky but would lock it all together ,are ya going for brass straps to secure the wood ?.cheers hillzabilly :handgestures-thumbupleft:

[Doubleuj]

It would be nice ta tongue and groove them as well , will be tricky but would lock it all together ,are ya going for brass straps to secure the wood ?.cheers hillzabilly :handgestures-thumbupleft:

Tounge and groove! I’m good but not that goood :laughing-rolling:
Not sure what strapping I’ll use, I might be able to get my hands on some copper earth strapping... here’s hoping.

[db1979]

Not sure what strapping I’ll use, I might be able to get my hands on some copper earth strapping... here’s hoping.

That'll look sweet :handgestures-thumbupleft: