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jcon
10-12-2011, 07:58 PM
I am trying to make a set of pattern to make castings for a small steam engine, that was in Popular Science in the summer of 1946. What I want to know is there a material that can be use to make cores rather than making core boxes, to make sand cores. My reasoning being it is easer to make a core rather than a core box. If there is such a material where can I buy it.


Jim Connell

PS
I failed to say that it is not a cylinder shaped core I need but a block wider than thick with a smaller block attached plus core prints , radius corners and draft.

bob ward
10-12-2011, 08:41 PM
Jim, I'm neither a pattern maker nor a metal caster, I hope to get there one day though, and from what I read when I peruse this site http://www.alloyavenue.com/vb/forumdisplay.php?4-Metalcasting-forums everyone still seems to make core boxes to cast their cores rather than making their cores directly.

macona
10-12-2011, 08:54 PM
You can use sodium silicate mixed with sand. Look up no-bake cores.

Stepside
10-12-2011, 09:23 PM
There are several ways to avoid making a core box.
1) Find someone with a Z-Corp printer and the correct materials to print your cores. You have to furnish or pay for a .stl mesh file of your cores. This could be hard to find such a source.

2) Find a foundry supply house that sells premade cores in the form of cylinders. You might have to buy a bunch of them.

3) Try carving the "no-bake material. This process will require you to have a method to infilltrate the mixture with CO2.

So it gets down to the cheapest method is a core box. This is more important when you either flub a casting or want to build another engine.

Duffy
10-12-2011, 09:27 PM
The only part that is usually cored is the cylinder. There is no reaason not to cast it solid and bore it out. It is not very much metal, so cost is not an issue.

SGW
10-12-2011, 09:51 PM
Isn't there a "lost foam" process in which you make the core of Styrofoam and the hot metal just vaporizes it when you pour? (I may be totally misguided, so seek independent confirmation.)

Oldbrock
10-12-2011, 09:59 PM
No, wherever there is foam it will be replaced with metal and you will have a shop full of foul smelling smoke. Peter.

gwilson
10-12-2011, 10:10 PM
To make a simple core for a cylinder,can you just clamp 2 pieces of wood together,and drill right through the center line,perhaps with a Forstner bit? Then,just keep one of the 2 halves to mold your cores. You also have to make core prints on the ends of your cylinder pattern to lay the core into.

Good suggestion to just make the cylinder solid,and bore it out. You might get a more solid casting that way,too(less holes).

I had to make 6" cores about 22"long when I made the 30 patterns for the 18th.C. reproduction fire engine for Williamsburg. Those I planed with a shop made core plane.

If there are other cores that aren't round,that's another matter,but they aren't terribly difficult to make. Especially if small.

macona
10-12-2011, 10:34 PM
Since it is just for the cylinder just get a pre-made core the right size.

Dr Stan
10-13-2011, 02:47 AM
I've made cores from mixing the sand with linseed oil and baking @ 350 degrees F. For the core mold I simply split cast iron pipe of the appropriate diameter and used hose clamps to hold them together.

One more thing. Go to Lindsay's Technical Books and buy their reprint of the Navy's Foundryman book. Hands down the best practical sand casting book you can get.

bob ward
10-13-2011, 03:07 AM
If its this vertical steam engine, March '46 pages 178 to 182, you will get away with, and its probably simpler too, to cast the cylinder solid and then bore it afterwards.

http://books.google.com.au/books?http://books.google.com.au/books?id=PSEDAAAAMBAJ&pg=PA178&source=gbs_toc_r&cad=2#v=onepage&q&f=false

jcon
10-13-2011, 09:31 AM
If its this vertical steam engine, March '46 pages 178 to 182, you will get away with, and its probably simpler too, to cast the cylinder solid and then bore it afterwards.

http://books.google.com.au/books?http://books.google.com.au/books?id=PSEDAAAAMBAJ&pg=PA178&source=gbs_toc_r&cad=2#v=onepage&q&f=false

Thanks Bob
But it is the base shown in April '46 PS, that I am having problems with the core not the cylinder. Plus it is the porest drawing in the whole atrical.

SGW
10-13-2011, 06:02 PM
Oops - I got that "lost foam" idea backwards....sorry about that....