Re: [ihc] Flaring tool?

[Richard Welty <rwelty@xxxxxxxxxxxxxxx>]

On Thu, 26 Feb 2004 14:27:04 -0600 Ryan Moore <baradium@domain.elided> wrote:
> Also, just FYI, aircraft use a different pitch to the flare than automotive
> applications do.  An automotive flare is 45* while a flare for an aviation
> application is 30*.

AN flares are 37 degrees, as i recall.

>  The idea is to prevent automotive fittings from being
> usable on aircraft (if you use the aviation flare equipement it won't fit).

i'm not sure if this was the original intent. the aircraft flaring system
dates from the late 30s or early 40s, when the US military standardized
what had previously been a very confusing situation.

> However, you *can* use the aviation fittings on an automotive applications,
> but it won't seal quite quite as well (only at certain points, although most
> likely, with most peoples' flare ability, it probobly won't many
> difference).

i have a friend who was putting AN hydraulic fittings onto his RX-7, he
was going crazy because of the unreliability of what he'd been told
was a very reliable system. i explained about 37 degrees vs 45 degrees,
and the necessary adapters, and the light went on in his head. oops.

> The double flare in SAE means that as the flare is made you do fold the end
> inside of the flare, this prevents a rough edge from being present in the
> flare and presents a better sealing surface.

in the Aircraft system, the sealing is done in a slightly different manner
mechanically, allowing single flares to work well in tubing sizes from
3/8" on down. 3/8" is right on the edge, i done AN single flares in this
size with good results using Moroso's aluminum fuel line, but i'm not
sure i'd want to try to get away with single flaring 3/8" steel.

> Hey, looks like I'm learning *something* from my systems class at least.
> BTW, the aviation flare tools make that automotive snap-on one look cheap
> and primative.

the flaring tool i use for AN fittings is a Rol-Aire Imperial which i suspect
is very similar to John H's prefered flaring tool.

richard
-- 
Richard Welty                                         rwelty@domain.elided
Averill Park Networking                                         518-573-7592
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