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I've been putting this off because it's hard to convey without pictures, and ascii art just doesn't have the angles available to depict it properly! I may, however, make an attempt. We'll just see how things go.

Pulling diamonds is a technique for tuning an African hand drum such as a djembe or an ashiko, which has a head of animal hide held on by rope that criss-crosses between metal rings.

First, some background.

In order to understand how to pull diamonds, you need to understand how the head of a drum is attached with rope. This involves three metal rings; two near the head, and one about halfway down the body of the drum. This bottom ring is kept there because its diameter won't allow it to ride any higher.

At the drum head end, there are two rings of the same size. The skin comes off the top, under both rings, up on the outside of the middle ring, and up on the inside of the upper ring. The rope attaches to the upper ring, and zig-zags between it and a smaller ring that stays further below towards the bottom of the drum.

           _   ___________________________
            \ /__    drum head
  ring---  O|||w |
           / ||o |
  ring--- |O ||o |
          \_/ |d |
              |  |
              |of|
              |drum
             
           bottom ring is down there |
                                     |
                                     v
The above shows a cross-section of the edge of the drum, with the two rings at the top, and how the skin of the drum threads between the two rings. It doesn't show the rope attached to the top ring, zig-zagging between it and the bottom ring. This zig-zagging rope forms "the verticals".

(There is actually a special method for attaching the verticals to the top and bottom rings. If I ever get around to noding it, I'l let you know!)

The heart of the issue:

When threading the rope between the top and bottom rings, one leaves the extra (hopefully 5 or 6 yards of rope, or more) coming off of the bottom ring, and uses it to pull the diamonds. Here's the sequence:

UNDER UNDER OVER UNDER

Basically, take the end of the rope and go under two of the verticals, then change direction. Go back over the last vertical, then under the first one.

Pull tight.

This will cause the first of the two verticals to snap over the other one, forming a triangle shape, because the two verticals, which had been perhaps a couple of inches apart, are now brought together.

One continues around the drum, bringing pairs of verticals together in this way, and that shortens them, tightening the drum head and raising its pitch. Once you get all the way around the drum, your weavings should be bringing pairs of verticals, that had been brought together, apart. Thus form the diamonds - triangles sharing one of their sides, which is the rope being threaded.

Here's how it looks when you have pulled a few rows of diamonds:


       v e r t i c a l s    t o   t o p

  | | | |           | | | |           | | | |
  | | | |           | | | |           | | | |
__| |_|_|___________| |_|_|___________| |_|_|______
__( (_______________( (______________ ( (_________ free end of the rope...
   \ / /             \ / /             \ / /
    / /               / /               / / 
   / / \             / / \             / / \
  / / \ \           / / \ \           / / \ \
 / /   \ \         / /   \ \         / /   \ \
/ /     \ \       / /     \ \       / /     \ \
 /       \ \     / /       \ \     / /       \ \
/         \ \   / /         \ \   / /         \ \
           \ \ / /           \ \ / /           \ \ / /
            \ \ /             \ \ /             \ \ /
             \ \               \ \               \ \
____________/ \_\_____________/ \_\_____________/ \_\__
___________( (_______________( (_______________( (________ wraps around ...
            \ / /             \ / /             \ / /
             / /               / /               / /\
            / / \             / / \             / /\ \
           / / \ \           / / \ \           / /  \ \
          / /   \ \         / /   \ \         / /    \ \ 
         / /     \ \       / /     \ \       / /      \ \
          /       \ \     / /       \ \     / /        \ \
 \ \   / /         \ \   / /         \ \   / /        
  \ \ / /           \ \ / /           \ \ / / 
   \ \ /             \ \ /             \ \ /
    \ \               \ \               \ \
___/ \_\_____________/ \_\_____________/ \_\___
__( (_______________( (_______________( (_________wraps around ...
   \ / /             \ / /             \ / /
    / /               / /               / / 
   / / \             / / \             / / \
  / / \ \           / / \ \           / / \ \
 / /   \ \         / /   \ \         / /   \ \
/ /     \ \       / /     \ \       / /     \ \
 /       \ \     / /       \ \     / /       \ \
/         \ \   / /         \ \   / /         \ \
 

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