[Hallicrafters] SX-101Mk3 frozen knobs

[Mike Everette]

If you can remove the set screws -- and I assume you are aware that these are Bristol-type spline socket head screws, which cannot be removed with an Allen key wrench; don't even try it -- then take them completely out, and put a drop of some kind of corrosion-buster penetrating oil into the screw hole.  The best two are P-B Blaster, and Liquid Wrench.  Of the two, P-B Blaster is better; but it does have a very strong scent and must be used with good ventilation.

Both these products come from auto supply or hardware stores.

Give the drop a few minutes to soak in, then go back and add another.  

The penetrant will circulate between the knob and shaft and eventually free it.

If you can't get the set screws to move, don't force them.  Use the penetrant.

Above all, use patience in large quantities.

If you strip a set screw out trying to remove it with the wrong tool, or trying to break it loose without penetrant -- well, you are in deep doo-doo.  You will probably have to split the plastic knob, remove it, and then split the metal knob collar by cutting it with a saw, to remove it.  This presents great risk (almost certain) of doing some damage to the panel, or the control, in the process.

Don't scoff... I have been there, done that, with an S-22R.  I know!  That particular knob defied everything.  It had a slotted (not Bristol) set screw which was very brittle, and half of the slotted head snapped off as I tried to turn it.

Be ESPECIALLY careful with the knob on the BFO pitch control.  The pitch control shaft is brass, probably hollow, and is secured to the BFO coil slug shaft with a set screw of its own.  It is the easiest thing to break on a Halli receiver.  Want proof?  Look at all the Halli receivers on eBay which have broken or missing pitch control knobs and shafts.

The best tool set for removing these knobs is the Xcelite product which has 9 or 10 different sizes of interchangeable spline shafts which plug into a screwdriver handle.  You can get better leverage with this than any key wrench.  This set is not cheap.  I bought one about 6-7 years ago and paid over $60.00 for it; but if you are going to work on much Halli gear from the 1950s, or any military gear, you definitely need it.  Bite the bullet and get one.

73

Mike
W4DSE


--- On Sat, 11/17/12, Larry Woodworth <larryw0hxs at yahoo.com> wrote:

> From: Larry Woodworth <larryw0hxs at yahoo.com>
> Subject: [Hallicrafters] SX-101Mk3 frozen knobs
> To: "hallicrafters at mailman.qth.net" <hallicrafters at mailman.qth.net>
> Date: Saturday, November 17, 2012, 10:21 PM
> Dear friends of Hali,
> 
> 
> Our handsome 101Mk3 has a case of knobs not budging from
> their non-metal shafts when set screws are loose. I didn't
> think removing the radio's face panel was needed at first
> while attempting to get the dial pointer to slide smoothly
> across the band scales. 
> 
> 
> Had to give up on thinking a spot of lube would carry across
> the metal rib that the pointer slides on and take care of
> jerky movement- not gonna happen. So this morning I began
> removing the knobs when this new problem joined the other to
> become a Rubic Cube puzzle. I stopped after two knobs
> displayed a oneness with their shafts. Two others came free.
> They were the smaller type.
> 
> TIME OUT!  
> 
> 
> Before I try dry ice and hair dryer outer space doctoring,
> who has proven techniques for this malady please. Before
> leaving the work table I let a drop of silicone into the
> hole of one after removing the set screw, and will check it
> tomorrow.
> 
> 
> Larry Woodworth
> Ensor Museum Mgr.
> Olathe, KS
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