Author Topic: Makeshift repairs and babbit  (Read 986 times)

MachineNLectricMan

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Makeshift repairs and babbit
« on: June 17, 2021, 12:49:50 AM »
   I was reading some posts about makeshift bearing journal repairs and there were surprisingly few mentions of babbit metal. Our early American railroad westward expansion was built with babbit bearings. The unique feature of this material was easy field repairs without needing machine shop equipment or having to keep a large inventory of spare parts. My grandfather use to often talk about this metal. In today's times with shortages all over, maybe it's time to re-visit this material.

   There are many different variations of babbit alloys for high speed, low speed, heavy loads, ect.. If I remember right, the metal expands slightly when it solidifies, so it adheres well to clean and properly prepared bearing case bores. Sometimes these bearing case bores were just rough cast using green sand molds at the cast iron foundry with no machining needed before the babbit was poured in. The shafts were simply coated with some greasy release material or special paint, centered in the bore and the metal poured in. Clay was often used to seal the bottom and any gaps, and if an oil hole was needed, a coated steel, or iron rod was inserted before pouring. After pouring, and when cooled, the shaft was removed easily if everything was done right, and the proper clearances were hand scraped into the bearing bore, along with smoothing out any imperfections.

   Also, the metal was extensively recycled in the field. When a bearing got excessively worn, the old metal was removed, often by melting, then it was re-melted and some extra metal added to make up for metal lost from wear and any melting slag, then re-poured back into the bearing case to form the renewed bearing.

   If babbit can support locomotives weighing more than 100 tons, it ought to work well for any emergency Lister repair if you choose the correct alloy, and I believe the early Lister's actually did use babbit. Henry Ford was likely responsible for the demise of the widespread use of this metal because he needed interchangeable parts for his auto manufacturing.  Although babbit was used in the early replaceable bearings, it was not well suited for thin coatings inside replaceable steel bearing shells.

   Sometimes modern technology throw's the baby out with the bathwater. Seldom does new technology actually completely eliminate the use or need for all of the older technologies. There is always some nich that only one type of technology does the best. We should think of new technology as adding another useful tool to the technology "toolbox", but not going and hastefully dumping out all of the other tools that will always have some special uses.
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cobbadog

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Re: Makeshift repairs and babbit
« Reply #1 on: June 17, 2021, 11:59:10 AM »
Sure, there is no reason that babbit bearings could  not be used in almost any old stationary engine. The hard part is sourcing the material easily then the preparation and setting up accuratly of the dummy shaft ready for pouring. Then the heating of the babbit material, pouring and finally scraping to size.
I have a few engines that run babbit bearings from mower engines, hit n miss engines and even a diesel engine made here in Australia.
At the end of the day the use of bearing shells is simpler and far easier to source and replace and is the main reason for the old system of babbit. So it would be the case of cost against effeciancy. I think I prefer bearing shells over babbit for convenience but there is nothing wrong with the way a babbit works or lasts.
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mikenash

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Re: Makeshift repairs and babbit
« Reply #2 on: June 17, 2021, 11:59:08 PM »
   I was reading some posts about makeshift bearing journal repairs and there were surprisingly few mentions of babbit metal. Our early American railroad westward expansion was built with babbit bearings. The unique feature of this material was easy field repairs without needing machine shop equipment or having to keep a large inventory of spare parts. My grandfather use to often talk about this metal. In today's times with shortages all over, maybe it's time to re-visit this material.

   There are many different variations of babbit alloys for high speed, low speed, heavy loads, ect.. If I remember right, the metal expands slightly when it solidifies, so it adheres well to clean and properly prepared bearing case bores. Sometimes these bearing case bores were just rough cast using green sand molds at the cast iron foundry with no machining needed before the babbit was poured in. The shafts were simply coated with some greasy release material or special paint, centered in the bore and the metal poured in. Clay was often used to seal the bottom and any gaps, and if an oil hole was needed, a coated steel, or iron rod was inserted before pouring. After pouring, and when cooled, the shaft was removed easily if everything was done right, and the proper clearances were hand scraped into the bearing bore, along with smoothing out any imperfections.

   Also, the metal was extensively recycled in the field. When a bearing got excessively worn, the old metal was removed, often by melting, then it was re-melted and some extra metal added to make up for metal lost from wear and any melting slag, then re-poured back into the bearing case to form the renewed bearing.

   If babbit can support locomotives weighing more than 100 tons, it ought to work well for any emergency Lister repair if you choose the correct alloy, and I believe the early Lister's actually did use babbit. Henry Ford was likely responsible for the demise of the widespread use of this metal because he needed interchangeable parts for his auto manufacturing.  Although babbit was used in the early replaceable bearings, it was not well suited for thin coatings inside replaceable steel bearing shells.

   Sometimes modern technology throw's the baby out with the bathwater. Seldom does new technology actually completely eliminate the use or need for all of the older technologies. There is always some nich that only one type of technology does the best. We should think of new technology as adding another useful tool to the technology "toolbox", but not going and hastefully dumping out all of the other tools that will always have some special uses.
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38ac

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Re: Makeshift repairs and babbit
« Reply #3 on: June 18, 2021, 02:38:06 AM »
Actually some if not all modern engine earing shells still use a layer of babbit over the backing metal it serves to cushion shock loads and provide crankshaft protection. How thick depends on the application. Ford may have had something to do with thin shell development but Henry's Model Ts and As had poured babbitt bearings.
As for pouring an emergency repair bearing it is indeed a satisfactory repair when there is no other option. As an example there are no big end shells available for the Z4 Banfords engines. When I rebuild one the rod goes to a specialist who pours babbitt directly in the rod and adds a shim pack so it can be adjusted down the road if needed. Same would work for a CS type but when replacement shells in every conceivable undersize are easy obained and cheap there is really no reason go another route outside of an emergency repair and try to find Babbitt in your home town, might as well order a bearing as order babbitt.
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scott p

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Re: Makeshift repairs and babbit
« Reply #4 on: June 18, 2021, 06:35:44 PM »
I use old poured babbit bearings on some of the sawmill shafts. I get the babbit from a comersial saw mill. They use the babbit in their gang saw. They call it high speed babbit or hard babbit.They also say it is lead free with a lot of tin.

I coat the shaft with a  coat of carbon applied by a Acetylene flame. As mentioned clay or something to seal the gaps. Poured directly through the oil hole and then drilled. No need to scrap. Works fine, no searching around for probably none existent bearing shells.

I am currently working on  replacing the small end bushing on a small, old, slow speed gas engine. I am not aware of any organization that sells bushings for these old engines. This hard babbit is a dream to mill. It will be a DIY schooling project. I might coat the wrist pin and pour the babbit around it and then machine it to fit the small end.


scott p

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Re: Makeshift repairs and babbit
« Reply #5 on: June 18, 2021, 09:53:24 PM »
Out of curiosity I did a search. Looks like babbit comes in a lot of different flavors,and is readily available.

MachineNLectricMan

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Re: Makeshift repairs and babbit
« Reply #6 on: June 19, 2021, 12:46:06 AM »
Actually some if not all modern engine earing shells still use a layer of babbit over the backing metal it serves to cushion shock loads and provide crankshaft protection. How thick depends on the application. Ford may have had something to do with thin shell development but Henry's Model Ts and As had poured babbitt bearings.
As for pouring an emergency repair bearing it is indeed a satisfactory repair when there is no other option. As an example there are no big end shells available for the Z4 Banfords engines. When I rebuild one the rod goes to a specialist who pours babbitt directly in the rod and adds a shim pack so it can be adjusted down the road if needed. Same would work for a CS type but when replacement shells in every conceivable undersize are easy obained and cheap there is really no reason go another route outside of an emergency repair and try to find Babbitt in your home town, might as well order a bearing as order babbitt.

Actually it is a thin layer of a special aluminum alloy applied over a layer of copper on the soft steel backing shell for most modern shell bearings. Some manufacturers cut corners and do not use the copper under-layer.  The copper under-layer also was once used when babbit was used for the bearing material as it helps the bonding of the babbit to the steel.

You have to appreciate the simplicity and effectiveness of some of the old technologies. With so much of the world going down the toilet now days, we may find ourselves reverting back to some of these older methods in the near future.

38ac

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Re: Makeshift repairs and babbit
« Reply #7 on: June 19, 2021, 11:54:55 AM »
Out of curiosity I did a search. Looks like babbit comes in a lot of different flavors,and is readily available.

Yes , Babbitt  is a blend of metals and there is no stabdard mixture. Hardness varies with the application. If the babbitt is too soft it actually flows over time and if too hard it cracks and chips,
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scott p

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Re: Makeshift repairs and babbit
« Reply #8 on: June 19, 2021, 09:29:13 PM »
Interesting observation 38ac. I hadn't considered that sort of thing. I think I will try brass rather than the babbit I have here.

I believe I read a post where you might have a lathe. Have you ever made bearings or bushings? 

I am including a couple pictures showing what I will try first in my attempt to make a proper bushing. One shows a shaft slightly smaller that the wrist pin. The second pict is the outer container to hold the brass. If I can get the brass out or off of the these two items I will consider myself lucky.

38ac

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Re: Makeshift repairs and babbit
« Reply #9 on: June 20, 2021, 01:46:34 AM »
Yes I do have a fairly complete machine shop. I have turned 1000s of press fit bushings and made a few sets of bearing shells from Silicon Bronze.
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mike90045

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Re: Makeshift repairs and babbit
« Reply #10 on: June 20, 2021, 03:06:17 AM »
Somewhere on the forums, I remember a post about using an aluminum can as shell material.  Of course now,
i can't find it.

starfire

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Re: Makeshift repairs and babbit
« Reply #11 on: June 20, 2021, 05:56:45 AM »
Somewhere on the forums, I remember a post about using an aluminum can as shell material.  Of course now,
i can't find it.
That  may have been me. Around 5/6 years ago   I made complete shells from aluminium sheet, 1.5mm thick by memory. These were pounded into shape using a wood dowel as an anvil.  The crank journal was badly scored, this was  smoothed out with a strip of emery paper, the shells were then mounted using shims made from a drink can. The rod was spun around the crank and high spots scraped off until the contact surface was great enough to support an oil film. The engine was run under no load for short times and shims were gradually removed from between rod and cap until it all bedded in. This engine runs great still after all this time. I figured at the time that if Briggs and Stratton can get away with a steel piston in an aluminium cylinder with very marginal lubrication, then my 3.5 CS should cope fine.  I never expected it to work so well, there is considerable loading on that shell. I did make larger oil grooves to increase oil flow from the dipper, was worried about the initial heating during the bedding in process.
« Last Edit: June 20, 2021, 06:02:59 AM by starfire »

starfire

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Re: Makeshift repairs and babbit
« Reply #12 on: June 20, 2021, 06:28:18 AM »
Just to expand on the process if anyone tries this. The alloy was cut 1 inch wider than the journal, bent roughly to shape and squashed into the big end using a 2 inch wooden dowel to force it into the shape of the big end hole. The sides are then peened over the sides of the big end to create the thrust faces. The shells then were filed to shape , the ends made nearly  level <crush> with the big end faces between cap and rod. The rest is very time consuming ,to get a good contact surface, using emery , files, and a sharp wood chisel to scrape the high spots
To repair a crank journal its not sufficient to just remove scoring, it also must be round, with as little taper as possible. Initially use strips of emery paper to remove as much damage as possible. Then tackle the finish.
The easiest way here is to make temporary steel shells to fit the rod, these become sacrificial to complete the process of final grinding with valve paste. Again, shims between cap and rod are removed as the journal  decreases in diameter. When there is no more binding throughout the rotation, job is done.
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scott p

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Re: Makeshift repairs and babbit
« Reply #13 on: June 20, 2021, 08:15:51 PM »
So 38ac glad to hear some one has been there done that. What would be your procedure for making a bushing to fit the small end of the con rod ?

Ingenuity and perseverance, just what MachineNlectricMan was talking about, well done.

All done without fancy tooling.

Did you need to use Prussian Blue or something to located high spots.

Nice touch, valve grinding paste.

starfire

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Re: Makeshift repairs and babbit
« Reply #14 on: June 21, 2021, 12:10:57 AM »
A permanent marker or sharpie will suffice for Prussian blue, or even nothing. After grinding, if the rod is spun dry, shiny marks on the shell will appear on the matt  to show the highs.  The small end bush could possibly be replaced with a section of copper pipe. If copper is heated to red and cooled slowly, it hardens, the complete opposite of steel. I cant see why it wouldnt work as well as the original bronze bush. In my experience, its the pin that wears, this easily remedied by a length of 1 inch bright shafting. Even without hollowing out the central hole, the extra weight does little, given its just  a  few grams over the total  kilos of rod and piston.  These engines are overly engineered for continuous rated duty, something the car people cannot figure when they wonder why their engines develop huge horsepower for only a comparatively  very short time.  So, there is a bit of  wiggle room in patching these things I think.
I have often wondered why Lister didnt spend a few more design minutes to make the barrel more symmetrical. This would allow it to be mounted upside down to  put the worn part at the bottom  where it wouldnt matter, thus saving a rebore and sleeve.