Hi solidworks user forum,

I am trying to model a custom wire spool used for fiber spooling.

I know the length that I'm after which is 5000meters and I'm using a .25mm fiber diameter.

What I'm trying to do is figure out the height and the total outside diamter if I start with a 25.4mm inside diameter.

Any suggestions.

Attached is my first attempt which represents two turns.

Ok here is my idea, which may be out there but I think it should get you close. You can assume that the strands stacking on top of each other will sit in a hex pattern. If you look up information on circle packing you will see that the density for circles packed this way is about .9069 (Circle packing - Wikipedia, the free encyclopedia). You know the volume of your total wire (pi * .125mm^2 * 5000000mm = 245437mm^2). So the total volume that will be taken up on the spool is the wire volume divided by the density (245435 / .9069 = 270633mm^2). Since you know the volume that the spool needs to hold, you can calculate that using the equation for the volume of a hollow cylinder (Volume = pi * r1^2 * h - pi * r2^2 * h). You will need to decide on either the height or the OD ahead of time, and solve for the other. So let's say you want the spool to be 150mm long, then you can solve for the OD.

270633 = pi * r1^2 * 150 - pi * 12.7^2 * 150 -> r1 = 27.1 mm -> OD = 54.2 mm

I hope I didn't make a math error in there somewhere. I am at home and don't have my graphinc claculator on hand so I'm trying to run the calculations in the windows calc. But anyway, I think that method shoudl get you close and then you can just add extra diameter to the flanges so they stick up above the wire a bit.