TPI – Or how to spin the yarn you want using….gasp Math!

I started down the path of the Master Spinner Program because I needed something that was mine.  Not mine and my kids, or my husband, just mine.  I learned to spin in highschool on a spindle and dabbled through college and then put it all away when I had babies.  When my youngest at the time was 5 and in Kindergarden, I finally made it to my first official spinning meeting with a local guild.  I sat down at a wheel for the very first time.  I came home and told my husband that I really needed this.  Luckily my man totally supports my hobby.  So two days latter I bought my first wheel and started spinning.  Almost from the first moment I had all of these questions. The problem is that I did not know enough to even begin to comprehend the answers.  I started reading spin off.  At that point when they highlighted a yarn in a project, they gave the readers all sorts of information about that yarn.  These were numbers proceeded by letters like TPI and WPI. along with ratios at which they were spun and what kind of wheel and drive was used.  I can remember asking a fellow spinner what it meant and she told me you only used that if you wanted to recreate a specific yarn and that she just spun one of a kind yarns all the time.  Well I WANTED to spin yarn that I could recreate.  I wanted to be able to look at a pattern and spin the kind of yarn they called for.  I also NEVER wanted to process my own raw wool either…. but that is another story.  Anyway, it was the desire to have the ultimate control over my fiber and my yarns that brought me down the road to the Master Spinners program.

I DO NOT spin art yarn.  I have NO desire to spin art yarn…. There have been assignments in this program that require art yarn, and then I have to say what I would use it for…. Composting is a frowned upon answer FWI.    So I have tactfully learned to say accent yarn…  Which I might conceivably use… Anyway, I digress.  TPI.

TPI or twists per inch is used to measure basically how fine of a yarn you are spinning.  In reality you take a plied yarn and count how many ply bumps there are in 1 inch and divide by the number of plies. 015  If there are 8 bumps per inch on a two ply yarn, then your TPI is 4.  On a finished skein, you can see that figuring out TPI is relatively simple.  What is difficult is deciding what TPI you want your yarn to be before spinning and then achieving it.  In order to even attempt such a feat, you must know your wheel ratios.  You can use the ratios you were given by the manufacturer, or you can check for your self.  Basically you count how many times the bobbin rotates per one revolution of your drive wheel.  I now have these numbers posted inside my notebook where I can find them in a moments notice.  I have to say there was a time in my life…. about 5 years ago when I would have laid my head down and cried to have to make these calculations.  Math was HARD.  REALLY HARD..  Then I began homeschooling my 3 children.  I now understand things about math that I am pretty sure I never really got when I was going through school… and I went all the way through Calc and Trig.  So It’s not like I wasn’t smart.  Math has just always been hard.  However, with the correct equations and knowledge of the steps and lots of notes, this does not have to be that hard. REALLY.

My first TPI assignment.  Spin a yarn with a TPI of 1.  TPI correlates directly with the thickness of your yarn, lower TPI thicker yarn.  See here BULKY.  As in 2 ply bumps in 1 inch.  For this assignment, I knew that a fine wool was NOT the best option.  Definitely a long wool should be the way to go.  Luckily for me my aunt just gave me a large amount of both Romney and Lincoln roving… I don’t know if I have mentioned before that I am not a huge fan of longwools.  Don’t get me wrong, if you are a weaver, they are amazing.  I am a knitter.  I like fine wool…. enough said.  So I get this Lincoln Roving out.  It is semi felted from sitting in my cousin’s trunk for months….  Perfect!  I do my calculations.  I need a REALLY low ratio on my drive wheel. So my Luet s10 is the logical option.  Not only does it have a huge bobbin for bulky yarns, it also has a large orifice and a ratio of EXACTLY 5:1.  No fractions.  I sit down and do my math.  In order for me to get a TPI of 1 I need to draft 3 inches per one treadle.  (when counting treadles on a double treadle wheel you only count one foot.  I count everytime I treadle with my right) Think about that, one treadle per 3 inches….  I am very worried about the integrity of this yarn. 014 013   However, along the way I pause and check the TPI on my singles and the result is a bouncy, soft, cushy yarn.  WOW and it’s Lincoln!  I think I may have found the place at which I like longwools.  It’s kind of amazing.  I am thinking that 1 TPI yarn is really not a practical goal for everyday.  It is really hard to get the evenness in your spinning as you can see from the picture.  This yarn has serious integrity issues.  My guess is that a 2 or 3 TPI long wool would give the integrity and consistency one would want without loosing the squishy bouncy softness.

You will note, I did not include the equations for getting TPI here.  It was just too much effort to type it all in.  Perhaps in another post I will take the time to do a step by step how to on it.



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