Thursday, April 19, 2012

The sum of what I know about spindles

I have often said that I do not really understand spindles.  It turns out that part of  the problem was that I did not like modern spindle designs for the kind of singles that I was trying to spin.  The conventional wisdom of modern spindle design did not apply to what I was trying to do.

Here are spindle designs that work for me.  They are designed to spin 9,000 to 12,000 ypp singles at a good rate of speed.  The removable whorl allows continued high speed spinning even after the the copp gains enough mass to affect the rotation speed of the spindle - just take the whorl off and use the copp for rotational momentum.  The materials are rosewood  or ash shafts and ebony or cocobolo whorls.  The  whorls are in the shape of perforated truncated cones. These are more effort to fabricate than cylinders or disks, but are traditional, and do seem to work better. I use steel hooks and brass brads on the bottom.

For a short time, someone using a Peruvian folk spindle

might be able to keep up while spinning 10,000 ypp singles, but not for long - the physics are against it. For a spinner to try and spin 10,000 ypp singles on such a large whorl spindle means that they do not really understand the spindle. Certainly, it can be done, but it is a lot of effort.  With the correct spindle, it is much less effort. On the other, hand spinning the low grist yarns in the photo above using one of my spindles designed for fine spinning would be a huge effort.  It could be done, but it would be a huge effort.  A spinner that understands spindles, chooses the right spindle for the task.

Teachers that say, "A good spinner can spin anything on any spindle" either do not understand the physics of spindles or they do not care if their students waste time and effort by working with the wrong tools.

As the copp grows, the rotational speed of the spindle declines, and with a large copp, the additional weight of the fixed whorl limits the maximum rotational speed of the spindle. This is the reason for a removable whorl.  It makes spinning that last third of the copp much faster.

Let us consider a recreational spinner drafting 100 inches per minute. If spinning singles to make 2-ply worsted weight yarn, then the spinner needs ~400 or 500 rpm, (average) and 3 inch whorls work very well. If the spinner is spinning 6,000 ypp lace singles then they need ~ 900 rpm to get the twist to hold the yarn together, and for the same weight whorl, it should be ~1.5" in diameter. (However, likely it will be lighter.)  My whorls have an average diameter of ~1".  A  10,000 ypp single requires 3 times as much twist per inch as  a 1,600 ypp single.  Thus, for me to spin 100 inches per minute, I need to average more than 1,200 rpm to insert the twist to hold that fine single together.

Spindles store energy! Twist is energy! Twist energy is inserted into the yarn from rotational energy stored in the spindle. If a spindle keeps spinning for a long time then it is slowly transferring energy to the yarn, that is: it is spinning slowly!  A belief that a spindle can transfer energy to the yarn and keep rotating is a belief in perpetual motion.  A spindle that slows down and stops, is a spindle that is doing its job.

The spindle with the smaller diameter whorl is going to spin faster. It is going to transfer its energy faster. Then, it is going to slow down and stop - it has done its job.  It is a fast worker.

Tools matter!  Any tool that can be made, can be made better.

ETA 4/23 Lignum is better than ebony for whorls.

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