Thursday, June 23, 2016

The Path to the Truth.

Run a test.
Do tests for significance.

Repeat until required significance is achieved.  For something like hand spinning or hand knitting, 30 trials is likely enough. All that is required is:

 A digital tachometer for various measures of revolutions per minute.
A stop watch and calculators (cell phone).
Needle gauge.
Rulers/ tape measure
Dividers to transfer measurements.
Vernier calipers for measuring small objects.
Scale to measure mass

The tape measure is used calibrate the skeiner, so I have accurate lengths of yarn.
mass divided by length is = grist; minimum weight measured by this scale is 0.5 gram, so samples need to be 10 grams or larger to get 5% accuracy. Mostly I work with 10s (560 yd/ 45 grams), so this is not a problem. If spinning 80s, then yes, I need to spin at least 1,000 yards to get a good grist measure.  (When I was considering entering Longest Thread, I also had a jeweler's scale. )

I have measured the grist of many commercial yarns, and am very confident of my measures of grist.

I have measured the grist of many yarns by measuring wraps per inch  (when packed to refusal)  and compared that measure of grist to the grist calculated by length divided by mass.  There is good correspondence, which gives me confidence in both methods.

I  use DRS to insert a known amount of twist into my hand spun singles.  Twist strongly affects grist, thus controlling the twist, allows me to produce 10 consecutive  hanks of the same kind single that vary in weight by no more than plus or minus 5%.  The grist of all of my hanks gets measured, both singles and plied or cabled yarns.  It has been years since I produced a hank that was as much as 10% off the desired grist for that hank.  And, even then light singles would be plied with heavy singles to produce finished  5-ply yarns within 5% of the desired 1,000 ypp.

The beeline to truth is  measuring, logging, and doing statistics. Statistics tells us that measuring 30 samples is about where good confidence begins.  Spin 30 hanks (16,800 yards) and measure the weight of each hank. If all are within 5% of the mean, then for a hand spinner, you have very good control over the process.

The path to the truth is to measure 30 samples.  If you are knitting, take 30 distinct measures of spi and rpi for that combination of yarn, needles, stitch and technique. I want density for needles and yarn with  hand held needles, gansey needles/ sheath, and swaving, so I  knit and measure a lot of swatches.  For example, I have knit more than 30 pounds of MacAusland yarns, and I know the gauge and needles for every object.  For years, I knit/swaved the medium weight on 2.38 mm needles.  Then my skill improved and now I knit it on 2 mm. On the other hand, my Rose Garden Sweater was knit from MacAusland 3-ply heavy on 3.17 mm needles, and it was perfectly weatherproof for the first few years of its life.  And, I know the difference between fabrics knit on US 3 and US2 or US1 needles, because I measure such things.  What some would call "paralysis by analysis, I call, " Giving Mother Nature the last word." The rest of that yarn package went to socks and mittens for folks at  the north end of the Endless Mountains.  Some had diabetes and tended toward cold feet.

The truth always comes to those that measure, measure, measure, and then do the math.

In the old days, spinners got paid by the yard.  They knew how much yarn they spun. They got charged for the wool.  They knew the grist of everything they spun.  They measured and did their bookkeeping like any business. Spinners that did not do their bookkeeping are the foolish ones.

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