Subject: Weld repair cast-iron centerboard?

From: [email-masked] (Dan Wold)
Date: 24 May 1995 23:17:33 -0400

[ Article crossposted from rec.boats.building ]
[ Author was Dan Wold ]
[ Posted on 24 May 1995 23:08:13 -0400 ]

I need to repair a cast-iron centerboard. It weighs 1900 lbs and is about 3"
thick at its pivot point. The problem is that the pivot hole has become very 
elongated. The hole was originally 1" diameter to accept the 1" bronze pivot 
shaft.                                                                       

Several fixes are being considered:

1) Clean out the hole with a burr-grinder and fill it up with
nickel-chromium weld. After welding grind the area flat and redrill the
hole.

2) Use a hole-saw and make a hole to encompass the elongated hole area
(about 2" dia). Make slug out of bronze or stainless-steel with a 1" hole
drilled in the right spot. Weld the slug in place with silicon bronze or
nickle-chromium.

I'm concerned about galvanic corrosion. 

Thanks for any input on this!

-Dan
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[email-masked]
Daniel Wold                               239 City Island Ave,Bronx,NY,10464
finger [email-masked]
-- 
[email-masked]
Daniel Wold                               239 City Island Ave,Bronx,NY,10464
finger [email-masked]

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From: [email-masked] (J. Kimberlin)
Date: 25 May 1995 18:15:21 -0700

>drilled in the right spot. Weld the slug in place with silicon bronze or

Consider solution #2 but do a good job of hole-sawing.  Turn a slug out 
of cast iron on a lathe to put in the hole.  Clean everything well in the 
centerboard with a chlorinated solvent (outside) as well as the plug.  
Then use Loctite to install the slug which can be center bored to fit the 
bronze pivot shaft.  Care in making the hole-saw cut, then finishing it 
round can increase the strength of the slug to centerboard joint.  After 
all is together, you could saturate the area with thin epoxy to seal off 
the surface around the joint.  Since the centerboard is so heavy, you may 
have to borrow a magnetic base drill press to do the hole-sawing.  In any 
case get the hole perpendicular to the centerboard then the lathe turned 
slug with the bored hole for the pivot shaft will be fairly true to what 
you want.

You do not need much Loctite, which is expensive.  Your local bearing 
distributor - Bearings, Inc., Bearing Engineering, King Bearing, etc., 
will have it.  Ask them for the ideal clearence between the centerboard 
and plug.  You won't need more than 10-15 drops of Locktite.  Also ask 
them for the proper type of Locktite.

JerryK