[Hallicrafters] Wrenches to remove knobs from SX 100

[wa1kbq at aol.com]

McMaster-Carr is an industrial supply house in Atlanta and is an excellent source for different types of replacement setscews and setscrew wrenches. Setscrews are available in many different types and drive styles with different types of formed ends which include, flat, pointed, cupped, and radiused depending on the degree of "locking" or "resetability" desired. The variety we are mostly concerned with in the case of Hallicrafters equipment includes 6-flute and 4-flute Bristol types which is an internal splined drive and Allen types which is an internal hex drive with "cupped" ends. Hallicrafters equipment is often found with a mixture of these three different drive styles. Try to look closely at each knob's setscrews to determine what you have before attempting to insert a wrench. For example, an Allen wrench will loosely fit the 6-flute Bristol but enough force will cause it to slip and ruin the setscrew's internal splines. If this has happened the correct Bristol wrench will probably no longer fit the setscrew. There is a procedure which is usually successful in repairing Bristol setscrews damaged by Allen wrenches, just ask if needed. 

The cupped ends of the hardened setscrews are designed to bite into softer shafts which will cause a burr to be pushed up. Sometimes it is necessary to push burrs back down to get the knobs off. I use a setscrew with the end ground flat to accomplish this. Just wiggle the knob slightly clockwise and counterclockwise back and forth as you gently tighten the flattened screw and the knob will soon come off.

The decorative front panel nuts are another problem. One often encounters previous owner tinkering which usually includes barked up decorative nuts with plier gouges in the paint around the nuts. General Cement once produced tools for splined decorative nuts but because there is no standard spline count for decorative nuts among manufacturers the GC tools never fit correctly and will do as much damage to the nuts as pliers. I bought some about ten years ago and when I discovered this I tossed them out. The earlier mention of round nut wrenches for cameras from Micro Tools is the best recommendation.

Sometimes you have access to the hexnut on the backside which is the best way to loosen if you can get to it. Sometimes you need a thin wrench to get in and sometimes you will need a thin wrench which has a bend. Sometimes there is no access and you have to loosen the decorative nut.

-Greg



-----Original Message-----
From: John King <k5pgw at yahoo.com>
To: hallicrafters at mailman.qth.net
Sent: Fri, Dec 25, 2009 10:03 pm
Subject: [Hallicrafters] Wrenches to remove knobs from SX 100


I need to remove the knobs and front panel from my SX 100. I note that the 
crews in the large knobs are larger than the screws in the  small knobs. They 
ook like screws that require Bristol wrenches. Is that correct and  is there a 
ecommended source for the correct set?
Does anyone  have suggestions for getting the nuts off the switches and controls 
n the SX 100 front panel without damaging the front panel? Suggestions 
ppreciated. 73, John, K5PGW

      
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