# How to Calculate the Number of Coils per Inch of the Roving Bobbin

Last Updated on 03/03/2021

Experiment name:
Calculation of no of coils per inch of the roving bobbin.

Objectives:

1. To know the necessary specification of roving bobbin for calculation.
2. To know how to calculate the coils/inch of roving bobbin.

Theory:

We know, coils per minute = Bobbin speed – Spindle speed

Therefore, coils per inch = (Coils per minute / Rate of lift in inches per minute)

Again, rate of lift = RPM of lifter shaft wheel x Teeth of lifter wheel x pitch of the lifter wheel

Rpm of lifter shaft wheel = Motor rpm x (Driver/Driven)

Machine specification:

1. Rpm of motor pulley = 960
2. Motor pulley diameter = 5″
3. Machine pulley diameter = 7″
5. Cradle carrier wheel = 55 T
6. No of teeth in TCP = 28T
7. No of teeth in TCCP = 30T
8. Diameter of top cone drum = 6.5″
9. Diameter of bottom cone drum = 3.87″
10. Bottom cone drum change wheel = 18T
11. No of teeth of fender wheel = 68T
12. No of teeth of fender shaft wheel = 30T
13. Fender swivel bracket carrier wheel = 36T
14. Top lifter change wheel = 18T
15. Wheel on stud bevel = 44T
16. Stud bevel wheel = 22T
17. Double upright bevel wheel = 22T
18. Double upright bevel wheel = 18T
19. Reversing bevel = 70T
20. Reversing bevel = 70T
21. Bobbin lifter change pinion = 16T
22. Socket swivel carrier wheel = 72T
23. Socket stud wheel = 13T
24. Differential motion carrier wheel = 57T

Gearing Diagram:

Calculation:

We know,
Bobbin speed = 822
Spindle speed = 749

Therefore, Coils per minute = 822 – 749
= 73

Result:
No. of coils per inch = 11.

Conclusion:
Our teacher and lab assistants are very much helpful to us. Their well teaching and instruction help us greatly to understand this practical. I think this practical will be very helpful in my future career.

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