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On Fri, 23 Mar 2007 12:40:12 -0400, "J.Kahn"
<jdkahn@REMOVEvideotron.ca> wrote:
>Ernest Christley wrote:
>> clare at snyder.on.ca wrote:
>>> On Thu, 22 Mar 2007 23:29:15 -0400, "Phil" <pdl@imaginenet.net> wrote:
>>>
>>>> Hello
>>>> Was watching American Chopper this evening , I see things on that
>>>> show that make me cringe but I do enjoy the antics of that family,
>>>> they always refer to Pipe if they are building a frame out of Tubing
>>>> etc. , this evening they were working on a dragster bike for NAPA and
>>>> when it came time to paint the machine they said that powder coat
>>>> couldn't be used because of the heat involved would ruin the 4130
>>>> tubing , seems like a lot of engine mounts and other A/C parts will
>>>> have to be junked , would like to hear some thoughts on this concept
>>>> , as an A/C welder it is of interest to me.
>>>> Thanks
>>>> Phil Lohiser
>>>> EAA 12873
>>> Powder coating won't hurt 4130, but is NOT RECOMMENDED for aircraft
>>> use because it can hide developing cracks.At least that's what I have
>>> been told.
>>>
>>
>> Bwhahaha!!
>>
>> Powder coating is done at what, 275 degree F? I gotten my airframe
>> hotter than that by cussing at it when members wouldn't meet up
>> properly. 4130 will see it as a pleasantly warm temperature, suitable
>> for shorts and maybe a light sweater.
>>
>> Some people do not recommend powder coating because it may hide
>> developing cracks. Others swear by it because it give better protection
>> to keep cracks from ever forming. Truth is, if the only thing you have
>> to identify developing cracks is a visual inspection, you're not going
>> to have much luck. Use white powder coat, and linseed oil inside the
>> tube. A hairline crack will seep the oil and make and ugly black mark.
>
>But if the hairline crack doesn't break the paint film the oil will
>still be contained. Besides the oil, weld a boss on a longeron tube end
>and install a tire valve and pressurize to 100 or so psi pressure during
>the annual. The pressure should be enough to make the paint film fail
>and cause leakdown. Find the leak by listening or water/soap.
>
>Llama helicopters charge the truss permanently with dry nitrogen and
>have a pressure gauge that is in view behind the cabin and can be
>checked on a DI.
>
>John
I find it very hard to believe that forces strong enough to crack 4130
wouldn't be strong enough to crack powder coating.
I suspect the real reason for not powdercoating the chopper frame has
a lot to do with filming schedules.
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Re: Powder Coat on 4130
