very basic 3/1 twill handout

3/1 twill is very similar to double face. The threads follow the same rotation, but they are staggered. Instead of a line of floats that runs across the band in a straight line, you will get a diagonal line of floats across the band. The direction of the diagonal lines is determined by S or Z threading. Instead of having your dark threads in the same position on each card they will be set up in the following sequence.

The one pack method is a repeat of four lines. All cards should be threaded the same direction, either S or Z.

1st line: 2 cards forward, 2 cards backwards, repeating across the line.
2nd line: 1 card forward, 2 cards backwards, then repeating 2F and 2B across the line.
3rd line: 2 cards backwards, 2 cards forward, repeating across the line.
4th line: 1 card backwards, 2 cards forward, then repeating 2B and 2F across the line.
Repeat.  (Forward is away from your body, while backwards is towards your body)

The two pack method is essentially the same weave, but the cards have been split into two packs that roll in different directions.  The first two cards will be threaded S (with 1st card dark in front, and 2nd in top), and the next cards will be threaded Z (same dark positions). Slide the first card from each pair into a new pack away from your body. The original pack is A, the second pack will be B.

1st line: Both packs roll forward.
2nd line: Pack A backwards, Pack B forwards.
3rd line: Both packs backwards.
4th line: Pack A forwards, Pack B backwards
Repeat.

A chart of the ground pattern all warped S:

\ / / \ \ / / \ \ / / \ \ / / \ \ / / \
\ \ / / \ \ / / \ \ / / \ \ / / \ \ / /
/ \ \ / / \ \ / / \ \ / / \ \ / / \ \ /
/ / \ \ / / \ \ / / \ \ / / \ \ / / \ \

 The pattern works from the bottom up.  Forward turns are notated with /, while backwards turns are \.  If your pattern is Z threaded, these notations reverse, as does the slant of the twill.  If you look at the pattern you should be able to see the diagonal twill lines.  Just as in double face, color changes occur when cards moved in the opposite direction from that of the ground pattern.  These color changes must occur along the twill line in order to get a clean pattern.

A diagonal stripe of the light color:

\ / / \ \ / / \ \ / / \ \ / / \ \ / / \
\ \ / / \ \ / / \ \ / / \ \ / / \ \ / /
\ \ \ / / \ \ / / \ \ / / \ \ / / \ \ /
\ \ \ \ / / \ \ / / \ \ / / \ \ / / \ \
\ \ \ \ \ / / \ \ / / \ \ / / \ \ / / \
 \ \ \ \ \ \ / / \ \ / / \ \ / / \ \ / /
/ \ \ \ \ \ \ / / \ \ / / \ \ / / \ \ /
 / / \ \ \ \ \ \ / / \ \ / / \ \ / / \ \
\ / / \ \ \ \ \ \ / / \ \ / / \ \ / / \
 \ \ / / \ \ \ \ \ \ / / \ \ / / \ \ / /
 / \ \ / / \ \ \ \ \ \ / / \ \ / / \ \ /
 / / \ \ / / \ \ \ \ \ \ / / \ \ / / \ \
 \ / / \ \ / / \ \ \ \ \ \ / / \ \ / / \
\ \ / / \ \ / / \ \ \ \ \ \ / / \ \ / /
/ \ \ / / \ \ / / \ \ \ \ \ \ / / \ \ / 
 / / \ \ / / \ \ / / \ \ \ \ \ \ / / \ \
 \ / / \ \ / / \ \ / / \ \ \ \ \ \ / / \
 \ \ / / \ \ / / \ \ / / \ \ \ \ \ \ / /
/ \ \ / / \ \ / / \ \ / / \ \ \ \ \ \ /
/ / \ \ / / \ \ / / \ \ / / \ \ \ \ \ \
\ / / \ \ / / \ \ / / \ \ / / \ \ \ \ \
\ \ / / \ \ / / \ \ / / \ \ / / \ \ \ \
/ \ \ / / \ \ / / \ \ / / \ \ / / \ \ \
/ / \ \ / / \ \ / / \ \ / / \ \ / / \ \


The two center cards in the stripe move in the same direction as the neighboring cards instead of moving in the opposite direction, as on the ground weave.  These cards will show the light color instead of the dark.  If you want to turn this stripe into a zigzag, you will need to reverse the turning direction.  This will change the twill line from S to Z.  Here is an example of this change.

/ / \ \ / / / / / / \ \ / / \ \ / / \ \
/ \ \ / / / / / / \ \ / / \ \ / / \ \ /
\ \ / / / / / / \ \ / / \ \ / / \ \ / /
\ / / / / / / \ \ / / \ \ / / \ \ / / \
/ / / / / / \ \ / / \ \ / / \ \ / / \ \
/ / / / / \ \ / / \ \ / / \ \ / / \ \ /
/ / / / \ \ / / \ \ / / \ \ / / \ \ / /
\ \ \ \ / / \ \ / / \ \ / / \ \ / / \ \
\ \ \ \ \ / / \ \ / / \ \ / / \ \ / / \
\ \ \ \ \ \ / / \ \ / / \ \ / / \ \ / /
/ \ \ \ \ \ \ / / \ \ / / \ \ / / \ \ /
/ / \ \ \ \ \ \ / / \ \ / / \ \ / / \ \

For something as simple as this change, mirror imaging at the pattern change works.  However for more complex patterns, I recommend reading  Phiala's  explanation of charting 3/1 twill.

I'll be charting a S, or the S like shape from Mammon for the class, but I have not had a chance to play with graph paper today.