Sunday, January 25, 2015

Power

Somebody said they wanted a wheel that was fast and easy to treadle.

However, on a high ratio wheel that will insert twist at thousands of rpm, each stroke of the treadle must deliver as much energy as 3 or 4 strokes of a lower ratio wheel.  Thus, the force behind each stroke of the treadle must 3 or 4 times greater than the force required for a wheel inserting only a 1,000 rpm of twist.

If your wheel produces 200 yards per hour of a yarn, and  my wheel puts out 600 yards per hour of the same yarn, then I have to treadle 3 times as hard as you, to twist 3 times as much yarn in the same time.  It can be done, it is like bicycling at a good pace up a gentile incline - just that one does not get to coast down back down the hill.  All that energy of the "climb" is captured as twist in yarn, rather than as potential energy on a hill.

Folks sit down at my wheel and say, "Oh, my god, that is hard to treadle!" Yes, it is ~3-times as hard to treadle because it is making yarn 3-times as fast.

There are good lunches, and there are fast lunches, but there is no such thing as a free lunch. Twist is energy, and it must come from somewhere. There is no such thing as "free energy".


The closest thing is :  http://en.wikipedia.org/wiki/Gibbs_free_energy

4 comments:

Advo said...

Hello, in a recent discussion the question came up just how much many man-hours it would have taken to produce a shirt prior to the industrial revolution. Someone stated that it took 400 hours to spin the required yarn (1500 yards).
The source is this link:

http://www.sleuthsayers.org/2013/06/the-3500-shirt-history-lesson-in.html

I believe that figure is way too high, but I have not been able to find reliable figures online just how much (wool) yarn a skilled medieval/rennaissance spinner might produce per day, by hand-spinning or with a wheel. How much yarn do you think can be produced per day with a drop spindle or other hand-spinning techniques?

Aaron said...

It depends on what "shirting" is.
assume a "shirt" requires 4 yards of fabric.

I think if one can weave enough cloth for a shirt out of 1,500 yards of thread, then the yarn is too thick to produce "shirting". If you want to produce such heavy, coarse fabrics, then you can divide my numbers by ~3.5.

I find that 5,600 ypp singles tend to bed and fill differently than mill spun and make a reasonably shirting fabric. At 24 epi / 24ppi that comes to about 7,500 yards of thread in the cloth. With my wheel that is 3-days (20 hours) of spinning and most of a day on the loom for a total time of ~30 hours (assuming that loom set up is distributed over a bolt of 40 yards.)

Real shirting at 22,400 ypp would take a little more than twice as long for spinning, so just over 5 full days (45 hours) of spinning and 1.5 days for the weaver, so a total of about 7 days (60 hours), because the shirting singles are more difficult to handle.

I see no reason why my gear should be faster than the wheel/loom of a professional spinner circa 1600.

Assuming a great wheel of 1,200 CE, then spinning time would about double for spinning times of 32 hr and 90 hours for the 2 different gristes.

Assuming drop spindles in Flanders circa 800, I would expect spinning times of 60 hr and 120 hours.

However, it is easy to spin a pound 1,500 ypp semi-worsted with a spindle in a couple of days. And such thick semi-worsted can be used as warp. Thus, if one assures only 1,500 yards of yarn for a shirt, it can be spun on a drop spindle in a couple of days. However, the Greeks and Romans had better and finer fabrics,

vampy said...

I was the one (or maybe one of a few) who said they'd like a wheel that was fast and easy to treadle. While I am aware that all the energy the for turning the flier has to come from my legs, so more speed needs either faster treading or a smaller whorl, which means more effort per treadle, not all wheels are created equal.

A wheel with wonderfully smooth bearings, which made no noise, with a perfectly balanced flyer, would lose less energy to noise/friction/useless movement than one which could go fast but wasted a lot of that energy. That is the sort of wheel I want, one that is very very well made. And if anyone ever makes one at a price I can afford, I will get one. Until that happens my physical limitations mean that I will have to spin as fast as I can allowing for the fact that i want to be able to use a wheel for more than 5 minutes before i feel pain or fatigue, as in the long run, even if your wheel is 3 times faster than mine, if i could only use such a wheel for a couple of minutes, I wouldn't get much yarn made.

Aaron said...

My wheel evolved to spin a lot of fine singles for the kind of fabrics that I wanted to produce.

My wheel is not meant to be all things to all people.

On the the other hand, some traditional spinning wheels that seem flimsy and shaky treadle very easily. At one time, I thought the "flimsy and shaky" was just because they were old. Now, I see some of that flimsy and shaky as good design to dissipate vibration generated in the drive band.