Twist per inch equals spindle speed in revolutions per minute divided by the yarn delivered per minute in inches, so to raise the twist you slow the front rollers or speed the spindle. For a medium yarn of about Ne 20 aim for 18-25 twists per inch if it will be loom warp and 12-18 if it will be weft, and scale the figure with the square root of the count for any other yarn.
Part of Spinning Frame
Inserting twist into drafted fiber at a set rate so the yarn holds together and carries load.
Twist Is Set By The Ratio Of Two Speeds
The flyer (or spindle) turns the yarn once per revolution, while the front rollers feed yarn forward at their own surface speed. The twist in each inch of yarn is the number of turns that went in while that inch passed:
twists per inch = spindle rpm ÷ inches delivered per minute
Winding on does not change this; only the flyer or spindle speed and the front roller speed do. The loom depends on that number, so it is the setting to protect.
Twist Must Scale With Yarn Count
Two yarns of the same fiber but different thickness behave alike when their twist angle is alike, and for the English cotton count Ne the standard relation (recalled, not from the corpus) is:
twists per inch = twist multiplier × √Ne
The overview’s ranges are for a medium yarn, its example being Ne 20, where √20 = 4.47. Dividing gives the multiplier those ranges imply: warp 18 ÷ 4.47 = 4.0 to 25 ÷ 4.47 = 5.6, and weft 12 ÷ 4.47 = 2.7 to 18 ÷ 4.47 = 4.0. Holding these multipliers for other counts gives:
| Count (Ne) | Tex | Warp twists per inch | Weft twists per inch |
|---|---|---|---|
| 10 | 59.1 | 12.6-17.7 | 8.5-12.6 |
| 16 | 36.9 | 16.0-22.4 | 10.8-16.0 |
| 20 | 29.5 | 17.9-25.0 | 12.1-17.9 |
| 30 | 19.7 | 21.9-30.7 | 14.8-21.9 |
A finer yarn has a smaller diameter, so the same twist angle, which is what makes yarns behave alike, takes more turns per inch. Quoting “18-25 twists per inch” without the count is meaningless. The table extends the overview’s figures by this formula; check it by Twist Testing and by weaving a trial warp.
Too Much Twist Is Also A Fault
More twist raises strength only up to a point. Past it the yarn kinks, hardens and loses strength; the cordage table in Spinning Singles puts excessive twist at 50 degrees and over. Soft yarn breaks under warp tension; hard yarn snarls and is harsh to weave. The overview’s note that more twist is stronger but stiffer holds between those limits.
Method: Setting And Verifying Twist
Step 1: Decide the use and count. Warp or weft, and the Ne or tex.
Step 2: Pick a twist from the table and compute the delivery needed: inches per minute = spindle rpm ÷ twists per inch.
Step 3: Set the front roller speed by its gear or pulley to match, then run and measure the delivered length in a minute.
Step 4: Measure the twist on a sample (Twist Testing) and adjust the change gear.
Worked Example
The spindle speed is an assumed input of 2,000 rpm (no sourced figure was found; time your own frame). At 20 twists per inch the delivery is 2,000 ÷ 20 = 100 inches per minute = 2.54 m per minute = 152.4 m per hour. At 12 twists per inch (soft weft) it is 2,000 ÷ 12 = 167 inches per minute = 254 m per hour. At 25 (hard warp) it is 2,000 ÷ 25 = 80 inches per minute = 122 m per hour. Warp costs about twice the spindle time per metre that soft weft does. If the spindle drive slips 5%, a nominal 20 becomes 19; to be sure of at least 18 under 5% slip the nominal setting must be 18 ÷ 0.95 = 18.9, so at least 19.
Common Mistakes
- Using the weft setting for warp to gain output, then losing the saving to broken ends on the loom.
- Comparing twist across counts without the √Ne scaling.
- Setting twist at a stalled frame. Twist is a ratio of two speeds; check it with both running.
Safety
The spindle is a fast, unguarded rotor
A flyer arm at thousands of revolutions per minute strikes hands and catches hair. Keep hair tied, sleeves buttoned and hands away while it runs; stop the frame and wait for the flyers to halt before touching any part. See Flyer Mechanism for the force on an unbalanced arm.
What’s Next
- Learn next: Winding On — collecting the twisted yarn on a bobbin
- Combine with: Thread Count System — the counts the table is indexed by