Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: solenoids



At 09:29 AM 4/3/01 -0400, David E. Clark wrote:
Has anyone come across manufactured left-hand wired solenoids?
McMasters and a few other machinist parts catalogs only list
right-hand wired solenoids.

a number of students in our intro physics
classes come to the conclusion that the current enters a solenoid on
the end with the south pole and leaves on the end with a north pole.

Huh? Every solenoid I've ever bought or made had both wires emerging from
the same end. Roughly speaking, that means that when the turns are laid
down, they form an even number of layers. No chirality. No problem. I
can hardly imagine doing it any other way. That's because I tend to be
interested in precision magnets. If the leads come out at the same point
you can twist them together so the produce zero field; if they come out
separately you need to worry about the stray field of one lead wire or the
other.

We are looking for them (and would rather not make them)

Suit yourself, but IMHO making them is fun. And easy. To make a long
skinny solenoid, I would would make the former out of a brass tube. Solder
brass washers to the end. On at least one end, make the washer rather
thick, to provide a place to anchor the terminals:

|| x x x x x |
_||_________________________|_

______________________________
|| |
|| + + + + + |

Hint: If there is a lathe around (and there usually is), chuck up the
former, put the lathe in *neutral* and spin the work by hand as you lay
down the wires. At this stage it helps to have an assistant.

If there's absolutely no lathe around, make one. Use clamp stands etc.
from the chemistry lab. Put a one-hole rubber stopper in each end of the
bore of the solenoid, so you can support it on a rod.