Wednesday, April 5, 2017

Weaving, the Original Programming Project

I just properly used the Excel SUMPRODUCT function to calculate the number of heddles I'd need on each shaft for my upcoming Summer and Winter weave structure project.  It is a real pain to have to move the heddles around once threading has started.

Here's the draft:

Summer and Winter is one of the ways where weaving gets, oh, complicated.  It is a block structure, where groups of ends (warp threads) can be aggregated as necessary to get the end result.  Software people, think subroutine.

In Summer and Winter, each block has 4 threads, and, with an 8 shaft loom, I can have 6 blocks.

Here's the profile threading draft:

As you can see, there's a start, a repeat (3 times), and a finish.

The numbers at the far right are the count of each block in the repeat.

I then totaled up the number of blocks for threading:

start/end pattern  total
A   2     6
B   7     21
C   4     12
D   6     18
E 4 4     16
F 9 9     36

Then created a table with the count of each heddle per shaft used in each block, and did the SUMPRODUCT thing with the total number of blocks and the heddle count within each block.

Heddles per shaft
1 2 3 4 5 6 7 8
A 1 1 2          
B 1 1   2        
C 1 1     2      
D 1 1       2    
E 1 1         2  
F 1 1           2
109 109 12 42 24 36 32 72

So, 109 heddles each on shafts 1 and 2 and much fewer on the other 6.  Which says I don't have to move any around, and can get to beaming on and threading.

I also had to do calculations to work out how to get complete pattern repeats in the width and length - there are 128 threads in the pattern repeat, and I wanted to weave 22" wide.  It worked out to 20 epi (sett, ends/threads per inch), including a selvage.  There was a bit of modeling to work that out, also accomplished via Excel.  There will be 3 pattern repeats width-wise and 5 length-wise.

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