[ARC5] Stuck set screw
Tom Bridgers
tarheel6 at msn.com
Sun Nov 17 22:56:11 EST 2019
For reasons that Ken and Glenn said, I once completely destroyed a frequency turning knob on an ARC-5 transmitter trying to remove it when the set screw was stuck.
I learned the hard way that a hardened steel set screw cannot be drilled out.
Since then i’ve had good luck using the before-cited alternate heat and cool methods, or a long soaking in penetrating oil. Or both.
73’s
Tom KE4RHH
Sent from my iPhone
> On Nov 17, 2019, at 10:40 PM, arc5-request at mailman.qth.net wrote:
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> Today's Topics:
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> 1. Re: Removing knobs - verse two. (Kenneth G. Gordon)
> 2. Re: Death Angel Flyby (Roy Morgan)
> 3. Re: Removing knobs (Scott Robinson)
> 4. Re: Removing knobs - verse two. (D C _Mac_ Macdonald)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 17 Nov 2019 16:48:16 -0800
> From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
> To: arc5 at mailman.qth.net, Waldo Magnuson
> <magnuson at mac.com>
> Subject: Re: [ARC5] Removing knobs - verse two.
> Message-ID: <5DD1EA50.625.1EB3F56 at kgordon2006.frontier.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
>> On 17 Nov 2019 at 11:08, Waldo Magnuson via ARC5 wrote:
>>
>> The set screw in the audio volume switch on a C-1254A control unit IS
>> a Bristol set screw. The wrench fits tightly, I?ve used Blaster
>> penetrating Oil but even with excessive torque the screw has not come
>> loose. Any suggestions- heat/cold/drill? Skip W7WGM
>
> Drilling won't work, since the set-screw is USUALLY hardened steel. Any attempt to drill will
> only damage the knob since the drill bit will usually slip off to one side. Even if it doesn't you
> are still left with enough of the thing left in the threads to have difficulty getting it off.
>
> Secondly, PB-Blaster takes some time to penetrate, IFF it is going to.
>
> Thirdly, since the knobs are usually aluminum, they form an aluminum oxide around the
> set-screw which is extremely hard to penetrate by penetrating oil. Others are brass, and
> brass is "sticky".
>
> Alternate heat from a BIG soldering iron or torch (but below the melting point of aluminum)
> and cold, like putting the entire unit in the freezer for an hour or two, then application of as
> much torque via your Bristol wrench as you safely can, will eventually break that sort of
> set-screw free.
>
> Keep working on it: you'll get it.
>
> Ken W7EKB
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 17 Nov 2019 21:54:40 -0500
> From: Roy Morgan <k1lky68 at gmail.com>
> To: Robert Eleazer <releazer at earthlink.net>
> Cc: arc5 at mailman.qth.net
> Subject: Re: [ARC5] Death Angel Flyby
> Message-ID: <0040A8F3-C7B0-4590-911C-9FDEE51A5BF1 at gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Wayne suggests an isolation transformer - very good if you find one. A few variable voltage transformers ARE isolation transformers but this type is very uncommon.
>
> But:
>
> Sola voltage regulation transformers are also isolation devices (do confirm this for any you may have - do not take my word for it!)
>
> In addition, they limit the available current to something above the transformer?s rating. (This varies from type to type and also depends on the input voltage. ) At 15 to 30 percent over the current rating, the output voltage collapses to near zero. This is effective built-in protection against overload and short circuits.
>
> Upon removal of the over current, the thing returns to normal operation with no damage to itself and no blown fuse.
>
> Roy sends.
>
>> On Nov 16, 2019, at 5:22 PM, Robert Eleazer wrote:
>> ..,
>> By the way, I picked up a 500W isolation transformer at the Melbourne hamfest several years ago for $5.00. Y'all might keep your eyes open for one. I have blown too many fuses when using a Variac and plan to discontinue that practice.
>>
>> Wayne
>> WB5WSV
>>
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> ------------------------------
>
> Message: 3
> Date: Sun, 17 Nov 2019 19:02:00 -0800
> From: Scott Robinson <spr at earthlink.net>
> To: Glenn Little WB4UIV <glennmaillist at bellsouth.net>,
> arc5 at mailman.qth.net
> Subject: Re: [ARC5] Removing knobs
> Message-ID: <95df48fd-8388-8e6b-62f5-2dd0f45b53a6 at earthlink.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Well, the screw is probably hardened, so the drill might not work.
>
>> On 11/16/19 8:29 PM, Glenn Little WB4UIV wrote:
>> Most likely a Bristol.
>> If it has been damaged bad enough by attempting removal with the wrong
>> tools, drilling is probably the only option.
>> I had to remove a knob from an ARC-5 control head by drilling because
>> previous owner did not use proper tools and attempted drilling.
>> If you have to resort to drilling, use a new bit with oil.
>> Try a left twist drill bit first, you may get lucky and get a good bite
>> on the set screw and back it out.
>> Start with a bit size that will just fit in the Bristol recess.
>> When you have drilled to the shaft, go to the next size drill.
>> Remember the oil.
>> The next size drill should complete the job.
>> If you have taken your time, what you will have left of the setscrew
>> will look like a spring when you remove it from the knob.
>>
>> 73
>> Good Luck
>>
>> Glenn
>> WB4UIV
>>
>>
>>
>>> On 11/16/2019 11:08 PM, Waldo Magnuson via ARC5 wrote:
>>> As a good friend frequency says, ???Before you do something, you
>>> always have to do something else first.???
>>> ?? Well, the audio volume switch on a C-1254A control unit I???m
>>> matching to a R-13B (108-135 mc) receiver no longer switches.? I have
>>> a new pot with switch to replace the bad switch but first have to
>>> remove the front panel knob. Allen wrenches don???t fit, it doesn???t
>>> seem to be a Phillips, a small screwdriver turns with resistance but
>>> nothing happens. I could resort to a demill (sp) and major surgery or
>>> try drilling out the knob holding screw but is probably hardened .
>>> ?? And suggestions would be appreciated.
>>> Skip Magnuson W7WGM
>>>
>>> PS:? Glad you came out ok Dave. Low voltages can get you too. I was
>>> changing the battery in my tractor and my crescent wrench hit my ring.
>>> I got the ring off right away but even after two years can see/feel
>>> the scar.
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>>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 18 Nov 2019 03:40:39 +0000
> From: D C _Mac_ Macdonald <k2gkk at hotmail.com>
> To: "taskaras at gmail.com" <taskaras at gmail.com>, ARC-5 Mail List
> <arc5 at mailman.qth.net>
> Subject: Re: [ARC5] Removing knobs - verse two.
> Message-ID:
> <BN6PR06MB3090F0F856E055B7E8D2F379F14D0 at BN6PR06MB3090.namprd06.prod.outlook.com>
>
> Content-Type: text/plain; charset="utf-8"
>
> NOT a good idea to use the red sealant (Loctite or equivalent)!
>
> Use the BLUE!
>
> 73 de Mac, K2GKK/5?
> Since 30 Nov 1953?
> Oklahoma City, OK?
> USAF, Retired ('61-'81)?
> FAA, Retired ('94-'10)
> ________________________________
> From: Tas Karas <taskaras at gmail.com>
> Sent: Sunday, November 17, 2019 16:01
> To: D C _Mac_ Macdonald <k2gkk at hotmail.com>
> Subject: Re: [ARC5] Removing knobs - verse two.
>
> use some heat, a flame of some sort, nothing too crazy....tap something directly down onto the damaged screw...then try and remove with whatever you have there, it should come out. You could even try red thread sealant ( permanent)...so you jam something in the damaged spline/pattern but before you do, coat the thing with red thread sealer first and let dry, that stuff is hell strong...use sparingly dont get any anywhere else, then try and turn off.
>
> On Mon, Nov 18, 2019 at 7:07 AM D C _Mac_ Macdonald <k2gkk at hotmail.com<mailto:k2gkk at hotmail.com>> wrote:
> Try tightening it first! If it doesn't break free immediately try both directions alternately.
>
> 73 de Mac, K2GKK/5?
> Since 30 Nov 1953?
> Oklahoma City, OK?
> USAF, Retired ('61-'81)?
> FAA, Retired ('94-'10)
>
> ________________________________
> From: arc5-bounces at mailman.qth.net<mailto:arc5-bounces at mailman.qth.net> <arc5-bounces at mailman.qth.net<mailto:arc5-bounces at mailman.qth.net>> on behalf of Waldo Magnuson via ARC5 <arc5 at mailman.qth.net<mailto:arc5 at mailman.qth.net>>
> Sent: Sunday, November 17, 2019 13:08
> To: arc5 at mailman.qth.net<mailto:arc5 at mailman.qth.net> <arc5 at mailman.qth.net<mailto:arc5 at mailman.qth.net>>
> Subject: [ARC5] Removing knobs - verse two.
>
> The set screw in the audio volume switch on a C-1254A control unit IS a Bristol set screw. The wrench fits tightly, I?ve used Blaster penetrating Oil but even with excessive torque the screw has not come loose. Any suggestions- heat/cold/drill?
> Skip W7WGM
> ______________________________________________________________
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