{"id":5750,"date":"2024-04-14T06:48:00","date_gmt":"2024-04-14T13:48:00","guid":{"rendered":"https:\/\/handweavingacademy.com\/?p=5750"},"modified":"2024-04-15T19:09:37","modified_gmt":"2024-04-16T02:09:37","slug":"who-or-what-is-an-ashenhurst","status":"publish","type":"post","link":"https:\/\/handweavingacademy.com\/who-or-what-is-an-ashenhurst\/","title":{"rendered":"How to calculate sett using Ashenhurst\u2019s Rule"},"content":{"rendered":"\n

Need to calculate sett for an unfamiliar yarn? Ashenhurst\u2019s Rule will help. In this blog post and its sequel, we\u2019ll explain how Ashenhurst\u2019s rule works and how you can apply it in your weaving.<\/p>\n\n\n\n

What is Ashenhurst\u2019s Rule?<\/h2>\n\n\n\n

Thomas R. Ashenhurst (1849-1902) was the chief instructor in weaving and pattern designing at the Bradford Technical College in West Yorkshire, England in the 1880s and 90s. In the course of writing several books, he compiled charts and mathematical equations useful to weavers of his time – and ours!<\/p>\n\n\n\n

To help solve one of the thorny problems of the day, Ashenhurst came up with a formula for determining the maximum possible sett for a fabric. His formula is based not on the subjective process of wrapping yarn around a measuring device Just So, but on an objective number: the yards per pound of the yarn used for warp and weft. <\/p>\n\n\n\n

Show me the formula!<\/h2>\n\n\n\n

There are actually two equations that make up Ashenhurst\u2019s formula. If you\u2019re only here to get the equations and run, here they are:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n

YPP <\/strong>is the number of yards per pound
D <\/strong>is the number of diameters per inch
EPR <\/strong>is the ends per repeat
IPR <\/strong>is the number of intersections per repeat
S <\/strong>is the maximum sett possible with the yarn in the structure<\/p>\n\n\n\n

That 0.9 multiplier assumes that the yarn in question is dense rather than lofty. If it\u2019s lofty, Ashenhurst recommends using 0.84 instead.<\/p>\n\n\n\n

Confused? Don\u2019t worry! The purpose of this post is to explain Ashenhurst\u2019s equations so that you can use his formula yourself..<\/p>\n\n\n\n

(Don\u2019t want to do the math? We have a handy Ashenhurst calculator that does it all for you! Plus lots of other tools, such as the Draft Editor and Twill Generator, inside the Academy<\/a>.)<\/p>\n\n\n\n

The next lessons explain what all those numbers mean, how to find them, and then how to plug them into the equation – or, if you\u2019re a member, into our Ashenhurst Calculator.<\/p>\n\n\n\n

The cheat sheet for plain weave and four shaft twill<\/h3>\n\n\n\n

Having said that, if you happen to be weaving plain weave or a twill on four shafts, then you can safely skip the complicated stuff related to EPR and IPR. Just calculate S using one of the following equations.<\/p>\n\n\n\n

The equation for plain weave:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The equation for a twill threaded on four shafts:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

IMPORTANT: the number produced is the maximum<\/em> possible sett, not the recommended sett! In our next blog post, we\u2019ll explain how to choose a more reasonable sett.<\/p>\n\n\n\n

What does his formula tell you?<\/h2>\n\n\n\n

Ashenhurst\u2019s equations tells you two things:<\/p>\n\n\n\n

    \n
  1. D = the number of yarn diameters that fit into an inch, and <\/li>\n\n\n\n
  2. S = the maximum number of warp ends and weft picks that can be jammed into a single inch of fabric with a particular structure. <\/li>\n<\/ol>\n\n\n\n

    Note that the second thing is the maximum possible sett, NOT a recommended sett!<\/p>\n\n\n\n

    For one thing, it would be very difficult to achieve this sett: you\u2019d have to pound the heck out of each and every weft pick to bash it into place and then keep it there. For another, fabric this dense would be very, very stiff. <\/p>\n\n\n\n

    If your goal IS a very dense and stiff – and durable! – fabric, then you might want to use a sett close to Ashenhurst\u2019s maximum. For most purposes, however, a lower percentage of this maximum is a more appropriate choice. We’ll talk about reasonable percentages in our next post.<\/p>\n\n\n\n

    Why is his formula useful?<\/h2>\n\n\n\n

    If it doesn\u2019t give you a usable sett directly, is Ashenhurst\u2019s formula really of any use? Yes, certainly!<\/p>\n\n\n\n

    It gives you more objective results<\/h3>\n\n\n\n

    The first thing it tells you is the number of yarn diameters that fit into an inch. This is just another way of saying \u201cwraps per inch\u201d. The advantage of using Ashenhurst\u2019s formula rather than wrapping around a ruler is that it\u2019s not as subjective. There\u2019s no worry about whether you\u2019re pulling the yarn too much, or squeezing the wraps too close together or not close enough. Using Ashenhurst\u2019s formula to determine diameters (wraps) per inch means you can\u2019t really go wrong. <\/p>\n\n\n\n

    It’s useful in more situations<\/h3>\n\n\n\n

    Ashenhurst\u2019s formula is also useful when the yarn is just too fine to make wrapping around a ruler practical. Wrapping a knitting yarn around a ruler might not be difficult, but imagine trying to do the same with sewing thread or 120\/2 silk!<\/p>\n\n\n\n

    It takes structure into account<\/h3>\n\n\n\n

    Ashenhurst\u2019s formula also takes the actual interlacement of threads into account more precisely than the usual \u201cuse half for plain weave, or two thirds for twill\u201d. 2\/3rds may be just right for four shaft twills, but twills on more shafts have different ratios and need a different multiplier.<\/p>\n\n\n\n

    WHEN is his formula useful?<\/h2>\n\n\n\n

    Ashenhurst designed his formula for cloth that <\/p>\n\n\n\n