Mechanical spinning does three jobs at once: it drafts a thick strand of loose fiber down to the thickness of the finished yarn, twists it so the fibers grip one another, and winds the yarn onto a bobbin. Twist is the setting that matters most downstream, because yarn meant as loom warp needs about 18-25 twists per inch at a medium count, against about 12-18 for weft.
Part of Spinning Frame
How a spinning frame converts prepared fiber into yarn by drafting, twisting and winding, and what the loom downstream asks of the result.
Draft, Twist And Wind Are Three Jobs On One Machine
A hand spinner does the same three jobs one after another: pull the fiber thinner, let twist run into it, wind it on (Spinning teaches the rhythm). A frame does them continuously, which is why the Spinning Frame overview puts one frame at the work of 50-200 hand spinners.
- Drafting pulls the strand thinner. The overview defines the draft ratio as input thickness divided by output thickness, typically 10:1 to 30:1. Read “thickness” as mass per length, not diameter: the fiber in must equal the fiber out, so a strand drafted 20:1 weighs one twentieth as much per metre. The diameter falls only by the square root of that.
- Twisting rotates the drafted strand. Twist makes the fibers press on each other, so they hold under tension. More twist means stronger but stiffer yarn, up to a limit past which strength falls again (Spinning Singles gives the twist-angle table for hand-spun cordage).
- Winding collects the yarn on a bobbin at the speed it is delivered.
Twist is the one you set deliberately and the one the loom tests hardest.
Yarn Is Made To The Loom’s Order
The loom treats the two thread systems differently. Warp is held under tension for the whole length of a piece of cloth and is rubbed by the heddles and the reed on every pick. Weft is used once, laid in and beaten up. So the overview’s twist targets split:
| Use | Twists per inch (overview) | Why |
|---|---|---|
| Weft | 12-18 | Softer, fills the cloth, needs little strength |
| Warp | 18-25 | Must survive tension and abrasion for the whole warp |
These ranges belong to a medium yarn, the overview’s example being Ne 20 (about 29.5 tex; Thread Count System shows the conversion). A finer or coarser yarn needs more or fewer twists per inch for the same behaviour; Twisting shows how the figure scales. A frame that cannot hold the warp range, because the spindle drive slips or the draft is too long for the fiber, produces yarn the loom cannot use. The Power Loom Construction overview is written to the same Ne 20 yarn.
The Frame Is A System, Not Just A Machine
A frame needs three things before it spins anything usable:
- Prepared fiber. Cleaned, carded and drawn to a sliver, then to roving (Mechanical Carding, Roving Frame). Hand-card preparation is in Fiber Preparation; that article notes combed fiber makes stronger yarn for warp and carded fiber softer yarn for weft.
- A steady drive. Twist per inch is spindle speed divided by delivery speed, so a drive that slips on the spindles but not on the rollers quietly lowers the twist (Drive System).
- Someone who can fix it. Spindles wear, rollers get cut, belts stretch. A frame without a person who can re-turn a spindle or recover a roller is a short-lived frame.
Worked Example: Tracing The Fiber
Start from a roving of Ne 1.0. Ne 1.0 is 590.5 tex (840 yards per pound, converted in the count article), and a draft of 20 gives 590.5 ÷ 20 = 29.5 tex, which is Ne 20. This sits inside the overview’s 10:1 to 30:1. If the roving came from a sliver that the roving frame reduced 5-10 times (the overview’s 1/5 to 1/10), the sliver was 590.5 × 5 = 2,952 to 590.5 × 10 = 5,905 tex, 3-6 g per metre. From sliver to yarn the total draft is 2,952 ÷ 29.5 = 100 to 5,905 ÷ 29.5 = 200.
Common Mistakes
- Treating the draft ratio as a diameter ratio. A 20:1 draft does not make a yarn one twentieth as wide.
- Setting twist for the finished article, not for the loom. Soft yarn that suits a shirt breaks as warp.
- Judging the frame by its output alone. The measure is how many ends the loom loses per hour on that yarn.
Safety
A frame cannot be stopped from where you stand
Rollers, flyers and the spindle drive are connected to a belt or line shaft that keeps turning after you step away. Stop points, coasting and the roller nips are covered in Drive System and Doffing. Tie hair back, keep sleeves buttoned and never clear a break on a moving frame. This is adult work; see Task Assignment by Age, which keeps children away from running machinery.
What’s Next
- Learn next: Drafting — how the roller pairs thin the strand
- Combine with: Thread Quality Control — measuring whether the yarn will serve as warp