I needed to replace the pattern that I used for various plaques.
The old one was copied from the Navy Foundry Manual and is pretty well shot now. I've repaired the ingates a couple times and the toll from removing letters and numbers has left a rough surface on the face. I got about 15 plaques out of it.
I decided to make the new one from 1/4" Lexan that I had laying around and use a full length knife gate. This should give me a good base that will release the alphanumerics when using contact cement. It should also be easy to de-spue on the table saw.
The overall size is 8 x 10 and the finished plaque will be 5 x 10. I left a 1/2" trash gate on the far side in case of sand wash and a place to put a vent.
The edges were cut at 10 degrees for draft and used 1/4" auto trim molding for the outline. I like using that as it has good glue on it and is easy to apply. Super glue with PoP sprinkled on it for the radii.
The sprue well / runner has a choke right after the well to trap sand and hopefully air.
I added a super glue/Pop radius on the bottom of the pattern by using painters tape on the runner and coating it with grease as a release agent, put it in place and then a couple applications of the glue/PoP to build the radius. This gives a secondary packing of the sand at the junction of the ingate.
I gave it a test mould and only had to cleanup one edge where the trim mold pulled the sand.
Hope to put it to use this week.