DRS v. Scotch Tension

 

Are there really threads that cannot be spun with Scotch tension, but can be spun with DRS?

I have been challenged for my statements that DRS can spin things that cannot be spun with Scotch or Irish tension or Double Drive with slippage.

I can spin some fibers at grist twice their spin count with Scotch or Irish tension; still, I stand by my statement that DRS can spin things that cannot be spun with Scotch or Irish tension or Double Drive with slippage.  Here are my reasons:

1. Early in my spinning, I bought a digital tachometer, and kept records of how fast my wheel inserted twist. My Ashford Traditional with double drive and double treadles, straight out of the box would insert twist at about 700 rpm. This was about as fast as the wheels Alden Amos had in his living room (all single treadle, single drive) that we measured with his strobe. The fancy flyers Alden made for me changed the rate of twist insertion very little.  I made DRS bobbins/ flyer whorls at about the same diameter as Alden had used, and twist insertion about doubled.  Larger whorls gave me 30% faster twist insertion, e.g., 2,100 rpm.  This was counter intuitive, because I had a lower ratio, but was spinning much faster. It was clear that the ratio between the drive wheel and the flyer/bobbin whorls was not determinative.
2. I made a series of “accelerators”, and got a lot faster twist insertion, because I could use much larger bobbin/ flyer whorls so vibrations in the drive bands did not propagate around the whorls allowing slippage. This is general wheel design, and not directly related to DRS, but faster twist insertion facilitates spinning fine threads when using DRS.
3. My wheel, as currently configured, is 6 to 8 times faster than it was out of the box in 2006.  With DRS, the nature of drafting changes.  I cannot inch worm draft at 500 yards per hour. The continuous twist insertion and continuous take-up allow well prepped fiber with good crimp, to flow through one’s hands and the drafting triangle rapidly. Both hands must stay busy, one regulating flow of twist into the drafting triangle and testing grist. The other regulates flow of fiber into the drafting triangle and positions the fiber.  However, both processes are very fast. And any pause in the actions of either hand result in instant breakoff.  For anyone accustomed to Scotch or Irish tension, these breakoffs are – infuriating. On the other hand, I could never form thread this fast with Scotch or Irish tension. Physics and physiology suggest that nobody could draft thread this fast with Scotch or Irish tension.
4. That speed means if I want a special yarn for a pair of mittens, I can spin it in a day, rather than a week. A yarn that costs me only a day, maybe possible when a yarn that costs me a week may be impossible. Worsted spun, 5-ply gansey yarn for a sweater can be spun/plied in ~25 man-hours. That may be possible when I cannot invest 175 man-hours in a sweater that will take me only 90 man-hours to knit. A 175-man-hour project requires more storage, record keeping, and cleanup than a project that can be done on the patio in a long weekend. It is easier to maintain consistency over a 25-hour project than over a 175-hour project.

The realities of production spinning mean that threads/projects that my DRS system will spin easily,  cannot be spun with Scotch or Irish tension or Double Drive with slippage.