[Steam-engine] Pouring Bearings

[Andy glines]

I took the plunge and tried my hand at pouring
bearings Sunday afternoon.  I started with the shaft
that drives the wheels because alignment isn't
critical on the Huber design.  So far, I have only
poured one half of the two bearings.  I have learned a
few things and now have a few questions.  I learned
that I can't trust Babbitrite to stay stuck to the
shaft and shell unassisted.  Dad was preheating while
I melted  babbit.  When the shaft and shell got good
and hot the Babbitrite fell off.  We were able to
secure more putty without losing preheat. This time
the putty was secured with wire and plumper's tape. 
The bread pan I placed under the shell turned out to
be a very good thing when a plug in an oil hole blew
out.  The pan caught the babbit and it was easily
recovered.  I am using the book "How I Pour Babbit
Bearings" by Gingery for reference.  Using the book's
suggestions the shell was preheated until a piece of
solder just started to melt and the shaft heated to
about 300 deg.  I am using tin-based babbit so I
heated it until my wooden stir stick caught fire.  The
cooled product looks pretty good.  The ends of the new
bearing are nice and shiny but it is dull gray near
the center where the cooling was a bit slower.  I
think that I may have been a little hot on my preheat
and my babbit and plan to back off on temperature a
little when I pour the caps.  One thing in my book
confuses me a little.  The book tells us that
tin-based babbit should be poured hotter than
lead-based.  I thought that lead has a higher melting
point than tin???  Is the book backwards?  We used a
propane weed burner for preheat and found that it
works very well.  I'm getting ready to pour the caps. 
I will shim the caps and secure them to the top
casting.  I can preheat the shell OK but how do I
preheat the shaft with the bearing cap in place?    

Andy Glines
Evansville, IN

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