3D Bottle Engine

[JorgensenSteam]

Jason-

I have seen some cores get off center and resulting in varying thickness on opposite walls.

I am not sure whether this was caused by the core not being located exactly in the beginning, or whether the core shifted during the pour.

I see what you are saying but I wonder whether a rod through the core would help hold it.

Pat J

Edit: Looking at the section shown in the Burrell casting photos, I don't see any wall thickness problems at all, so I guess if the cores are accurate, they will line up.

 

[Jasonb]

You need to look closer Edward did a write up in Model Engineer and if you look at top right of teh HP cylinder its very close to the port. The core mould was altered for subsequent iron pours.

If the core print is a good fit around the core then there should be no need for extra rods or dowels.

 

[maury]

There are a couple of reasons why cores get off center. If the fit in the mold is bad, or because of floating. The core will tend to float, and the effect is more pronounced with heavier metals. The type of sand you are using determines the dimensions of the core print. If you are using green sand, the core print should fit quite tight so the sand compresses when the mold is closed. If not, the core trying to float will compress the sand when the metal is poured in and will thus float off center. If you are using a hard sand like no-bake, the core should fit sightly loose or the mold will not close properly, causing excessive flash at the parting line. No-bake does not compress when hard.

For green sand I have been told the core print length should be 1.5x the diameter, and for no bake,
the length is not as critical.

Try this and see if your results don't improve.

maury

 

[JorgensenSteam]

Thanks Jason and Maury-

I will look again and keep what you guys have said in mind.

Pat J

 

[steamer]

Pat,

Nice looking engine! :bow:

If your going to bring that to a commercial foundry....like the one I mentioned, you will need to located the patterns on match plates. The Foundry Foreman can help you with that like he helped me.

Loose pattern work is simple enough....but that's not how commercial foundries work today.

It's not so bad....here's a picture of one of my patterns on a match board.

Dave

 

[steamer]

Additionally,

Before you start making patterns and coreboxes....bring the drawings to the foundry. They will give you some pointers and some ideas about what to be careful with.

Dave

 

[JorgensenSteam]

Dave-

Thanks much for the info and picture.
Very helpful stuff.

Pat J