sand core ??

[Dave the plumber]

    I was cleaning up a James shell the other day without the lead, tin or canvas sabot, and I got to thunkin'.........   if you put me on an island, with a machine shop and a cast iron foundry [ or heck - even a CNC milling machine ] I probably wouldn't be able to create the intricicies of the James shell 'bird cage ' area in ten years !!     I understand the process of the sand core [ I once visited a cast iron pipe foundry and watched the process go from engine blocks and bedframes being smelted to usable CI fittings ], but how the heck did they do the James ??!!  The fineness of the area is so crisp, it doesn't look like a sand core.........  and a lot of the area is unable to be finished by machining because it would be hard to get inside the cage...  could the bottom area have been cast in some kind of mold ??  Or molded bottom with sand core shell powder  area ??   Anyone know ??   I'm sure other fondlers of the James projectiles have had the same thoughts.....

[joevann]

Good question!  I'll cogitate on the matter.

[John D. Bartleson Jr.]

David,
   Aboard a DD tender I visited the pattern and moulding shops regularly to watch how they sand casted different items for the ship.
     I am not certain I can answer your question completely but I do know foundries use several grades of casting sand and I have seen some very smooth pieces turned out of the box.
     I do believe that the pattern maker for the 'bird cage' was skilled.
      The sand core for the explosive cavity was formed by a sand core mixed with linseed oil and baked in an overn to harden it.  Perhaps the'cage' was made the same way.
      If you have a foundry in your area visit them, take your James, and ask how they would cast it.  I am sure casting basic principles have not changed too much from the ACW.
Cheers,
John

[joevann]

Good answer, John!  I'll stop cogitating now.

[Dave the plumber]

             I want to know, if anyone hits the patents or James books !!   Let us know.....   and Joe - keep on cogitating the matter !!

[joevann]

After much cogitation,  I propose that the James shell was indeed cast in a sand core box, using wooden patterns to form the mold.  Extremely complicated shapes can be made by this method, and it was at the time and still is the method used in about 70% of all foundry iron castings.

[joevann]

http://www.youtube.com/watch?v=AW7Dy6iW0G0&list=PLFC9A1F1B83819AD4

[John D. Bartleson Jr.]

Labor intensive for sure. I don't speak that language and frankly I could not tell what was going on other than tamping the sand box.
John
try this one:
http://www.bing.com/videos/search?q=sand+casting&mid=2671B1DC3C6966E26DEC2671B1DC3C6966E26DEC&view=detail&FORM=VIRE1

[joevann]

Here's how I think it was done:  A wooden pattern the shape of a James shell, without the hollow portion is used to create a mold it two sand boxes.  A two piece wooden mold is used to make a sand core in the shape of the hollow portion.  The two boxes are separated, the wooden pattern of the outside is removed, and the sand core is put in it's place.  The two sand boxes are put together and it's ready to cast.  Does this seem reasonable to everyone?  I left out forming the flow channels, but I figured that was self-evident.

[Bryan]

It would work with a solid piece but with the slots in the Bird Cage how do you pull the mold out keeping the sand where the slots would be.   

[Dave the plumber]

                Bryan,       my thoughts exactly........

[John D. Bartleson Jr.]

Someone with a good James tell me where the seam mark is located, post animage.
John

[John D. Bartleson Jr.]

David,
   I envision the shell body and explosive cavity to be formed in the normal manner.
   If you look inside the cage, you will notice that the ribs and slots are angled towards the middle of the cone that forms the center hole in the cage.  These tapered ribs and slots are so angled for ease of removal.
   I believe that a sand cone is placed in the center of the body and sand wedges are placed at equal intervals around the body which extend and touch the sand cone or core of the cage.
   After pouring and cooling the body is knocked free of its sand box, the sand is then removed from the cage cone area and the sand wedges knocked loose and the sand removed from the explosive cavity.
   There is probably a jib to permit equal spacing of the sand wedges.  Remeber the sand corne and wedges are cast separately into a very hard texture.
Please understand that my drawing was a quicky and only meaat to convey the idea, not profice specifications.
    An alternate method would be to make a wooden pattern of the cage core with wood wedges glued in positon around thid core or cone. Make a mold of the the completed core and wedges, make a hardened sand replica and place it in the body mould.  Like Joe said the casting mould would be made in two halves.


Regards,
John