Carpenter or Math Genius

Taiwan Where Can I Find...?
1

Hello Members, Not sure I can afford a carpenter yet, but someone handy
in “Math” or Carpentry advice would be great !!

I am building some shelves for my wife, whose upper kitchen cabinet
has a big Oven Air machine in it, instead of shelves. This air machine
takes the oven odors and fumes and vents them outside this through big
Tin tube which takes up a lot of the space of this cabinet.

However, there is some space to make some cabinet shelves for her to
regain some utility space for her kitchen stuff. I am not a math genius
but I did buy some pieces of wood from B & Q, and measured all of the
sides of the cabinet to build some shelves.

My problem is I have to shape the wood so there is a circle in the middle
of the wood shelf to make the round air machine tube go through the center
of the wood.

Tin Air Tube Curmference Circle = 47 centimers
Cabinet width 87 centimeters
Cabinet deep 28 centimeters

How do I figure out the Radius of the Circle given Circle Circumference of 47 centimeters ?
Or How do I figure out the diameter of the cirlce of 47 centimers

I know where to draw the circle from the front of the cabinet, since it is sitting
right exactly in the front of the cabinet as you open up the doors, but I do not
know mathematically where to draw the circle from side to side, that is the width from
each side, where to start. I do not have a protractor, but can measure from
each side with my tape measure, if I know the diameter of the circle given its circumference 47 CM, if I know its diameter, or radius I can them subract that from the Cabinet width which
is 87 centimeters. If someone can tell me the diameter or radius or better
yet how to do this big headache step by step, that would be great. Thanks again all,
Ric

2

Circumference = 2 x Pi x Radius, where Pi is approximately 3.14159

3

So the radius of the tube is about 7.5 cm. (I hope I’m right.)

4

You’ll have to unplug the tin tube to put it through the wood, no? Why not just unplug it first and draw a line around it wherever you need the hole to be?

Another thing you could do is sit the shelf on top of the exhaust fan in its rightful position(after you unplug the exhaust tube) and reach from underneath with a pencil to trace the hole directly from the fan exhaust circular orifice. You probably will need to dismantle the exhaust fan a bit, but that would be the best way to both line up the hole and cut it to the right size. Just cut 1/4 inch bigger to give yourself some room to fit it easily.

marboulette

5

thanks, I forgot my geometry, and so it would be 47 cm divided by Pie 3.14
thanks for the formula.

The dismantling the exhaust tin is a great idea, that’s another great idea. I’ll probably try that tonight,
thanks again

Ric