A cloth dresser raises fibres at the surface of a fabric. The historical arrangement shown here has a central teasel drum and cloth-guide rollers above and below it. Teasel-bearing rows rotate with the drum while cloth travels past them. The calculator relates nominal row events to cloth speed and area throughput; it does not predict the resulting nap.
Cloth Dresser Interactive Calculator
Set the teasel-row count, drum speed, nominal row events per metre and cloth width. The animation follows a continuous cloth path over two guides and past the rotating teasel drum.
Equation Used
- Each fixed teasel row crosses a stationary reference once per revolution.
- The density input counts nominal row events per metre of transported cloth.
- Uniform cloth width and steady transport are assumed.
- Nap, contact pressure, cloth tension, fibre condition and relative surface-speed effects are not solved.
The calculator relates nominal row-event density to cloth speed and area throughput. It does not predict nap depth, fabric strength or a suitable production setting. Rows are fixed to the teasel drum in this historical model; modern planetary wire-raising rollers are a different arrangement.
A teasel drum between cloth guides
Hiscox figure 1440 identifies the central wheel as the teasel drum and the upper and lower rollers as cloth guides. The end view shows this arrangement: fixed teasel rows rotate with the central drum, while a continuous cloth strip follows tangent spans and curved contact regions over the guides and drum.
The illustrated drum turns against cloth movement at the contact region. The guide rollers turn with the passing cloth. Their bearings remain fixed in the frame; the teasel rows do not spin independently on miniature planetary axes. Machine dimensions and the contact arc are illustrative.
Knockando Woolmill describes its historical teasel gig as a large drum carrying rods filled with teasel heads. The barbs engage the passing fabric surface. The degree of raising depends on the textile and engagement conditions, not just on a nominal row count.
Historical raising and modern machines
Raising changes the surface of a textile by bringing fibres out of its ground structure. Historical teasel gigs and modern wire-raising machines use different working elements and drive arrangements. Modern planetary raising machines may use separately rotating pile and counter-pile rollers; that construction should not be inferred from this historical teasel-drum diagram.
What the calculator measures
Let N be the number of rows fixed to the drum and n its speed in revolutions per second. A fixed reference sees Nn row events each second. If cloth travels at v metres per second, define the nominal row-event density P as Nn/v.
v = N × (RPM/60)/P. Multiplying v by 60 gives line speed in metres per minute; multiplying that by cloth width gives area throughput in square metres per minute.
This definition does not count the actual fibre contacts on a moving piece of cloth. Those depend on contact arc, relative surface speed, barbs, engagement and fabric response. A complete pass through the machine is also different from one row event. The tool supplies no nap-depth or production-quality prediction.
Worked nominal-throughput example
At 36 rows and 25 RPM, the drum turns at 0.4167 rev/s and 15 rows cross a fixed reference each second. A nominal density of 11 events per metre gives v = 15/11 = 1.3636 m/s, or 81.82 m/min.
For 0.85 m wide cloth, area throughput is 81.82 × 0.85 = 69.55 m²/min. These are the arithmetic results for the entered event-counting convention, not recommended settings for a teasel gig. A finishing-speed selection also needs textile and engagement data that are absent from this event-counting calculation.
Using the controls
More rows or a faster drum increase the cloth speed calculated for the same nominal event density. A higher density target reduces that speed. Width changes area throughput and the separate width diagram; it does not change drum speed or line speed.
The illustration uses a nominal one-metre drum diameter solely to keep cloth and guide motion geometrically consistent. Its transport and drum motion share a four-times-slower display clock. This illustrative dimension does not enter the throughput equation and is not a specification for a historical machine.
Cloth dresser questions
Are the small elements separate driven rollers?
No. This model shows teasel-bearing rows fixed to one drum. Planetary wire-raising machines are a different design.
Does 11 events per metre mean 11 complete fabric passes?
No. It is the nominal frequency of rows crossing a fixed reference divided by transported cloth length.
Why is the calculated speed higher than a particular mill uses?
The tool solves a stated event balance. It has no calibrated relation between that density and finishing quality, so it cannot select a mill operating speed.
Does width change the line speed?
No. It changes area throughput at the calculated line speed. The width view changes while the end view stays the same.
References & Further Reading
- G. D. Hiscox, Mechanical Movements, Powers, Devices and Appliances, printed page 345, figure 1440.
- Knockando Woolmill, Teasels, description of rods carrying teasel heads on its historical gig.
- Science Museum Group, Model of a teasing mill, object 1895-117. This separate two-drum example also documents teasel-bearing bars.
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