Sunday, March 17, 2013

Motions of a Knitting Needle

A knitting needle is really a lever ( for moving loops of yarn. 

A knitting needle's position in space can be described by its pitch, yaw, and roll.  (   The needle changes pitch, yaw, and roll by rotation around a center of  rotation (or the fulcrum point, when the needle is considered as a lever).  Thus, a change in pitch allows both ends of the needle to describe arcs in space while the center of rotation has zero motion vector in space.  And a needle can vector in space without changing its pitch, yaw, or roll.   When a straight needle rolls, there is no apparent motion, but when a bent needle rolls, one or both ends of the needle describe arcs in space.

Moreover, a knitting needle can flex.

1)  The motions of a hand held held knitting needle are those of a class 1 lever, and limited to pitch and yaw, and the applied leverage is about 1:3.

2)  With a knitting stick and short, stiff, straight needles,  the motions are still limited to pitch and yaw, but the fulcrum is at the cow band, so it is a  class 3 lever with and the applied leverage is in the range of  1:20 to 1:40.  This takes a lot of stress off of the hands when knitting tight sock fabrics.

3)  With a knitting pouch,  long, straight, needles act as class 3 levers, and the traditional needles provide leverage of 1:40. With short needles the leverage is more like 1:20.  A common use is to reduce the stress allowing sustained knitting.

4)  In gansey knitting, the long needles flex, store energy, and that energy is then returned to the knitting stitch.  The effective leverage is very high e.g., (1:50)  This allows sustained knitting of very tight fabrics.

5) Swaving is different because the needle rolls. In swaving, one leg of the working stitch acts as one fulcrum, the knitting sheath acts as another fulcrum to produce a compound lever as the needle rolls.  ( effective leverage is very high e.g., ( more than 1:50)  This allows sustained knitting of very tight/ fine fabrics.

6)  In the various methods of knitting that use hooks, the needles vector, and there is essentially no useful leverage.  The motion is driven by the large muscles of the shoulders and upper arms, so it is a powerful motion that can produce very tight fabrics, but no mechanical advantage is gained.

Thus, in fact, there are 6 different hand knitting motions that competent knitters understand.  Each knitting motion has virtues and vices, which need to be understood.  Knitting sticks, knitting pouches, and knitting sheaths provide additional leverage for knitting fabrics that  cannot be reasonably knit with hand held needles by even the strongest and most expert knitters.  Anyone that thinks that knitting with 1:3 leverage can produce all the fabrics that knitting with 1:50 leverage can produce, simply does not understand the basic physics of their craft. 

When the Victorian Ladies of fashion established knitting as a leisure pastime (as distinct from a professional craft) they set the social conventions of the pastime.  Every pastime from cricket to horse racing and grouse hunting has social conventions.  One of the social conventions of knitting as a pastime was that both needles must be hand held. This did away with professional knitting techniques   All modern knitting needles from Faberge to Signature to the various cable needles, all have the same leverage.  Long (gansey) needles, used as hand held needles still have the same leverage, and provide no advantage.  Any knitter that used a knitting sheath or knitting stick was not considered a person of fashion.  If you wanted to use a knitting pouch or knitting sheath, you had to do it behind the closed doors of a commercial establishment or live someplace like Shetland.

This social convention limited the leverage available to the leisure knitter. It provided a level playing field, the difference in quality between any two samples of knitting was the skill of the knitter, and a knitter could not use different tools to knit better.  This social convention took knitting technology off the table. The mind set that knitting technology does not matter persists. 


Kathe Lewis said...

Hi Aaron

Would it be possible for you to make close-up videos seen from your side of the knitting, showing the lever function in the knitting needles in the techniques you mention?
In slow motion, and in full speed to give an idea of how effective it is?

One aspect I believe was a factor in the leisure knitting was that it really didn't matter how long it took to finish a project, so effectivity was not an issue.
Personally I think that the fabrics made this way was supposed to be looser and softer with a luxorious feel as upposed to the strong, tight hardwearing fabric of the professional knitter.
In Denmark the leisure knitting survived in an unbrokrn tradition, but the use of knitting tools was forgotten. Such a shame.

Aaron said...

I agree that knitting luxury objects showed that the knitter had leisure time. The longer it took, the more it demonstrated the knitter that the knitter had large amounts of leisure time.

I simply mark the points of contact on the needle with an ink marker, and measure. I do it over and over and get an average. Since it is ratios, you can freeze a video and use a pair of dividers to measure ratios of distance of the various points of contact.

The only really hard one is swaving,with its complex lever.

Elizabeth McMurrey said...

Hi Aaron,

I was wondering if the knitting sheath can be used by someone with only one hand? I used to be a pretty prolific knitter and found it very relaxing. Then recently, as a side affect of cancer had to have my left arm amputated above the elbow. I have been looking for ways to regain my beloved hobby and wondered if you have any experience with someone with my challenge. Thanks,

Aaron said...



I had a left handed pit knitter, and I got her belted up and turned to help other students. Fifteen minutes later, I turned back to her, and she was knitting one handed. I knew there were stories of knitters in the Dales knitting one handed, but I had never really believed them. Since then, I had another student show up for the second lesson knitting one handed. Both were left handed, and I have never seen competent one handed knitting in a right handed knitter.

That said, it is not easy, and I have certainly not put the effort in to learning to do it well enough to confidently teach it.(e.g., doing it right handed or left handed - it would be a good cause, but I have not followed up on it.

On the other hand, I do give knitting sheaths to disabled knitters at no charge.

Unknown said...

That's a very generous offer. I do have some other things I'm looking into as well (perhaps with less of a learning curve). I am getting a prosthetic so that should help as well it just may be a while. Thanks for letting me know about this.


Anonymous said...

How would you know that swaving is hard? You clearly have no idea what swaving really was despite your claims.

Aaron said...

From the tools and the descriptions of the motion, I knew what the physics of the process were. Then, it was just a matter of working out what the ergonomics were. Once that was worked out, I had a family of techniques that were very fast, produce fine fabrics, and are easy on the hands. You seem to have missed the point that while what I call swaving is technically difficult, it is very ergonomic and easy on the hands, wrists, and arms. Variations can be done right handed, left handed or upside down, it is still the same physics -- the same kind of knitting.

You are just whining that I have not provided YOU with enough evidence to convince you. You have not said that it is not swaving because swaving was a particular motion and I use a different motion.