Mold making

[vrh]

https://youtu.be/m1YPTarNliw?t=49

Ever wondered how bullet molds were made. Here is a video for you.
Talked to a friend who is a machinist. He said that when the cutter blade is new, then it cuts to true size. As the cutter is used ( IE 250 times or more) then the cutter gets worn and actual cavity size decreases. Meaning that the bullet will way less, than the first one cut.

[RED BEAR]

as a retired machinist most companies would replace cutter before it got to the point were it would make a difference . cnc machines i used could be adjusted for tool wear. never made molds but imagine its pretty much the same.

[country gent]

We would routinely run the cncs with the cutter programed off size ( big if outside small if inside work) then re program the tool to the correct sizes and run for a finish pass on fine work. Mostly of our machines were 2 or 2 1/2 axis machines with out tool changers so this was faster for us. I believe an undersized form cutter and "circle pocket could make some very nice moulds very accuratly and quickly. I did some moulds and form dies in the edm also that really worked out well. It was a Charmay cnc plunger. The one form die was for a medallion we gave out during plant tours. Ran the polish cycle and the aluminum medalions came out from the press showing no tooling marks and a nice burnished surface. A copper tungsten electrode turned to the bullet shape and .010-.020 undersize would burn in steel pretty fast and leave enough for final finish in the circle pocket and polish.