[SEL] White metal to bronze question

[Elden DuRand]

Russell:

If you can get the big end into a lathe or mill, most of the critical work is easy.  Beings I've never rebabbitted a bearing (scraped in a set of mains on my American LaFrance a few years ago), I might give some wrong advice.

To make the babbitt stick to the bronze, first clean up the surfaces with sandpaper, etc. and use a good solder flux and tin the bearings with babbitt until the surfaces are completely covered. 

To keep the babbitt from sticking to the mandrel, one way is to use an acetylene torch with no oxygen to smoke the mandrel.  Babbitt won't stick to the carbon.

Before pouring the bearing, make up several shims so you can take-up wear in the bearing in the future.  I suppose you'd be good to go with about 0.030" or so of shims.  Then, assemble the bearing with the shims.

If you can easily machine the new babbitt to fit the journal, you can leave a gap of 1/8 inch or so between the mandrel and the bearing.  This will allow the white metal to flow to all parts of the bearing.  Also, you need to heat the bearing to very near the melting temperature of the babbitt so the poured metal will fuse to the tin coating.

After the whole works has cooled, machine to fit.

Take care - Elden
edurand at mchsi.com
http://www.oldengine.org/members/durand 

> -----Original Message-----
> From: sel-bounces at lists.stationary-engine.com
> [mailto:sel-bounces at lists.stationary-engine.com]On
>  Behalf Of Russell
> Gilbert
> Sent: Tuesday, March 20, 2007 06:09 AM
> To: The SEL email discussion list
> Subject: [SEL] White metal to bronze question
> 
> 
> Howdy ya all.
> I want to have a go of fixing the bearing gap (if 
> you like) in the 
> big Graham engine I have. It runs fine but has a 
> little jump in the 
> crank shaft in the bearings itself on the 
> compression stroke. So yes 
> they are warn, but not major or it does look like 
> a major problem 
> anyway. Some of my past engines have actually had 
> a very thin layer 
> of white metal placed on the original bronze 
> bearings so I thought I 
> could do the same thing. I have plenty of white 
> metal. Just have 
> never used it before. How would I go about 
> melting the white metal 
> and attaching it to the bronze bearings. I 
> imagine I would clamp the 
> bearings together and put something similar in 
> size to my crank shaft 
> inside. Melt the white metal and pour! But I need 
> to prep the bronze 
> surface area first ... Yes? How would that be 
> done? second when I 
> pour the metal ...... should the bronze be 
> preheated at all? and what 
> should I use to on the shaft bit so the metal 
> doesn't stick to it 
> when I remove it from the set casting?
> I have never done this stuff before so I will 
> probably stuff 
> something up but one will not learn if one does 
> not have a go.  In 
> case some of you are wondering how big the gap I 
> trying to fill is 
> .... I would have a guess to say about the 
> thickness of 2 to 3 playing cards.
> regards Russell
> 
> 
> 
> Russell Gilbert
> Sunny Sunraysia
> russell at ncable.com.au
> http://community.webshots.com/user/russellsrelics 
> 
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