You can increase the thickness of the wall or because you have a knife edge can be left hanging knife cut into the insert or insert into a small alloy can take the alloy knife to cut
Copper is metal net is better at do not know what kind of jump is too small but impossible to wash the mouth of copper may be the cause of your knife into the block wall is too thin.
Small can take the knife to cut CR12 alloy heat treatment should be no problem if not what problems there may be a stripper abdicating groove is too shallow enough pressure way too tight knife edge breaking into a block or higher die face if it is broken and tungsten steel will be is the bite check gap is the gap is not too small copper is generally larger SKD11 is a better material can be considered
