The Fine Things are Always Hand Made
After buying a Philharmonic pointer dial with no knobs, I thought that a set of Scott style wooden knobs as fitted to the Allwave sets would look ok,
the original knobs appear to be made from Walnut with a rock maple inlay, the photo shows the blanks of timber prepared ready for turning.
the walnut blanks are then machined with a 12mm hole,
I used a router bit here as this will give a flat bottom, although a regular drill could be used,
the tool is wrapped with tape as an aid to drilling all of the holes to the same depth
once this is done it leaves us with a set of knob blanks,
the next step is to drill a clearance hole in the blanks for the grub screw fixing in the finished knob, I used 4mm here,once this is done the brass centers can be glued in, these are made from 12mm brass bar with a 1/4inch hole, this gives roughly 1/8 inch thickness for the thread in the side wall, commercial ones are less than 2mm.
used a m3 grub screw for fixing the knob, the corners are also trimmed off ready for turning,
when the inserts are glued in, to stop glue from creeping up the thread I found a cotton bud shaft a perfect size for plugging the grub screw hole,
once the glue has set the cotton bud is removed and the knob blank is mounted on a dummy 1/4 inch shaft held in the lathe chuck,
the knobs are then turned to 24mm diameter, this size was taken from my AW15,
the next step involves a special tool to be made, this is made from tool steel and hardened and tempered to a straw color, this could be made from an old screwdriver at a pinch,
the tool has one finger longer than the other, the long finger acts as a guide and the short finger as a scraper,
the short finger is 2.5mm across and the gap between fingers is 3.5mm,
this will leave a center island of 12mm in the knob end with a 2.5mm groove.
The tool is then set against the edge of the knob so as it is just rubbing, this is then slowly advanced into the job,
this will then cut a groove in the end of the knob, the cut can be fairly deep, about 1/8" is ok,
the next photo shows the knob blanks so far.
a maple blank is then placed in the chuck and the center is bored to 12mm, the outside is then machined to 17mm dia, this gives a tube that will fit into the groove in the end of the knob,
at this stage there is a fiddle factor, the fit should be tight but allow some slight play for glue,
these wooden 'tubes' are then glued into the knobs, and allowed to set,
once the glue has fully hardened the excess maple is cut off, the job is then returned to the 1/4 inch stub fitted in the lathe chuck, the ends are cleaned up and cut with a radius, this can be sanded, the end radius of the original knob measures somewhere around 2".
The next photo shows the finished knobs in the first coat of garnet shellac,
and finally after several coats and a buffing,
the larger concentric knob at the left is made in the same way but has a 3/8" hole, to fit the outer coarse tuning shaft on the radio,
it's not finished yet as it needs a few more coats of polish.
I hope that this will inspire someone to try making their own knobs,
Good job Mike.
Cool results. A major project with all the set ups involved. Interesting. Thanks.
Nice Michael. Curious what lathe you have there ? I use my grandfathers trusty old 1936 Oliver pattern lathe for such projects. I enjoy bowl turning large burls and the sliding bed allows 4’ ! BC !!
the lathe is a myford ml1, almost as old as Scott radios, dates to 1934, still going strong, would not be without it.
Very cool! Those look really good!
Now, you need to find a way to turn the Scott "S" style wooden knobs...
Hmmm, let me see, I think that the "s" style knobs were pressed, so, we can make a mold form an original, electroform in nickel, buy a hydraulic press to emboss the logo, well maybe not...
Very nice. Wish I had your talent!
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