Re: Ejector pin marks

Dennis Storzek

---In STMFC@..., <midcentury@...> wrote :

Jimi Booth, tool maker, told me he does not use ejector pins on his molds. Neither does Brian Leppert. Parts may fall off on their own by good design, or a person would need to manually extract each part.
-Andy Carlson
Ojai CA

Certainly doable. IIRC, some of Grandt's molds are that way.

But as with all aspects of mold design, this requires trade-offs in other areas. If you want the parts to "fall off", you need to increase the amount of draft on surfaces perpendicular to the parting line, adding angled surfaces to details that may look objectionable, and angles to edges that may affect the fit of parts.

In the case of Brian's trucks, the "lifters" that retract the cores that make the axle bearing points also serve to lift the parts out of the mold.

Dennis Storzek

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