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repouring a babbit bearing

 
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bw dolan



Joined: 03 Dec 2006
Posts: 8
Location: northampton, ma

PostPosted: Sun Jan 07, 2007 10:54 am    Post subject: repouring a babbit bearing Reply with quote

Does anyone have any suggestions on what to use as a release agent on a steel shaft when pouring a one piece babbit bearing?
I'm having a hard time finding the whale oil lamp smoke perscribed by my handbook.
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crzypete



Joined: 16 Dec 2004
Posts: 1689
Location: New York State

PostPosted: Sun Jan 07, 2007 1:18 pm    Post subject: Reply with quote

I've heard of using an oxy acetylene rig with the flame severely reduced to the point where it is generating lots of soot. I believe they want several passes to really build it up.

I don't have personal experience with re-pouring, I have generally tried to avoid babbit.

Please let us know how you make out I am curious about the technique. My old porter cable 10" vertical belt actually uses babbit for the tilting table.

Pete
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Mike Henry



Joined: 25 May 2005
Posts: 49
Location: Chicago area

PostPosted: Mon Jan 08, 2007 10:08 pm    Post subject: Reply with quote

A few years ago I scanned in an old booklet from the 1920's on Babbit bearings and William Gray at Metal Web News kindly agreed to host it:

http://www.metalwebnews.com/howto/babbitt/babbitt.html

The booklet was OCR'd so you should be able to search for terms or phrases. It's been a while since I looked at it but there should be something of interest there for those that want or need to wrk with Babbitt metal.

Mike
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mystry_tour



Joined: 13 Mar 2006
Posts: 357
Location: Greenville Tenn

PostPosted: Tue Jan 09, 2007 10:28 pm    Post subject: Reply with quote

We have a few forgeing presses here t work and they use graphite, liquid type
Reg
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bw dolan



Joined: 03 Dec 2006
Posts: 8
Location: northampton, ma

PostPosted: Sun Jan 14, 2007 5:14 pm    Post subject: Reply with quote

Thanks for the advice everybody! If we had a few of you in our shop we could really get stuff done.

The shop I work in is ghetto as hell so we don't have any acetelene as Pete suggested, insurance reasons I think. We ended up using a can of silicon/styrene mould relese and it worked fine.

I was only peripheraly involved in this project since I'm still the new guy. We have a managing engeneer who gets to do all the interesting stuff.

It's a pretty hilarious story if anyone's interested.

The bearing in question was for an idler arm on an old Mattison stroke sander, not the bearing that allows the drum to spin, the one that pivots to put the tension on the belt.

When I used it the day before it was taken apart it worked fine, so I have my doubts as to weather it was even broken in the first place. I suspect that it had more to do with getting out of some monotinus finishing work as necessity.

By the time I became aware of what was going on the engeneer and the "senior fabricator" had the shaft out and were trying to remove the old babbit. One was on one side with a sawsall and had cut thru the babbit and about a quarter of the way thru the iron casting. The other guy was on the other side with a hunk of steel and a small sledge whaling away at the babbit, which was at the end of a rather slender 3' cast iron arm.

I said "What's up fellas?"

They responded, "We're trying to get this lead out of here, but it's really hard"

I informed them that it was in fact babbit and suggested that they might have an easier time melting it out.

They said it would be too hard to take the whole arm off (4 easily accessable bolts).

4 hours later they finaly took the arm off and melted the babbit out without incedent.

Now they just had to repour. The engineer read an article online and learned about using oily soot as a relese agent so he figured a regular candle should work.

Attempt #1, they set up the pour, heated the babbit, brought the crucble over, and realized that there were two holes in the side of the casting that had to be pluged so that the molten babbit wouldent just run out. So they aborted attempt #1, found some corks to plug the holes, reheated the babbit and tried again.

Attempt #2, this time they actualy poured some babbit. Unfortunately they had blocked off the bottom of the bore with cardbord, which the molten (perhapse overheated) babbit instanty burned thru, and spattered all over the "senoir fabricator"'s sneakers. Fortunately no one was seriously injured.

Attempt #3, They replaced the cardboard with some thin brass stock and tried again. This time the pour seemed sucessful. There was much back patting and self congradulation untill to cooled and they found that not only was the shaft hopelessly stuck due to the inadequet soot coating from the regular candle, but it was also about 1/2 inch crooked.

Attempt #4, This time they used spray on mould relese and rigged it up better. I'm told that it works (after 2 "skilled" guys worked on it for 3 whole days) but I'll believe it after I actually use the machine.

Anyone know of any job openings?
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crzypete



Joined: 16 Dec 2004
Posts: 1689
Location: New York State

PostPosted: Mon Jan 15, 2007 10:29 am    Post subject: Reply with quote

Funny story, How were they melting the Babbit?

Pete
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bw dolan



Joined: 03 Dec 2006
Posts: 8
Location: northampton, ma

PostPosted: Tue Jan 16, 2007 11:33 pm    Post subject: Reply with quote

The melting went pretty smoothly. They made a crucible by tig welding a piece of steel plate onto the bottom of a 8" length of 2" diameter iron pipe. They put the babbit inside and heated it thru the side with a torch burning oxygen and natural gas from the street (+- 3psi). Once it melted we used a piece of pine to skim off the slag; when the wood chars but doesn't burst into flames the temp is just about right to pour.
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