SC bobbin ends flaring a little, and not sure why...

[John Carlsen]

Hey guys. Just wanted to see if there's someone else who has encountered this and has a solution. It doesn't seem to be affecting the sound or anything, and it isn't really extreme, but it has been really annoying, me being the perfectionist and all. Any advice?

[SonnyW]

I think it is from too much winding tension. Tighter makes a good sound, but it is easy to get too much tension when handwinding. I just posted a little analysis on this in another thread on warranty period for handwound pickups. The winding tension multiplied by 2x the number of turns is the compression force on the axis of the bobbin. It can be 990 pounds or so in a strat for 30 g average winding tension. I have measured that much on my winder with a gauge. I have heard of but never actually seen it that it can even break the alnico rods. Also it bugs me too. Looks bad. Mine sometimes tend to flare some, but so do a lot of the vintage ones I have seen photos of. - just my humble opinion.

[Ward]

Try winding those plastic P-90 bobbins for some serious "curl up"

[big_teee]

Too much tension is one cause.
Another is loose forbon.
beveling magnets helps keep the forbon tight.
Sealing the bobbin before winding also helps.
I use Spray lacquer. That helps lock the forbon to the magnets.
Good Luck,
Terry

[copperheadroads]

I superglue the end magnets
Kind of like illustrated in Jason's book

[FunkyKikuchiyo]

How are you doing your traverse? Do you have a mechanism, or are you hand guiding? If you're hand guiding, do you have stoppers? If you wind too far out, it puts a lot of wire on the outer edges and can tend to push the ends out a bit.

[David King]

I always set my limits .020" to .050" inside the forbon and I've never had the problem again. Tension has some effect when you wind right to the edges but it won't have much effect if you move your stops in.

[John Carlsen]

Thanks guys! I put my tension down a little and didn't wind to the edges and wound a *perfect* (I know there's no such thing, just excited) coil. So, yay! Thanks again!

John

[David King]

John,
I'm glad that worked for you. We should move this thread to the beginners section for future reference.

[David Schwab]

John,
I'm glad that worked for you. We should move this thread to the beginners section for future reference.

Moved.

[SonnyW]

I think it is from too much winding tension. Tighter makes a good sound, but it is easy to get too much tension when handwinding. I just posted a little analysis on this in another thread on warranty period for handwound pickups. The winding tension multiplied by 2x the number of turns is the compression force on the axis of the bobbin. It can be 990 pounds or so in a strat for 30 g average winding tension. I have measured that much on my winder with a gauge. I have heard of but never actually seen it that it can even break the alnico rods. Also it bugs me too. Looks bad. Mine sometimes tend to flare some, but so do a lot of the vintage ones I have seen photos of. - just my humble opinion.

I have to retract the part about the 990 pounds of pressure. I calculated that number, but the model I was using was incorrect, because I neglected friction which makes a lot more difference than I thought. I measured the tension with a gauge and calculated thatnumber by multiplying by 2x the number of turns, as if it worked like a block and tackle. But after several people commented, I checked with a mechanical engineer. He pointed out that the friction between the wires is increased by the compression and so it doesn't keep pulling on the inner turns because of friction which keeps them from being able to move freely. I don't know what the compression force on the bobbins is. I do observe some amount of pressure though.