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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
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Re: Powder Coat on 4130
