Trade Secrets!

Replacing damaged tuner knobs

Issue 14 January 25, 2007

Rotten tuner knob
What happened to the knob on this tuner?!

The rest of the tuners on this ’57 Gibson looked worse than this one! Plastic rots, especially plastic tuner knobs from the 50s and 60s. I replaced these knobs, but kept the tuning machines. Read on...

Dan Erlewine signature Dan Erlewine, January 24, 2007
Photo: Dan Erlewine
We had fun saving this ’57 Junior from decay
Photo: 1957 Les Paul Junior
This ’57 Les Paul Junior is a beauty. It’s still with its original owner, named Wyn, who was given it on his 17th birthday. (How cool is that?) That’s a picture of Wyn playing it back in the day.

Photo: damaged tuners
The guitar hadn’t been played for 25 years, and the tuner knobs were shriveled into brittle pieces of brown plastic clinging to the tuning key shafts. What’s more, the finish was so dull and cloudy that I told Wyn, “There’s no way to clean a finish that far gone. This guitar will never play again. I’ll give you $75 for it, and use it for parts.” (Just kidding! A Junior like this is worth a lot of dough nowadays.)
Step 1: off with the old
Photo: removing old knobs
A few gentle bites from my fret pullers crumbled the rotted plastic and it fell off the shaft easily.
Step 2: clean up the shafts
Photo: old tuner shafts
With the dead plastic removed the spear-shaped button shafts looked like this — green with corrosion.
Photo: brushing on naptha

Photo: Dremel flex-shaft
I used a glue brush dipped in naphtha to wet the crud, making it easier to scrub off most of it with a file cleaning brush.

Photo: file cleaning brush

A wire wheel on a Dremel flex shaft is perfect for getting down to bare metal in seconds.
Image: trimming a brush
I use glue brushes for lots of things, often trimming them to a short point. This makes the bristles stiff enough to scrub small nooks and crannies.

Step 3: on with the new
Photo: Weller soldering iron
When the shaft is clean, I heat it with a soldering gun and press on a new tuner knob.

I use a Weller 140/100 watt gun, replacing the tip with two pieces of 3/32” dia. copper wire (the ground from a scrap of heavy-duty electrical wire). With the two wires placed against the tuner shaft, the circuit is complete, and the shaft gets hot fast. It takes 15-20 seconds to heat it enough to install the new knob. The buttons slide onto the heated shaft with ease — wear gloves, though!

Step 4: a drop of glue
Photo: super glue
As added insurance that the buttons will stay put, I run a drop of #10 super glue into each button. Use a pipette to get a small drop of glue in the right spot.
Photo: repaired tuners
I thouroughly cleaned the peghead before re-installing the tuners. That took some doing — cleaning this guitar is worth a Trade Secrets issue all by itself!

Dan Erlewine signature

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