[ARC5] [Milsurplus] Control Box Mounts

[J. Forster]

Mike,

Upon reflection, I think the butterfly spring is not onlt to prevent
rattling. It's too flimsy for that, IMO.  I'm more inclined to think it
for bonding the Control Box to the aircraft structure for EMI purposes.

FWIW,

-John

==============


> That's correct.  The key is making the inside of the "U" ~.005" larger
> than the .063" dimension of the control box bottom plate so that it will
> slide into the "U" without a lot of fiddling and forcing.  In the
> production design there are some stainless steel "butterfly" plates that
> are riveted to the mount to exert pressure on the back of the control
> box to avoid rattling, but frankly they are not needed unless you mount
> the mount in a vibrating aircraft.  Using a bar folder, you brake the
> aluminum to about 150 degrees, and then remove the workpiece and add a
> 1/16" shim along with a .005" shim under the "U".  Then you clamp the
> assembly in a press (or large vise) to complete the fold.  It's easier
> than it may sound at first.
>
> You really want to use an alloy that is designed for braking - 5052 is
> the closest I have found to the original ARC specification.  You can
> anneal some of the more common alloys like 6061, but they discolor in
> the process and it is cheaper to just get the right stuff off of ebay.
>
> Best 73,
> Mike
>
> On 6/5/2010 6:32 PM, J. Forster wrote:
>> I just looked at a similar type mount and the rear catchs were bent into
>> a
>> "U" rotated 90 degrees CCW.
>>
>> On the plus side, there are no "dished" areas on the mounts. They are on
>> the CB underside. This makes it easier.
>>
>> Best,
>>
>> -John
>>
>> ===============
>>
>>
>>
>>
>>> On Sat, Jun 5, 2010 at 12:44 AM, Mike Hanz<aaf-radio-1 at aafradio.org>
>>> wrote:
>>>
>>>> Steve KB4DMF was making these for a while, but I'm not sure he is
>>>> still
>>>> in the business.
>>>>
>>>
>>> Isn't he the gentleman who was also making shock mounts?  Last I saw,
>>> that was all he was making.
>>>
>>>
>>>> manual. Â The only thing missing are the dimensions of the folded over
>>>> portion, with the milled cutouts along the top, but those and the
>>>> location of the snap slide stud can be inferred from an actual control
>>>> box.
>>>>
>>> When I made 1:1 scale drawings using proportional dividers, I was able
>>> to dimension these fairly closely from the original drawings.  I can't
>>> say they were perfect but it did work and appeared correct.  One thing
>>> I did was to anneal the aluminum first (I'll be darned if I can
>>> remember what type I used but it wasn't 5052 nor was it anything like
>>> 2S.  2024?) to make the fold easier.  When I compared mine to a "real"
>>> set of mounts, I found my fold wasn't quite as it should have been but
>>> it did work.
>>>
>>> Those drawings got left behind when I moved here and I have to make a
>>> new set.  Darn it.  But then I left my metal shop behind too and
>>> that's slowly getting rebuilt now.
>>>
>>> Best regards,
>>>
>>> Michael, WH7HG
>>> --
>>> http://www.nationalmssociety.org/chapters/NTH/index.aspx
>>> http://wh7hg.blogspot.com/
>>> http://kludges-other-blog.blogspot.com
>>> Hiki Nô!
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