John Doe fired this volley in news:k1jm5q$s22$1
@dont-email.me:

If steel should be used, should it be lighter than that?

I'm planning to use bearings in the shaft. The original flexible
driveshaft was contained within a long continuous (maybe HDPE, or
UHMW) bearing along the entire curved shaft.

Let's see, now. It's not a gear-head whacker, it's a curved shaft job.

Five feet of speedo cable is too heavy? What can it weigh... five or six
ounces? Half a pound?

You expect ordinary drawn tubing to take a near-30-degree bend at only
about 50x radius/diameter, be bent and re-bent continually as it rotates
in the bearings, and _last_? It'll part company with itself in a few
hundred revolutions.

There's a reason they use flexible shafting in those toy weed whackers.

I think you're nuts, unless you plan to go to a straight shaft, AND plan
on not whacking weeds with it anymore.

LLoyd