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Potentiometer Shaft Adapter / Extender (Updated)
Adapts an available (Philmore) D-Shaft volume control pot to a long split-spline-shaft.Other
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My late Mom's old Panasonic table radio needed its volume control (with integrated power switch) replaced. The replacement parts would apparently be considered vintage now, but Philmore sells an appropriate value pot with an integrated switch. The only problem: it has a D-shaft, where Mom's radio knobs are for split-spline shafts.
No problem: I printed a shaft extender! See the instructions below.
Materials and methods
I printed via FDM with PETG, 90% infill, NO support (see below) standing vertically, highest quality settings, and printed slooooowly. After improving the model, the blobbing seen in the picture is gone.
The STL has one small integrated support under the D-shaft bit, which you'll have to pry out before the round part of the shaft will fit in there.
You may have to edit the STL to your particular needs for replacement part and the shafts you're adapting to. No parametric model here, sorry.
I cut the D-shaft part of the pot shaft down to about 2.5mm long (extending from the much longer round part of the shaft). This is a simple friction fit. Rotating the extender as you slip it on the shaft will help it go on easier, and will help you find the D-cutout in the recess.
Be careful to do two things:
1. Get your pot final-mounted before you put the extender on: the nut and washer won't go on over it.
2. Be careful not to stress and break your pot while shoving around the tight-fitting shaft extender.
PS: After a month or so, I managed to twist the first version of the extender off, and needed to make another. In the process, I improved the model, made it more robust, and as a result, the print was also cleaner. This version _feels_ more robust as I turn it, (noting a nice solid click as I reach the on-off switch). I've uploaded that model here.
If this one twists off (less likely than before), my next approach will be to brush a little epoxy on the exterior and let it dry before putting it on the pot. The epoxy won't form a chemical bond with the PET-G, but the texture of the printed part ought to be enough to keep encircling epoxy in place mechanically, and hopefully the epoxy will shore it up well. But that's for the next try.
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