Coreboxes, cores, coreprints, parting lines, etc.

[GreenTwin]

I have been working on a 3D model of a Soule Speedy Twin steam engine for a while, and luckily have access to an original disassembled engine, and also access to the Soule foundry/manufacturing plant, which has been converted to a museum (in Meridian MS).

This engine is what I consider a late-era steam engine design, and is very compact, and quite unique.
The engine has two eccentrics, and even though it has no reversing valvegear or links, it can easily and quickly be reversed.
I am not aware of any other steam engine that has this capability.

This engine was used to power sawmill carriages, and was preferred over an electric motor, since it had more torque than an analogous electric motor, and could be reversed repeatedly without failing (a must for high output sawmill operation).

The bore on this engine is 5".

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[GreenTwin]

I have been able to find a number of the original patterns that were used for this engine, and some of the coreboxes used for this engine.

Most importantly I found the frame corebox.
I have studied it in great detail, and I think I understand most aspects of how it was used.

This is the frame corebox.

(I don't have my photo downsizer on this computer, but will reduce these photos and upload them again tomorrow).

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[GreenTwin]

This is the frame/cylinder pattern.
Note the coreprints in strategic locations.

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[GreenTwin]

The frame and cylinders are cast in a single unit.
There are several steam/exhaust passages that run from side-to-side on the top of this engine, and this is the key to being able to reverse it with only two eccentrics and no links.

This is what the frame/cylinder casting looks like.

The pull direction for the bottom of the cylinder/frame is down (down with the engine oriented horizontally in its normal operating position).
The bottom feed are loose pattern parts to allow a down pull direction.

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[GreenTwin]

This is the frame/cylinder casting compared to the frame/cylinder pattern.

The horizontal feet are made with retracts on the pattern, and those loose parts are not on the pattern in the photo.
Lots of core prints on the pattern to support all the passages.

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[GreenTwin]

This appears to be the jig for boring the cylinders ?

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[GreenTwin]

The windows in the sides of the frame where the crossheads operate are an interesting item.
A window can be created when the mold and the core touch.
Careful design of the frame/cylinder pattern and corebox allows this.

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[GreenTwin]

Some sandblasted parts.
I did not have a dryer on my compressed air, and so had a lot of clogging when I cleaned these parts.

The sandblasting reveals some repairs that have been made to this engine.


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[GreenTwin]

Some additional cleaned parts.
The engine in general appears to be in pretty good condition.
Not sure what year it was made.
They supposedly manufactured the Speedy Twin up into the 1950's.

The pistons are one-piece, but hollow, and cast with a core that had to be removed after casting.

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[GreenTwin]

All three triangular counterbalances are hollow, and are filled with lead.
One restoration guy heated his crankshaft, melted out the lead, and poured in "new" lead.
Go figure.
I guess he felt better about the new lead, as if lead would go bad inside of a counterbalance space (LOL).

Crankshafts could be purchased in either steel or gray iron (perhaps ductile or malleable iron).
The steel crankshaft was significantly more expensive, but no doubt lasted longer with the constant reversing.

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[GreenTwin]

My incomplete cylinder/frame 3D model.
One view shows some loose part planning.\

No fillets added to this model yet, but they will get added once the model is complete and verified.

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[GreenTwin]

Some 3D prints of the progress to date, for a display at one of the Soule yearly shows at the Museum in Meridian MS.
These are more like paper weights, due to the tiny size, but the manager of the Soule Museum wants to make a 1/4 functional model, and with some TLC, and a lot of machining talent, I think that would be possible.

It took me several years to figure out the steam/exhaust routing, and how the semi-balanced multi-chamber slide valve worked.

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[GreenTwin]

Original patent drawings for the Speedy Twin.

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[GreenTwin]

You can create 2D drawings and isometric views in Solidworks by inserting the model, and then dragging views in whatever direction you want.

You can have solid surface images, images with hidden lines, images with hidden lines concealed, etc.

I have not studied what angle Solidworks uses for the isometrics, and I am not sure if you can change the isometric angle, but I would assume you could if you knew how.

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