Pattern Area measurement: Manual method – Part 2
…continued from Part -1
2. Hall’s Scaling Board: This method was developed by Mr.K.W.Hall. The board was commercially available along with an instruction booklet.
In this method, each pattern is placed on the given scaling board. Then need to find the parallelogram area and perimeter of each component. Then calculate the perimeter and area of the total patterns and skin. If you know the area and a description of the leather to be used, the information can be obtained from a list, contained in the scaling board booklet.
The raw calculations are converted into a useful result, which is a tedious job. To simplify this a nomogram (a graphical chart using a series of straight lines) is printed on the reverse of the scaling board. The following should be read in conjunction with the nomogram. See the below image
First the perimeter of the pattern is divided by the area. Perimeter and area of the patterns are marked on the two scales G (perimeter) and S1 (pattern area). Mark P/A value on line B.
Find out the perimeter and area of the leather and mark them on H and L scales. Mark P/A value of leather on scale D. Points on scale D and B are joined and the value is read on scale F1. The scales on the right side are used to transfer the values from F1 to scale F2. Then mark the number of patterns on the scale N. Join the points on F2 and N. when this line crosses the line on W read the second waste which will occur, from cutting that size and shape of upper from that size and shape of leather. Total pattern value is marked on scale S2. Join the points on S2 and W. find the cutting area necessary for one pair and one dozen pairs. For this we have to add leather grade and clicking efficiency.
Disadvantages: This is very tedious and time-consuming technique.