Author Topic: Dividing  (Read 1947 times)

Offline chipenter

  • Hero Member
  • *****
  • Posts: 705
  • Country: gb
Dividing
« on: August 23, 2015, 02:26:51 PM »
A case of I thought I had ! or not how to do it . Thats an awfull photo  behind the reflection I missed one line and now have 12 degrees insted od ten
« Last Edit: August 23, 2015, 02:53:43 PM by chipenter »
Jeff

Offline Fergus OMore

  • Hero Member
  • *****
  • Posts: 959
Re: Dividing
« Reply #1 on: August 23, 2015, 04:19:55 PM »
My Quorn has 359 divisions. Lost the other one. Small reward only if found! :wack:

Norman

Offline DavidA

  • Hero Member
  • *****
  • Posts: 1167
  • Country: gb
Re: Dividing
« Reply #2 on: August 24, 2015, 01:59:27 PM »
On another site I was discussing the Anti Kythera mechanism.

I got to wondering 'how would an ancient Greek, or even a youngish Greek in ancient times, mark out a large(ish) gear prior to hand cutting prime numbers of teeth ?'

How would you folks do it ?

Dave.

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5426
  • Country: gb
  • East Sussex, UK
Re: Dividing
« Reply #3 on: August 24, 2015, 02:38:21 PM »
Fix it to a large wooden disk and inscribe the divisions on the periphery using a pair of dividers and a few iterations to adjust them to the right spacing.
Andrew Mawson
East Sussex

Offline ieezitin

  • Hero Member
  • *****
  • Posts: 674
Re: Dividing
« Reply #4 on: August 24, 2015, 05:35:08 PM »
I would use dividers but let me answer for the Greeks...

They could have laid a rope equaling the linear length of the circumference and tied knots in it equaling the amount of divisions needed, they could have found the chord length then transferred it to the circumference, we know they new PI and the golden ratio, geometry was a doddle to them.   

The angle of the pyramids comes from sand falling from a bucket with a hole in it, and the base to height are equally proportional they were 2500 years before the Greeks, we know the Greeks new it all as the Romans stole there work. 

To sum up... all you need to build a pyramid is a bucket with a hole in it, sand, a round wooden wheel (any diameter) 1.8 million tons of stone from a quarry 600 miles away from your building site and a unionized work force of 100,000 men working two shifts.

Hope this helps.

Anthony
If you cant fix it, get another hobby.