Reed Calculations

Reed Calculations

In weaving, the reed is an important part of the loom. It helps to keep the warp ends evenly spaced and also helps in beating the weft into the fell of the cloth. Therefore, understanding reed count is essential for calculating the number of warp ends per inch in the fabric.

Reed calculations are often taught in a very short form, but a small mistake in terminology can create confusion. The reed count tells us about the number of dents, while the actual ends per inch depend on how many warp ends are passed through each dent. Similarly, heald calculations are related to the distribution of warp ends across shafts, not to the reed itself.

Table of Contents

• Stockport Reed System
• Particulars of Reed While Ordering
• Example 1: Finding Ends per Inch from Reed Count
• General Formula for Stockport Reed Count
• Plain Set and Heald Count
• Example 2: Heald Count for a 6-Shaft Satin Fabric
• Important Distinction Between Reed Count and Heald Count
• Summary
• Corrected Key Points
• General Disclaimer

Stockport Reed System

Reeds are commonly counted by the Stockport system. In this system, the reed count is based on the number of dents in two inches. This point is important. The Stockport system does not directly tell us the number of warp ends in two inches; it tells us the number of reed dents in two inches.

For example, a 72s Stockport reed means:

\[ 72 \text{ dents in 2 inches} \]

Therefore:

\[ \text{Dents per inch} = \frac{72}{2} = 36 \]

So, a 72s Stockport reed has 36 dents per inch. If one end is passed through each dent, the ends per inch will be 36. If two ends are passed through each dent, the ends per inch will be 72. If three ends are passed through each dent, the ends per inch will be 108.

Visual 1: Stockport reed count explained as dents in two inches and converted into dents per inch.

Particulars of Reed While Ordering

A reed may be specified as:

100s ST, 18 G., 44" × 5", blue

This means that the reed has a Stockport count of 100. Since Stockport count is based on two inches, this means that the reed has 100 dents in two inches, or 50 dents per inch.

• 100s ST: Stockport reed count is 100.
• 18 G.: The reed is made using dents of 18s wire gauge.
• 44": The reed is 44 inches long.
• 5": The reed is 5 inches deep.
• Blue: There will be blue paper on the baulk of the reed.

Here, “ST” refers to Stockport. The count tells us how many dents are present in two inches. The actual ends per inch will depend on the draft plan and the number of ends drawn through each dent.

Example 1: Finding Ends per Inch from Reed Count

Question: What will be the number of ends per inch at the reed in a reed of 3/80s Stockport?

Here, 80s Stockport means:

\[ 80 \text{ dents in 2 inches} \]

Therefore:

\[ \text{Dents per inch} = \frac{80}{2} = 40 \]

The expression 3/80s Stockport means that the reed is being drawn with 3 ends per dent.

Therefore:

\[ \text{Ends per inch} = 3 \times 40 = 120 \]

So, the reed will give:

\[ \boxed{120 \text{ ends per inch}} \]

This calculation is correct. However, it is technically clearer to say “ends per inch at the reed” rather than “ends per inch in the reed.” The reed contains dents; the warp sheet contains ends.

General Formula for Stockport Reed Count

For a Stockport reed:

\[ \text{Dents per inch} = \frac{\text{Stockport reed count}}{2} \]

If there are \(n\) ends per dent, then:

\[ \text{Ends per inch} = \frac{\text{Stockport reed count}}{2} \times n \]

Or:

\[ EPI = \frac{R \times n}{2} \]

Where:

• \(EPI\) = ends per inch
• \(R\) = Stockport reed count
• \(n\) = number of ends per dent

For example, if a reed is 72s Stockport and the drawing is 3 ends per dent:

\[ EPI = \frac{72 \times 3}{2} = 108 \]

Thus, the fabric will have 108 ends per inch at the reed, assuming no other change due to contraction, crimp, or finishing.

Visual 2: Formula flow showing Stockport count, dents per inch, ends per dent, and final ends per inch.

Plain Set and Heald Count

When a set contains 4 shafts, it is called a plain set. The count of healds is expressed by the number of heald eyes per inch across the complete set of shafts.

For example, a 60s plain set means:

\[ 60 \text{ heald eyes per inch across 4 shafts} \]

Therefore, the number of heald eyes per inch per shaft is:

\[ \frac{60}{4} = 15 \]

So, in a 60s plain set, each shaft has:

\[ 15 \text{ heald eyes per inch per shaft} \]

If the same total of 60 heald eyes per inch is distributed across 6 shafts, then:

\[ \frac{60}{6} = 10 \]

So, for a 6-shaft set, each shaft would have:

\[ 10 \text{ heald eyes per inch per shaft} \]

This distinction is useful because the reed controls spacing at the reed, while the healds control the lifting and lowering of warp ends according to the weave structure.

Example 2: Heald Count for a 6-Shaft Satin Fabric

Question: Find the count of healds required for weaving a 6-shaft satin fabric using a 72s Stockport reed, drawn 3 ends per dent.

First, calculate the dents per inch:

\[ \text{Dents per inch} = \frac{72}{2} = 36 \]

Since the reed is drawn 3 ends per dent:

\[ \text{Ends per inch} = 36 \times 3 = 108 \]

So:

\[ EPI = 108 \]

Now, the fabric is woven on 6 shafts. Therefore, the number of heald eyes required per inch per shaft is:

\[ \frac{108}{6} = 18 \]

So, each shaft must have:

\[ 18 \text{ heald eyes per inch} \]

To express this in terms of an equivalent plain set, remember that a plain set has 4 shafts. Therefore:

\[ \text{Plain set equivalent count} = 18 \times 4 = 72 \]

Thus, the required heald arrangement is:

\[ \boxed{18 \text{ heald eyes per inch per shaft on 6 shafts}} \]

Or, expressed as a plain-set equivalent:

\[ \boxed{72s \text{ plain-set equivalent heald count}} \]

Visual 3: Heald count calculation showing 108 EPI divided over 6 shafts and converted to plain-set equivalent.

Important Distinction Between Reed Count and Heald Count

A common confusion in weaving calculations is between reed count and heald count. The two are connected through warp density, but they are not the same thing.

A reed count tells us how many dents are present in a given length. In the Stockport system, this length is two inches. The reed controls the spacing of warp ends at the reed and helps beat the weft into the fabric.

A heald count tells us how many heald eyes are available per inch across the set of shafts. The healds control the lifting and lowering of warp ends according to the weave design.

Therefore, reed calculations are mainly concerned with:

\[ \text{Dents per inch and ends per dent} \]

Heald calculations are mainly concerned with:

\[ \text{Ends per inch and number of shafts} \]

Point of Comparison	Reed Count	Heald Count
What it refers to	Number of reed dents	Number of heald eyes
Main function	Spaces warp ends and beats the weft	Controls warp lifting according to weave design
Key calculation	Dents per inch × ends per dent	Total EPI divided by number of shafts
Common mistake	Calling dents “ends”	Confusing heald count with reed count

Related Reading on Weaving and Textile Calculations

• Textile Calculations: How to change the EPI and PPI when changing counts for a given fabric
• Warp and Weft Calculations: How to Make a Fabric Heavier Without Changing Its Character
• Calculations: Changing Cloth Weight and Weave Pattern While Keeping the Same Structure
• Textile Calculation: Finding the Length and Weight of Yarn in a Given Length of Cloth
• How to calculate the weight of Fabric

Summary

The Stockport reed system is based on the number of dents in two inches. To find dents per inch, divide the Stockport reed count by 2. To find ends per inch, multiply the dents per inch by the number of ends drawn through each dent.

For a 3/80s Stockport reed:

\[ \frac{80}{2} \times 3 = 120 \text{ ends per inch} \]

For a 6-shaft satin fabric using a 72s Stockport reed with 3 ends per dent:

\[ \frac{72}{2} \times 3 = 108 \text{ ends per inch} \]

Then:

\[ \frac{108}{6} = 18 \text{ heald eyes per inch per shaft} \]

And the plain-set equivalent heald count is:

\[ 18 \times 4 = 72 \]

So, the correct conclusion is:

\[ \boxed{\text{Required heald count = 72s plain-set equivalent}} \]

Or:

\[ \boxed{\text{6 shafts with 18 heald eyes per inch per shaft}} \]

General Disclaimer

This article is intended for educational understanding of basic weaving calculations. Actual production values may vary depending on loom type, yarn type, yarn tension, weave structure, crimp, reed space, drawing-in plan, fabric width, finishing shrinkage, and mill practice. The calculations shown here should be used as a technical starting point and should be verified through sampling before final production.

Process Control in Drawing-in

Process Control in Drawing-in

The term drawing-in and warp tying refers to the operations involved in preparing the weaver's beam for the purpose of weaving fabrics on the loom.

The drawing-in process primarily consists of drawing ends from the weaver's beam through heald eyes of different harnesses and then through the dents of a reed in the order that is determined by the design of the fabric.

If a beam is to be worked with warp stop motion on the loom, specially when using closed drop-pins, the ends have to be drawn through these pins before drawing them through the heald eyes and reed dents.

conventionally drawing-in is carried out manually by two persons-one, the reacher for selecting and presenting the ends from the beam, and the other, the drawer for pulling ends through the drop-pins, heald eys and reed dents.

The main requirements of carrying out this process properly and efficiently are:

1. The operator should be aware of the principles of drawing-in and be trained to do the job speedily because any mistakes or delays in carrying out the process would prove to be costly.

2. The healds and reeds should be in good condition and of suitable specifications for ensuring that these are not the cause of warp breaks on the loom and of defects in the fabric.

3. The drawing of the beam should be done properly to avoid cross ends on the beam.

4. Suitable precautions should be taken to reduce the incidence of extra-ends and to compensate for the missing ends during the weaving of the loom.

CARE OF HEALDS AND REED

1. The healds and reed from the exhausted beam of the loom must be cleaned throughly to free them from fluff, size, rust etc. before using them for a new weaver's beam.

2. When warp tying is practiced, it should be ensured that the same set of healds and reed do not work on the loom for a long time, even if no apparent defect is noticed in them. This is because through cleaning of healds cannot be done on the loom itself and dirty healds are prone to give high warp breaks.

COMMON DEFECTS IN DRAWING-IN

1. Cross ends- To minimise the incidence of cross ends on the beam during weaving, the ends presented for drawing in or warp tying should be made to be parallel and in their respective positions as in the beam. Proper dressing of ends is, therefore, of great importance.

2. Extra Ends- some ends are generally cast out during drawing-in/warp tying to compensate for long missing ends on the weaver's beam.Whether to leave these ends or not should be governed by the method of cutting lappers at sizing.

If the lappers are cut and mended only after completion of a weaver's beam, there is no need of leaving extra-ends at drawing-in or warp tying. If however, the lappers are cut no sooner these are detected, the same ends should not be withdrawn or not taken for tying.

Cost of Sizing

Cost of Sizing

The cost of sizing ( excluding cost of sizing chemicals) is generally expressed as cost per unit length. Hence contribution of sizing cost can be calculated as:

cost of sizing= cost per unit length x tape length

cost of sizing chemcials is expressed as cost per unit length of size mixture. The cost per piece of fabric can be calculated as:

Cost of sizing chemicals per piece length= cost/kg x (warp weight per piece length x size add on %)

Basic stitches- Animation

Basic Stitches Animations

This site talks about how sewing machine works. It is replete with animations. It starts by saying that it was inefficient to mechanically copy the process of hand sewing. This site has animations for the following stitches:

1. Basic chain stitch
2. Twisted chain stitch
3. Lock stitch
4. Oscillating hook lockstitch
5. Rotating hook lockstitch
6. Double locking chainstitch

A very nice site to visit !

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