Machining A Female Half-moon Shaft?

[joshua43214]

I have seen them with a small flat spring that presses on the flats.
It might take a bit of trial and error, but should not be too hard to make.
Just plunge mill two slots (more like grooves) on the edge of the hole, bend a piece of steel packing strap into an arc, and fit it into the slots.
I remember pulling the knobs off a stereo amp when I was a teenager and losing a spring
The spring also had a bit of a tab bent back on the opening end of the knob to aide getting it over the shaft.

 

[Riaan]

randyc did the post on the rotary broach. http://www.hobby-machinist.com/threads/a-simple-compact-rotary-broach.33032/

Re: buy vs. build, I had the impression that the OP was asking how it would be made, not stating that he wanted to make one.

I'm busy restomodding a 280ZX (Fairlady Z), the interior will be getting the 80's hi-fi treatment in this vein, with brushed aluminium facia and toggle switches:



Suffice to say that none of the stuff I've seen online delivers the same look and I'll rot before I butcher a vintage amplifier to repurpose the knobs.

 

[RJSakowski]

Restoring a vintage amplifier does present its problems. I would expect that Pioneer had their knobs and switches custom made. I have a Scott receiver of similar vintage with machined aluminum knobs. The knobs have plastic inserts which are pressed into the aluminum shell. Perhaps you could use a similar process by purchasing off-the-shelf knobs and turning them down to fit a milled pocket in your machined shells.

 

[Fabrickator]

Sleeve it, did one last week for my Power Feed Lever converting it to a knob. Find another old knob with the same half-moon, slip-fit style mount. Machine it down to about 3/8" (for a 1/4" shaft). Drill out the hole in your good (new) knob to accept it with a slight press fit and a drop of red locktite. No set screw needed, looks original. True restoration. There should be almost zero torque on a stereo knob.

 

[chips&more]

A +1 on the insert idea. And would also entertain the rotary broach method, but have concerns on not enough clearance and or too much metal removal…Dave

 

[Riaan]

Some truly excellent ideas bubbling up in this thread. Thank you, gentlemen!

 

[TC0853]

Now why would we buy a $3.00 knob when we can make one for $30.00 and several hours of labor.

Good point

 

[higgite]

Now why would we buy a $3.00 knob when we can make one for $30.00 and several hours of labor.

For the same reason that I bought a $1500 mill so I can make a carriage stop for my $1800 lathe that I bought so I could make one of these.



It’s science.

Tom

 

[TOOLMASTER]

LOTS OF KNOBS ON EBAY

 

[Tony Wells]

How many do you need? I have quite a few I can look through.