Maths help
- Thread starter WoZZeR
- Start date
Soldato
- Joined
- 18 Mar 2008
- Posts
- 12,751
Wouldn't you just draw a rectangle, except with one side diagnol rather than straight?
I can't post a drawing until I am back home tomorrow but here goes:
I want to build a wooden box, it is 100cm wide,61cm long and 61cm high at one end and perhaps 30cm high at the other.
2 of the corners will have a 30cm radius viewed top down.
The walls of the box will be made from that bending plywood.
I would like to cut the lid at an angle as stated with the radiused edges at the lowest point.
I am trying to work out what shape the bending plywood would need to be cut in.
But I'm rubbish at maths.
I want to build a wooden box, it is 100cm wide,61cm long and 61cm high at one end and perhaps 30cm high at the other.
2 of the corners will have a 30cm radius viewed top down.
The walls of the box will be made from that bending plywood.
I would like to cut the lid at an angle as stated with the radiused edges at the lowest point.
I am trying to work out what shape the bending plywood would need to be cut in.
But I'm rubbish at maths.
May not be the quickest or easiest way but it might be worth playing about with Google Sketchup. Once you get used to the tools and view, it isn't too hard to make virtual mockups and you then have all the measurements and angles to work from.
I think a 'jaunty angle' on a cylinder would mean a sort of 0-360 cosine shape for one edge. So a radius corner would follow the first 90 degrees shape of a cosine shape? (just guessing here!)
So depending on what ratio the 'jaunty angle' will be you would have:
xcosy
So for a gradient of 1, x = 1, for gradient of 0.5, x = 0.5.
(with y being the position along the curve, if it is divided up into 90 subdivisions.(or pi/2 if that's what you fancy.))
So:
start: xcos0
middle: xcos45
end: xcos90
(for each 90 degree corner).
So depending on what ratio the 'jaunty angle' will be you would have:
xcosy
So for a gradient of 1, x = 1, for gradient of 0.5, x = 0.5.
(with y being the position along the curve, if it is divided up into 90 subdivisions.(or pi/2 if that's what you fancy.))
So:
start: xcos0
middle: xcos45
end: xcos90
(for each 90 degree corner).
Last edited:
Hmmm. This is a PITA.
Okay for the wrap around part, this is going to be so hard to describe in words. Imagine where it curves round that it is in fact just a square/rectangle.
From where the curve begins to where the corner would be is the length of the radius of the circle (if it is a circle and not an elipse) you can then work out the circumference of that small part.
pi x diameter divided by 4.
Then you can just work out the straight lengths pretty easily.
Okay for the wrap around part, this is going to be so hard to describe in words. Imagine where it curves round that it is in fact just a square/rectangle.
From where the curve begins to where the corner would be is the length of the radius of the circle (if it is a circle and not an elipse) you can then work out the circumference of that small part.
pi x diameter divided by 4.
Then you can just work out the straight lengths pretty easily.
Like this?
Or not?
3DS Max \o/
Yup, nice one, very impressive.
I think I understand Mason-'s method of getting the length of the piece of plywood.
I am puzzled by the cosine formula, although it sounds complicated enough to be right.
Last edited: