28 Jul
2015
28 Jul
'15
8:29 a.m.
On 27/07/2015 23:13, Tothwolf wrote:
On Mon, 27 Jul 2015, John Wilson wrote:
> The only thing here is, it's a *terrible* design. Those damn nubs
> snap off so easily (I'm sure decades of outgassing haven't helped),
> even when you're expecting it and being super careful.
Yes, even in the late 70s i recall them being considered fragile.
Are the original parts made of nylon? If so, that
might explain the
tendency for them to break. Nylon 6/6 is hygroscopic, and over a long
period of time, it could very well be swelling up just enough so the
bulb portions are more likely to break off.
No, they're ABS - at least mine are, I just tested a few. I don't know
what grade, though, and perhaps something more flexible and forgiving -
a different grade of ABS, semi-rigid PVC, or nylon would be better.
My suggestion, however, would be to incorporate a vertical slit in the
ball and a couple of millimeters of the stem, so they're a less tight
and less critical fit. Might help, especially with a less brittle plastic.
--
Pete
Pete Turnbull