A heddle is a loop of 0.5-0.8 mm wire or string with an eye in the middle, one for each warp end, and the loom lifts the ends by lifting the heddles. A 1 m loom at 20 ends per cm needs 2,000 of them, all the same length to within a millimetre or so, and on only two frames they sit 1 mm apart, which leaves no room for 0.8 mm wire, so a fine warp is better spread over four frames.
Part of Power Loom Construction
Making the wire and string heddles that carry each warp end, and fitting them to the heddle frames.
One Heddle Per End, Shared Out Among The Frames
The overview: wire heddles are the better kind, 0.5-0.8 mm steel wire bent into a loop with a central eye, each warp thread passing through one eye; a 1 m fabric at 30 threads per cm needs 3,000 heddles in total, shared among the frames. String heddles are simpler, less durable and adequate to start. The heddles are mounted on rectangular frames that move up and down; two frames make plain weave and four allow twill. For the reference loom (20 ends per cm, Weaving Mechanics) the count is 20 × 100 = 2,000. On two frames each carries 1,000.
The hand-loom versions, string heddles with a jig and the rule that every heddle must be exactly the same length, are in Heddle System and Floor Loom Construction.
Pitch Decides How Many Frames
On one frame the heddles are spaced along its bar. For plain weave on two frames alternate ends go to alternate frames: at 20 ends per cm, each frame carries 10 per cm, a pitch of 1.0 mm. The wire alone is 0.5-0.8 mm thick, and a twisted eye is wider than a single wire, so a row of 0.8 mm wire leaves 0.2 mm between neighbours and cannot hold a clean eye. At the overview’s 30 ends per cm the pitch on two frames is 0.67 mm, less than the wire. So at a dense sett the heddles must be spread over four frames for plain weave (frames 1 and 3 lifting together, 2 and 4 together), where the pitch is 2.0 mm at 20 ends per cm. This is derived from the overview’s wire gauge and the reference sett.
Length Errors Eat The Shuttle’s Clearance
The corpus says all heddles on a rod must be exactly the same length and that a 5 mm variation causes an uneven shed. On the shed in Shedding the clearance above the 30 mm shuttle was 10 mm; a heddle 5 mm short lifts its end 5 mm less at the heddle and about 2.5 mm less at the reed, a quarter of the clearance. Aim for a spread well under 1 mm. That figure is a design choice scaled from the corpus warning, not a sourced tolerance.
Wire: A Wire-Drawing Job
Heddle wire is drawn iron or steel wire. Iron Wire gives 24 gauge (0.6 mm) as 20-25 passes through progressively smaller dies from a 6 mm rod, with annealing stops. A heddle of assumed length 280 mm (the corpus string heddle is 25-30 cm) uses about 2 × 280 + 30 = 590 mm of wire, say 0.6 m. For 2,000 heddles that is 1,200 m of wire. The area ratio (6 ÷ 0.6)² = 100 means 12 m of 6 mm rod draws to 1,200 m; its mass is 12 m × 28.3 mm² × 7.8 mg per mm³ = 2.6 kg (iron density 7.8 g/cm³ is recalled). So the loom’s heddles are the output of a wire-drawing line, not a quick job (Draw Plate for the dies).
What You Need
- Drawn wire of 0.5-0.8 mm, smooth and annealed so it bends without cracking.
- A jig with pegs at the exact heddle length and a mandrel for the eye.
- Pliers and snips.
- Heddle bars and frames.
- String and a spare set for repairs (Heddle System).
Method: Making Wire Heddles
Step 1: Make the jig and one master heddle, checked against a rule.
Step 2: Cut wire to length and bend the eye on the mandrel, polishing it so the yarn does not catch; draw a thread through to test.
Step 3: Form the end loops that slip onto the frame bars.
Step 4: Check every heddle against the master for length and against a thick knot for the eye.
Step 5: Hang them on the frames in the order of the threading draft, alternating frames for plain weave.
Worked Example
Count for a two-frame plain-weave warp of 2,000 ends: 1,000 heddles on each frame, a pitch of 1.0 mm on a 1 m bar. Wire of 0.6 mm leaves 0.4 mm, enough only if the eye is not wider than the wire, which a twisted eye is. On four frames the count is 500 per frame, a pitch of 2.0 mm, and the 1.4 mm gap is comfortable. At the overview’s 3,000 heddles, four frames put 750 on each with a pitch of 1.33 mm.
Common Mistakes
- Rough eyes, which fray the warp and are a cause of broken ends.
- Heddles of different length on one frame.
- A wire too stiff or too hard, which cracks at the bend.
- Too many heddles on a bar for the sett.
Safety
Cut wire ends and a loom that moves
Wire snips leave sharp points and fly-off pieces; wear eye protection and collect scraps. Tying and threading are done on a stopped, locked loom; the frames lift on every pick and close on a hand reaching in (Power Drive System). Fine-wire work is adult work in good light.
What’s Next
- Learn next: Cam Shedding Mechanism — lifting the frames in time
- Combine with: Dobby Mechanism Basics — choosing which frames lift