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Here is the view inside the 2HP Hercules piston. Recreating the cross under the crown will prove the most difficult part of the pattern and corebox.
Making a pattern is fairly straightforward. This is the cope side. The core print is on the left, the pattern in the center, and the tall riser on the right.
In the foreground, is the runner and downsprue landing. This foundry uses replaceable rubber downsprues.
This is the underside, or the drag side. Notice the lower portion of the riser and runner directly under the same on the cope side.
Here is the completed corebox snapped together.
A view from the core print end. The round part in the middle will create the wrist pin bosses.
Since the core will be trapped after setting up, the cap has to be removable, to allow a core half to be removed. The "T" in the end cap, forms the cross under the crown of the piston.
A closeup of the removable cap. The fillets are only as long as needed inside the form of the core box.
And finally a view of the other end.
The pattern and core box are painted in polyurethane and are ready to go to the foundry.
Hope you enjoyed the photos.