Scott W. Harvey wrote in message
...
Tim Shoppa wrote:
On Apr 11, 7:10 am, "N_Cook" wrote:
Another old piece of kit this week. Steel case with a bakelite closure
that
was a devil to separate. Metal not rusted and I'm assuming steel does
not
shrink over decades.

I have found that many of the pot metal castings used for metal parts
on old radios, turntables, etc. have expanded over time.

I was astonished to learn that metal can do that in a timescale
measured in decades.

Oh, yeah. I've got an old Philips bakelite radio that has one of those
schemes where the tuning and volume are on the same shaft. The metal
used in the construction of this gizmo has expanded enough that the
tuning only moves as far as the volume control, and turning either one
makes both of them move. I can't even extract the chassis to try to fix
this because the knob is literally fused to the shaft from the
expansion. I haven't figured out how I'm going to deal with that yet, so
the set is a shelf queen.

-Scott


Faced with a similar situation some years ago and wanting to save the knob
and so knobs.
I found a piece of steel or Al round bar, drilled through axially on a
lathe, 1/8 inch hole. Mounted co-axially over the knob held there with
Jubilee / hose clip and some padding.
Then 1/8 inch drilled into the knob and into the shaft. Saved the bakelite
dust to mix with epoxy to make good afterwards. Luckily the 1/8 inch
drilling was enough to loosen the knob and filled the shaft with epoxy as
well, in the end. Otherwise it would have been a matter of drilling larger
holes until freed