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Calculating the length of wire in a coil.

  • 06-08-2013 8:36pm
    #1
    muddle84
    Registered Users, Registered Users 2 Posts: 1,769 ✭✭✭


    Hi Folks,
    I would like a second opinion on a method I am using to calculate the amount of wire each coil should consume.

    W = Length of wire used
    OD = Diameter of mandrel
    P= Pitch or distance between each coil
    Pi = pi
    L = length of coil

    W = (Pi*OD)*(L/P)

    Basically I am multiplying the circumference by the amount of coils along the length of the mandrel.

    Does this sound right or is there a better way to do this?

    Thank you for any help you can offer.


Comments

  • #2
    FoxT
    Closed Accounts Posts: 4,204 ✭✭✭FoxT


    I don't know how accurate you need to be here. You might want to consider the diameter of the wire also, especially if it is comparable to the diameter of the mandrel.

    1 turn around the mandrel will require pi(D1+D2) cm of wire, where D1 = mandrel diameter, and D2 = wire diameter.

    Also if the pitch is wide, you will find 1 turn around the mandrel will be somewhat longer.


  • #3
    MoogPoo
    Registered Users, Registered Users 2 Posts: 156 ✭✭MoogPoo


    yeah the longer diameter is the problem. You can unwrap the cylindar into a rectangle and work out the length of wire from corner to corner. So draw a rectangle of the height of the cylinder and draw a line from bottom corner at angle of wire. Then extend it to draw a wider rectangle until it reaches the top. Then pythagoras theorem for the length of wire. Not sure if thats what you mean though. Also there I just googled and there are some helical coil calculators which could work


  • #4
    muddle84
    Registered Users, Registered Users 2 Posts: 1,769 ✭✭✭muddle84


    Ok so the coil has two different sections with two different pitches. The first section is short and the pitch is the width of the wire (0.0148 in). So i think it is safe to assume the length of each individual coil for this section to be the circumference. For the second section the pitch widens out to 0.030 in so I will try what you have suggested MoogPoo. This way I can compare and see if the first method I devised is sufficiently accurate.
    Thanks for the feedback people.


  • #5
    muddle84
    Registered Users, Registered Users 2 Posts: 1,769 ✭✭✭muddle84


    So the original calculation I used returned a value of 1116.737 in. The more accurate calculation using pythagrus to determine the length of each coil returned a value of 1117.092 in.
    I wasn't too far out!!
    But it does show that it needs to be taken into account when using wider pitches.

    Thank you both for your help!!


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