Wind weft onto small bobbins with a belt- or crank-driven spindle and a thread guide that traverses the bobbin, at an even, light tension: loose spots tangle and tight spots break. A loom running 100 picks a minute uses 100 m of weft a minute, so on an assumed 25 mm bobbin the winder spindle must turn about 1,270 rpm to keep one loom supplied, which needs a belt drive, since a hand crank at 60 rpm would need 21:1 gearing.
Part of Power Loom Construction
Preparing weft bobbins that fit inside the shuttle, at the rate a power loom consumes them.
The Winder Must Keep Pace With The Loom
The overview’s bobbin winder is a spindle driven by a belt from the main shaft or a hand crank, with a thread guide that traverses the bobbin length. The weft must be wound at consistent tension: loose spots cause tangles, tight spots break the thread.
How fast must it be? The reference loom uses 1 m of weft per pick, at 100 picks a minute, so 100 m a minute (Shuttle Mechanism). The yarn goes on at π × D × rpm. For an assumed mean winding diameter of 25 mm:
- rpm for 100 m a minute = 100 ÷ (π × 0.025) = 1,273
- a hand crank turned at 60 rpm needs a gear ratio of 1,273 ÷ 60 = 21:1
The corpus puts one person’s steady arm power at about 50 W and shows a hand crank geared up many times (Hand-Cranked Centrifuge). A winder takes little power, but one person cranking at 21:1 gearing at that speed is doing nothing else; the winder is a continuous job, or a belt-driven spindle. One winder spindle per running loom is the minimum on these figures, and a spare for breakdowns.
What You Need
- A spindle that holds a bobbin, in good bearings (Bearings and Bushings).
- A traverse guide that moves back and forth along the bobbin once the layers are built.
- A tension device: a pair of disks or a pad the yarn passes through.
- A drive, with a stop that can be reached from the winder (Power Drive System).
- Source cones or bobbins of weft yarn, with the soft twist of 12-18 per inch (Twisting).
Method: Winding Weft
Step 1: Fit an empty bobbin that matches the shuttle, with a smooth barrel.
Step 2: Thread the yarn through the tension device and the guide and tie it to the barrel.
Step 3: Start slowly, check the layer pattern, then bring the spindle to speed.
Step 4: Watch tension. The yarn should run firmly but not hard; a humming, taut line is too tight.
Step 5: Stop at the target diameter, which must leave clearance in the shuttle hollow.
Step 6: Inspect while winding. Knots, thick places and weak spots can be removed here at low cost, much cheaper than finding them in the shuttle.
Worked Example
A 25 g bobbin (assumed) holds 25,000 mg ÷ 29.5 mg per metre = 847 m of Ne 20 weft. At 100 m a minute it takes 847 ÷ 100 = 8.5 minutes to wind, equal to the time the loom takes to use it. So the winder stays exactly in step with one loom, with no slack for a stop to clear a knot. With two spindles on a winder, one fills while the other is changed, and a stock of 3-4 full bobbins at the loom (a design choice, not sourced) absorbs the stops.
Common Mistakes
- Winding hard to fit more yarn, which stretches it and makes the weft shrink up in the cloth.
- Uneven layers, which pull off in lumps.
- Oversized bobbins that jam in the shuttle.
- No inspection at the winder.
Safety
A winder is a fast spindle on a belt
A belt-driven spindle at about 1,270 rpm catches fingers, hair and cuffs, and the yarn can be pulled round a finger and tighten. Stop the spindle with the shifter before touching the bobbin, and keep the stop within reach (Power Drive System). Winding is a seated job that has often been given to children; the corpus keeps children away from running machinery (Task Assignment by Age), so run the winder with adults, and a learner on a stopped spindle with an adult beside them.
What’s Next
- Learn next: Warp Tensioning and Let-Off — the other thread system
- Combine with: Shuttle Mechanism — where the bobbin is used