REFLECTOR:173 Exhaust pipes ....

Chuck Jensen reflector@tvbf.org
Sun, 25 Jan 2004 09:41:18 -0500


Jim,

I was referencing drawing, not bending.  By heating on one side of the pipe
and quenching (cold wet towel) the other side, even heavy gauge piping can
be "drawn" a surprising distance.  Heating and bending is not likely to have
a satisfactory outcome...unless your pipe is made of wrought iron.  If the
shop says they can't do it or it won't work; that's one thing.  If the
machine shop says they don't understand what you are asking about, "bolt"
for the door, as they are "nuts."  This is not breakthru, leading edge type
stuff.  It may not work, but any machine shop that doesn't understand how to
try it is likely located under a shade tree.

Chuck

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Jim Sower
Sent: Saturday, January 24, 2004 9:28 PM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:173 Exhaust pipes ....


The machine shop said they might be able to heat it enough over a wide
enough area to
bend it.  I got it back a couple of days later with a note that they
couldn't bend
it.  I could see it had been heated, and there was a wrinkle where they
tried to bend
it, but it wasn't bent and they couldn't do it.  If that sounds like thin
info, you
couldn't be more right.
But I've already told you more than I know .... Jim S.


Chuck Jensen wrote:

> Jim,
>
> Did you ask if they would try the heating/quinching method of drawing the
> pipe into the alignment you needed.  It's kind of surprising how much
> strategic heating and quinching can move even Sched 10 and 40 pipe around.
> If it doesn't screw up the metallurgy, it would maintain the integrity of
> the pipe by eliminating cuts/welds/creases.
>
> Chuck
>
> -----Original Message-----
> From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
> Behalf Of Jim Sower
> Sent: Saturday, January 24, 2004 5:18 PM
> To: reflector@tvbf.org
> Subject: REFLECTOR:173 Exhaust pipes ....
>
> All,
> I've got a situation here that I don't know if it is about me or
> the factory.  I have a 173 FG (with the 3" nipples in the cowl
> for the exhaust to exit).  The plane came at me with exhaust
> pipes (mild steel)  :-( that fit the cowl well.  About 18 months
> ago the one on the starboard side cracked so I replaced it with
> a SS unit.  The pipe didn't fit.  It pointed outboard about 1/2"
> so it rested against the glass cowl.  I looked all over for a
> place to bend it a little and finally got an exhaust shop that
> would try (machine shops begged off saying they couldn't bend SS
> pipes at all).  Well, they bent it so it would fit, but it
> crinkled the pipe some where the bend was.  Recently I broke off
> the last 6" of the other pipe (earlier post on Catto props) and
> ordered another SS unit for the port side.  Took two months, but
> it finally got here.  It was just a little tough to get the
> flanges over the studs (but not near as bad as the previous one)
> but OK.  When I went to put the cowl on, damned if it wasn't
> splayed 1/2" INboard.  Once again, nobody can bend it, so I got
> a machine shop welder (who I had used for some other stuff) to
> make a cut (or two) to take a tiny wedge out of the pipe, bend
> it back closed and stitch it up again.  HATE to do that, since
> that's most likely where it will fail, but I had no alternative.
>
> My question to the list is:
> Has anyone else had this problem (on replacement pipes)?  If it
> is a common problem, one could surmise that the guy's jigs are a
> little off.  If I'm the only one who has the problem, it would
> seem that someone (the builder?) fastened the exhaust nipples
> onto the cowl [in the wrong place / pointing the wrong
> direction] and this is going to be an ongoing problem unless and
> until I fix my cowl.
>

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