Stuart 10V - Missing Part I.D.

[GreenTwin]

I purchased some babbitt bearing material, and intend to pour it for bearings on engines.

There were several grades of hardness, and picked the hardest grade, which was rated for use on connecting rod bearings.

Babbitt is not cheap, and so I went with what would work in any situation.

For an engine what will run loaded for extended periods of time, softer babbitt should be used in the crankshaft bearings.

I did a design project a few years ago for a stormwater pump station, and there was a debate about replacing the motor bearings, which were very large babbitt units.

The motor rewind shop recommended replacing the bearings, since they were 110 years old.
The actual wear on the bearings was negligable, since the motors run very slowly.

The motor shop said that large babbitt bearings tend to delaminate from the shell over time, and these bearings were showing signs of that.
The delaminated areas will overheat, and then cause further delamination.

We replaced the bearings with turbine-grade babbitt bearings.

These motors were rebuilt because modern motors run at a much higher rpm, which requires a gearbox, and the new motors and gearboxes are not very reliable compared to the old slow-speed motors.

It took five big burly guys to life off one bearing cap, and they struggled with it.

The entire bearing rotates in a ball joint, which I think is very clever.

This is what a journal running in a babbitt bearing looks like after 110 years.
They basically gave the journals a light polishing, since they were still in spec.

The brass/bronze rings drag the oil up to the top of the bearing.
No oil pumps to fail.

 

[GreenTwin]

Here is one of the rewound motors in action.

They will be running perfectly long after I am gone, which was the idea behind rewinding them.

This was the first motor to be rewound, and its first startup.
The first start is always a little intense with such a large machine, but the motor shop we used is absolutely top of the line, and all the motors including this one started and ran flawlessly.

These are wound-rotor induction motors, and unlike a standard squirrel-cage induction motor, the starting current of these motors can be limited, while still producing a significant amount of starting torque.

You can hear the starter contactors stepping through I think three steps of resistors to control the rotor current, before the motor reaches full speed.

I was instructed to get rid of these old motors and install new units.
My response was "No way, we will rewind them".


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[GreenTwin]

Here is the old bearing, and you can see signs of delamination.

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[GreenTwin]

Here are the new turbine-grade bearings.

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[GreenTwin]

I did not know it, but you can actually build up the surface of babbitt bearings with a torch, and then re-machine them, saving a lot of money.

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[GreenTwin]

So you will be throwing those Stuart extruded brass bearings into the melting pot along with the hot pressed brass eccentric strap/rod and conrod.

And no chance of you doing any model aero engines either

I would guess that what folks call the Stuart "brass" pieces are actually some bronze alloy.

There is the brightly polished brass you seen on many non-structural coverings, and then other metals that may have a brass color, but are more on the bronze spectrum if you dug into the chemical composition.

With its high zinc content, brass is difficult to melt and pour without using something like a glass cover on the melt.
The zinc fumes are not good to breath either.
The bronze family are easier to cast since they generally have significantly less if any zinc in them.

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[GreenTwin]

There is a wide variety just in the bronze family.

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https://www.metaltek.com/blog/a-guide-to-different-types-of-bronze-alloys/

 

[GreenTwin]

A brass/bronze standard casting chart.

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https://nationalbronze.com/pdfs/spec_reference.pdf

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[Jasonb]

The Stuart stuff is Brass, similar to CZ121 to work not what we call a bronze. It is a copper zinc alloy.

It's not usually an alloy used for casting as those parts are extruded or hot pressed as I said earlier so won't be on those charts you posted though the 857 "yellow brass" is getting close though it still has a lower zinc content.

 

[GreenTwin]

I use to think the difference between brass and bronze was just a matter of having zinc, or not, but then I found alloys of bronze with zinc, and alloys of brass with tin.

If a foundry were casting a part for a customer, I would guess that they would adhere to whatever alloy was requested, since the customer may check that with a spectral analysis.

For model engine work, a manufacturer could tweek their alloy to give whatever characteristics they wanted.

Its like adding a bit of additive to steel, and suddenly you have chrome-moly, which creates an entirely different thing.

I have seen some backyard guys create their own custom blend of brass/bronze (whatever you want to call it).

I look at machinability, strength, wear, and very closely at sticktion.
Beyond that, I don't really care what the alloy is called.

Color is important to some, and the bronzes tend towards the redish side, and the brasses towards the yellow side.
I look at function over color, since if it does not function correctly, then it is just a decorative piece (some pieces like lagging are basically decorative, and also functional).

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[Richard Hed]

I have transitioned away from aluminum in the shop for anything except permanent pattern castings, using alloy 356.

I got tired of the tool bit and drill bit loading up with aluminum that was not heat treated, and the ease at which aluminum threads strip out.

So no aluminum in my shop except for casting work.

And while they did have aluminum at least back to the Wright Flyer engine days, and probably before, I think it was considered an exotic metal, and not normally used for engine work, especially old steam engines.

The adonized aluminum no doubt would look good, but from a personal standpoint, you will never see me wrap a piece of aluminum around cast iron engine (that is just my preference). Your chances of finding Bigfoot would be much better than me doing that.

Some folks create an alloy called aluminum-bronze, and the piece of it that someone sent me was absolutely hard as a rock.
I think aluminum-bronze could possibly be used in aerospace, but its machinability seems to be very low.
After seeing that piece of aluminum-bronze, I was cured of using any type of exotic metals.

I use gray cast iron, brass, or bronze, with aluminum 356 for pattern work, and that is it for me.
I have a lot of boat shaft bronze, but that material is so sticky as to be useless for other than ornamental purposes.

And I am phasing out brass too, since it makes for a very poor bearing material that wears out too fast.
Any brass that I have will probably be melted and alloyed into bearing bronze.

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I'm using Aluminum bronze to repair some gouges in a shaft. TIGging it on. It is tough material for sure, tough AND strong which are two different properties. However, I was practicing on a separate shaft and I turned the shaft after TIGging the practice pieces. It machined off nicely but I had to cut small cuts. Left a nice finish. Don't know if Al-Bronze is used in much else. It's strength while not as strong as steel, it is in the same approx area of strength.

 

[GreenTwin]

A buddy of mine sent me a piece of aluminum bronze that he cast.

It was a most impressive piece; very nice color, very light, supremely strong, but it seemed to have very low machinability.

One website gives a range of machinability of aluminum bronze at 20-50%, which is way too low for my liking.
The site also said that the heat caused by machining aluminum bronze can cause a lot of expansion, which then brings the part out of spec when it cools down.

My dad had a variety of metals in his shop, and some of steel-looking bar stock, which was about 6" diameter, I thought would make perfect flywheels.
I started trying to cut it, and it was basically the hardness of tool steel. The bandsaw just had all its teeth dulled in seconds.

I tried making some parts from brass, and it has a terrible habit of snagging tool bits and drill bits, and so generally I would get the part almost perfect in the lathe, and then it would snag, and ruin the part.

Bronze does not seem nearly as bad about snagging, probably due to the lead that is in some of it.

Gray cast iron is king in my opinion as far as machinability (free cutting brass is rated at 100% machinability), and gray iron can vary at values perhaps at 70% for many gray irons, but the fine chips make iron easy to machine in any position, and give a very consistent finish, especially with a carbide bit.

Gray iron is easy to drill, machine, tap, etc., and so is my preference for almost everything on an engine.
It machines very consistently, unless you are unfortunate enough to get a kit part from a foundry, where the part is on the thin side and the incorrect or no amount of ferrosilicon was added, and also if the casting is quickly removed from the mold instead of letting it cool overnight.
And adding exactly the right amount of ferrosilicon 75% is critical for keeping the thin sections machinable.

There is absolutely no reason to ever get a chill (hard spot) in any model engine castings.


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[Jasonb]

The downside of grey cast iron is it is brittle so not suitable for every part. Thin small parts are usually better in ductile or SG iron though that still runs the risk of "white corner" or hard areas if it cools to quickly hence why many a casting kit has the smaller items in a bronze or gun metal or even brass.

Pics below show the likely Ductile Iron parts, other makers just do the whole engine in Ductile.

 

[ajoeiam]

I did not know it, but you can actually build up the surface of babbitt bearings with a torch, and then re-machine them, saving a lot of money.

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View attachment 151989

TIG and a slow turning lathe also work.

Nice job on the cladding!!!

 

[william_b_noble]

ok, I learned the word "lagging" from this thread, as metal you wrap around a cylinder - why is it called "lagging"? there is "cladding" that is somewhat similar .....???? curious minds want to know

 

[ajoeiam]

ok, I learned the word "lagging" from this thread, as metal you wrap around a cylinder - why is it called "lagging"? there is "cladding" that is somewhat similar .....???? curious minds want to know

I was using 'cladding' to refer to the metal buildup done using the oxy-fuel torch.

Believe (not 100% sure!!!) that lagging can also refer to the covering (I think its insulating and covering - - - used to be done with woods for covering) of the 'hot parts'.

This is an area of arcanery that I've only more read about that heard in practice so I could be quite (re: the lagging) out too lunch! ymmv (!!!)

 

[Jasonb]

The metal sheet is cladding or cleading depending on where in the world you come from. Lagging is the insulation material that is placed around the cylinder and covered by the cladding/cleading.

When it is wood then either term can be used as the wood has insulating properties and is what was often found under the metal cleading as the insulation material particularly on traction engines and locos.

 

[william_b_noble]

The metal sheet is cladding or cleading depending on where in the world you come from. Lagging is the insulation material that is placed around the cylinder and covered by the cladding/cleading.

When it is wood then either term can be used as the wood has insulating properties and is what was often found under the metal cleading as the insulation material particularly on traction engines and locos.

that's helpful and clarifies the meaning - I wonder how it came to have that name.... Lagging to me usually means following behind... <consulting Oxford English Dictionary>...it says Lagging (the action of the verb Lag) ... the action of covering boiler, an arch, a wall, etc with strips of wood or felt. The earliest reference is in 1870 "this can be prevented by careful lagging with non-conductors of heat". The second definition is the material used for lagging, and that has a quote from 1851.

there is about a full page of definition of the word "lag", but one of them refers to the staves of a barrel, and another definition relates to "wet and muddy" .... so, how did this word "lag" or Lagging" come to represent covering with insulating material ..... it's a puzzle isn't it?

 

[GreenTwin]

The downside of grey cast iron is it is brittle so not suitable for every part. Thin small parts are usually better in ductile or SG iron though that still runs the risk of "white corner" or hard areas if it cools to quickly hence why many a casting kit has the smaller items in a bronze or gun metal or even brass.

Pics below show the likely Ductile Iron parts, other makers just do the whole engine in Ductile.

I found a supplier who would discuss selling nickle-mag 4, and he descriped exactly hot to make ductile iron without getting to much of a reaction and boiling all the iron out of the ladle.

But I could never convince him to actually sell me any nicklemag.

I found a guy who runs his own foundry, and makes ductile iron castings for steam engines, but no luck talking him into sharing nicklemag.
He is across the country, and so I don't have time to go knock on his door and beg.

I think the large foundries use an "in-stream" innoculation, which would avoid the reaction problems.

I don't think in-stream would work for a backyard casting setting, since it would be difficult to get the exact amount mixed in with such a small stream of metal.

I would like to make crankshafts and connecting rods from ductile iron.

I am not sure if the typical model engine parts are ductile iron or not.
Lone star did offer a cast iron crankshaft.

Class 40 gray iron is quite strong, and not really what you would call "brittle".
It takes a sledge hammer to break it up, with difficulty most times.

The problem with gray iron is its low strength in tension.

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Edit:
I think the suppliers won't sell nicklemag because they are afraid of somebody having a big reaction/explosion, which is an entirely valid assumption depending on the exact alloy and how you handle it.

There is no doubt in my mind that I could make ductile iron, if I had some nicklemag 4.

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[Jasonb]

I am not sure if the typical model engine parts are ductile iron or not.
Lone star did offer a cast iron crankshaft.

Class 40 gray iron is quite strong, and not really what you would call "brittle".
It takes a sledge hammer to break it up, with difficulty most times.


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As I said some suppliers do certain parts in Ductile, the ones marked in the Gade photo were the Ductile iron ones. Other makers such as Nick Rowland of RMC and also Dennis at Historic Reproductions both do all there iron parts in ductile iron. So yes Typical models are using ductile iron. Moving on to things like model traction engines then again axles and crankshafts are SG or Ductile.

Even Stuarts when they were supplying their crankshafts as castings did not us egrey iron for those, early ones were described as cast steel and I think later were SG Iron so yes "Typical" models use ductile iron.

You missed my point about using ductile iron for small section parts, would not need to use a sledge hammer to break a delicate part like this if it were in grade 40, but it was cast in ductile iron so will tend to bend rather than snap.